Initial commit

Connected.Caching/Annotations/CacheKeyAttribute.cs

@@ -0,0 +1,6 @@
+namespace Connected.Caching.Annotations;
+
+[AttributeUsage(AttributeTargets.Property)]
+public sealed class CacheKeyAttribute : Attribute
+{
+}

Connected.Caching/Cache.cs

@@ -0,0 +1,432 @@
+using System.Collections.Concurrent;
+using System.Collections.Immutable;
+using Connected.Interop;
+
+namespace Connected.Caching;
+
+internal abstract class Cache : ICache
+{
+	private bool _disposedValue;
+	private readonly ConcurrentDictionary<string, Entries> _items;
+	private readonly Task _scavenger;
+	private readonly CancellationTokenSource _cancel = new();
+
+	public event CacheInvalidateHandler? Invalidating;
+	public event CacheInvalidateHandler? Invalidated;
+
+	public Cache()
+	{
+		_scavenger = new Task(OnScaveging, _cancel.Token, TaskCreationOptions.LongRunning);
+		_items = new ConcurrentDictionary<string, Entries>();
+
+		_scavenger.Start();
+	}
+	private ConcurrentDictionary<string, Entries> Items => _items;
+	private CancellationTokenSource Cancel => _cancel;
+
+	private void OnScaveging()
+	{
+		var token = Cancel.Token;
+
+		while (!token.IsCancellationRequested)
+		{
+			try
+			{
+				foreach (var i in Items)
+					i.Value.Scave();
+
+				var empties = Items.Where(f => f.Value.Count == 0).Select(f => f.Key);
+
+				foreach (var i in empties)
+					Items.TryRemove(i, out _);
+
+				token.WaitHandle.WaitOne(TimeSpan.FromMinutes(1));
+			}
+			catch { }
+		}
+	}
+	public virtual bool IsEmpty(string key)
+	{
+		if (Items.TryGetValue(key, out Entries? value))
+			return value.Any();
+
+		return true;
+	}
+
+	public virtual bool Exists(string key)
+	{
+		return Items.ContainsKey(key);
+	}
+
+	public void CreateKey(string key)
+	{
+		if (Exists(key))
+			return;
+
+		Items.TryAdd(key, new Entries());
+	}
+
+	public IEnumerator<T>? GetEnumerator<T>(string key)
+	{
+		if (Items.TryGetValue(key, out Entries? value))
+			return value.GetEnumerator<T>();
+
+		return new List<T>().GetEnumerator();
+	}
+	public virtual ImmutableList<T>? All<T>(string key)
+	{
+		if (Items.TryGetValue(key, out Entries? value))
+			return value.All<T>();
+
+		return default;
+	}
+
+	public int Count(string key)
+	{
+		if (Items.TryGetValue(key, out Entries? value))
+			return value.Count;
+
+		return 0;
+	}
+
+	public virtual T? Get<T>(string key, Func<T, bool> predicate)
+	{
+		if (Items.TryGetValue(key, out Entries? value) && value.Get(predicate) is IEntry entry)
+			return GetValue<T>(entry);
+
+		return default;
+	}
+	public virtual async Task<T?> Get<T>(string key, Func<T, bool> predicate, Func<EntryOptions, Task<T>> retrieve)
+	{
+		if (Items.TryGetValue(key, out Entries? value) && value.Get(predicate) is IEntry entry)
+			return GetValue<T>(entry);
+
+		if (retrieve is null)
+			return default;
+
+		var options = new EntryOptions();
+		T instance = await retrieve(options);
+
+		if (EqualityComparer<T>.Default.Equals(instance, default))
+		{
+			if (!options.AllowNull)
+				return default;
+		}
+
+		if (string.IsNullOrWhiteSpace(options.Key))
+			throw new SysException(this, SR.ErrCacheKeyNull);
+
+		Set(key, options.Key, instance, options.Duration, options.SlidingExpiration);
+
+		return instance;
+	}
+
+	public virtual async Task<T?> Get<T>(string key, object id, Func<EntryOptions, Task<T>>? retrieve)
+	{
+		if (Items.TryGetValue(key, out Entries? value) && value.Get(id is null ? null : id.ToString()) is IEntry entry)
+			return GetValue<T>(entry);
+
+		if (retrieve is null)
+			return default;
+
+		var options = new EntryOptions
+		{
+			Key = id is null ? null : id.ToString()
+		};
+
+		T instance = await retrieve(options);
+
+		if (EqualityComparer<T>.Default.Equals(instance, default))
+		{
+			if (!options.AllowNull)
+				return default;
+		}
+
+		Set(key, options.Key, instance, options.Duration, options.SlidingExpiration);
+
+		return instance;
+	}
+
+	internal void ClearCore(string key)
+	{
+		if (Items.TryGetValue(key, out Entries? value))
+			value.Clear();
+	}
+
+	public virtual async Task Clear(string key)
+	{
+		if (Items.TryGetValue(key, out Entries? value))
+			value.Clear();
+
+		await Task.CompletedTask;
+	}
+
+	public virtual T? Get<T>(string key, object id)
+	{
+		if (Items.TryGetValue(key, out Entries? value) && value.Get(id is null ? null : id.ToString()) is IEntry entry)
+			return GetValue<T>(entry);
+
+		return default;
+	}
+
+	public IEntry? Get(string key, object id)
+	{
+		if (Items.TryGetValue(key, out Entries? value))
+			return value.Get(id is null ? null : id.ToString());
+
+		return default;
+	}
+
+	public virtual T? Get<T>(string key, Func<dynamic, bool> predicate)
+	{
+		if (Items.TryGetValue(key, out Entries? value) && value.Get(predicate) is IEntry entry)
+			return GetValue<T>(entry);
+
+		return default;
+	}
+
+	public virtual T? First<T>(string key)
+	{
+		if (Items.TryGetValue(key, out Entries? value) && value.First() is IEntry entry)
+			return GetValue<T>(entry);
+
+		return default;
+	}
+
+	public virtual ImmutableList<T>? Where<T>(string key, Func<T, bool> predicate)
+	{
+		if (Items.TryGetValue(key, out Entries? value))
+			return value.Where(predicate);
+
+		return default;
+	}
+
+	public void CopyTo(string key, object id, IEntry instance)
+	{
+		if (!Items.TryGetValue(key, out Entries? value))
+		{
+			value = new Entries();
+
+			if (!Items.TryAdd(key, value))
+				return;
+		}
+
+		value.Set(id is null ? null : id.ToString(), instance.Instance, instance.Duration, instance.SlidingExpiration);
+	}
+
+	public virtual T? Set<T>(string key, object id, T? instance)
+	{
+		return Set(key, id, instance, TimeSpan.Zero);
+	}
+
+	public virtual T? Set<T>(string key, object id, T? instance, TimeSpan duration)
+	{
+		return Set(key, id, instance, duration, false);
+	}
+
+	public virtual T? Set<T>(string key, object id, T? instance, TimeSpan duration, bool slidingExpiration)
+	{
+		if (!Items.TryGetValue(key, out Entries? value))
+		{
+			value = new Entries();
+
+			if (!Items.TryAdd(key, value))
+				return default;
+		}
+
+		value.Set(id is null ? null : id.ToString(), instance, duration, slidingExpiration);
+
+		return instance;
+	}
+
+	internal void RemoveCore(string key, object id)
+	{
+		if (id is null)
+			return;
+
+		if (Items.TryGetValue(key, out Entries? value))
+			value.Remove(id.ToString());
+	}
+	public virtual async Task Remove(string key, object id)
+	{
+		await Remove(key, id, true);
+	}
+
+	private async Task Remove(string key, object id, bool removing)
+	{
+		if (Items.TryGetValue(key, out Entries? value))
+			value.Remove(id is null ? null : id.ToString());
+
+		if (removing)
+			await OnRemove(key, id);
+	}
+
+	protected virtual async Task OnRemove(string key, object id)
+	{
+		await Task.CompletedTask;
+	}
+
+	public async Task Invalidate(string key, object id)
+	{
+		await InvalidateCore(key, id, false);
+	}
+
+	internal async Task InvalidateCore(string key, object id, bool fromNotification)
+	{
+		/*
+			* we store existing instance but it is not
+			* removed from the cache yet. This is because other
+			* threads can access this instance while we are
+			* retrieving a new version from the source
+			*/
+		var existing = Get<object>(key, id);
+		var args = new CacheEventArgs(id is null ? null : id.ToString(), key);
+		/*
+			* this two events invalidate that cache reference.
+			* note that if no new version exists the existing one
+			* is still available to other threads.
+			*/
+		try
+		{
+			Invalidating?.Invoke(args);
+		}
+		catch { }
+
+		try
+		{
+			if (!fromNotification)
+				await OnInvalidating(args);
+
+			await OnInvalidate(args);
+		}
+		catch { }
+		/*
+			* now find out if a new version has been set for the
+			* specified key
+			*/
+		var newInstance = Get<object>(key, id);
+		/*
+			* if no existing reference exists there is no need for
+			* removing anything
+			*/
+		if (existing is not null)
+		{
+			/*
+				 * we have an existing instance. we are dealing with two possible scenarios:
+				 * - newInstance is null because entity has been deleted
+				 * - newInstance is actually the same instance as the existing which means a new
+				 * version does not exist. In both cases we must remove existing reference because
+				 * at this point it is not valid anymore.
+				 * note that the third case exists: reference has been replaced. in that case there
+				 * is nothing to do because Invalidating events has already replaced reference with a
+				 * new version.
+				 */
+			if (newInstance is null)
+				await Remove(key, id, false);
+			else if (existing.Equals(newInstance) && args.Behavior == InvalidateBehavior.RemoveSameInstance)
+				await Remove(key, id, false);
+		}
+
+		try
+		{
+			Invalidated?.Invoke(args);
+		}
+		catch { }
+	}
+
+	protected internal virtual async Task OnInvalidating(CacheEventArgs e)
+	{
+		await Task.CompletedTask;
+	}
+
+	protected virtual async Task OnInvalidate(CacheEventArgs e)
+	{
+		await Task.CompletedTask;
+	}
+
+	private void Clear()
+	{
+		foreach (var i in Items)
+			i.Value.Clear();
+
+		Items.Clear();
+	}
+
+	public virtual async Task<ImmutableList<string>?> Remove<T>(string key, Func<T, bool> predicate)
+	{
+		if (Items.TryGetValue(key, out Entries? value))
+		{
+			var result = value.Remove(predicate);
+
+			if (result is not null && result.Any())
+				await OnRemove(key, result);
+		}
+
+		return default;
+	}
+
+	protected virtual async Task OnRemove(string key, ImmutableList<string> ids)
+	{
+		await Task.CompletedTask;
+	}
+
+	public ImmutableList<string>? Keys(string key)
+	{
+		if (Items.TryGetValue(key, out Entries? value))
+			return value.Keys;
+
+		return default;
+	}
+
+	public ImmutableList<string> Keys()
+	{
+		return Items.Keys.ToImmutableList();
+	}
+
+	public bool Any(string key)
+	{
+		if (Items.TryGetValue(key, out Entries? value))
+			return value.Any();
+
+		return false;
+	}
+
+	private static T? GetValue<T>(IEntry entry)
+	{
+		if (entry is null || entry.Instance is null)
+			return default;
+
+		if (TypeConversion.TryConvert(entry.Instance, out T? result))
+			return result;
+
+		return default;
+	}
+
+	protected virtual void OnDisposing(bool disposing)
+	{
+		if (!_disposedValue)
+		{
+			if (disposing)
+			{
+				Cancel.Cancel();
+				Clear();
+
+				if (_scavenger is not null)
+				{
+					_cancel.Cancel();
+
+					if (_scavenger.IsCompleted)
+						_scavenger.Dispose();
+				}
+			}
+
+			_disposedValue = true;
+		}
+	}
+
+	public void Dispose()
+	{
+		OnDisposing(true);
+		GC.SuppressFinalize(this);
+	}
+}

Connected.Caching/CacheClient.cs

@@ -0,0 +1,128 @@
+using System.Collections;
+using System.Collections.Immutable;
+
+namespace Connected.Caching;
+
+public abstract class CacheClient<TEntry, TKey> : ICacheClient<TEntry, TKey> where TEntry : class
+{
+	protected CacheClient(ICachingService cachingService, string key)
+	{
+		if (cachingService is null)
+			throw new ArgumentException(nameof(cachingService));
+
+		CachingService = cachingService;
+		Key = key;
+	}
+
+	public string Key { get; }
+	protected bool IsDisposed { get; set; }
+	protected async Task Remove(TKey id)
+	{
+		if (id is null)
+			throw new ArgumentNullException(nameof(id));
+
+		await CachingService.Remove(Key, id);
+	}
+
+	protected async Task Remove(Func<TEntry, bool> predicate)
+	{
+		await CachingService.Remove(Key, predicate);
+	}
+
+	protected async Task Refresh(TKey id)
+	{
+		if (id is null)
+			throw new ArgumentNullException(nameof(id));
+
+		await CachingService.Invalidate(Key, id);
+	}
+
+	protected ICachingService CachingService { get; }
+
+	public int Count => CachingService.Count(Key);
+	protected virtual ICollection<string>? Keys => CachingService.Keys(Key);
+
+	protected virtual Task<ImmutableList<TEntry>?> All()
+	{
+		return Task.FromResult(CachingService.All<TEntry>(Key));
+	}
+
+	protected virtual async Task<TEntry?> Get(TKey id, Func<EntryOptions, Task<TEntry>> retrieve)
+	{
+		if (id is null)
+			throw new ArgumentNullException(nameof(id));
+
+		return await CachingService.Get(Key, id, retrieve);
+	}
+
+	protected virtual Task<TEntry?> Get(TKey id)
+	{
+		if (id is null)
+			throw new ArgumentNullException(nameof(id));
+
+		return Task.FromResult(CachingService.Get<TEntry>(Key, id));
+	}
+
+	protected virtual Task<TEntry?> First()
+	{
+		return Task.FromResult(CachingService.First<TEntry>(Key));
+	}
+
+	protected virtual async Task<TEntry?> Get(Func<TEntry, bool> predicate)
+	{
+		return await CachingService.Get(Key, predicate, null);
+	}
+
+	protected virtual Task<ImmutableList<TEntry>?> Where(Func<TEntry, bool> predicate)
+	{
+		return Task.FromResult(CachingService.Where(Key, predicate));
+	}
+
+	protected virtual void Set(TKey id, TEntry instance)
+	{
+		if (id is null)
+			throw new ArgumentNullException(nameof(id));
+
+		CachingService.Set(Key, id, instance);
+	}
+
+	protected virtual void Set(TKey id, TEntry instance, TimeSpan duration)
+	{
+		if (id is null)
+			throw new ArgumentNullException(nameof(id));
+
+		CachingService.Set(Key, id, instance, duration);
+	}
+
+	private void Dispose(bool disposing)
+	{
+		if (!IsDisposed)
+		{
+			if (disposing)
+				OnDisposing();
+
+			IsDisposed = true;
+		}
+	}
+
+	protected virtual void OnDisposing()
+	{
+
+	}
+
+	public void Dispose()
+	{
+		Dispose(true);
+		GC.SuppressFinalize(this);
+	}
+
+	public virtual IEnumerator<TEntry> GetEnumerator()
+	{
+		return CachingService?.GetEnumerator<TEntry>(Key);
+	}
+
+	IEnumerator IEnumerable.GetEnumerator()
+	{
+		return GetEnumerator();
+	}
+}

Connected.Caching/CacheContext.cs

@@ -0,0 +1,220 @@
+using System.Collections.Immutable;
+using System.Reflection;
+using Connected.Interop;
+using Connected.ServiceModel.Transactions;
+
+namespace Connected.Caching;
+
+internal class CacheContext : Cache, ICacheContext
+{
+	public CacheContext(ICachingService cachingService, ITransactionContext transactionContext)
+	{
+		CachingService = cachingService;
+		TransactionContext = transactionContext;
+
+		TransactionContext.StateChanged += OnTransactionContextStateChanged;
+	}
+
+	private void OnTransactionContextStateChanged(object? sender, EventArgs e)
+	{
+		if (TransactionContext.State == MiddlewareTransactionState.Committing)
+			Flush();
+	}
+
+	private ICachingService CachingService { get; }
+	private ITransactionContext TransactionContext { get; }
+
+	public override bool Exists(string key)
+	{
+		return base.Exists(key) || (CachingService is not null && CachingService.Exists(key));
+	}
+
+	public override bool IsEmpty(string key)
+	{
+		return base.IsEmpty(key) || (CachingService is not null && CachingService.IsEmpty(key));
+	}
+
+	public override ImmutableList<T>? All<T>(string key)
+	{
+		return Merge(base.All<T>(key), CachingService?.All<T>(key));
+	}
+
+	public override async Task<T> Get<T>(string key, object id, Func<EntryOptions, Task<T>>? retrieve)
+	{
+		if (!TransactionContext.IsDirty)
+		{
+			if (retrieve is null)
+				return default;
+
+			return await CachingService.Get(key, id, retrieve);
+		}
+
+		return await base.Get(key, id, (f) =>
+		{
+			var shared = CachingService.Get<T>(key, id);
+
+			if (shared is not null)
+				return Task.FromResult(shared);
+
+			if (retrieve is null)
+				return default;
+
+			return retrieve(f);
+		});
+	}
+
+	public override async Task<T> Get<T>(string key, Func<T, bool> predicate, Func<EntryOptions, Task<T>>? retrieve)
+	{
+		if (!TransactionContext.IsDirty)
+		{
+			if (retrieve is null)
+				return default;
+
+			return await CachingService.Get(key, predicate, retrieve);
+		}
+
+		return await base.Get(key, predicate, (f) =>
+		{
+			var shared = CachingService.Get(key, predicate);
+
+			if (shared is not null)
+				return Task.FromResult(shared);
+
+			return retrieve(f);
+		});
+	}
+
+	public override T Get<T>(string key, object id)
+	{
+		var contextItem = base.Get<T>(key, id);
+
+		if (contextItem is not null)
+			return contextItem;
+
+		return CachingService.Get<T>(key, id);
+	}
+
+	public override T Get<T>(string key, Func<T, bool> predicate)
+	{
+		var contextItem = base.Get<T>(key, predicate);
+
+		if (contextItem is not null)
+			return contextItem;
+
+		return CachingService.Get(key, predicate);
+	}
+
+	public override async Task Clear(string key)
+	{
+		await base.Clear(key);
+		await CachingService.Clear(key);
+	}
+	public override T First<T>(string key)
+	{
+		if (base.First<T>(key) is T result)
+			return result;
+
+		return CachingService.First<T>(key);
+	}
+
+	public override ImmutableList<T> Where<T>(string key, Func<T, bool> predicate)
+	{
+		return Merge(base.Where(key, predicate), CachingService.Where(key, predicate));
+	}
+
+	public override T Set<T>(string key, object id, T instance)
+	{
+		if (!TransactionContext.IsDirty)
+			return CachingService.Set(key, id, instance);
+
+		return base.Set(key, id, instance);
+	}
+
+	public override T Set<T>(string key, object id, T instance, TimeSpan duration)
+	{
+		if (!TransactionContext.IsDirty)
+			return CachingService.Set(key, id, instance, duration);
+
+		return base.Set(key, id, instance, duration);
+	}
+
+	public override T Set<T>(string key, object id, T instance, TimeSpan duration, bool slidingExpiration)
+	{
+		if (!TransactionContext.IsDirty)
+			return CachingService.Set(key, id, instance, duration, slidingExpiration);
+
+		return base.Set(key, id, instance, duration, slidingExpiration);
+	}
+
+	public override async Task Remove(string key, object id)
+	{
+		await base.Remove(key, id);
+		await CachingService.Remove(key, id);
+	}
+
+	public override async Task<ImmutableList<string>?> Remove<T>(string key, Func<T, bool> predicate)
+	{
+		var local = await base.Remove(key, predicate);
+		var shared = await CachingService.Remove(key, predicate);
+
+		if (local is not null && shared is not null)
+			return local.AddRange(shared);
+
+		return local is not null ? local : shared;
+	}
+
+	public void Flush()
+	{
+		CachingService.Merge(this);
+	}
+
+	private static ImmutableList<T>? Merge<T>(ImmutableList<T>? contextItems, ImmutableList<T>? sharedItems)
+	{
+		if (contextItems is null)
+			return sharedItems;
+
+		var result = new List<T>(contextItems);
+
+		foreach (var sharedItem in sharedItems)
+		{
+			if (sharedItem is null)
+				continue;
+
+			if (CachingExtensions.GetCacheKeyProperty(sharedItem) is not PropertyInfo cacheProperty)
+			{
+				//Q: should we compare every property and add only if not matched?
+				contextItems.Add(sharedItem);
+				continue;
+			}
+
+			if (FindExisting(cacheProperty.GetValue(sharedItems), contextItems) is null)
+				result.Add(sharedItem);
+		}
+
+		return result.ToImmutableList();
+	}
+
+	private static T? FindExisting<T>(object value, ImmutableList<T> items)
+	{
+		if (items is null || items.IsEmpty)
+			return default;
+
+		if (CachingExtensions.GetCacheKeyProperty(items[0]) is not PropertyInfo cacheProperty)
+			return default;
+
+		foreach (var item in items)
+		{
+			var id = cacheProperty.GetValue(item);
+
+			if (TypeComparer.Compare(id, value))
+				return item;
+		}
+
+		return default;
+	}
+
+	protected override async Task OnInvalidate(CacheEventArgs e)
+	{
+		await CachingService.Invalidate(e.Key, e.Id);
+	}
+}

Connected.Caching/CacheEventArgs.cs

@@ -0,0 +1,27 @@
+namespace Connected.Caching;
+
+public enum InvalidateBehavior : byte
+{
+	RemoveSameInstance = 1,
+	KeepSameInstance = 2
+}
+public class CacheEventArgs : EventArgs
+{
+	public CacheEventArgs(string id, string key)
+	{
+		Key = key;
+		Id = id;
+	}
+
+	public CacheEventArgs(string id, string key, InvalidateBehavior behavior)
+	{
+		Key = key;
+		Id = id;
+		Behavior = behavior;
+	}
+
+	public string Id { get; init; }
+	public string Key { get; init; }
+
+	public InvalidateBehavior Behavior { get; set; } = InvalidateBehavior.RemoveSameInstance;
+}

Connected.Caching/CacheNotificationArgs.cs

@@ -0,0 +1,16 @@
+namespace Connected.Caching;
+
+public class CacheNotificationArgs
+{
+	public CacheNotificationArgs(string method)
+	{
+		if (string.IsNullOrWhiteSpace(method))
+			throw new ArgumentException(null, nameof(method));
+
+		Method = method;
+	}
+
+	public string? Key { get; init; }
+	public List<string>? Ids { get; init; }
+	public string Method { get; }
+}

Connected.Caching/CachingExtensions.cs

@@ -0,0 +1,13 @@
+using System.Reflection;
+using Connected.Caching.Annotations;
+using Connected.Interop;
+
+namespace Connected.Caching;
+
+public static class CachingExtensions
+{
+	public static PropertyInfo? GetCacheKeyProperty(object instance)
+	{
+		return Properties.GetPropertyAttribute<CacheKeyAttribute>(instance);
+	}
+}

Connected.Caching/CachingService.cs

@@ -0,0 +1,151 @@
+using System.Collections.Immutable;
+using Connected.Caching.Net;
+using Connected.Net.Server;
+
+namespace Connected.Caching;
+
+internal sealed class CachingService : MemoryCache, ICachingService, IDisposable, IAsyncDisposable
+{
+	public CachingService(IEndpointServer server, CacheServer state, CacheServerConnection backplaneClient)
+	{
+		if (server is null)
+			throw new ArgumentException(null, nameof(server));
+
+		if (state is null)
+			throw new ArgumentException(null, nameof(state));
+
+		BackplaneClient = backplaneClient;
+
+		Server = server;
+		BackplaneServer = state;
+
+		server.Changed += OnServerChanged;
+		server.Initialized += OnServerInitialized;
+		BackplaneServer.Received += OnReceived;
+		BackplaneClient.Received += OnReceived;
+	}
+
+	private CacheServerConnection BackplaneClient { get; set; }
+	private CacheServer BackplaneServer { get; }
+	private IEndpointServer Server { get; }
+
+	private async void OnServerInitialized(object? sender, EventArgs e)
+	{
+		await Initialize();
+	}
+
+	public async Task Initialize()
+	{
+		await BackplaneClient.Disconnect();
+
+		try
+		{
+			if (!await Server.IsServer())
+			{
+				await BackplaneClient.Initialize(Server.ServerUrl);
+				await BackplaneClient.Connect();
+			}
+		}
+		catch
+		{
+			// Server probably not initalized yet
+		}
+	}
+
+	private async void OnReceived(object? sender, CacheNotificationArgs e)
+	{
+		if (string.Equals(e.Method, nameof(Clear), StringComparison.Ordinal))
+			ClearCore(e.Key);
+		else if (string.Equals(e.Method, nameof(Remove), StringComparison.Ordinal))
+		{
+			if (e.Ids is not null && e.Ids.Any())
+			{
+				foreach (var id in e.Ids)
+					RemoveCore(e.Key, id);
+			}
+		}
+		else if (string.Equals(e.Method, nameof(Invalidate), StringComparison.Ordinal))
+		{
+			if (e.Ids is not null && e.Ids.Any())
+			{
+				foreach (var id in e.Ids)
+					await InvalidateCore(e.Key, id, true);
+			}
+		}
+	}
+
+	private async void OnServerChanged(object? sender, ServerChangedArgs e)
+	{
+		await Initialize();
+	}
+
+	public override async Task Clear(string key)
+	{
+		await base.Clear(key);
+
+		var args = new CacheNotificationArgs(nameof(Clear)) { Key = key };
+
+		if (await Server.IsServer())
+			await BackplaneServer.Send(args);
+		else
+			await BackplaneClient.Notify(nameof(Clear), args);
+
+
+	}
+	protected internal override async Task OnInvalidating(CacheEventArgs e)
+	{
+		var args = new CacheNotificationArgs(nameof(Invalidate))
+		{
+			Ids = new List<string> { e.Id },
+			Key = e.Key
+		};
+
+		if (await Server.IsServer())
+			await BackplaneServer.Send(args);
+		else
+			await BackplaneClient.Notify(nameof(Invalidate), args);
+	}
+
+	protected override async Task OnRemove(string key, ImmutableList<string> ids)
+	{
+		await base.OnRemove(key, ids);
+
+		var args = new CacheNotificationArgs(nameof(Remove))
+		{
+			Ids = ids.ToList(),
+			Key = key
+		};
+
+		if (await Server.IsServer())
+			await BackplaneServer.Send(args);
+		else
+			await BackplaneClient.Notify(nameof(Remove), args);
+	}
+
+	protected override async Task OnRemove(string key, object? id)
+	{
+		await base.OnRemove(key, id);
+
+		var ids = new List<string>();
+
+		if (id is not null)
+			ids.Add(id.ToString());
+
+		await OnRemove(key, ids.ToImmutableList());
+	}
+
+	public async ValueTask DisposeAsync()
+	{
+		Server.Changed -= OnServerChanged;
+		Server.Initialized -= OnServerInitialized;
+	}
+
+
+	protected override void OnDisposing(bool disposing)
+	{
+		Server.Changed -= OnServerChanged;
+		Server.Initialized -= OnServerInitialized;
+
+		base.OnDisposing(disposing);
+	}
+}

Connected.Caching/CachingStartup.cs

@@ -0,0 +1,32 @@
+using Connected.Annotations;
+using Connected.Caching.Net;
+using Microsoft.AspNetCore.Builder;
+using Microsoft.Extensions.DependencyInjection;
+
+[assembly: MicroService(MicroServiceType.Sys)]
+
+namespace Connected.Caching;
+
+internal class CachingStartup : Startup
+{
+	public const string CachingHub = "/caching";
+
+	protected override void OnConfigure(WebApplication app)
+	{
+		app.MapHub<CacheHub>(CachingHub);
+	}
+
+	protected override void OnConfigureServices(IServiceCollection services)
+	{
+		services.AddSingleton(typeof(CacheServer));
+		services.AddSingleton(typeof(CacheServerConnection));
+		services.AddSingleton(typeof(ICachingService), typeof(CachingService));
+		services.AddScoped(typeof(ICacheContext), typeof(CacheContext));
+	}
+
+	protected override async Task OnInitialize(Dictionary<string, string> args)
+	{
+		if (Services is not null && Services.GetService<ICachingService>() is ICachingService service)
+			await service.Initialize();
+	}
+}

Connected.Caching/Connected.Caching.csproj

@@ -0,0 +1,36 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+	<PropertyGroup>
+		<TargetFramework>net7.0</TargetFramework>
+		<ImplicitUsings>enable</ImplicitUsings>
+		<Nullable>enable</Nullable>
+	</PropertyGroup>
+
+	<ItemGroup>
+		<PackageReference Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="7.0.0-rc.2.22472.3" />
+	</ItemGroup>
+
+	<ItemGroup>
+		<ProjectReference Include="..\..\Connected\Connected\Connected.csproj" />
+		<ProjectReference Include="..\Connected.Interop\Connected.Interop.csproj" />
+		<ProjectReference Include="..\Connected.Net\Connected.Net.csproj" />
+		<ProjectReference Include="..\Connected.Runtime\Connected.Runtime.csproj" />
+		<ProjectReference Include="..\Connected.Threading\Connected.Threading.csproj" />
+	</ItemGroup>
+
+	<ItemGroup>
+	  <Compile Update="SR.Designer.cs">
+	    <DesignTime>True</DesignTime>
+	    <AutoGen>True</AutoGen>
+	    <DependentUpon>SR.resx</DependentUpon>
+	  </Compile>
+	</ItemGroup>
+
+	<ItemGroup>
+	  <EmbeddedResource Update="SR.resx">
+	    <Generator>ResXFileCodeGenerator</Generator>
+	    <LastGenOutput>SR.Designer.cs</LastGenOutput>
+	  </EmbeddedResource>
+	</ItemGroup>
+
+</Project>

Connected.Caching/Entries.cs

@@ -0,0 +1,260 @@
+using System.Collections.Concurrent;
+using System.Collections.Immutable;
+using Connected.Interop;
+
+namespace Connected.Caching;
+
+internal class Entries
+{
+	private readonly Lazy<ConcurrentDictionary<string, IEntry>> _items = new();
+
+	private ConcurrentDictionary<string, IEntry> Items => _items.Value;
+	public ImmutableList<string> Keys => Items.Keys.ToImmutableList();
+	public int Count => Items.Count;
+
+	public bool Any()
+	{
+		return Items.Any();
+	}
+
+	public void Scave()
+	{
+		var expired = new HashSet<string>();
+
+		foreach (var i in Items)
+		{
+			var r = i.Value;
+
+			if (r is null || r.Expired)
+				expired.Add(i.Key);
+		}
+
+		foreach (var i in expired)
+			Remove(i);
+	}
+
+	public ImmutableList<T> All<T>()
+	{
+		var r = new List<T>();
+		var expired = Items.Where(f => f.Value.Expired);
+
+		foreach (var e in expired)
+			Remove(e.Value.Id);
+
+		var instances = Items.Select(f => f.Value.Instance);
+
+		foreach (var i in instances)
+		{
+			if (TypeConversion.TryConvert(i, out T? result) && result is not null)
+				r.Add(result);
+		}
+
+		return r.ToImmutableList();
+	}
+
+	public void Remove(string key)
+	{
+		if (Items.IsEmpty)
+			return;
+
+		if (Items.TryRemove(key, out IEntry? v))
+			v.Dispose();
+	}
+
+	public void Set(string key, object? instance, TimeSpan duration, bool slidingExpiration)
+	{
+		Items[key] = new Entry(key, instance, duration, slidingExpiration);
+	}
+
+	public IEnumerator<T> GetEnumerator<T>()
+	{
+		return new EntryEnumerator<T>(Items);
+	}
+	public IEntry? Get(string key)
+	{
+		return Find(key);
+	}
+
+	public IEntry? First()
+	{
+		if (!Any())
+			return default;
+
+		return Items.First().Value;
+	}
+
+	public IEntry? Get<T>(Func<T, bool> predicate)
+	{
+		return Find(predicate);
+	}
+
+	public IEntry? Get<T>(Func<dynamic, bool> predicate)
+	{
+		return Find<T>(predicate);
+	}
+
+	public ImmutableList<string>? Remove<T>(Func<T, bool> predicate)
+	{
+		if (Where(predicate) is not ImmutableList<string> ds || ds.IsEmpty)
+			return default;
+
+		var result = new HashSet<string>();
+
+		foreach (var i in ds)
+		{
+			var key = Items.FirstOrDefault(f => InstanceEquals(f.Value?.Instance, i)).Key;
+
+			RemoveInternal(key);
+
+			result.Add(key);
+		}
+
+		return result.ToImmutableList();
+	}
+
+	public ImmutableList<T>? Where<T>(Func<T, bool> predicate)
+	{
+		var values = Items.Select(f => f.Value.Instance).Cast<T>();
+
+		if (values is null || !values.Any())
+			return default;
+
+		var filtered = values.Where(predicate);
+
+		if (filtered is null || !filtered.Any())
+			return default;
+
+		var r = new List<T>();
+
+		foreach (var i in filtered)
+		{
+			var ce = Items.FirstOrDefault(f => InstanceEquals(f.Value?.Instance, i));
+
+			if (ce.Value is null)
+				continue;
+
+			if (ce.Value.Expired)
+			{
+				RemoveInternal(ce.Value.Id);
+				continue;
+			}
+
+			ce.Value.Hit();
+			r.Add(i);
+		}
+
+		return r.ToImmutableList();
+	}
+
+	private void RemoveInternal(string key)
+	{
+		if (Items.TryRemove(key, out IEntry? d))
+			d.Dispose();
+	}
+
+	private IEntry? Find<T>(Func<T, bool> predicate)
+	{
+		var instances = Items.Select(f => f.Value?.Instance).Cast<T>();
+
+		if (instances is null || !instances.Any())
+			return default;
+
+		if (instances.FirstOrDefault(predicate) is not T instance)
+			return default;
+
+		var ce = Items.Values.FirstOrDefault(f => InstanceEquals(f.Instance, instance));
+
+		if (ce is null)
+			return default;
+
+		if (ce.Expired)
+		{
+			RemoveInternal(ce.Id);
+			return default;
+		}
+
+		ce.Hit();
+
+		return ce;
+	}
+
+	private IEntry? Find<T>(Func<dynamic, bool> predicate)
+	{
+		var instances = Items.Select(f => f.Value?.Instance).Cast<dynamic>();
+
+		if (instances is null || !instances.Any())
+			return default;
+
+		if (instances.FirstOrDefault(predicate) is not T instance)
+			return default;
+
+		if (Items.Values.FirstOrDefault(f => InstanceEquals(f.Instance, instance)) is not IEntry ce)
+			return default;
+
+		if (ce.Expired)
+		{
+			RemoveInternal(ce.Id);
+			return default;
+		}
+
+		ce.Hit();
+
+		return ce;
+	}
+
+	private IEntry? Find(string key)
+	{
+		if (!Items.ContainsKey(key))
+			return default;
+
+		if (Items.TryGetValue(key, out IEntry? d))
+		{
+			if (d.Expired)
+			{
+				RemoveInternal(key);
+				return default;
+			}
+
+			d.Hit();
+
+			return d;
+		}
+		else
+		{
+			RemoveInternal(key);
+
+			return default;
+		}
+	}
+
+	public bool Exists(string key)
+	{
+		return Find(key) is not null;
+	}
+
+	public void Clear()
+	{
+		foreach (var i in Items)
+			Remove(i.Key);
+	}
+
+	private static bool InstanceEquals(object? left, object? right)
+	{
+		/*
+		 * TODO: implement IEquality check
+		 */
+		if (left is null || right is null)
+			return false;
+
+		if (left.GetType().IsPrimitive)
+			return left == right;
+
+		if (left is string && right is string)
+			return string.Compare(left.ToString(), right.ToString(), false) == 0;
+
+		if (left.GetType().IsValueType && right.GetType().IsValueType)
+			return left.Equals(right);
+
+		return ReferenceEqualityComparer.Instance.Equals(left, right);
+	}
+}

Connected.Caching/Entry.cs

@@ -0,0 +1,35 @@
+namespace Connected.Caching;
+
+internal class Entry : IEntry
+{
+	public Entry(string id, object? instance, TimeSpan duration, bool slidingExpiration)
+	{
+		Id = id;
+		Instance = instance;
+		SlidingExpiration = slidingExpiration;
+		Duration = duration;
+
+		if (Duration > TimeSpan.Zero)
+			ExpirationDate = DateTime.UtcNow.AddTicks(duration.Ticks);
+	}
+
+	public bool SlidingExpiration { get; }
+	private DateTime ExpirationDate { get; set; }
+	public TimeSpan Duration { get; set; }
+
+	public object? Instance { get; }
+	public string Id { get; }
+	public bool Expired => ExpirationDate != DateTime.MinValue && ExpirationDate < DateTime.UtcNow;
+
+	public void Hit()
+	{
+		if (SlidingExpiration && Duration > TimeSpan.Zero)
+			ExpirationDate = DateTime.UtcNow.AddTicks(Duration.Ticks);
+	}
+
+	public void Dispose()
+	{
+		if (Instance is IDisposable disposable)
+			disposable.Dispose();
+	}
+}

Connected.Caching/EntryEnumerator.cs

@@ -0,0 +1,43 @@
+using System.Collections;
+using System.Collections.Concurrent;
+using Connected.Interop;
+
+namespace Connected.Caching;
+
+internal class EntryEnumerator<T> : IEnumerator<T>
+{
+	public EntryEnumerator(ConcurrentDictionary<string, IEntry> items)
+	{
+		Items = items;
+		Index = -1;
+	}
+
+	private int Count => Items.Count;
+	private int Index { get; set; }
+	private ConcurrentDictionary<string, IEntry> Items { get; }
+
+	public T Current => TypeConversion.TryConvert(Items.ElementAt(Index).Value.Instance, out T result) ? result : default;
+
+	object IEnumerator.Current => Current;
+
+	public void Dispose()
+	{
+	}
+
+	public bool MoveNext()
+	{
+		if (Index < Count - 1)
+		{
+			Index++;
+
+			return true;
+		}
+
+		return false;
+	}
+
+	public void Reset()
+	{
+		Index = -1;
+	}
+}

Connected.Caching/EntryOptions.cs

@@ -0,0 +1,16 @@
+namespace Connected.Caching;
+
+public class EntryOptions
+{
+	public string Key { get; set; }
+	public string? KeyProperty { get; set; }
+	public TimeSpan Duration { get; set; }
+	public bool SlidingExpiration { get; set; }
+	public bool AllowNull { get; set; }
+
+	public EntryOptions()
+	{
+		Duration = TimeSpan.FromMinutes(5);
+		SlidingExpiration = true;
+	}
+}

Connected.Caching/ICache.cs

@@ -0,0 +1,39 @@
+using System.Collections.Immutable;
+
+namespace Connected.Caching;
+
+public delegate void CacheInvalidateHandler(CacheEventArgs e);
+public interface ICache : IDisposable
+{
+	event CacheInvalidateHandler? Invalidating;
+	event CacheInvalidateHandler? Invalidated;
+
+	ImmutableList<T>? All<T>(string key);
+
+	Task<T?> Get<T>(string key, object id, Func<EntryOptions, Task<T?>>? retrieve);
+	T? Get<T>(string key, object id);
+	IEntry? Get(string key, object id);
+	Task<T?> Get<T>(string key, Func<T, bool> predicate, Func<EntryOptions, Task<T?>>? retrieve);
+	T? Get<T>(string key, Func<T, bool> predicate);
+	T? First<T>(string key);
+	IEnumerator<T>? GetEnumerator<T>(string key);
+
+	ImmutableList<T>? Where<T>(string key, Func<T, bool> predicate);
+	bool Exists(string key);
+	bool IsEmpty(string key);
+	void CreateKey(string key);
+	Task Clear(string key);
+
+	T? Set<T>(string key, object id, T? instance);
+	T? Set<T>(string key, object id, T? instance, TimeSpan duration);
+	T? Set<T>(string key, object id, T? instance, TimeSpan duration, bool slidingExpiration);
+	void CopyTo(string key, object id, IEntry entry);
+	Task<ImmutableList<string>?> Remove<T>(string key, Func<T, bool> predicate);
+	Task Remove(string key, object id);
+	Task Invalidate(string key, object id);
+
+	int Count(string key);
+	bool Any(string key);
+	ImmutableList<string>? Keys(string key);
+	ImmutableList<string>? Keys();
+}

Connected.Caching/ICacheClient.cs

@@ -0,0 +1,7 @@
+namespace Connected.Caching;
+
+public interface ICacheClient<TEntry, TKey> : IEnumerable<TEntry>, IDisposable
+{
+	string Key { get; }
+	int Count { get; }
+}

Connected.Caching/ICacheContext.cs

@@ -0,0 +1,6 @@
+namespace Connected.Caching;
+
+public interface ICacheContext : ICache
+{
+	void Flush();
+}

Connected.Caching/ICachingService.cs

@@ -0,0 +1,7 @@
+namespace Connected.Caching;
+
+public interface ICachingService : ICache
+{
+	void Merge(ICache cache);
+	Task Initialize();
+}

Connected.Caching/IEntry.cs

@@ -0,0 +1,11 @@
+namespace Connected.Caching;
+
+public interface IEntry : IDisposable
+{
+	object? Instance { get; }
+	string Id { get; }
+	bool Expired { get; }
+	TimeSpan Duration { get; }
+	bool SlidingExpiration { get; }
+	void Hit();
+}

Connected.Caching/IMemoryCache.cs

@@ -0,0 +1,6 @@
+namespace Connected.Caching;
+
+public interface IMemoryCache : ICache
+{
+	void Merge(ICache cache);
+}

Connected.Caching/IStatefulCacheClient.cs

@@ -0,0 +1,6 @@
+namespace Connected.Caching;
+
+public interface IStatefulCacheClient<TEntry, TKey> : ICacheClient<TEntry, TKey>
+{
+	event CacheInvalidateHandler Invalidate;
+}

Connected.Caching/MemoryCache.cs

@@ -0,0 +1,24 @@
+using System.Collections.Immutable;
+
+namespace Connected.Caching;
+
+internal class MemoryCache : Cache, IMemoryCache
+{
+	public void Merge(ICache cache)
+	{
+		if (cache.Keys() is not ImmutableList<string> keys)
+			return;
+
+		foreach (var key in keys)
+		{
+			if (cache.Keys(key) is not ImmutableList<string> entryKeys)
+				continue;
+
+			foreach (var entryKey in entryKeys)
+			{
+				if (cache.Get(key, entryKey) is IEntry entry)
+					CopyTo(key, entryKey, entry);
+			}
+		}
+	}
+}

Connected.Caching/Net/CacheHub.cs

@@ -0,0 +1,11 @@
+using Connected.Net.Hubs;
+
+namespace Connected.Caching.Net;
+
+//TODO: implement authorization and add logic to reject connections if not an endpoint server
+internal class CacheHub : StatefulHub<CacheNotificationArgs>
+{
+	public CacheHub(CacheServer server) : base(server)
+	{
+	}
+}

Connected.Caching/Net/CacheServer.cs

@@ -0,0 +1,11 @@
+using Connected.Net.Hubs;
+using Microsoft.AspNetCore.SignalR;
+
+namespace Connected.Caching.Net;
+
+internal class CacheServer : Server<CacheHub, CacheNotificationArgs>
+{
+	public CacheServer(IHubContext<CacheHub> hub) : base(hub)
+	{
+	}
+}

Connected.Caching/Net/CacheServerConnection.cs

@@ -0,0 +1,36 @@
+using Connected.Net.Hubs;
+using Connected.Net.Messaging;
+using Connected.Net.Server;
+using Microsoft.AspNetCore.SignalR.Client;
+using Microsoft.Extensions.Logging;
+
+namespace Connected.Caching.Net;
+
+internal class CacheServerConnection : ServerConnection
+{
+	public event EventHandler<CacheNotificationArgs>? Received;
+
+	public CacheServerConnection(IEndpointServer server, ILogger<CacheServerConnection> logger) : base(server)
+	{
+		Logger = logger;
+	}
+
+	private ILogger<CacheServerConnection> Logger { get; }
+
+	public override async Task Initialize(string hubUrl)
+	{
+		await base.Initialize(hubUrl);
+
+		Connection.On<MessageAcknowledgeArgs, CacheNotificationArgs>("Notify", (a, e) =>
+		{
+			Connection.InvokeAsync(nameof(CacheHub.Acknowledge), a);
+
+			Received?.Invoke(this, e);
+		});
+
+		Connection.On<ServerExceptionArgs>("Exception", (e) =>
+		{
+			Logger.LogError("Caching hub exception: {message}", e.Message);
+		});
+	}
+}

Connected.Caching/Net/CacheWorker.cs

@@ -0,0 +1,11 @@
+using Connected.Net.Hubs;
+using Microsoft.AspNetCore.SignalR;
+
+namespace Connected.Caching.Net;
+
+internal sealed class CacheWorker : ServerWorker<CacheNotificationArgs, CacheHub>
+{
+	public CacheWorker(CacheServer server, IHubContext<CacheHub> hub) : base(server, hub)
+	{
+	}
+}

Connected.Caching/SR.Designer.cs

@@ -0,0 +1,72 @@
+//------------------------------------------------------------------------------
+// <auto-generated>
+//     This code was generated by a tool.
+//     Runtime Version:4.0.30319.42000
+//
+//     Changes to this file may cause incorrect behavior and will be lost if
+//     the code is regenerated.
+// </auto-generated>
+//------------------------------------------------------------------------------
+
+namespace Connected.Caching {
+    using System;
+    
+    
+    /// <summary>
+    ///   A strongly-typed resource class, for looking up localized strings, etc.
+    /// </summary>
+    // This class was auto-generated by the StronglyTypedResourceBuilder
+    // class via a tool like ResGen or Visual Studio.
+    // To add or remove a member, edit your .ResX file then rerun ResGen
+    // with the /str option, or rebuild your VS project.
+    [global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Resources.Tools.StronglyTypedResourceBuilder", "17.0.0.0")]
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
+    [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]
+    internal class SR {
+        
+        private static global::System.Resources.ResourceManager resourceMan;
+        
+        private static global::System.Globalization.CultureInfo resourceCulture;
+        
+        [global::System.Diagnostics.CodeAnalysis.SuppressMessageAttribute("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
+        internal SR() {
+        }
+        
+        /// <summary>
+        ///   Returns the cached ResourceManager instance used by this class.
+        /// </summary>
+        [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Advanced)]
+        internal static global::System.Resources.ResourceManager ResourceManager {
+            get {
+                if (object.ReferenceEquals(resourceMan, null)) {
+                    global::System.Resources.ResourceManager temp = new global::System.Resources.ResourceManager("Server.Caching.SR", typeof(SR).Assembly);
+                    resourceMan = temp;
+                }
+                return resourceMan;
+            }
+        }
+        
+        /// <summary>
+        ///   Overrides the current thread's CurrentUICulture property for all
+        ///   resource lookups using this strongly typed resource class.
+        /// </summary>
+        [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Advanced)]
+        internal static global::System.Globalization.CultureInfo Culture {
+            get {
+                return resourceCulture;
+            }
+            set {
+                resourceCulture = value;
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Cache Key property not set. Please set &apos;Key&apos; property before returning value from cache retrieve handler or set CacheKeyAttribute on at least one property..
+        /// </summary>
+        internal static string ErrCacheKeyNull {
+            get {
+                return ResourceManager.GetString("ErrCacheKeyNull", resourceCulture);
+            }
+        }
+    }
+}

Connected.Caching/SR.resx

@@ -0,0 +1,123 @@
+<?xml version="1.0" encoding="utf-8"?>
+<root>
+  <!-- 
+    Microsoft ResX Schema 
+    
+    Version 2.0
+    
+    The primary goals of this format is to allow a simple XML format 
+    that is mostly human readable. The generation and parsing of the 
+    various data types are done through the TypeConverter classes 
+    associated with the data types.
+    
+    Example:
+    
+    ... ado.net/XML headers & schema ...
+    <resheader name="resmimetype">text/microsoft-resx</resheader>
+    <resheader name="version">2.0</resheader>
+    <resheader name="reader">System.Resources.ResXResourceReader, System.Windows.Forms, ...</resheader>
+    <resheader name="writer">System.Resources.ResXResourceWriter, System.Windows.Forms, ...</resheader>
+    <data name="Name1"><value>this is my long string</value><comment>this is a comment</comment></data>
+    <data name="Color1" type="System.Drawing.Color, System.Drawing">Blue</data>
+    <data name="Bitmap1" mimetype="application/x-microsoft.net.object.binary.base64">
+        <value>[base64 mime encoded serialized .NET Framework object]</value>
+    </data>
+    <data name="Icon1" type="System.Drawing.Icon, System.Drawing" mimetype="application/x-microsoft.net.object.bytearray.base64">
+        <value>[base64 mime encoded string representing a byte array form of the .NET Framework object]</value>
+        <comment>This is a comment</comment>
+    </data>
+                
+    There are any number of "resheader" rows that contain simple 
+    name/value pairs.
+    
+    Each data row contains a name, and value. The row also contains a 
+    type or mimetype. Type corresponds to a .NET class that support 
+    text/value conversion through the TypeConverter architecture. 
+    Classes that don't support this are serialized and stored with the 
+    mimetype set.
+    
+    The mimetype is used for serialized objects, and tells the 
+    ResXResourceReader how to depersist the object. This is currently not 
+    extensible. For a given mimetype the value must be set accordingly:
+    
+    Note - application/x-microsoft.net.object.binary.base64 is the format 
+    that the ResXResourceWriter will generate, however the reader can 
+    read any of the formats listed below.
+    
+    mimetype: application/x-microsoft.net.object.binary.base64
+    value   : The object must be serialized with 
+            : System.Runtime.Serialization.Formatters.Binary.BinaryFormatter
+            : and then encoded with base64 encoding.
+    
+    mimetype: application/x-microsoft.net.object.soap.base64
+    value   : The object must be serialized with 
+            : System.Runtime.Serialization.Formatters.Soap.SoapFormatter
+            : and then encoded with base64 encoding.
+
+    mimetype: application/x-microsoft.net.object.bytearray.base64
+    value   : The object must be serialized into a byte array 
+            : using a System.ComponentModel.TypeConverter
+            : and then encoded with base64 encoding.
+    -->
+  <xsd:schema id="root" xmlns="" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
+    <xsd:import namespace="http://www.w3.org/XML/1998/namespace" />
+    <xsd:element name="root" msdata:IsDataSet="true">
+      <xsd:complexType>
+        <xsd:choice maxOccurs="unbounded">
+          <xsd:element name="metadata">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" />
+              </xsd:sequence>
+              <xsd:attribute name="name" use="required" type="xsd:string" />
+              <xsd:attribute name="type" type="xsd:string" />
+              <xsd:attribute name="mimetype" type="xsd:string" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="assembly">
+            <xsd:complexType>
+              <xsd:attribute name="alias" type="xsd:string" />
+              <xsd:attribute name="name" type="xsd:string" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="data">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+                <xsd:element name="comment" type="xsd:string" minOccurs="0" msdata:Ordinal="2" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" msdata:Ordinal="1" />
+              <xsd:attribute name="type" type="xsd:string" msdata:Ordinal="3" />
+              <xsd:attribute name="mimetype" type="xsd:string" msdata:Ordinal="4" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="resheader">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" />
+            </xsd:complexType>
+          </xsd:element>
+        </xsd:choice>
+      </xsd:complexType>
+    </xsd:element>
+  </xsd:schema>
+  <resheader name="resmimetype">
+    <value>text/microsoft-resx</value>
+  </resheader>
+  <resheader name="version">
+    <value>2.0</value>
+  </resheader>
+  <resheader name="reader">
+    <value>System.Resources.ResXResourceReader, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <resheader name="writer">
+    <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <data name="ErrCacheKeyNull" xml:space="preserve">
+    <value>Cache Key property not set. Please set 'Key' property before returning value from cache retrieve handler or set CacheKeyAttribute on at least one property.</value>
+  </data>
+</root>

Connected.Caching/StatefulCacheClient.cs

@@ -0,0 +1,113 @@
+using System.Collections.Immutable;
+using System.Globalization;
+using Connected.Interop;
+using Connected.Threading;
+
+namespace Connected.Caching;
+
+public abstract class StatefulCacheClient<TEntry, TKey> : CacheClient<TEntry, TKey>, IStatefulCacheClient<TEntry, TKey> where TEntry : class
+{
+	public event CacheInvalidateHandler Invalidate;
+	protected StatefulCacheClient(ICachingService cachingService, string key) : base(cachingService, key)
+	{
+		Locker = new AsyncLockerSlim();
+
+		CachingService.Invalidating += OnInvalidate;
+	}
+	private AsyncLockerSlim? Locker { get; set; }
+	protected virtual InvalidateBehavior InvalidateBehavior { get; } = InvalidateBehavior.KeepSameInstance;
+	private bool Initialized { get; set; }
+	private async void OnInvalidate(CacheEventArgs e)
+	{
+		if (string.Equals(e.Key, Key, StringComparison.OrdinalIgnoreCase))
+		{
+			if (Initialized)
+				await OnInvalidate(TypeConversion.Convert<TKey>(e.Id, CultureInfo.InvariantCulture));
+
+			Invalidate?.Invoke(e);
+
+			e.Behavior = InvalidateBehavior;
+		}
+	}
+	protected virtual async Task OnInvalidate(TKey id)
+	{
+		await Task.CompletedTask;
+	}
+	protected virtual async Task OnInitializing()
+	{
+		await Task.CompletedTask;
+	}
+	protected async Task Initialize()
+	{
+		if (Initialized || IsDisposed || Locker is null)
+			return;
+
+		await Locker.LockAsync(async () =>
+		{
+			if (Initialized || IsDisposed)
+				return;
+
+			await OnInitializing();
+
+			Initialized = true;
+		});
+
+		if (Initialized)
+			await OnInitialized();
+	}
+	protected virtual async Task OnInitialized()
+	{
+		await Task.CompletedTask;
+	}
+	protected override async Task<ImmutableList<TEntry>?> All()
+	{
+		await Initialize();
+
+		return base.All().Result;
+	}
+	protected override async Task<TEntry?> First()
+	{
+		await Initialize();
+
+		return await base.First();
+	}
+	protected override async Task<TEntry?> Get(Func<TEntry, bool> predicate)
+	{
+		await Initialize();
+
+		return await base.Get(predicate);
+	}
+	protected override async Task<TEntry?> Get(TKey id)
+	{
+		await Initialize();
+
+		return await base.Get(id);
+	}
+	protected override async Task<TEntry?> Get(TKey id, Func<EntryOptions, Task<TEntry>> retrieve)
+	{
+		await Initialize();
+
+		return await base.Get(id, retrieve);
+	}
+	protected override async Task<ImmutableList<TEntry>?> Where(Func<TEntry, bool> predicate)
+	{
+		await Initialize();
+
+		return await base.Where(predicate);
+	}
+	protected override void OnDisposing()
+	{
+		if (Locker is not null)
+		{
+			Locker?.Dispose();
+			Locker = null;
+		}
+	}
+
+	public override IEnumerator<TEntry> GetEnumerator()
+	{
+		AsyncUtils.RunSync(Initialize);
+
+		return base.GetEnumerator();
+	}
+}

Connected.Collections/CollectionExtensions.cs

@@ -0,0 +1,76 @@
+using System.Collections.Immutable;
+using System.Reflection;
+using Connected.Annotations;
+
+namespace Connected.Collections;
+
+public static class CollectionExtensions
+{
+	public static ImmutableArray<TSource> ToImmutableArray<TSource>(this IEnumerable<TSource> items, bool performLock)
+	{
+		if (!performLock)
+			return items.ToImmutableArray();
+
+		lock (items)
+			return items.ToImmutableArray();
+	}
+
+	public static ImmutableList<TSource> ToImmutableList<TSource>(this IEnumerable<TSource> items, bool performLock)
+	{
+		if (!performLock)
+			return items.ToImmutableList();
+
+		lock (items)
+			return items.ToImmutableList();
+	}
+
+	public static void SortByOrdinal<TElement>(this List<TElement> items)
+	{
+		items.Sort((left, right) =>
+		{
+			var leftOrdinal = left is Type lt ? lt.GetCustomAttribute<OrdinalAttribute>() : left?.GetType().GetCustomAttribute<OrdinalAttribute>();
+			var rightOrdinal = right is Type rt ? rt.GetCustomAttribute<OrdinalAttribute>() : right?.GetType().GetCustomAttribute<OrdinalAttribute>();
+
+			if (leftOrdinal is null && rightOrdinal is null)
+				return 0;
+
+			if (leftOrdinal is not null && rightOrdinal is null)
+				return -1;
+
+			if (leftOrdinal is null && rightOrdinal is not null)
+				return 1;
+
+			if (leftOrdinal?.Value == rightOrdinal?.Value)
+				return 0;
+			else if (leftOrdinal?.Value < rightOrdinal?.Value)
+				return 1;
+			else
+				return -1;
+		});
+	}
+
+	public static void SortByPriority<TElement>(this List<TElement> items)
+	{
+		items.Sort((left, right) =>
+		{
+			var leftPriority = left is Type lt ? lt.GetCustomAttribute<PriorityAttribute>() : left?.GetType().GetCustomAttribute<PriorityAttribute>();
+			var rightPriority = right is Type rt ? rt.GetCustomAttribute<PriorityAttribute>() : right?.GetType().GetCustomAttribute<PriorityAttribute>();
+
+			if (leftPriority is null && rightPriority is null)
+				return 0;
+
+			if (leftPriority is not null && rightPriority is null)
+				return -1;
+
+			if (leftPriority is null && rightPriority is not null)
+				return 1;
+
+			if (leftPriority?.Value == rightPriority?.Value)
+				return 0;
+			else if (leftPriority?.Value > rightPriority?.Value)
+				return -1;
+			else
+				return 1;
+		});
+	}
+}

Connected.Collections/CollectionRoutes.cs

@@ -0,0 +1,6 @@
+namespace Connected.Collections;
+
+public static class CollectionRoutes
+{
+	public const string Queue = "/sys/queue";
+}

Connected.Collections/CollectionsStartup.cs

@@ -0,0 +1,16 @@
+using Connected.Annotations;
+using Microsoft.AspNetCore.Builder;
+
+[assembly: MicroService(MicroServiceType.Sys)]
+
+namespace Connected.Collections;
+
+internal class CollectionsStartup : Startup
+{
+	public static WebApplication? Application { get; private set; }
+
+	protected override void OnConfigure(WebApplication app)
+	{
+		Application = app;
+	}
+}

Connected.Collections/Concurrent/Dispatcher.cs

@@ -0,0 +1,177 @@
+using System.Collections.Concurrent;
+using Connected;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace Connected.Collections.Concurrent;
+
+public abstract class Dispatcher<TArgs, TJob> : IDispatcher<TArgs, TJob>
+	where TJob : IDispatcherJob<TArgs>
+{
+	private CancellationTokenSource _tokenSource;
+	protected Dispatcher(int size)
+	{
+		WorkerSize = size;
+
+		_tokenSource = new();
+
+		Queue = new();
+		Jobs = new();
+		QueuedDispatchers = new();
+	}
+
+	public CancellationToken CancellationToken => _tokenSource.Token;
+	private ConcurrentQueue<TArgs> Queue { get; set; }
+	private List<DispatcherJob<TArgs>> Jobs { get; set; }
+	protected bool IsDisposed { get; private set; }
+	private int WorkerSize { get; }
+	public int Available => Math.Max(0, WorkerSize * 4 - Queue.Count - QueuedDispatchers.Sum(f => f.Value.Count));
+	private ConcurrentDictionary<string, QueuedDispatcher<TArgs, TJob>> QueuedDispatchers { get; set; }
+	public DispatcherProcessBehavior Behavior => DispatcherProcessBehavior.Parallel;
+
+	public void Cancel()
+	{
+		_tokenSource?.Cancel();
+	}
+
+	public bool Dequeue(out TArgs? item)
+	{
+		return Queue.TryDequeue(out item);
+	}
+	public bool Enqueue(string queue, TArgs item)
+	{
+		if (EnsureDispatcher(queue) is not QueuedDispatcher<TArgs, TJob> dispatcher)
+			throw new SysException(this, $"{SR.ErrCreateQueuedDispatcher} ({queue})");
+
+		return dispatcher.Enqueue(item);
+	}
+	public bool Enqueue(TArgs item)
+	{
+		Queue.Enqueue(item);
+
+		if (Jobs.Count < WorkerSize)
+		{
+			/*
+			 * Dispatcher jobs should be transient so it's safe to request a service from the root collection.
+			 */
+			if (CollectionsStartup.Application.Services.GetService<TJob>() is not DispatcherJob<TArgs> job)
+				throw new NullReferenceException($"{SR.ErrCreateService} ({typeof(DispatcherJob<TArgs>).Name})");
+
+			job.Completed += OnCompleted;
+
+			lock (Jobs)
+			{
+				Jobs.Add(job);
+			}
+
+			job.Run(Queue, CancellationToken);
+		}
+
+		return true;
+	}
+
+	private void OnCompleted(object? sender, EventArgs e)
+	{
+		if (sender is not DispatcherJob<TArgs> job)
+			return;
+
+		if (Queue.IsEmpty)
+		{
+			lock (Jobs)
+			{
+				Jobs.Remove(job);
+			}
+
+			job.Dispose();
+		}
+		else
+			job.Run(Queue, CancellationToken);
+	}
+
+	private QueuedDispatcher<TArgs, TJob>? EnsureDispatcher(string queueName)
+	{
+		if (QueuedDispatchers.TryGetValue(queueName, out QueuedDispatcher<TArgs, TJob>? result))
+			return result;
+
+		result = new QueuedDispatcher<TArgs, TJob>(this, queueName);
+
+		result.Completed += OnQueuedCompleted;
+
+		if (!QueuedDispatchers.TryAdd(queueName, result))
+		{
+			result.Completed -= OnQueuedCompleted;
+
+			if (QueuedDispatchers.TryGetValue(queueName, out QueuedDispatcher<TArgs, TJob>? retryResult))
+				return retryResult;
+			else
+				return default;
+		}
+
+		return result;
+	}
+	private void OnQueuedCompleted(object? sender, EventArgs e)
+	{
+		if (sender is not QueuedDispatcher<TArgs, TJob> dispatcher)
+			return;
+
+		if (dispatcher.Count > 0)
+			return;
+
+		QueuedDispatchers.Remove(dispatcher.QueueName, out _);
+
+		dispatcher.Dispose();
+	}
+	private void Dispose(bool disposing)
+	{
+		if (!IsDisposed)
+		{
+			if (disposing)
+			{
+				if (_tokenSource is not null)
+				{
+					if (!_tokenSource.IsCancellationRequested)
+						_tokenSource.Cancel();
+
+					_tokenSource.Dispose();
+					_tokenSource = null;
+				}
+
+				if (Queue is not null)
+				{
+					Queue.Clear();
+					Queue = null;
+				}
+
+				if (Jobs is not null)
+				{
+					foreach (var job in Jobs)
+						job.Dispose();
+
+					Jobs.Clear();
+					Jobs = null;
+				}
+
+				if (QueuedDispatchers is not null)
+				{
+					foreach (var dispatcher in QueuedDispatchers)
+						dispatcher.Value.Dispose();
+
+					QueuedDispatchers.Clear();
+					Queue = null;
+				}
+			}
+
+			IsDisposed = true;
+		}
+	}
+
+	protected virtual void OnDisposing()
+	{
+
+	}
+	public void Dispose()
+	{
+		Dispose(true);
+		GC.SuppressFinalize(this);
+	}
+}
+

Connected.Collections/Concurrent/DispatcherJob.cs

@@ -0,0 +1,103 @@
+using System.Collections.Concurrent;
+using System.ComponentModel;
+using Connected.Data;
+
+namespace Connected.Collections.Concurrent;
+
+/// <summary>
+/// This class acts as a job unit of the <see cref="IDispatcher{T}"/>.
+/// </summary>
+/// <typeparam name="TArgs"></typeparam>
+public abstract class DispatcherJob<TArgs> : IDispatcherJob<TArgs>, IDisposable
+{
+	public event EventHandler? Completed;
+	public bool IsRunning { get; private set; }
+	protected bool IsDisposed { get; private set; }
+	private CancellationToken CancellationToken { get; set; }
+
+	internal void Run(ConcurrentQueue<TArgs> queue, CancellationToken cancellationToken)
+	{
+		CancellationToken = cancellationToken;
+
+		if (IsRunning)
+			return;
+
+		Task.Run(async () =>
+		{
+			IsRunning = true;
+			TArgs? item = default;
+
+			try
+			{
+				while (queue.TryDequeue(out item))
+				{
+					if (item is null)
+						continue;
+
+					if (item is IPopReceipt pr && pr.NextVisible <= DateTime.UtcNow)
+						continue;
+
+					await Invoke(item);
+
+					if (cancellationToken.IsCancellationRequested || IsDisposed)
+						break;
+				}
+			}
+			catch (Exception ex)
+			{
+				await HandleException(item, ex);
+			}
+
+			IsRunning = false;
+			Completed?.Invoke(this, EventArgs.Empty);
+
+		}, CancellationToken);
+	}
+
+	private void OnCompleted(object? sender, RunWorkerCompletedEventArgs e)
+	{
+		Completed?.Invoke(this, EventArgs.Empty);
+	}
+
+	public async Task Invoke(TArgs args)
+	{
+		await OnInvoke(args, CancellationToken);
+	}
+
+	protected virtual async Task OnInvoke(TArgs args, CancellationToken cancellationToken)
+	{
+		await Task.CompletedTask;
+	}
+
+	private async Task HandleException(TArgs? args, Exception ex)
+	{
+		await OnHandleEception(args, ex);
+	}
+
+	protected virtual async Task OnHandleEception(TArgs? args, Exception ex)
+	{
+		await Task.CompletedTask;
+	}
+
+	public void Dispose()
+	{
+		Dispose(true);
+		GC.SuppressFinalize(this);
+	}
+
+	protected virtual void Dispose(bool disposing)
+	{
+		if (IsDisposed)
+			return;
+
+		if (disposing)
+			OnDisposing();
+
+		IsDisposed = true;
+	}
+
+	protected virtual void OnDisposing()
+	{
+
+	}
+}

Connected.Collections/Concurrent/IDispatcher.cs

@@ -0,0 +1,19 @@
+namespace Connected.Collections.Concurrent;
+
+public enum DispatcherProcessBehavior
+{
+	Parallel = 1,
+	Queued = 2
+}
+
+public interface IDispatcher<TArgs, TJob> : IDisposable
+	where TJob : IDispatcherJob<TArgs>
+{
+	bool Dequeue(out TArgs? item);
+	bool Enqueue(TArgs item);
+	bool Enqueue(string queue, TArgs item);
+	DispatcherProcessBehavior Behavior { get; }
+
+	CancellationToken CancellationToken { get; }
+	void Cancel();
+}

Connected.Collections/Concurrent/IDispatcherJob.cs

@@ -0,0 +1,7 @@
+namespace Connected.Collections.Concurrent;
+
+public interface IDispatcherJob<TArgs> : IDisposable
+{
+	Task Invoke(TArgs args);
+	bool IsRunning { get; }
+}

Connected.Collections/Concurrent/QueuedDispatcher.cs

@@ -0,0 +1,99 @@
+using System.Collections.Concurrent;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace Connected.Collections.Concurrent;
+
+internal sealed class QueuedDispatcher<TArgs, TJob> : IDispatcher<TArgs, TJob>
+	where TJob : IDispatcherJob<TArgs>
+{
+	public event EventHandler? Completed;
+
+	public QueuedDispatcher(IDispatcher<TArgs, TJob> dispatcher, string queueName)
+	{
+		Dispatcher = dispatcher;
+		Queue = new();
+		QueueName = queueName;
+
+		/*
+		 * Dispatcher jobs should be transient so it's safe to request a service from the root collection.
+		 */
+		if (CollectionsStartup.Application?.Services.GetService<DispatcherJob<TArgs>>() is not DispatcherJob<TArgs> job)
+			throw new SysException(this, $"{SR.ErrCreateService} ({typeof(DispatcherJob<TArgs>).Name})");
+
+		job.Completed += OnCompleted;
+
+		Job = job;
+	}
+
+	public CancellationToken CancellationToken => Dispatcher.CancellationToken;
+	public bool IsDisposed { get; private set; }
+	public DispatcherProcessBehavior Behavior => DispatcherProcessBehavior.Queued;
+	public string QueueName { get; }
+	private DispatcherJob<TArgs> Job { get; set; }
+	private IDispatcher<TArgs, TJob> Dispatcher { get; set; }
+	public int Count => Queue.Count;
+	private ConcurrentQueue<TArgs> Queue { get; set; }
+
+	public void Cancel()
+	{
+
+	}
+
+	public bool Dequeue(out TArgs? item)
+	{
+		return Queue.TryDequeue(out item);
+	}
+	public bool Enqueue(TArgs item)
+	{
+		if (IsDisposed)
+			return false;
+
+		Queue.Enqueue(item);
+
+		if (!Job.IsRunning)
+			Job.Run(Queue, CancellationToken);
+
+		return true;
+	}
+
+	private void OnCompleted(object? sender, EventArgs e)
+	{
+		if (sender is not DispatcherJob<TArgs> job)
+			return;
+
+		if (!Queue.IsEmpty)
+		{
+			job.Run(Queue, CancellationToken);
+			return;
+		}
+
+		Completed?.Invoke(this, EventArgs.Empty);
+	}
+
+	public bool Enqueue(string queue, TArgs args)
+	{
+		return Dispatcher.Enqueue(queue, args);
+	}
+
+	private void Dispose(bool disposing)
+	{
+		if (!IsDisposed)
+		{
+			if (disposing)
+			{
+				if (Job is not null)
+				{
+					Job.Dispose();
+					Job = null;
+				}
+			}
+
+			IsDisposed = true;
+		}
+	}
+	public void Dispose()
+	{
+		Dispose(true);
+		GC.SuppressFinalize(this);
+	}
+}

Connected.Collections/Connected.Collections.csproj

@@ -0,0 +1,30 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+	<PropertyGroup>
+		<TargetFramework>net7.0</TargetFramework>
+		<ImplicitUsings>enable</ImplicitUsings>
+		<Nullable>enable</Nullable>
+	</PropertyGroup>
+
+	<ItemGroup>
+		<ProjectReference Include="..\..\Connected\Connected\Connected.csproj" />
+		<ProjectReference Include="..\Connected.Interop\Connected.Interop.csproj" />
+		<ProjectReference Include="..\Connected.Runtime\Connected.Runtime.csproj" />
+	</ItemGroup>
+
+	<ItemGroup>
+		<Compile Update="SR.Designer.cs">
+			<DesignTime>True</DesignTime>
+			<AutoGen>True</AutoGen>
+			<DependentUpon>SR.resx</DependentUpon>
+		</Compile>
+	</ItemGroup>
+
+	<ItemGroup>
+		<EmbeddedResource Update="SR.resx">
+			<Generator>ResXFileCodeGenerator</Generator>
+			<LastGenOutput>SR.Designer.cs</LastGenOutput>
+		</EmbeddedResource>
+	</ItemGroup>
+
+</Project>

Connected.Collections/Iterator.cs

@@ -0,0 +1,33 @@
+using Connected.Collections.Iterators;
+
+namespace Connected.Collections;
+
+public class Iterator
+{
+	private IIterator _iterator;
+	public Iterator(object value)
+	{
+		if (value is null)
+			throw new ArgumentException(nameof(value));
+
+		if (DictionaryIterator.CanHandle(value))
+			_iterator = new DictionaryIterator(value);
+		else if (ListIterator.CanHandle(value))
+			_iterator = new ListIterator(value);
+		else if (ArrayIterator.CanHandle(value))
+			_iterator = new ArrayIterator(value);
+	}
+
+	public async Task<bool> MoveNext(Func<object, Task<object>> processor)
+	{
+		if (!_iterator.MoveNext())
+			return false;
+
+		if (await processor(_iterator.Current) is object value)
+			_iterator.Add(value);
+
+		return true;
+	}
+
+	public object? Result => _iterator.Result;
+}

Connected.Collections/Iterators/ArrayIterator.cs

@@ -0,0 +1,32 @@
+namespace Connected.Collections.Iterators;
+
+internal class ArrayIterator : IIterator
+{
+	public ArrayIterator(object value)
+	{
+
+	}
+	public object? Result => throw new NotImplementedException();
+
+	public object Current => throw new NotImplementedException();
+
+	public static bool CanHandle(object value)
+	{
+		return value.GetType().IsArray;
+	}
+
+	public void Add(object value)
+	{
+		throw new NotImplementedException();
+	}
+
+	public bool MoveNext()
+	{
+		throw new NotImplementedException();
+	}
+
+	public void Reset()
+	{
+		throw new NotImplementedException();
+	}
+}

Connected.Collections/Iterators/DictionaryIterator.cs

@@ -0,0 +1,75 @@
+using System.Collections;
+using System.Collections.Immutable;
+using Connected.Interop;
+
+namespace Connected.Collections.Iterators;
+
+internal class DictionaryIterator : IIterator
+{
+	private readonly object _value;
+	private IDictionary _result;
+	public DictionaryIterator(object value)
+	{
+		_value = value;
+
+		if (value is not IDictionary dictionary)
+			return;
+
+		Enumerator = dictionary.GetEnumerator();
+
+		CreateResult();
+	}
+
+	public static bool CanHandle(object value)
+	{
+		var arguments = value.GetType().GetGenericArguments();
+		var kvp = typeof(KeyValuePair<,>).MakeGenericType(arguments);
+		var en = typeof(IEnumerable<>).MakeGenericType(kvp);
+
+		return value.GetType() == en;
+	}
+	private void CreateResult()
+	{
+		if (_value.GetType() == typeof(IImmutableDictionary<,>))
+			_result = _value.GetType().MakeGenericType(_value.GetType().GenericTypeArguments).CreateInstance<IDictionary>();
+	}
+
+	private IDictionaryEnumerator? Enumerator { get; }
+	public object? Current => Enumerator?.Value;
+
+	public object? Result
+	{
+		get
+		{
+			if (_value is null)
+				return null;
+
+			throw new NotImplementedException();
+		}
+	}
+
+	public bool MoveNext()
+	{
+		if (Enumerator is null)
+			return false;
+
+		return Enumerator.MoveNext();
+	}
+
+	public void Reset()
+	{
+		if (Enumerator is null)
+			return;
+
+		Enumerator.Reset();
+	}
+
+
+	public void Add(object value)
+	{
+		if (Current is null || Enumerator is null)
+			throw new InvalidOperationException(SR.ErrIteratorCurrentNull);
+
+		_result.Add(Enumerator.Key, value);
+	}
+}

Connected.Collections/Iterators/IIterator.cs

@@ -0,0 +1,10 @@
+using System.Collections;
+
+namespace Connected.Collections.Iterators;
+
+internal interface IIterator : IEnumerator
+{
+	void Add(object value);
+
+	object? Result { get; }
+}

Connected.Collections/Iterators/ListIterator.cs

@@ -0,0 +1,36 @@
+namespace Connected.Collections.Iterators;
+
+internal class ListIterator : IIterator
+{
+	public ListIterator(object value)
+	{
+
+	}
+
+	public object? Result => throw new NotImplementedException();
+
+	public object Current => throw new NotImplementedException();
+
+	public static bool CanHandle(object value)
+	{
+		var arguments = value.GetType().GetGenericArguments();
+		var list = typeof(IList<>).MakeGenericType(arguments);
+
+		return value.GetType() == list;
+	}
+
+	public void Add(object value)
+	{
+		throw new NotImplementedException();
+	}
+
+	public bool MoveNext()
+	{
+		throw new NotImplementedException();
+	}
+
+	public void Reset()
+	{
+		throw new NotImplementedException();
+	}
+}

Connected.Collections/Queues/IQueueClient.cs

@@ -0,0 +1,6 @@
+namespace Connected.Collections.Queues;
+public interface IQueueClient<TArgs> : IMiddleware
+	where TArgs : QueueArgs
+{
+	Task Invoke(IQueueMessage message, TArgs args);
+}

Connected.Collections/Queues/IQueueMessage.cs

@@ -0,0 +1,48 @@
+using Connected.Data;
+
+namespace Connected.Collections.Queues;
+/// <summary>
+/// Represents a single queue message.
+/// </summary>
+/// <remarks>
+/// A queue message represents a unit of queued or deferred work which
+/// can be processed distributed anywhere or in any client which
+/// has access to the Queue REST service.
+/// </remarks>
+public interface IQueueMessage : IPrimaryKey<long>, IPopReceipt
+{
+	/// <summary>
+	/// Date date and time the queue message was created.
+	/// </summary>
+	DateTime Created { get; init; }
+	/// <summary>
+	/// The number of times the clients dequeued the message.
+	/// </summary>
+	/// <remarks>
+	/// There are numerous reasons why queue message gets dequeued multiple
+	/// times. It could be that not all conditions were met at the time
+	/// of processing or that queue message was not processed quich enough and 
+	/// its pop receipt expired. In such cases message returns to the queue and 
+	/// waits for the next client to dequeue it.
+	/// </remarks>
+	int DequeueCount { get; init; }
+	/// <summary>
+	/// The timestamp message was last dequeued.
+	/// </summary>
+	DateTime? DequeueTimestamp { get; init; }
+	/// <summary>
+	/// The queue to which the message belongs. 
+	/// </summary>
+	/// <remarks>
+	/// Every queue client must specify which queue processes.
+	/// </remarks>
+	string Queue { get; init; }
+	/// <summary>
+	/// The arguments object which contains information about the message.
+	/// </summary>
+	/// <remarks>
+	/// Most queue messages do have an argument object, mostly providing na id of the
+	/// entity or record for which processing should be performed.
+	/// </remarks>
+	QueueArgs Arguments { get; init; }
+}

Connected.Collections/Queues/IQueueService.cs

@@ -0,0 +1,34 @@
+using System.Collections.Immutable;
+using Connected.Annotations;
+
+namespace Connected.Collections.Queues;
+/// <summary>
+/// Represents a distributed service for processing queue messages.
+/// </summary>
+/// <remarks>
+/// Queue mechanism is mostly used as an internal logic of processes
+/// and resources to offload work from the main thread to achieve better
+/// responsiveness of the system. Aggregations and calculations are good
+/// examples of queue usage. You should use queue whenever you must
+/// perform any kind of work that is not necessary to perform it in a single
+/// transaction scope.
+/// </remarks>
+[Service]
+[ServiceUrl(CollectionRoutes.Queue)]
+public interface IQueueService
+{
+	/// <summary>
+	/// Enqueues the queue message.
+	/// </summary>
+	/// <typeparam name="TArgs">The type of the arguments used in queue message</typeparam>
+	/// <param name="args">The arguments containing information about a queue message.</param>
+	Task Enqueue<TClient, TArgs>(TArgs args)
+		where TClient : IQueueClient<TArgs>
+		where TArgs : QueueArgs;
+	/// <summary>
+	/// Dequeues the queue messages based on the provided arguments.
+	/// </summary>
+	/// <param name="args">The arguments containing information about dequeue criteria.</param>
+	/// <returns>A list of valid queue messages that can be immediatelly processed.S</returns>
+	Task<ImmutableList<IQueueMessage>> Dequeue(DequeueArgs args);
+}

Connected.Collections/Queues/QueueArgs.cs

@@ -0,0 +1,44 @@
+using System.ComponentModel.DataAnnotations;
+using Connected.Annotations;
+using Connected.ServiceModel;
+
+namespace Connected.Collections.Queues;
+
+public class QueueArgs : Dto
+{
+	public QueueArgs()
+	{
+		Options = new();
+	}
+
+	public EnqueueOptions Options { get; set; }
+}
+
+public class PrimaryKeyQueueArgs<TPrimaryKey> : QueueArgs
+	where TPrimaryKey : notnull
+{
+	public TPrimaryKey Id { get; set; } = default!;
+}
+
+public sealed class EnqueueOptions
+{
+	/// <summary>
+	/// The date and time the queue message expires.
+	/// </summary>
+	/// <remarks>
+	/// Queue messages that are not processed until they expire
+	/// gets automatically deleted by the system.
+	/// </remarks>
+	public DateTime Expire { get; set; } = DateTime.UtcNow.AddHours(48);
+}
+
+public sealed class DequeueArgs : Dto
+{
+	[NonDefault]
+	public List<string> Queues { get; set; } = default!;
+
+	[Range(1, int.MaxValue)]
+	public int MaxCount { get; set; }
+
+	public TimeSpan NextVisible { get; set; }
+}

Connected.Collections/SR.Designer.cs

@@ -0,0 +1,90 @@
+//------------------------------------------------------------------------------
+// <auto-generated>
+//     This code was generated by a tool.
+//     Runtime Version:4.0.30319.42000
+//
+//     Changes to this file may cause incorrect behavior and will be lost if
+//     the code is regenerated.
+// </auto-generated>
+//------------------------------------------------------------------------------
+
+namespace Connected.Collections {
+    using System;
+    
+    
+    /// <summary>
+    ///   A strongly-typed resource class, for looking up localized strings, etc.
+    /// </summary>
+    // This class was auto-generated by the StronglyTypedResourceBuilder
+    // class via a tool like ResGen or Visual Studio.
+    // To add or remove a member, edit your .ResX file then rerun ResGen
+    // with the /str option, or rebuild your VS project.
+    [global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Resources.Tools.StronglyTypedResourceBuilder", "17.0.0.0")]
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
+    [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]
+    internal class SR {
+        
+        private static global::System.Resources.ResourceManager resourceMan;
+        
+        private static global::System.Globalization.CultureInfo resourceCulture;
+        
+        [global::System.Diagnostics.CodeAnalysis.SuppressMessageAttribute("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
+        internal SR() {
+        }
+        
+        /// <summary>
+        ///   Returns the cached ResourceManager instance used by this class.
+        /// </summary>
+        [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Advanced)]
+        internal static global::System.Resources.ResourceManager ResourceManager {
+            get {
+                if (object.ReferenceEquals(resourceMan, null)) {
+                    global::System.Resources.ResourceManager temp = new global::System.Resources.ResourceManager("Server.Collections.SR", typeof(SR).Assembly);
+                    resourceMan = temp;
+                }
+                return resourceMan;
+            }
+        }
+        
+        /// <summary>
+        ///   Overrides the current thread's CurrentUICulture property for all
+        ///   resource lookups using this strongly typed resource class.
+        /// </summary>
+        [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Advanced)]
+        internal static global::System.Globalization.CultureInfo Culture {
+            get {
+                return resourceCulture;
+            }
+            set {
+                resourceCulture = value;
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Cannot create queued dispatcher.
+        /// </summary>
+        internal static string ErrCreateQueuedDispatcher {
+            get {
+                return ResourceManager.GetString("ErrCreateQueuedDispatcher", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Cannot create service instance.
+        /// </summary>
+        internal static string ErrCreateService {
+            get {
+                return ResourceManager.GetString("ErrCreateService", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Iterator does not have current value.
+        /// </summary>
+        internal static string ErrIteratorCurrentNull {
+            get {
+                return ResourceManager.GetString("ErrIteratorCurrentNull", resourceCulture);
+            }
+        }
+    }
+}

Connected.Collections/SR.resx

@@ -0,0 +1,129 @@
+<?xml version="1.0" encoding="utf-8"?>
+<root>
+  <!-- 
+    Microsoft ResX Schema 
+    
+    Version 2.0
+    
+    The primary goals of this format is to allow a simple XML format 
+    that is mostly human readable. The generation and parsing of the 
+    various data types are done through the TypeConverter classes 
+    associated with the data types.
+    
+    Example:
+    
+    ... ado.net/XML headers & schema ...
+    <resheader name="resmimetype">text/microsoft-resx</resheader>
+    <resheader name="version">2.0</resheader>
+    <resheader name="reader">System.Resources.ResXResourceReader, System.Windows.Forms, ...</resheader>
+    <resheader name="writer">System.Resources.ResXResourceWriter, System.Windows.Forms, ...</resheader>
+    <data name="Name1"><value>this is my long string</value><comment>this is a comment</comment></data>
+    <data name="Color1" type="System.Drawing.Color, System.Drawing">Blue</data>
+    <data name="Bitmap1" mimetype="application/x-microsoft.net.object.binary.base64">
+        <value>[base64 mime encoded serialized .NET Framework object]</value>
+    </data>
+    <data name="Icon1" type="System.Drawing.Icon, System.Drawing" mimetype="application/x-microsoft.net.object.bytearray.base64">
+        <value>[base64 mime encoded string representing a byte array form of the .NET Framework object]</value>
+        <comment>This is a comment</comment>
+    </data>
+                
+    There are any number of "resheader" rows that contain simple 
+    name/value pairs.
+    
+    Each data row contains a name, and value. The row also contains a 
+    type or mimetype. Type corresponds to a .NET class that support 
+    text/value conversion through the TypeConverter architecture. 
+    Classes that don't support this are serialized and stored with the 
+    mimetype set.
+    
+    The mimetype is used for serialized objects, and tells the 
+    ResXResourceReader how to depersist the object. This is currently not 
+    extensible. For a given mimetype the value must be set accordingly:
+    
+    Note - application/x-microsoft.net.object.binary.base64 is the format 
+    that the ResXResourceWriter will generate, however the reader can 
+    read any of the formats listed below.
+    
+    mimetype: application/x-microsoft.net.object.binary.base64
+    value   : The object must be serialized with 
+            : System.Runtime.Serialization.Formatters.Binary.BinaryFormatter
+            : and then encoded with base64 encoding.
+    
+    mimetype: application/x-microsoft.net.object.soap.base64
+    value   : The object must be serialized with 
+            : System.Runtime.Serialization.Formatters.Soap.SoapFormatter
+            : and then encoded with base64 encoding.
+
+    mimetype: application/x-microsoft.net.object.bytearray.base64
+    value   : The object must be serialized into a byte array 
+            : using a System.ComponentModel.TypeConverter
+            : and then encoded with base64 encoding.
+    -->
+  <xsd:schema id="root" xmlns="" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
+    <xsd:import namespace="http://www.w3.org/XML/1998/namespace" />
+    <xsd:element name="root" msdata:IsDataSet="true">
+      <xsd:complexType>
+        <xsd:choice maxOccurs="unbounded">
+          <xsd:element name="metadata">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" />
+              </xsd:sequence>
+              <xsd:attribute name="name" use="required" type="xsd:string" />
+              <xsd:attribute name="type" type="xsd:string" />
+              <xsd:attribute name="mimetype" type="xsd:string" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="assembly">
+            <xsd:complexType>
+              <xsd:attribute name="alias" type="xsd:string" />
+              <xsd:attribute name="name" type="xsd:string" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="data">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+                <xsd:element name="comment" type="xsd:string" minOccurs="0" msdata:Ordinal="2" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" msdata:Ordinal="1" />
+              <xsd:attribute name="type" type="xsd:string" msdata:Ordinal="3" />
+              <xsd:attribute name="mimetype" type="xsd:string" msdata:Ordinal="4" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="resheader">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" />
+            </xsd:complexType>
+          </xsd:element>
+        </xsd:choice>
+      </xsd:complexType>
+    </xsd:element>
+  </xsd:schema>
+  <resheader name="resmimetype">
+    <value>text/microsoft-resx</value>
+  </resheader>
+  <resheader name="version">
+    <value>2.0</value>
+  </resheader>
+  <resheader name="reader">
+    <value>System.Resources.ResXResourceReader, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <resheader name="writer">
+    <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <data name="ErrCreateQueuedDispatcher" xml:space="preserve">
+    <value>Cannot create queued dispatcher</value>
+  </data>
+  <data name="ErrCreateService" xml:space="preserve">
+    <value>Cannot create service instance</value>
+  </data>
+  <data name="ErrIteratorCurrentNull" xml:space="preserve">
+    <value>Iterator does not have current value</value>
+  </data>
+</root>

Connected.Configuration/Authentication/AuthenticationConfiguration.cs

@@ -0,0 +1,11 @@
+namespace Connected.Configuration.Authentication;
+
+internal class AuthenticationConfiguration : IAuthenticationConfiguration
+{
+	public AuthenticationConfiguration()
+	{
+		JwToken = new JwTokenConfiguration();
+	}
+
+	public IJwTokenConfiguration JwToken { get; }
+}

Connected.Configuration/Authentication/IAuthenticationConfiguration.cs

@@ -0,0 +1,6 @@
+namespace Connected.Configuration.Authentication;
+
+public interface IAuthenticationConfiguration
+{
+	IJwTokenConfiguration JwToken { get; }
+}

Connected.Configuration/Authentication/IJwTokenConfiguration.cs

@@ -0,0 +1,10 @@
+namespace Connected.Configuration.Authentication
+{
+	public interface IJwTokenConfiguration
+	{
+		string Issuer { get; }
+		string Audience { get; }
+		string Key { get; }
+		int Duration { get; }
+	}
+}

Connected.Configuration/Authentication/JwTokenConfiguration.cs

@@ -0,0 +1,13 @@
+namespace Connected.Configuration.Authentication
+{
+	internal class JwTokenConfiguration : IJwTokenConfiguration
+	{
+		public string? Issuer { get; set; }
+
+		public string? Audience { get; set; }
+
+		public string? Key { get; set; } = "D78RF30487F4G0F8Z34F834F";
+
+		public int Duration { get; set; } = 30;
+	}
+}

Connected.Configuration/ConfigurationService.cs

@@ -0,0 +1,23 @@
+using Connected.Configuration.Authentication;
+using Connected.Configuration.Endpoints;
+
+namespace Connected.Configuration;
+
+internal class ConfigurationService : IConfigurationService
+{
+	public ConfigurationService()
+	{
+		Endpoint = new EndpointConfiguration();
+		Storage = new StorageConfiguration();
+	}
+
+	public IEndpointConfiguration Endpoint { get; }
+
+	public IAuthenticationConfiguration Authentication => throw new NotImplementedException();
+	public IStorageConfiguration Storage { get; }
+
+	/*
+	 * TODO: hardcoded
+	 */
+	public ProcessType Type => ProcessType.BackEnd;
+}

Connected.Configuration/ConfigurationStart.cs

@@ -0,0 +1,16 @@
+using Connected.Annotations;
+using Connected.Configuration.Environment;
+using Microsoft.Extensions.DependencyInjection;
+
+[assembly: MicroService(MicroServiceType.Sys)]
+
+namespace Connected.Configuration;
+
+internal class ConfigurationStart : Startup
+{
+	protected override void OnConfigureServices(IServiceCollection services)
+	{
+		services.AddSingleton(typeof(IConfigurationService), typeof(ConfigurationService));
+		services.AddSingleton(typeof(IEnvironmentService), typeof(EnvironmentService));
+	}
+}

Connected.Configuration/ConfigurationUrls.cs

@@ -0,0 +1,7 @@
+namespace Connected.Configuration
+{
+	public static class ConfigurationUrls
+	{
+		public const string Settings = "/configuration/settings";
+	}
+}

Connected.Configuration/Connected.Configuration.csproj

@@ -0,0 +1,13 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net7.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Connected.Runtime\Connected.Runtime.csproj" />
+  </ItemGroup>
+
+</Project>

Connected.Configuration/DatabaseConfiguration.cs

@@ -0,0 +1,23 @@
+using System.Collections.Immutable;
+
+namespace Connected.Configuration
+{
+	internal class DatabaseConfiguration : IDatabaseConfiguration
+	{
+		private List<string> _shards;
+
+		public DatabaseConfiguration()
+		{
+			/*
+			 * TODO: read from config
+			 */
+			DefaultConnectionString = "server=PIT-ZBOOK\\sqlexpress; database=connected; trusted_connection=true;TrustServerCertificate=True;multiple active result sets=true";
+
+			_shards = new();
+		}
+
+		public string? DefaultConnectionString { get; init; }
+
+		public ImmutableList<string> Shards => _shards.ToImmutableList();
+	}
+}

Connected.Configuration/Endpoints/EndpointConfiguration.cs

@@ -0,0 +1,7 @@
+namespace Connected.Configuration.Endpoints
+{
+	internal sealed class EndpointConfiguration : IEndpointConfiguration
+	{
+		public string? Address { get; set; }
+	}
+}

Connected.Configuration/Endpoints/IEndpointConfiguration.cs

@@ -0,0 +1,7 @@
+namespace Connected.Configuration.Endpoints
+{
+	public interface IEndpointConfiguration
+	{
+		string Address { get; }
+	}
+}

Connected.Configuration/Environment/EnvironmentService.cs

@@ -0,0 +1,33 @@
+using System.Collections.Immutable;
+using System.Reflection;
+using Connected.Annotations;
+
+namespace Connected.Configuration.Environment;
+
+internal class EnvironmentService : IEnvironmentService
+{
+	private List<Assembly>? _assemblies;
+	public List<Assembly> All => _assemblies ??= QueryAssemblies();
+
+	public EnvironmentService()
+	{
+		Services = new EnvironmentServices();
+	}
+
+	public ImmutableList<Assembly> MicroServices => All.ToImmutableList();
+
+	public IEnvironmentServices Services { get; }
+
+	private static List<Assembly> QueryAssemblies()
+	{
+		var result = new List<Assembly>();
+
+		foreach (var assembly in AppDomain.CurrentDomain.GetAssemblies())
+		{
+			if (assembly.GetCustomAttribute<MicroServiceAttribute>() is not null)
+				result.Add(assembly);
+		}
+
+		return result;
+	}
+}

Connected.Configuration/Environment/EnvironmentServices.cs

@@ -0,0 +1,17 @@
+using System.Collections.Immutable;
+
+namespace Connected.Configuration.Environment
+{
+	internal class EnvironmentServices : IEnvironmentServices
+	{
+		public ImmutableList<Type> Services => RegisteredServices.Services;
+
+		public ImmutableList<Type> ServiceMethods => RegisteredServices.ServiceOperations;
+
+		public ImmutableList<Type> Arguments => RegisteredServices.Arguments;
+
+		public ImmutableList<Type> IoCEndpoints => RegisteredServices.Middleware;
+
+		public ImmutableList<Type> EntityCache => RegisteredServices.EntityCache;
+	}
+}

Connected.Configuration/Environment/IEnvironmentService.cs

@@ -0,0 +1,12 @@
+using System.Collections.Immutable;
+using System.Reflection;
+
+namespace Connected.Configuration.Environment
+{
+	public interface IEnvironmentService
+	{
+		ImmutableList<Assembly> MicroServices { get; }
+
+		IEnvironmentServices Services { get; }
+	}
+}

Connected.Configuration/Environment/IEnvironmentServices.cs

@@ -0,0 +1,13 @@
+using System.Collections.Immutable;
+
+namespace Connected.Configuration.Environment
+{
+	public interface IEnvironmentServices
+	{
+		ImmutableList<Type> Services { get; }
+		ImmutableList<Type> ServiceMethods { get; }
+		ImmutableList<Type> Arguments { get; }
+		ImmutableList<Type> IoCEndpoints { get; }
+		ImmutableList<Type> EntityCache { get; }
+	}
+}

Connected.Configuration/IConfigurationService.cs

@@ -0,0 +1,21 @@
+using Connected.Configuration.Authentication;
+using Connected.Configuration.Endpoints;
+
+namespace Connected.Configuration;
+
+public enum ProcessType
+{
+	FrontEnd = 1,
+	BackEnd = 2,
+	Service = 3
+}
+
+public interface IConfigurationService
+{
+	IEndpointConfiguration Endpoint { get; }
+
+	IAuthenticationConfiguration Authentication { get; }
+	IStorageConfiguration Storage { get; }
+
+	ProcessType Type { get; }
+}

Connected.Configuration/IDatabaseConfiguration.cs

@@ -0,0 +1,11 @@
+using System.Collections.Immutable;
+
+namespace Connected.Configuration
+{
+	public interface IDatabaseConfiguration
+	{
+		string DefaultConnectionString { get; }
+
+		ImmutableList<string> Shards { get; }
+	}
+}

Connected.Configuration/IStorageConfiguration.cs

@@ -0,0 +1,7 @@
+namespace Connected.Configuration
+{
+	public interface IStorageConfiguration
+	{
+		IDatabaseConfiguration Databases { get; }
+	}
+}

Connected.Configuration/RegisteredServices.cs

@@ -0,0 +1,56 @@
+using System.Collections.Immutable;
+
+namespace Connected.Configuration
+{
+	public static class RegisteredServices
+	{
+		private static readonly List<Type> _services;
+		private static readonly List<Type> _serviceOperations;
+		private static readonly List<Type> _arguments;
+		private static readonly List<Type> _middleware;
+		private static readonly List<Type> _entityCache;
+
+		static RegisteredServices()
+		{
+			_services = new List<Type>();
+			_serviceOperations = new List<Type>();
+			_arguments = new List<Type>();
+			_middleware = new List<Type>();
+			_entityCache = new List<Type>();
+		}
+
+		public static ImmutableList<Type> Services => _services.ToImmutableList();
+
+		public static ImmutableList<Type> ServiceOperations => _serviceOperations.ToImmutableList();
+
+		public static ImmutableList<Type> Arguments => _arguments.ToImmutableList();
+		public static ImmutableList<Type> Middleware => _middleware.ToImmutableList();
+
+		public static ImmutableList<Type> EntityCache => _entityCache.ToImmutableList();
+
+		public static void AddApiService(Type type)
+		{
+			_services.Add(type);
+		}
+
+		public static void AddApi(Type type)
+		{
+			_serviceOperations.Add(type);
+		}
+
+		public static void AddArgument(Type type)
+		{
+			_arguments.Add(type);
+		}
+
+		public static void AddMiddleware(Type type)
+		{
+			_middleware.Add(type);
+		}
+
+		public static void AddEntityCache(Type type)
+		{
+			_entityCache.Add(type);
+		}
+	}
+}

Connected.Configuration/Settings/ISetting.cs

@@ -0,0 +1,9 @@
+using Connected.Data;
+
+namespace Connected.Configuration.Settings;
+
+public interface ISetting : IPrimaryKey<int>
+{
+	string Name { get; init; }
+	string Value { get; init; }
+}

Connected.Configuration/Settings/ISettingsService.cs

@@ -0,0 +1,25 @@
+using System.Collections.Immutable;
+using Connected.Annotations;
+using Connected.ServiceModel;
+
+namespace Connected.Configuration.Settings;
+
+[Service]
+[ServiceUrl(ConfigurationUrls.Settings)]
+public interface ISettingsService
+{
+	[ServiceMethod(ServiceMethodVerbs.Get | ServiceMethodVerbs.Post)]
+	Task<ISetting?> Select(PrimaryKeyArgs<int> args);
+
+	[ServiceMethod(ServiceMethodVerbs.Get | ServiceMethodVerbs.Post)]
+	Task<ISetting?> Select(NameArgs args);
+
+	[ServiceMethod(ServiceMethodVerbs.Get)]
+	Task<ImmutableList<ISetting>> Query();
+
+	[ServiceMethod(ServiceMethodVerbs.Post | ServiceMethodVerbs.Patch)]
+	Task Update(SettingsArgs args);
+
+	[ServiceMethod(ServiceMethodVerbs.Post | ServiceMethodVerbs.Delete)]
+	Task Delete(PrimaryKeyArgs<int> args);
+}

Connected.Configuration/Settings/SettingsArgs.cs

@@ -0,0 +1,14 @@
+using System.ComponentModel.DataAnnotations;
+using Connected.ServiceModel;
+
+namespace Connected.Configuration.Settings;
+
+public class SettingsArgs : Dto
+{
+	[Required]
+	[MaxLength(128)]
+	public string? Name { get; set; }
+
+	[MaxLength(1024)]
+	public string? Value { get; set; }
+}

Connected.Configuration/StorageConfiguration.cs

@@ -0,0 +1,12 @@
+namespace Connected.Configuration
+{
+	internal class StorageConfiguration : IStorageConfiguration
+	{
+		public StorageConfiguration()
+		{
+			Databases = new DatabaseConfiguration();
+		}
+
+		public IDatabaseConfiguration Databases { get; }
+	}
+}

Connected.Data/Annotations/ColumnAttribute.cs

@@ -0,0 +1,15 @@
+using Connected.Entities.Annotations;
+
+namespace Connected.Data.Annotations;
+
+[AttributeUsage(AttributeTargets.Property | AttributeTargets.Field, AllowMultiple = true)]
+internal sealed class ColumnAttribute : MemberAttribute
+{
+	public string? Name { get; set; }
+	public string? TableId { get; set; }
+	public string? DbType { get; set; }
+	public bool IsComputed { get; set; }
+	public bool IsPrimaryKey { get; set; }
+	public bool IsGenerated { get; set; }
+	public bool IsReadOnly { get; set; }
+}

Connected.Data/Annotations/MemberExtensionAttribute.cs

@@ -0,0 +1,8 @@
+namespace Connected.Data.Annotations
+{
+   [AttributeUsage(AttributeTargets.Property | AttributeTargets.Field)]
+   internal class MemberExtensionAttribute : Attribute
+   {
+      public string TableId { get; set; }
+   }
+}

Connected.Data/Annotations/NestedEntityAttribute.cs

@@ -0,0 +1,9 @@
+using Connected.Entities.Annotations;
+
+namespace Connected.Data.Annotations;
+
+[AttributeUsage(AttributeTargets.Property | AttributeTargets.Field, AllowMultiple = true)]
+internal class NestedEntityAttribute : MemberAttribute
+{
+	public Type? RuntimeType { get; set; }
+}

Connected.Data/Connected.Data.csproj

@@ -0,0 +1,40 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+	<PropertyGroup>
+		<TargetFramework>net7.0</TargetFramework>
+		<ImplicitUsings>enable</ImplicitUsings>
+		<Nullable>enable</Nullable>
+		<GenerateDocumentationFile>False</GenerateDocumentationFile>
+	</PropertyGroup>
+
+	<ItemGroup>
+		<PackageReference Include="Microsoft.Data.SqlClient" Version="5.1.0-preview1.22279.3" />
+	</ItemGroup>
+
+	<ItemGroup>
+		<ProjectReference Include="..\..\Connected\Connected\Connected.csproj" />
+		<ProjectReference Include="..\Connected.Caching\Connected.Caching.csproj" />
+		<ProjectReference Include="..\Connected.Entities\Connected.Entities.csproj" />
+		<ProjectReference Include="..\Connected.Expressions\Connected.Expressions.csproj" />
+		<ProjectReference Include="..\Connected.Globalization\Connected.Globalization.csproj" />
+		<ProjectReference Include="..\Connected.Interop\Connected.Interop.csproj" />
+		<ProjectReference Include="..\Connected.Threading\Connected.Threading.csproj" />
+		<ProjectReference Include="..\Connected.Validation\Connected.Validation.csproj" />
+	</ItemGroup>
+
+	<ItemGroup>
+		<Compile Update="SR.Designer.cs">
+			<DesignTime>True</DesignTime>
+			<AutoGen>True</AutoGen>
+			<DependentUpon>SR.resx</DependentUpon>
+		</Compile>
+	</ItemGroup>
+
+	<ItemGroup>
+		<EmbeddedResource Update="SR.resx">
+			<Generator>ResXFileCodeGenerator</Generator>
+			<LastGenOutput>SR.Designer.cs</LastGenOutput>
+		</EmbeddedResource>
+	</ItemGroup>
+
+</Project>

Connected.Data/DataExtensions.cs

@@ -0,0 +1,100 @@
+using Connected.Data.Storage;
+using Connected.Entities.Annotations;
+using Connected.Entities.Storage;
+using Connected.Interop;
+using Connected.ServiceModel;
+using System.Data;
+using System.Reflection;
+
+namespace Connected.Data;
+
+public static class DataExtensions
+{
+	/// <summary>
+	/// Sets <see cref="StorageConnectionMode.Isolated"/> value to the <see cref="IConnectionProvider"/> on the
+	/// provided <see cref="IContext"/>.
+	/// </summary>
+	/// <param name="context">The <see cref="IContext"/> to set the <see cref="StorageConnectionMode.Isolated"/> value.</param>
+	public static void UseIsolatedConnections(this IContext context)
+	{
+		if (context.GetService<IConnectionProvider>() is IConnectionProvider provider)
+			provider.Mode = StorageConnectionMode.Isolated;
+	}
+
+	public static DbType ToDbType(PropertyInfo property)
+	{
+		var type = property.PropertyType;
+
+		if (type.IsEnum)
+			type = Enum.GetUnderlyingType(type);
+
+		if (type == typeof(char) || type == typeof(string))
+		{
+			if (property.FindAttribute<ETagAttribute>() != null)
+				return DbType.Binary;
+
+			var str = property.FindAttribute<StringAttribute>();
+
+			if (str is null)
+				return DbType.String;
+
+			return str.Kind switch
+			{
+				StringKind.NVarChar => DbType.String,
+				StringKind.VarChar => DbType.AnsiString,
+				StringKind.Char => DbType.AnsiStringFixedLength,
+				StringKind.NChar => DbType.StringFixedLength,
+				_ => DbType.String,
+			};
+		}
+		else if (type == typeof(byte))
+			return DbType.Byte;
+		else if (type == typeof(bool))
+			return DbType.Boolean;
+		else if (type == typeof(DateTime) || type == typeof(DateTimeOffset))
+		{
+			var att = property.FindAttribute<DateAttribute>();
+
+			if (att is null)
+				return DbType.DateTime2;
+
+			return att.Kind switch
+			{
+				DateKind.Date => DbType.Date,
+				DateKind.DateTime => DbType.DateTime,
+				DateKind.DateTime2 => DbType.DateTime2,
+				DateKind.SmallDateTime => DbType.DateTime,
+				DateKind.Time => DbType.Time,
+				_ => DbType.DateTime2,
+			};
+		}
+		else if (type == typeof(decimal))
+			return DbType.Decimal;
+		else if (type == typeof(double))
+			return DbType.Double;
+		else if (type == typeof(Guid))
+			return DbType.Guid;
+		else if (type == typeof(short))
+			return DbType.Int16;
+		else if (type == typeof(int))
+			return DbType.Int32;
+		else if (type == typeof(long))
+			return DbType.Int64;
+		else if (type == typeof(sbyte))
+			return DbType.SByte;
+		else if (type == typeof(float))
+			return DbType.Single;
+		else if (type == typeof(TimeSpan))
+			return DbType.Time;
+		else if (type == typeof(ushort))
+			return DbType.UInt16;
+		else if (type == typeof(uint))
+			return DbType.UInt32;
+		else if (type == typeof(ulong))
+			return DbType.UInt64;
+		else if (type == typeof(byte[]))
+			return DbType.Binary;
+		else
+			return DbType.Binary;
+	}
+}

Connected.Data/DataStartup.cs

@@ -0,0 +1,23 @@
+using Connected.Annotations;
+using Connected.Data.DataProtection;
+using Connected.Data.Schema;
+using Connected.Data.Sharding;
+using Connected.Data.Storage;
+using Connected.Entities.Storage;
+using Microsoft.Extensions.DependencyInjection;
+
+[assembly: MicroService(MicroServiceType.Sys)]
+
+namespace Connected.Data;
+
+internal sealed class DataStartup : Startup
+{
+	protected override void OnConfigureServices(IServiceCollection services)
+	{
+		services.AddScoped(typeof(ISchemaService), typeof(SchemaService));
+		services.AddScoped(typeof(IShardingService), typeof(ShardingService));
+		services.AddScoped(typeof(IConnectionProvider), typeof(ConnectionProvider));
+		services.AddScoped(typeof(IStorageProvider), typeof(StorageProvider));
+		services.AddScoped(typeof(IEntityProtectionService), typeof(EntityProtectionService));
+	}
+}

Connected.Data/EntityProtection/EntityProtectionArgs.cs

@@ -0,0 +1,14 @@
+using Connected.Entities;
+
+namespace Connected.Data.EntityProtection;
+public sealed class EntityProtectionArgs<TEntity> : EventArgs
+{
+	public EntityProtectionArgs(TEntity entity, State state)
+	{
+		Entity = entity;
+		State = state;
+	}
+
+	public TEntity Entity { get; }
+	public State State { get; }
+}

Connected.Data/EntityProtection/EntityProtectionService.cs

@@ -0,0 +1,25 @@
+using Connected.Data.EntityProtection;
+using Connected.Middleware;
+
+namespace Connected.Data.DataProtection;
+
+internal class EntityProtectionService : IEntityProtectionService
+{
+	public EntityProtectionService(IMiddlewareService middleware)
+	{
+		Middleware = middleware;
+	}
+
+	public IMiddlewareService Middleware { get; }
+
+	public async Task Invoke<TEntity>(EntityProtectionArgs<TEntity> args)
+	{
+		var middleware = await Middleware.Query<IEntityProtector<TEntity>>();
+
+		if (!middleware.Any())
+			return;
+
+		foreach (var m in middleware)
+			await m.Invoke(args);
+	}
+}

Connected.Data/EntityProtection/IEntityProtectionService.cs

@@ -0,0 +1,9 @@
+using Connected.Data.EntityProtection;
+
+namespace Connected.Data.DataProtection
+{
+	public interface IEntityProtectionService
+	{
+		Task Invoke<TEntity>(EntityProtectionArgs<TEntity> args);
+	}
+}

Connected.Data/EntityProtection/IEntityProtector.cs

@@ -0,0 +1,8 @@
+using Connected.Data.EntityProtection;
+
+namespace Connected.Data.DataProtection;
+
+public interface IEntityProtector<TEntity> : IMiddleware
+{
+	Task Invoke(EntityProtectionArgs<TEntity> args);
+}

Connected.Data/EntityVersion.cs

@@ -0,0 +1,125 @@
+using Connected.Interop;
+
+namespace Connected.Data;
+
+internal class EntityVersion : IComparable, IEquatable<EntityVersion>, IComparable<EntityVersion>
+{
+	public static readonly EntityVersion? Zero = default;
+
+	private readonly ulong Value;
+
+	private EntityVersion(ulong value)
+	{
+		Value = value;
+	}
+
+	public static EntityVersion? Parse(object value)
+	{
+		if (!TypeConversion.TryConvert(value, out string? v))
+			return Zero;
+
+		if (string.IsNullOrWhiteSpace(v))
+			return Zero;
+
+		return new EntityVersion(Convert.ToUInt64(v, 16));
+	}
+
+	public static implicit operator EntityVersion(ulong value)
+	{
+		return new EntityVersion(value);
+	}
+
+	public static implicit operator EntityVersion(long value)
+	{
+		return new EntityVersion(unchecked((ulong)value));
+	}
+
+	public static explicit operator EntityVersion?(byte[] value)
+	{
+		if (value is null)
+			return null;
+
+		return new EntityVersion((ulong)value[0] << 56 | (ulong)value[1] << 48 | (ulong)value[2] << 40 | (ulong)value[3] << 32 | (ulong)value[4] << 24 | (ulong)value[5] << 16 | (ulong)value[6] << 8 | value[7]);
+	}
+
+	public static implicit operator byte[](EntityVersion timestamp)
+	{
+		var r = new byte[8];
+
+		r[0] = (byte)(timestamp.Value >> 56);
+		r[1] = (byte)(timestamp.Value >> 48);
+		r[2] = (byte)(timestamp.Value >> 40);
+		r[3] = (byte)(timestamp.Value >> 32);
+		r[4] = (byte)(timestamp.Value >> 24);
+		r[5] = (byte)(timestamp.Value >> 16);
+		r[6] = (byte)(timestamp.Value >> 8);
+		r[7] = (byte)timestamp.Value;
+
+		return r;
+	}
+
+	public override bool Equals(object? obj)
+	{
+		return obj is Version version && Equals(version);
+	}
+
+	public override int GetHashCode()
+	{
+		return Value.GetHashCode();
+	}
+
+	public bool Equals(EntityVersion? other)
+	{
+		return other?.Value == Value;
+	}
+
+	int IComparable.CompareTo(object? obj)
+	{
+		return obj is null ? 1 : CompareTo((EntityVersion)obj);
+	}
+
+	public int CompareTo(EntityVersion? other)
+	{
+		return Value == other?.Value ? 0 : Value < other?.Value ? -1 : 1;
+	}
+
+	public static bool operator ==(EntityVersion comparand1, EntityVersion comparand2)
+	{
+		return comparand1.Equals(comparand2);
+	}
+
+	public static bool operator !=(EntityVersion comparand1, EntityVersion comparand2)
+	{
+		return !comparand1.Equals(comparand2);
+	}
+
+	public static bool operator >(EntityVersion comparand1, EntityVersion comparand2)
+	{
+		return comparand1.CompareTo(comparand2) > 0;
+	}
+
+	public static bool operator >=(EntityVersion comparand1, EntityVersion comparand2)
+	{
+		return comparand1.CompareTo(comparand2) >= 0;
+	}
+
+	public static bool operator <(EntityVersion comparand1, EntityVersion comparand2)
+	{
+		return comparand1.CompareTo(comparand2) < 0;
+	}
+
+	public static bool operator <=(EntityVersion comparand1, EntityVersion comparand2)
+	{
+		return comparand1.CompareTo(comparand2) <= 0;
+	}
+
+	public override string ToString()
+	{
+		return Value.ToString("x16");
+	}
+
+	public static EntityVersion Max(EntityVersion comparand1, EntityVersion comparand2)
+	{
+		return comparand1.Value < comparand2.Value ? comparand2 : comparand1;
+	}
+}

Connected.Data/FieldMappings.cs

@@ -0,0 +1,192 @@
+using Connected.Entities.Annotations;
+using Connected.Interop;
+using System.Data;
+using System.Reflection;
+
+namespace Connected.Data;
+/// <summary>
+/// Performs mapping between <see cref="IDataReader"/> fields and entity properties.
+/// </summary>
+/// <typeparam name="TEntity">The entity type to be used.</typeparam>
+internal class FieldMappings<TEntity>
+{
+	private Dictionary<int, PropertyInfo> _properties;
+	/// <summary>
+	/// Creates a new <see cref="FieldMappings{TEntity}"/> object.
+	/// </summary>
+	/// <param name="reader">The <see cref="IDataReader"/> providing entity records.</param>
+	public FieldMappings(IDataReader reader)
+	{
+		Initialize(reader);
+	}
+	/// <summary>
+	/// Cached properties use when looping through the records.
+	/// </summary>
+	private Dictionary<int, PropertyInfo> Properties => _properties;
+	/// <summary>
+	/// Initializes the mappings base on the provided <see cref="IDataReader"/>
+	/// and <typeparamref name="TEntity"/>
+	/// </summary>
+	/// <param name="reader">The active reader containing records.</param>
+	private void Initialize(IDataReader reader)
+	{
+		/*
+		 * For primitive types there are no mappings since it's an scalar call.
+		 */
+		if (typeof(TEntity).IsTypePrimitive())
+			return;
+
+		_properties = new Dictionary<int, PropertyInfo>();
+		/*
+		 * We are binding only properties, not fields.
+		 */
+		var properties = typeof(TEntity).GetProperties(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance);
+
+		for (var i = 0; i < reader.FieldCount; i++)
+		{
+			if (FieldMappings<TEntity>.ResolveProperty(properties, reader.GetName(i)) is PropertyInfo property)
+				_properties.Add(i, property);
+		}
+	}
+	/// <summary>
+	/// Creates a new instance of the <see cref="TEntity"/> and binds
+	/// properties from the provided <see cref="IDataReader"/>.
+	/// </summary>
+	/// <param name="reader">The <see cref="IDataReader"/> containing the record.</param>
+	/// <returns>A new instance of the <see cref="TEntity"/> with bound values from the <see cref="IDataReader"/>.</returns>
+	public TEntity? CreateInstance(IDataReader reader)
+	{
+		/*
+		 * For primitive return values we'll use only the first field and return itž
+		 * to the caller.
+		 */
+		if (typeof(TEntity).IsTypePrimitive())
+		{
+			if (reader.FieldCount == 0)
+				return default;
+
+			if (TypeConversion.TryConvert(reader[0], out TEntity? result))
+				return result;
+
+			return default;
+		}
+		/*
+		 * It's an actual entity. First, create a new instance. Entities should have
+		 * public parameterless constructor.
+		 */
+		if (typeof(TEntity?).CreateInstance<TEntity>() is not TEntity instance)
+			throw new NullReferenceException(typeof(TEntity).FullName);
+
+		foreach (var property in Properties)
+			Bind(instance, property, reader);
+
+		return instance;
+	}
+	/// <summary>
+	/// Resolves a correct property from the entity's properties based on a <see cref="IDataReader"/> field name.
+	/// </summary>
+	/// <param name="properties">The entity's properties.</param>
+	/// <param name="name">The <see cref="IDataReader"/> field name.</param>
+	/// <returns>A <see cref="PropertyInfo"/> if found, <c>null</c> otherwise.</returns>
+	private static PropertyInfo? ResolveProperty(PropertyInfo[] properties, string name)
+	{
+		/*
+		 * There are two ways to map a property (evaluated in the following order):
+		 * 1. from property name
+		 * 2. from MemberAttribute
+		 * 
+		 * We'll first perform case insensitive comparison because fields in the database are usually stored in a camelCase format.
+		 */
+		if (properties.FirstOrDefault(f => string.Equals(f.Name, name, StringComparison.OrdinalIgnoreCase)) is PropertyInfo property && property.CanWrite)
+		{
+			/*
+			 * Property is found, examine if the persistence from the storage is supported.
+			 */
+			var att = property.FindAttribute<PersistenceAttribute>();
+
+			if (att is null || att.Persistence.HasFlag(ColumnPersistence.Read))
+				return property;
+		}
+		/*
+		 * Property wasn't found, let's try to find it via MemberAttribute.
+		 */
+		foreach (var prop in properties)
+		{
+			/*
+			 * It's case insensitive comparison again because we don't want bother user with exact matching. Since a database is probably case insensitive anyway
+			 * there is no option to store columns with case sensitive names.
+			 */
+			if (prop.FindAttribute<MemberAttribute>() is MemberAttribute nameAttribute && string.Compare(nameAttribute.Member, name, true) == 0 && prop.CanWrite)
+				return prop;
+		}
+		/*
+		 * Property could't be found. The field will be ognored when reading data.
+		 */
+		return default;
+	}
+	/// <summary>
+	/// Binds the <see cref="IDataReader"/> value to the entity's property.
+	/// </summary>
+	/// <param name="instance">The instance of the entity.</param>
+	/// <param name="property">The property on which value to be set.</param>
+	/// <param name="reader">The <see cref="IDataReader"/>providing the value.</param>
+	private static void Bind(object instance, KeyValuePair<int, PropertyInfo> property, IDataReader reader)
+	{
+		var value = reader.GetValue(property.Key);
+		/*
+		 * We won't bind null values. We'll leave the property as is.
+		 */
+		if (value is null || Convert.IsDBNull(value))
+			return;
+		/*
+		 * We have a few exceptions when binding values.
+		 */
+		if (property.Value.PropertyType == typeof(string) && value is byte[] bv)
+		{
+			/*
+			 * If the property is string and the reader's value is byte array we are probably dealing
+			 * with Consistency field. We'll first check if the property contains the attribute. If so,
+			 * we'll convert byte array to eTag kind of value. If not we'll simply convert value to base64
+			 * string.
+			 */
+			if (property.Value.FindAttribute<ETagAttribute>() is not null)
+			{
+				var versionValue = (EntityVersion?)bv;
+
+				if (versionValue is null)
+					value = Convert.ToBase64String(bv);
+				else
+					value = versionValue.ToString();
+			}
+			else
+				value = Convert.ToBase64String(bv);
+		}
+		else if (property.Value.PropertyType == typeof(DateTimeOffset))
+		{
+			/*
+			 * We don't perform any conversions on dates. All dates should be stored in a UTC
+			 * format so we simply set the correct kind of date so it can be later correctly
+			 * converted
+			 */
+			value = new DateTimeOffset(DateTime.SpecifyKind((DateTime)value, DateTimeKind.Utc));
+		}
+		else if (property.Value.PropertyType == typeof(DateTime))
+		{
+			/*
+			 * Like DateTimeOffset, the same is true for DateTime values
+			 */
+			value = DateTime.SpecifyKind((DateTime)value, DateTimeKind.Utc);
+		}
+		else
+		{
+			/*
+			 * For other values we just perform a conversion.
+			 */
+			value = TypeConversion.Convert(value, property.Value.PropertyType);
+		}
+		/*
+		 * Now bind the property from the converted value.
+		 */
+		property.Value.SetValue(instance, value);
+	}
+}

Connected.Data/SR.Designer.cs

@@ -0,0 +1,72 @@
+//------------------------------------------------------------------------------
+// <auto-generated>
+//     This code was generated by a tool.
+//     Runtime Version:4.0.30319.42000
+//
+//     Changes to this file may cause incorrect behavior and will be lost if
+//     the code is regenerated.
+// </auto-generated>
+//------------------------------------------------------------------------------
+
+namespace Connected.Data {
+    using System;
+    
+    
+    /// <summary>
+    ///   A strongly-typed resource class, for looking up localized strings, etc.
+    /// </summary>
+    // This class was auto-generated by the StronglyTypedResourceBuilder
+    // class via a tool like ResGen or Visual Studio.
+    // To add or remove a member, edit your .ResX file then rerun ResGen
+    // with the /str option, or rebuild your VS project.
+    [global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Resources.Tools.StronglyTypedResourceBuilder", "17.0.0.0")]
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
+    [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]
+    internal class SR {
+        
+        private static global::System.Resources.ResourceManager resourceMan;
+        
+        private static global::System.Globalization.CultureInfo resourceCulture;
+        
+        [global::System.Diagnostics.CodeAnalysis.SuppressMessageAttribute("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
+        internal SR() {
+        }
+        
+        /// <summary>
+        ///   Returns the cached ResourceManager instance used by this class.
+        /// </summary>
+        [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Advanced)]
+        internal static global::System.Resources.ResourceManager ResourceManager {
+            get {
+                if (object.ReferenceEquals(resourceMan, null)) {
+                    global::System.Resources.ResourceManager temp = new global::System.Resources.ResourceManager("Connected.Data.SR", typeof(SR).Assembly);
+                    resourceMan = temp;
+                }
+                return resourceMan;
+            }
+        }
+        
+        /// <summary>
+        ///   Overrides the current thread's CurrentUICulture property for all
+        ///   resource lookups using this strongly typed resource class.
+        /// </summary>
+        [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Advanced)]
+        internal static global::System.Globalization.CultureInfo Culture {
+            get {
+                return resourceCulture;
+            }
+            set {
+                resourceCulture = value;
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Data concurrency issue occured.
+        /// </summary>
+        internal static string ErrDataConcurrency {
+            get {
+                return ResourceManager.GetString("ErrDataConcurrency", resourceCulture);
+            }
+        }
+    }
+}

Connected.Data/SR.resx

@@ -0,0 +1,123 @@
+<?xml version="1.0" encoding="utf-8"?>
+<root>
+  <!-- 
+    Microsoft ResX Schema 
+    
+    Version 2.0
+    
+    The primary goals of this format is to allow a simple XML format 
+    that is mostly human readable. The generation and parsing of the 
+    various data types are done through the TypeConverter classes 
+    associated with the data types.
+    
+    Example:
+    
+    ... ado.net/XML headers & schema ...
+    <resheader name="resmimetype">text/microsoft-resx</resheader>
+    <resheader name="version">2.0</resheader>
+    <resheader name="reader">System.Resources.ResXResourceReader, System.Windows.Forms, ...</resheader>
+    <resheader name="writer">System.Resources.ResXResourceWriter, System.Windows.Forms, ...</resheader>
+    <data name="Name1"><value>this is my long string</value><comment>this is a comment</comment></data>
+    <data name="Color1" type="System.Drawing.Color, System.Drawing">Blue</data>
+    <data name="Bitmap1" mimetype="application/x-microsoft.net.object.binary.base64">
+        <value>[base64 mime encoded serialized .NET Framework object]</value>
+    </data>
+    <data name="Icon1" type="System.Drawing.Icon, System.Drawing" mimetype="application/x-microsoft.net.object.bytearray.base64">
+        <value>[base64 mime encoded string representing a byte array form of the .NET Framework object]</value>
+        <comment>This is a comment</comment>
+    </data>
+                
+    There are any number of "resheader" rows that contain simple 
+    name/value pairs.
+    
+    Each data row contains a name, and value. The row also contains a 
+    type or mimetype. Type corresponds to a .NET class that support 
+    text/value conversion through the TypeConverter architecture. 
+    Classes that don't support this are serialized and stored with the 
+    mimetype set.
+    
+    The mimetype is used for serialized objects, and tells the 
+    ResXResourceReader how to depersist the object. This is currently not 
+    extensible. For a given mimetype the value must be set accordingly:
+    
+    Note - application/x-microsoft.net.object.binary.base64 is the format 
+    that the ResXResourceWriter will generate, however the reader can 
+    read any of the formats listed below.
+    
+    mimetype: application/x-microsoft.net.object.binary.base64
+    value   : The object must be serialized with 
+            : System.Runtime.Serialization.Formatters.Binary.BinaryFormatter
+            : and then encoded with base64 encoding.
+    
+    mimetype: application/x-microsoft.net.object.soap.base64
+    value   : The object must be serialized with 
+            : System.Runtime.Serialization.Formatters.Soap.SoapFormatter
+            : and then encoded with base64 encoding.
+
+    mimetype: application/x-microsoft.net.object.bytearray.base64
+    value   : The object must be serialized into a byte array 
+            : using a System.ComponentModel.TypeConverter
+            : and then encoded with base64 encoding.
+    -->
+  <xsd:schema id="root" xmlns="" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
+    <xsd:import namespace="http://www.w3.org/XML/1998/namespace" />
+    <xsd:element name="root" msdata:IsDataSet="true">
+      <xsd:complexType>
+        <xsd:choice maxOccurs="unbounded">
+          <xsd:element name="metadata">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" />
+              </xsd:sequence>
+              <xsd:attribute name="name" use="required" type="xsd:string" />
+              <xsd:attribute name="type" type="xsd:string" />
+              <xsd:attribute name="mimetype" type="xsd:string" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="assembly">
+            <xsd:complexType>
+              <xsd:attribute name="alias" type="xsd:string" />
+              <xsd:attribute name="name" type="xsd:string" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="data">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+                <xsd:element name="comment" type="xsd:string" minOccurs="0" msdata:Ordinal="2" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" msdata:Ordinal="1" />
+              <xsd:attribute name="type" type="xsd:string" msdata:Ordinal="3" />
+              <xsd:attribute name="mimetype" type="xsd:string" msdata:Ordinal="4" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="resheader">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" />
+            </xsd:complexType>
+          </xsd:element>
+        </xsd:choice>
+      </xsd:complexType>
+    </xsd:element>
+  </xsd:schema>
+  <resheader name="resmimetype">
+    <value>text/microsoft-resx</value>
+  </resheader>
+  <resheader name="version">
+    <value>2.0</value>
+  </resheader>
+  <resheader name="reader">
+    <value>System.Resources.ResXResourceReader, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <resheader name="writer">
+    <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <data name="ErrDataConcurrency" xml:space="preserve">
+    <value>Data concurrency issue occured</value>
+  </data>
+</root>

Connected.Data/Schema/EntitySchema.cs

@@ -0,0 +1,38 @@
+namespace Connected.Data.Schema
+{
+	internal class EntitySchema : ISchema
+	{
+		public EntitySchema()
+		{
+			Columns = new();
+		}
+		public List<ISchemaColumn> Columns { get; }
+
+		public string? Schema { get; set; }
+		public string? Name { get; set; }
+		public string? Type { get; set; }
+		public bool Ignore { get; set; }
+		public bool Equals(ISchema? other)
+		{
+			if (other is null)
+				return false;
+
+			if (!string.Equals(Name, other.Name, StringComparison.Ordinal))
+				return false;
+
+			if (!string.Equals(Schema, other.Schema, StringComparison.Ordinal))
+				return false;
+
+			if (Columns.Count != other.Columns.Count)
+				return false;
+
+			for (var i = 0; i < Columns.Count; i++)
+			{
+				if (Columns[i] is not IEquatable<ISchemaColumn> left || !left.Equals(other.Columns[i]))
+					return false;
+			}
+
+			return true;
+		}
+	}
+}

Connected.Data/Schema/ExistingColumn.cs

@@ -0,0 +1,62 @@
+using System.Collections.Immutable;
+using System.Data;
+using Connected.Data.Schema.Sql;
+using Connected.Entities.Annotations;
+
+namespace Connected.Data.Schema;
+
+internal class ExistingColumn : ISchemaColumn, IExistingSchemaColumn
+{
+	public ExistingColumn(ISchema schema)
+	{
+		Schema = schema;
+	}
+
+	private ISchema Schema { get; }
+
+	public string Name { get; set; }
+
+	public DbType DataType { get; set; }
+
+	public bool IsIdentity { get; set; }
+	public bool IsVersion { get; set; }
+
+	public bool IsUnique { get; set; }
+
+	public bool IsIndex { get; set; }
+
+	public bool IsPrimaryKey { get; set; }
+
+	public string DefaultValue { get; set; }
+
+	public int MaxLength { get; set; }
+
+	public bool IsNullable { get; set; }
+
+	public string DependencyType { get; set; }
+
+	public string DependencyProperty { get; set; }
+
+	public string Index { get; set; }
+	public int Precision { get; set; }
+	public int Scale { get; set; }
+
+	public DateKind DateKind { get; set; } = DateKind.DateTime;
+	public BinaryKind BinaryKind { get; set; } = BinaryKind.VarBinary;
+
+	public int DatePrecision { get; set; }
+
+	public ImmutableArray<string> QueryIndexColumns(string column)
+	{
+		if (Schema is not ExistingSchema existing)
+			return ImmutableArray<string>.Empty;
+
+		foreach (var index in existing.Indexes)
+		{
+			if (index.Columns.Contains(column, StringComparer.OrdinalIgnoreCase))
+				return index.Columns.ToImmutableArray();
+		}
+
+		return ImmutableArray<string>.Empty;
+	}
+}

Connected.Data/Schema/IDatabase.cs

@@ -0,0 +1,7 @@
+namespace Connected.Data.Schema
+{
+	internal interface IDatabase
+	{
+		List<ITable> Tables { get; }
+	}
+}

Connected.Data/Schema/IExistingSchemaColumn.cs

@@ -0,0 +1,9 @@
+using System.Collections.Immutable;
+
+namespace Connected.Data.Schema
+{
+	internal interface IExistingSchemaColumn
+	{
+		ImmutableArray<string> QueryIndexColumns(string column);
+	}
+}

Connected.Data/Schema/IReferentialConstraint.cs

@@ -0,0 +1,12 @@
+namespace Connected.Data.Schema
+{
+	internal interface IReferentialConstraint
+	{
+		string Name { get; }
+		string ReferenceSchema { get; }
+		string ReferenceName { get; }
+		string MatchOption { get; }
+		string UpdateRule { get; }
+		string DeleteRule { get; }
+	}
+}

Connected.Data/Schema/ISchema.cs

@@ -0,0 +1,12 @@
+namespace Connected.Data.Schema
+{
+	public interface ISchema : IEquatable<ISchema>
+	{
+		List<ISchemaColumn> Columns { get; }
+
+		string? Schema { get; }
+		string? Name { get; }
+		string? Type { get; }
+		bool Ignore { get; }
+	}
+}

Connected.Data/Schema/ISchemaColumn.cs

@@ -0,0 +1,24 @@
+using System.Data;
+using Connected.Entities.Annotations;
+
+namespace Connected.Data.Schema;
+
+public interface ISchemaColumn
+{
+	string? Name { get; }
+	DbType DataType { get; }
+	bool IsIdentity { get; }
+	bool IsUnique { get; }
+	bool IsIndex { get; }
+	bool IsPrimaryKey { get; }
+	bool IsVersion { get; }
+	string? DefaultValue { get; }
+	int MaxLength { get; }
+	bool IsNullable { get; }
+	string? Index { get; }
+	int Scale { get; }
+	int Precision { get; }
+	DateKind DateKind { get; }
+	BinaryKind BinaryKind { get; }
+	int DatePrecision { get; }
+}

Connected.Data/Schema/ISchemaMiddleware.cs

@@ -0,0 +1,9 @@
+namespace Connected.Data.Schema;
+
+public interface ISchemaMiddleware : IMiddleware
+{
+	Task<bool> IsEntitySupported(Type entity);
+	Task Synchronize(Type entity, ISchema schema);
+	Type ConnectionType { get; }
+	string DefaultConnectionString { get; }
+}

Connected.Data/Schema/ISchemaService.cs

@@ -0,0 +1,7 @@
+namespace Connected.Data.Schema
+{
+	public interface ISchemaService
+	{
+		Task Synchronize(List<Type>? entities);
+	}
+}

Connected.Data/Schema/ISchemaSynchronizationContext.cs

@@ -0,0 +1,7 @@
+namespace Connected.Data.Schema;
+
+public interface ISchemaSynchronizationContext
+{
+    Type ConnectionType { get; }
+    string ConnectionString { get; }
+}

Connected.Data/Schema/ITable.cs

@@ -0,0 +1,8 @@
+namespace Connected.Data.Schema
+{
+    internal interface ITable : ISchema
+    {
+        List<ITableColumn> Columns { get; }
+        List<ITableIndex> Indexes { get; }
+    }
+}

Connected.Data/Schema/ITableColumn.cs

@@ -0,0 +1,22 @@
+namespace Connected.Data.Schema
+{
+    internal interface ITableColumn
+    {
+        string Name { get; }
+        string DataType { get; }
+        bool Identity { get; }
+        bool IsNullable { get; }
+        string DefaultValue { get; }
+        int Ordinal { get; }
+        int CharacterMaximumLength { get; }
+        int CharacterOctetLength { get; }
+        int NumericPrecision { get; }
+        int NumericPrecisionRadix { get; }
+        int NumericScale { get; }
+        int DateTimePrecision { get; }
+        string CharacterSetName { get; }
+
+        IReferentialConstraint Reference { get; }
+        List<ITableConstraint> Constraints { get; }
+    }
+}

Connected.Data/Schema/ITableConstraint.cs

@@ -0,0 +1,6 @@
+namespace Connected.Data.Schema
+{
+	internal interface ITableConstraint : ISchema
+	{
+	}
+}

Connected.Data/Schema/ITableIndex.cs

@@ -0,0 +1,8 @@
+namespace Connected.Data.Schema
+{
+    internal interface ITableIndex
+    {
+        string Name { get; }
+        List<string> Columns { get; }
+    }
+}