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MagicOnion

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Unified Realtime/API framework for .NET platform and Unity.

📖 Table of contents

About MagicOnion

MagicOnion is a modern RPC framework for .NET platform that provides bi-directional real-time communications such as SignalR and Socket.io and RPC mechanisms such as WCF and web-based APIs.

This framework is based on gRPC, which is a fast and compact binary network transport for HTTP/2. However, unlike plain gRPC, it treats C# interfaces as a protocol schema, enabling seamless code sharing between C# projects without .proto (Protocol Buffers IDL).

image

Interfaces are schemas and provide API services, just like the plain C# code

image

Using the StreamingHub real-time communication service, the server can broadcast data to multiple clients

MagicOnion can be adopted or replaced in the following use cases:

  • RPC services such as gRPC, used by Microservices, and WCF, commonly used by WinForms/WPF
  • API services such as ASP.NET Core MVC targeting Unity, Xamarin, and Windows clients
  • Bi-directional real-time communication such as Socket.io, SignalR, Photon and UNet

MagicOnion uses MessagePack for C# to serialize call arguments and return values. NET primitives and other complex types that can be serialized into MessagePack objects. See MessagePack for C# for details about serialization.

Requirements

MagicOnion server requires NET Core 3.1 or .NET 5.0+.

MagicOnion client supports a wide range of platforms, including .NET Framework 4.6.1 to .NET 5.0 as well as Unity.

  • Server-side (MagicOnion.Server)
    • .NET 5.0+
    • .NET Core 3.1
  • Client-side (MagicOnion.Client)
    • .NET Standard 2.1 (.NET Core 3.x+, .NET 5.0+, Xamarin)
    • .NET Standard 2.0 (.NET Framework 4.6.1+, Universal Windows Platform, .NET Core 2.x)
    • Unity 2018.3+

Quick Start

Server-side project

Setup a project for MagicOnion

First, you need to create a gRPC Service project from within Visual Studio or the .NET CLI tools. MagicOnion Server is built on top of ASP.NET Core and gRPC, so the server project must be an ASP.NET Core project.

When you create a project, it contains Protos and Services folders, which are not needed in MagicOnion projects and should be removed.

Add NuGet package MagicOnion.Server to your project. If you are using the .NET CLI tools to add it, you can run the following command.

dotnet add package MagicOnion.Server

Open Startup.cs and add the following line to ConfigureServices method.

services.AddMagicOnion();

app.UseEndpoints call in Configure method is rewritten as follows.

app.UseEndpoints(endpoints =>
{
    endpoints.MapMagicOnionService();

    endpoints.MapGet("/", async context =>
    {
        await context.Response.WriteAsync("Communication with gRPC endpoints must be made through a gRPC client. To learn how to create a client, visit: https://go.microsoft.com/fwlink/?linkid=2086909");
    });
});

The complete Startup.cs will look like this:

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;
namespace MyApp
{
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddGrpc();
            services.AddMagicOnion(); // Add this line
        }
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            app.UseRouting();
            app.UseEndpoints(endpoints =>
            {
                // Replace to this line instead of MapGrpcService<GreeterService>()
                endpoints.MapMagicOnionService();
                endpoints.MapGet("/", async context =>
                {
                    await context.Response.WriteAsync("Communication with gRPC endpoints must be made through a gRPC client. To learn how to create a client, visit: https://go.microsoft.com/fwlink/?linkid=2086909");
                });
            });
        }
    }
}

Now you are ready to use MagicOnion on your server project.

Implements a service on MagicOnion

MagicOnion provides a Web API-like RPC service and a StreamingHub for real-time communication. This section implements a Web API-like RPC service.

Add an IMyFirstService interface to be shared between the server and the client (namespace should match the project).

using System;
using MagicOnion;

namespace MyApp.Shared
{
    // Defines .NET interface as a Server/Client IDL.
    // The interface is shared between server and client.
    public interface IMyFirstService : IService<IMyFirstService>
    {
        // The return type must be `UnaryResult<T>`.
        UnaryResult<int> SumAsync(int x, int y);
    }
}

Add a class that implements the interface IMyFirstService. The client calls this class.

using System;
using MagicOnion;
using MagicOnion.Server;
using MyApp.Shared;

namespace MyApp.Services
{
    // Implements RPC service in the server project.
    // The implementation class must inehrit `ServiceBase<IMyFirstService>` and `IMyFirstService`
    public class MyFirstService : ServiceBase<IMyFirstService>, IMyFirstService
    {
        // `UnaryResult<T>` allows the method to be treated as `async` method.
        public async UnaryResult<int> SumAsync(int x, int y)
        {
            Console.WriteLine($"Received:{x}, {y}");
            return x + y;
        }
    }
}

The service is now defined and implemented. That's it.

Now you can start MagicOnion server as you would a ASP.NET Core project using the F5 key or the dotnet run command.

Client-side: Call the service on MagicOnion

NOTE: If you want to use MagicOnion client with Unity clients, see also Support for Unity client section.

Create a Console application project and add NuGet package MagicOnion.Client to the project.

Share IMyFirstService interface with the client. Share the interface definition in some way, such as file links, shared libraries, or copy and paste.

In the client code, Create MagicOnionClient client proxy on the shared interface and calls the service transparently.

using Grpc.Net.Client;
using MagicOnion.Client;
using MyApp.Shared;

// Connect to the server using gRPC channel.
var channel = GrpcChannel.ForAddress("https://localhost:5001");

// NOTE: If your project targets non-.NET Standard 2.1, use `Grpc.Core.Channel` class instead.
// var channel = new Channel("localhost", 5001, new SslCredentials());

// Create a proxy to call the server transparently.
var client = MagicOnionClient.Create<IMyFirstService>(channel);

// Call the server-side method using the proxy.
var result = await client.SumAsync(123, 456);
Console.WriteLine($"Result: {result}");

Installation

MagicOnion is available in four NuGet packages. Please install any of the packages as needed.

NOTE: If you want to use MagicOnion client with Unity clients, see also Support for Unity client section.

The package MagicOnion.Server to implement the server. You need to install this package to implement services on your server.

dotnet add package MagicOnion.Server

The package MagicOnion.Client to implement the client. To implement the client such as as WPF and Xamarin, you need to install this package.

dotnet add package MagicOnion.Client

The package MagicOnion.Abstractions provides interfaces and attributes commonly used by servers and clients. To create a class library project which is shared between the servers and the clients, you need to install this package.

dotnet add package MagicOnion.Abstractions

The package MagicOnion is meta package to implements the role of both server and client. To implement server-to-server communicaiton such as Microservices, that can be both a server and a client, we recommend to install this package.

dotnet add package MagicOnion

📖 Table of contents

Fundamentals

StreamingHub

StreamingHub is a fully-typed realtime server<->client communication framework.

This sample is for Unity(use Vector3, GameObject, etc) but StreamingHub supports .NET Core, too.

// Server -> Client definition
public interface IGamingHubReceiver
{
    // return type shuold be `void` or `Task`, parameters are free.
    void OnJoin(Player player);
    void OnLeave(Player player);
    void OnMove(Player player);
}
 
// Client -> Server definition
// implements `IStreamingHub<TSelf, TReceiver>`  and share this type between server and client.
public interface IGamingHub : IStreamingHub<IGamingHub, IGamingHubReceiver>
{
    // return type shuold be `Task` or `Task<T>`, parameters are free.
    Task<Player[]> JoinAsync(string roomName, string userName, Vector3 position, Quaternion rotation);
    Task LeaveAsync();
    Task MoveAsync(Vector3 position, Quaternion rotation);
}
 
// for example, request object by MessagePack.
[MessagePackObject]
public class Player
{
    [Key(0)]
    public string Name { get; set; }
    [Key(1)]
    public Vector3 Position { get; set; }
    [Key(2)]
    public Quaternion Rotation { get; set; }
}
// Server implementation
// implements : StreamingHubBase<THub, TReceiver>, THub
public class GamingHub : StreamingHubBase<IGamingHub, IGamingHubReceiver>, IGamingHub
{
    // this class is instantiated per connected so fields are cache area of connection.
    IGroup room;
    Player self;
    IInMemoryStorage<Player> storage;

    public async Task<Player[]> JoinAsync(string roomName, string userName, Vector3 position, Quaternion rotation)
    {
        self = new Player() { Name = userName, Position = position, Rotation = rotation };

        // Group can bundle many connections and it has inmemory-storage so add any type per group. 
        (room, storage) = await Group.AddAsync(roomName, self);

        // Typed Server->Client broadcast.
        Broadcast(room).OnJoin(self);

        return storage.AllValues.ToArray();
    }

    public async Task LeaveAsync()
    {
        await room.RemoveAsync(this.Context);
        Broadcast(room).OnLeave(self);
    }

    public async Task MoveAsync(Vector3 position, Quaternion rotation)
    {
        self.Position = position;
        self.Rotation = rotation;
        Broadcast(room).OnMove(self);
    }

    // You can hook OnConnecting/OnDisconnected by override.
    protected override async ValueTask OnDisconnected()
    {
        // on disconnecting, if automatically removed this connection from group.
        return CompletedTask;
    }
}

You can write client like this.

public class GamingHubClient : IGamingHubReceiver
{
    Dictionary<string, GameObject> players = new Dictionary<string, GameObject>();
 
    IGamingHub client;
 
    public async Task<GameObject> ConnectAsync(Channel grpcChannel, string roomName, string playerName)
    {
        var client = StreamingHubClient.Connect<IGamingHub, IGamingHubReceiver>(grpcChannel, this);
 
        var roomPlayers = await client.JoinAsync(roomName, playerName, Vector3.zero, Quaternion.identity);
        foreach (var player in roomPlayers)
        {
            (this as IGamingHubReceiver).OnJoin(player);
        }
 
        return players[playerName];
    }
 
    // methods send to server.
 
    public Task LeaveAsync()
    {
        return client.LeaveAsync();
    }
 
    public Task MoveAsync(Vector3 position, Quaternion rotation)
    {
        return client.MoveAsync(position, rotation);
    }
 
    // dispose client-connection before channel.ShutDownAsync is important!
    public Task DisposeAsync()
    {
        return client.DisposeAsync();
    }
 
    // You can watch connection state, use this for retry etc.
    public Task WaitForDisconnect()
    {
        return client.WaitForDisconnect();
    }
 
    // Receivers of message from server.
 
    void IGamingHubReceiver.OnJoin(Player player)
    {
        Debug.Log("Join Player:" + player.Name);
 
        var cube = GameObject.CreatePrimitive(PrimitiveType.Cube);
        cube.name = player.Name;
        cube.transform.SetPositionAndRotation(player.Position, player.Rotation);
        players[player.Name] = cube;
    }
 
    void IGamingHubReceiver.OnLeave(Player player)
    {
        Debug.Log("Leave Player:" + player.Name);
 
        if (players.TryGetValue(player.Name, out var cube))
        {
            GameObject.Destroy(cube);
        }
    }
 
    void IGamingHubReceiver.OnMove(Player player)
    {
        Debug.Log("Move Player:" + player.Name);
 
        if (players.TryGetValue(player.Name, out var cube))
        {
            cube.transform.SetPositionAndRotation(player.Position, player.Rotation);
        }
    }
}

Filter

MagicOnion filter is powerful feature to hook before-after invoke. It is useful than gRPC server interceptor.

image

// You can attach per class/method like [SampleFilter]
// for StreamingHub methods, implement StreamingHubFilterAttribute instead.
public class SampleFilterAttribute : MagicOnionFilterAttribute
{
    public override async ValueTask Invoke(ServiceContext context, Func<ServiceContext, ValueTask> next)
    {
        try
        {
            /* on before */
            await next(context); // next
            /* on after */
        }
        catch
        {
            /* on exception */
            throw;
        }
        finally
        {
            /* on finally */
        }
    }
}

Here is example of what kind of filter can be stacked.

image

GlobalFilter can attach to MagicOnionOptions.

MagicOnion filters supports DI.

public class MyStreamingHubFilterAttribute : StreamingHubFilterAttribute
{
    private readonly ILogger _logger;

    // the `logger` parameter will be injected at instantiating.
    public MyStreamingHubFilterAttribute(ILogger<MyStreamingHubFilterAttribute> logger)
    {
        _logger = logger;
    }

    public override async ValueTask Invoke(StreamingHubContext context, Func<StreamingHubContext, ValueTask> next)
    {
        _logger.LogInformation($"MyStreamingHubFilter Begin: {context.Path}");
        await next(context);
        _logger.LogInformation($"MyStreamingHubFilter End: {context.Path}");
    }
}

Register filters using attributes with constructor injection(you can use [FromTypeFilter] and [FromServiceFilter]).

[FromTypeFilter(typeof(MyFilterAttribute))]
public class MyService : ServiceBase<IMyService>, IMyService
{
    // The filter will instantiate from type.
    [FromTypeFilter(typeof(MySecondFilterAttribute))]
    public UnaryResult<int> Foo()
    {
        return UnaryResult(0);
    }

    // The filter will instantiate from type with some arguments. if the arguments are missing, it will be obtained from `IServiceLocator` 
    [FromTypeFilter(typeof(MyThirdFilterAttribute), Arguments = new object[] { "foo", 987654 })]
    public UnaryResult<int> Bar()
    {
        return UnaryResult(0);
    }

    // The filter instance will be provided via `IServiceLocator`.
    [FromServiceFilter(typeof(MyFourthFilterAttribute))]
    public UnaryResult<int> Baz()
    {
        return UnaryResult(0);
    }
}

ClientFilter

MagicOnion client-filter is a powerful feature to hook before-after invoke. It is useful than gRPC client interceptor.

Currently only suppots on Unary.

// you can attach in MagicOnionClient.Create.
var client = MagicOnionClient.Create<ICalcService>(channel, new IClientFilter[]
{
    new LoggingFilter(),
    new AppendHeaderFilter(),
    new RetryFilter()
});

You can create custom client-filter by implements IClientFilter.SendAsync.

public class IDemoFilter : IClientFilter
{
    public async ValueTask<ResponseContext> SendAsync(RequestContext context, Func<RequestContext, ValueTask<ResponseContext>> next)
    {
        try
        {
            /* Before Request, context.MethodPath/CallOptions/Items, etc */

            var response = await next(context); /* Call next filter or method body */

            /* After Request, response.GetStatus/GetTrailers/GetResponseAs<T>, etc */

            return response;
        }
        catch (RpcException ex)
        {
            /* Get gRPC Error Response */
            throw;
        }
        catch (OperationCanceledException ex)
        {
            /* If canceled */
            throw;
        }
        catch (Exception ex)
        {
            /* Other Exception */
            throw;
        }
        finally
        {
            /* Common Finalize */
        }
    }
}

Here is the sample filters, you can imagine what you can do.

public class AppendHeaderFilter : IClientFilter
{
    public async ValueTask<ResponseContext> SendAsync(RequestContext context, Func<RequestContext, ValueTask<ResponseContext>> next)
    {
        // add the common header(like authentcation).
        var header = context.CallOptions.Headers;
        if (!header.Any(x => x.Key == "x-foo"))
        {
            header.Add("x-foo", "abcdefg");
            header.Add("x-bar", "hijklmn");
        }

        return await next(context);
    }
}

public class LoggingFilter : IClientFilter
{
    public async ValueTask<ResponseContext> SendAsync(RequestContext context, Func<RequestContext, ValueTask<ResponseContext>> next)
    {
        Console.WriteLine("Request Begin:" + context.MethodPath); // Debug.Log in Unity.

        var sw = Stopwatch.StartNew();
        var response = await next(context);
        sw.Stop();

        Console.WriteLine("Request Completed:" + context.MethodPath + ", Elapsed:" + sw.Elapsed.TotalMilliseconds + "ms");

        return response;
    }
}

public class ResponseHandlingFilter : IClientFilter
{
    public async ValueTask<ResponseContext> SendAsync(RequestContext context, Func<RequestContext, ValueTask<ResponseContext>> next)
    {
        var response = await next(context);

        if (context.MethodPath == "ICalc/Sum")
        {
            // You can cast response type.
            var sumResult = await response.GetResponseAs<int>();
            Console.WriteLine("Called Sum, Result:" + sumResult);
        }

        return response;
    }
}

public class MockRequestFilter : IClientFilter
{
    public async ValueTask<ResponseContext> SendAsync(RequestContext context, Func<RequestContext, ValueTask<ResponseContext>> next)
    {
        if (context.MethodPath == "ICalc/Sum")
        {
            // don't call next, return mock result.
            return new ResponseContext<int>(9999);
        }

        return await next(context);
    }
}

public class RetryFilter : IClientFilter
{
    public async ValueTask<ResponseContext> SendAsync(RequestContext context, Func<RequestContext, ValueTask<ResponseContext>> next)
    {
        Exception lastException = null;
        var retryCount = 0;
        while (retryCount != 3)
        {
            try
            {
                // using same CallOptions so be careful to add duplicate headers or etc.
                return await next(context);
            }
            catch (Exception ex)
            {
                lastException = ex;
            }
            retryCount++;
        }

        throw new Exception("Retry failed", lastException);
    }
}

public class EncryptFilter : IClientFilter
{
    public async ValueTask<ResponseContext> SendAsync(RequestContext context, Func<RequestContext, ValueTask<ResponseContext>> next)
    {
        context.SetRequestMutator(bytes => Encrypt(bytes));
        context.SetResponseMutator(bytes => Decrypt(bytes));
        
        return await next(context);
    }
}

ServiceContext and Lifecycle

Service/StreamingHub's method or MagicOnionFilter can access this.Context it is

Property Description
ConcurrentDictionary<string, object> Items Object storage per request/connection.
Guid ContextId Unieuq ID per request(Service)/connection(StreamingHub).
DateTime Timestamp Timestamp that request/connection is started time.
Type ServiceType Invoked Class.
MethodInfo MethodInfo Invoked Method.
`ILookup<Type, Attribute> AttributeLookup Cached Attributes that merged both service and method.
ServerCallContext CallContext Raw gRPC Context.
MessagePackSerializerOptions SerializerOptions Using MessagePack serializer options.
IServiceProvider ServiceProvider Get the service provider.

Items is useful, for example authentication filter add UserId to Items and take out from service method.

If using StreamingHub, ServiceContext means per connected context so Items is not per method invoke. StreamingHubContext.Items supports per streaming hub method request but currently can not take from streaming hub method(only use in StreamingHubFilter). Issue:#67, it will fix.

MagicOnion supports get current context globaly like HttpContext.Current. ServiceContext.Current can get it but it requires MagicOnionOptions.EnableCurrentContext = true, default is false.

Lifecycle image of ServiceBase

gRPC In(
    var context = new ServiceContext();
    Filter.Invoke(context, 
        var service = new ServiceImpl();
        service.ServiceContext = context;
        service.MethodInvoke(
            /* method impl */
        )
    )
)

Lifecycle image of StreamingHub(StreamingHub is inherited from ServiceBase)

gRPC In(
    var context = new ServiceContext();
    Filter.Invoke(context, 
        var hub = new StreamingHubImpl();
        hub.ServiceContext = context;
        hub.Connect(
            while (connecting) {
                Streaming In(
                    var streamingHubContext = new StreamingHubContext(context);
                    StreamingHubFilter.Invoke(streamingHubContext,
                        hub.MethodInvoke(
                            /* method impl */
                        )
                    )
                )
            }
        )
    )
)

StreamingHub instance is shared while connecting so StreamingHub's field can use cache area of connection.

ExceptionHandling and StatusCode

If you are return custom status code from server to client, you can use throw new ReturnStatusException.

public Task SendMessageAsync(string message)
{
    if (message.Contains("foo"))
    {
        //
        throw new ReturnStatusException((Grpc.Core.StatusCode)99, "invalid");
    }

    // ....

Client can receive exception as gRPC's RpcException. If performance centric to avoid exception throw, you can use raw gRPC CallContext.Status(ServiceContext.CallCaontext.Status) and set status directly.

MagicOnion's engine catched exception(except ReturnStatusException), set StatusCode.Unknown and client received gRPC's RpcException. If MagicOnionOption.IsReturnExceptionStackTraceInErrorDetail is true, client can receive StackTrace of server exception, it is very useful for debugging but has critical issue about sercurity so should only to enable debug build.

Group and GroupConfiguration

StreamingHub's broadcast system is called Group. It can get from StreamingHub impl method, this.Group(this.Group type is HubGroupRepository, not IGroup).

Current connection can add to group by this.Group.AddAsync(string groupName), return value(IGroup) is joined group broadcaster so cache to field. It is enable per connection(if disconnected, automaticaly leaved from group). If you want to use some restriction, you can use TryAddAsync(string groupName, int incluciveLimitCount, bool createIfEmpty).

IGroup can pass to StreamingHub.Broadcast, BroadcastExceptSelf, BroadcastExcept and calls client proxy.

public class ChatHub : StreamingHubBase<IChatHub, IMessageReceiver>, IChatHub
{
    string userName;
    IGroup room;

    public async Task JoinAsync(string userName, string roomName)
    {
        this.userName = userName;
        this.room = await Group.AddAsync(roomName);
    }

    public async Task SendMessageAsync(string message)
    {
        Broadcast(room).OnReceiveMessage(userName, message);
    }
}

GroupRepository is created per StreamingHub type

If you want to create ServerSide loop and broadcast out of StreamingHub, you can pass Broadcast(room) result but it is unnatural, I'll add support kit of create server-side loop

Group has in-memory storage, it can store extra data to group member. It can set Group.AddAsync(string groupName, TStorage data) instead of standard AddAsync.

Data is can get from group.GetInMemoryStorage<T> and can invoke AllValues, Set(Guid connectionId, T Value), Get(Guid connectionId).

StreamingHub's ConnectionId is ServiceContext.ContextId

Default MagicOnion's group is inmemory and using ImmutableArrayGroup. This group implementation is tuned for small room, not enter/leave frequently. If large room and enter/leave frequently design, you can use ConcurrentDictionaryGroup. It can configure by GroupConfigurationAttribute or MagicOnionOptions.DefaultGroupRepositoryFactory.

// use ***GroupRepositoryFactory type.
[GroupConfiguration(typeof(ConcurrentDictionaryGroupRepositoryFactory))]
public class ChatHub : StreamingHubBase<IChatHub, IMessageReceiver>, IChatHub
{
    // ...
}

MagicOnion has distribute system called redis-backplane for group broadcast.

image

dotnet add package MagicOnion.Server.Redis
services.AddMagicOnion()
    .UseRedisGroupRepository(options =>
    {
        options.ConnectionMultiplexer = ConnectionMultiplexer.Connect("localhost:6379");
    });
    // If you want to use Redis backplane by default, you can specify `registerAsDefault: true`.
// Use Redis as backplane
[GroupConfiguration(typeof(RedisGroupRepositoryFactory))]
public class ...
{
}

Project Structure

If creates Server-Client project, I recommend make three projects. Server, ServerDefinition, Client.

image

ServerDefinition is only defined interface(IService<>, IStreamingHub<,>)(and some share request/response types).

If debugging, I recommend use SwitchStartupProject exteinson of VisualStudio and launch both Server and Client.

"MultiProjectConfigurations": {
    "Server + Client": {
        "Projects": {
            "FooService": {},
            "FooClient": {}
        }
    }
}

It can step-in/out seamlessly in server and client.

for Unity, you can't share by DLL(because can't share IServer<> because it is different reference both Unity and Server). It is slightly complex so we provides sample project and explanation.

see: samples page and ReadMe.

Dependency Injection

You can use DI(constructor injection) on the server.

public class MyFirstService : ServiceBase<IMyFirstService>, IMyFirstService
{
    IOptions<MyConfig> config;
    ILogger<MyFirstService> logger;

    public MyFirstService(IOptions<MyConfig> config, ILogger<MyFirstService> logger)
    {
        this.config = config;
        this.logger = logger;
    }

    // ...
}

Clients

Support for Unity client

MagicOnion supports Unity version, which is available for .NET 4.x runtime and C# 7.3 or later. (Unity 2018.3+)

Using MagicOnion with Unity client requires the following four things:

  • MagicOnion.Client.Unity.package (Unity asset package for MagicOnion library)
  • gRPC library for Unity client (gRPC official)
  • MessagePack for C#
  • MagicOnion code generator (for IL2CPP)

MagicOnion.Client.Unity.package (Unity asset package for MagicOnion library)

MagicOnion.Client.Unity.package is available for download from Releases page of this repository.

The package contains the code to use MagicOnion with Unity. It consists of several extensions for Unity in addition to MagicOnion.Client NuGet package.

gRPC library for Unity client (gRPC official)

gRPC library is not included in MagicOnion package. You need to download and install separately.

gRPC library can be found at gRPC daily builds, click Build ID, then click grpc_unity_package.*.*.*-dev.zip to download the library. See gRPC C# - experimental support for Unity for details.

NOTE: If you encounter error about Google.Protobuf.dll, you can remove the library. MagicOnion does not depend Google.Protobuf.dll. (Issue#296)

NOTE: gRPC native library for iOS has a file size of over 100MB, which may cause problems when pushing to GitHub or others. For more information on solutions, see Stripping debug symbols from ios/libgrpc.a.

MessagePack for C#

MessagePack for C# is not included in MagicOnion package. You need to download and install separately.

See MessagePack for C# installation for Unity for details.

MagicOnion code generator (for IL2CPP)

MagicOnion's default client only supports Unity Editor or non-IL2CPP environments (e.g. Windows/macOS/Linux Standalone). If you want to use MagicOnion on IL2CPP environments, you need to generate a client and register it in your Unity project.

There are two ways to generate code:

  • Using mpc (MagicOnion Codegen) command line tool
  • Using MagicOnion.MSBuild.Task (MSBuild Integration)

MessagePack for C#

For the same reason, MessagePack for C# code generation is also required.

See MessagePack-CSharp AOT Code Generation (to support Unity/Xamarin) section for more details about MessagePack code generation.

MagicOnion code generator also generates code for MessagePack and requires Resolver registration.

[RuntimeInitializeOnLoadMethod(RuntimeInitializeLoadType.BeforeSceneLoad)]
static void RegisterResolvers()
{
    // NOTE: Currently, CompositeResolver doesn't work on Unity IL2CPP build. Use StaticCompositeResolver instead of it.
    StaticCompositeResolver.Instance.Register(
        // This resolver is generated by MagicOnion's code generator.
        MagicOnion.Resolvers.MagicOnionResolver.Instance,
        // This resolver is generated by MessagePack's code generator.
        MessagePack.Resolvers.GeneratedResolver.Instance,
        StandardResolver.Instance
    );

    MessagePackSerializer.DefaultOptions = MessagePackSerializer.DefaultOptions
        .WithResolver(StaticCompositeResolver.Instance);
}

moc (MagicOnion Codegen) command line tool

moc is a cross-platform application. It requires .NET Core 3.1 SDK to run it.

You can download a binary from Releases page in this repository or install the tool as .NET Core tools. We recommend installing it as a local tool for .NET Core tools because of its advantages, such as fixing version per project.

To install as a .NET Core tools (local tool), you can run the following command:

dotnet new tool-manifest
dotnet tool install MagicOnion.Generator

If moc is installed as a local tool, you can run it with dotnet moc command.

dotnet moc -h
argument list:
-i, -input: Input path of analyze csproj or directory.
-o, -output: Output path(file) or directory base(in separated mode).
-u, -unuseUnityAttr: [default=False]Unuse UnityEngine's RuntimeInitializeOnLoadMethodAttribute on MagicOnionInitializer.
-n, -namespace: [default=MagicOnion]Set namespace root name.
-c, -conditionalSymbol: [default=null]Conditional compiler symbols, split with ','.

dotnet moc -i ./Assembly-CSharp.csproj -o Assets/Scripts/MagicOnion.Generated.cs

MagicOnion.MSBuild.Tasks (MSBuild Integration)

MagicOnion.MSBuild.Tasks is easy way of generate code that target to shared project. We're mostly recommended to use this way. For example, PostCompile sample.

<!-- in Shared.csproj -->

<ItemGroup>
    <!-- Install MSBuild Task(with PrivateAssets="All", it means to use dependency only in build time). -->
    <PackageReference Include="MessagePack.MSBuild.Tasks" Version="*" PrivateAssets="All" />
    <PackageReference Include="MagicOnion.MSBuild.Tasks" Version="*" PrivateAssets="All" />
</ItemGroup>

<!-- Call code generator after compile successfully. -->
<Target Name="GenerateMessagePack" AfterTargets="Compile">
    <MessagePackGenerator Input="$(ProjectPath)" Output="..\UnityClient\Assets\Scripts\Generated\MessagePack.Generated.cs" />
</Target>
<Target Name="GenerateMagicOnion" AfterTargets="Compile">
    <MagicOnionGenerator Input="$(ProjectPath)" Output="..\UnityClient\Assets\Scripts\Generated\MagicOnion.Generated.cs" />
</Target>

Full options are below.

<MagicOnionGenerator
    Input="string:required"
    Output="string:required"
    ConditionalSymbol="string:optional"
    ResolverName="string:optional"
    Namespace="string:optional"
    UnuseUnityAttr="bool:optional"
/>

Project structure and code generation samples are found in samples directory and README.

iOS build with gRPC

gRPC iOS build require two additional operation on build.

  1. Disable Bitcode
  2. Add libz.tbd

We introduce OnPostProcessingBuild sample BuildIos.cs for ChatApp.Unity to automate these steps.

#if UNITY_IPHONE
using System.IO;
using UnityEngine;
using UnityEditor;
using UnityEditor.Callbacks;
using UnityEditor.iOS.Xcode;

public class BuildIos
{
    /// <summary>
    /// Handle libgrpc project settings.
    /// </summary>
    /// <param name="target"></param>
    /// <param name="path"></param>
    [PostProcessBuild(1)]
    public static void OnPostProcessBuild(BuildTarget target, string path)
    {
        var projectPath = PBXProject.GetPBXProjectPath(path);
        var project = new PBXProject();
        project.ReadFromString(File.ReadAllText(projectPath));
        var targetGuid = project.TargetGuidByName(PBXProject.GetUnityTargetName());

        // libz.tbd for grpc ios build
        project.AddFrameworkToProject(targetGuid, "libz.tbd", false);

        // libgrpc_csharp_ext missing bitcode. as BITCODE exand binary size to 250MB.
        project.SetBuildProperty(targetGuid, "ENABLE_BITCODE", "NO");
        
        File.WriteAllText(projectPath, project.WriteToString());
    }
}
#endif

Stripping debug symbols from ios/libgrpc.a

When you download gRPC daily build and extract Native Libararies for Unity, you will find file size of Plugins/Grpc.Core/runtime/ios/libgrpc.a beyonds 100MB. GitHub will reject commit when file size is over 100MB, therefore libgrpc.a often become unwelcome for gif-low. The reason of libgrpc.a file size is because it includes debug symbols for 3 architectures, arm64, armv7 and x86_64.

We introduce strip debug symbols and generate reduced size libgrpc_stripped.a, it's about 17MB. This may useful for whom want commit libgrpc.a to GitHub, and understanding stripped library missing debug symbols.

How to strip

Download gRPC lib grpc_unity_package.*.*.*-dev.zip from gRPC daily builds and extract it, copy Plugins folder to Unity's Assets path.

Open terminal on Plugins/Grpc.Core/runtimes/ios/ and execute following will generate libgrpc_stripped.a and replace original libgrpc.a with stripped version.

$ cd ${UNITY_PATH}/Plugins/Grpc.Core/runtimes/ios
$ strip -S -x libgrpc.a -o libgrpc_stripped.a
$ rm libgrpc.a && mv libgrpc_stripped.a libgrpc.a

Make sure you can build app with iOS and works fine.

gRPC Keepalive

When you want detect network termination on Client or vice-versa, you can configure gRPC Keepalive.

Applied to .NET Standard 2.1 platforms (Grpc.Net.Client)

See keep alive pings | Performance best practices with gRPC | Microsoft Docs for information on setting up keepalive for Grpc.Net.Client.

Applied to .NET Standard 2.0 or Unity platforms (Grpc.Core)

Follow to the Keepalive UserGuide for gRPC Core but let's see how in actual.

ChannelOption

ChannelOptions is primitive way to configure options. Below uses ChannelOption and offer keepalive for every 10 second even RPC is not called.

// If you want configure KEEP_ALIVE interval, then....
// * set same value for `grpc.keepalive_time_ms` and `grpc.http2.min_time_between_pings_ms`
// * keep `grpc.http2.min_ping_interval_without_data_ms < grpc.http2.min_time_between_pings_ms`
var options = new[]
{
    // send keepalive ping every 10 second, default is 2 hours
    new ChannelOption("grpc.keepalive_time_ms", 10000),
    // keepalive ping time out after 5 seconds, default is 20 seoncds
    new ChannelOption("grpc.keepalive_timeout_ms", 5000),
    // allow grpc pings from client every 10 seconds
    new ChannelOption("grpc.http2.min_time_between_pings_ms", 10000),
    // allow unlimited amount of keepalive pings without data
    new ChannelOption("grpc.http2.max_pings_without_data", 0),
    // allow keepalive pings when there's no gRPC calls
    new ChannelOption("grpc.keepalive_permit_without_calls", 1),
    // allow grpc pings from client without data every 5 seconds
    new ChannelOption("grpc.http2.min_ping_interval_without_data_ms", 5000),
};

Pass this options to Channel on Client will configure Keepalive.

// Client
this.channel = new Channel("localhost", 12345, ChannelCredentials.Insecure, options);

Now you can detect client network disconnection on serverside, let's override OnDisconnected and set debugger, disconnect Client network and wait for interval sec!

HTTPS (TLS)

MagicOnion supports TLS encrypted connection.

Server-side

In general, HTTPS encryption settings on the server follow ASP.NET Core. For more information, see Enforce HTTPS in ASP.NET Core | Microsoft Docs.

NOTE: The limitations on macOS environment and when running on Docker are also described in ASP.NET Core documentation.

Client-side

Depending on whether the client supports .NET Standard 2.1 or .NET Standard 2.1 (including Unity), the configuration is different.

.NET Standard 2.1 (.NET Core 3.x, .NET 5, Xamarin)

If the client supports .NET Standard 2.1 or newer, MagicOnion uses Grpc.Net.Client (a pure C# implementation) for gRPC connection.

Grpc.Net.Client uses HttpClient internally, so it handles certificates the same way as HttpClient. For example, on Windows, it uses Windows's certificate store to validate certificates.

.NET Standard 2.0 (.NET Core 2.x, .NET Framework 4.6.1+) / Unity

If the client supports .NET Standard 2.0, MagicOnion uses Grpc.Core (C-library binding) for gRPC connection.

Grpc.Core has its own certificate store built into the library and uses it unless you specify a certificate. This certificate store contains common CAs and is rarely a problem in production environment.

However, there is a problem when connecting with a server using ASP.NET Core development certificate. For example, if you see the following exceptions when you try to connect, the server certificate validation may have failed.

Grpc.Core.RpcException: 'Status(StatusCode="Unavailable", Detail="failed to connect to all addresses", ...')

The following workarounds are suggested for such cases:

  • Issue and configure a trusted certificate to the server
  • Use OpenSSL commands to issue and configure self-signed certificates to servers and clients
  • Unencrypted connection without TLS

Use HTTP unencrypted connection without TLS

It is recommended to use HTTPS for server-client connection, but in some cases during development you may want to configure unencrypted connection. Also, you need to configure unencrypted connection in macOS because ALPN over TLS is not supported.

Server-side

To allow your server to accept unencrypted HTTP/2, you must configure an endpoint to listen to Kestrel. Endpoints can be configured either by using appsettings.json or directly in the source code.

See also Unable to start ASP.NET Core gRPC app on macOS | Troubleshoot gRPC on .NET Core for details.

{
    ...
    "Kestrel": {
        "Endpoints": {
            "Grpc": {
                "Url": "http://localhost:5000",
                "Protocols": "Http2"
            },
            "Https": {
                "Url": "https://localhost:5001",
                "Protocols": "Http1AndHttp2"
            },
            "Http": {
                "Url": "http://localhost:5002",
                "Protocols": "Http1"
            }
        }
    },
    ...
}
webBuilder
    .UseKestrel(options =>
    {
        // WORKAROUND: Accept HTTP/2 only to allow insecure HTTP/2 connections during development.
        options.ConfigureEndpointDefaults(endpointOptions =>
        {
            endpointOptions.Protocols = HttpProtocols.Http2;
        });
    })
    .UseStartup<Startup>();

Client-side (.NET Standard 2.1; Grpc.Net.Client)

When calling GrpcChannel.FromAddress, change the URL scheme to HTTP and the port to an unencrypted port.

var channel = GrpcChannel.ForAddress("http://localhost:5000");

Enable AppSwitch to allow HTTP/2 without encryption.

// WORKAROUND: Use insecure HTTP/2 connections during development.
AppContext.SetSwitch("System.Net.Http.SocketsHttpHandler.Http2UnencryptedSupport", true);

See also Call insecure gRPC services with .NET Core client | Troubleshoot gRPC on .NET Core | Microsoft Docs for details.

Client-side (.NET Standard 2.0/Unity; Grpc.Core)

When creating Channel, specify the unencrypted port and pass ChannelCredentials.Insecure.

var channel = new Channel("localhost", 5000, ChannelCredentials.Insecure);

Limitations

If unencrypted HTTP/2 connection is accepted, HTTP/1 and HTTP/2 cannot be served on the same port. When TLS is enabled, ALPN is used for HTTP/2 negotiation, but with non-TLS, this is not possible.

If you want HTTP/1 and HTTP/2 to work together for the convenience of hosting a web site or API, you can listen on multiple ports by configuring Kestrel.

Deployment

MagicOnion is also supported in Docker containers and running on Kubernetes.

See docs/articles/deployment/ for information on deploying to Amazon Web Service and other cloud services.

Integrations

Swagger

MagicOnion has built-in HTTP/1.1 JSON Gateway and Swagger integration for Unary operation. It can execute and debug RPC-API easily.

dotnet add package MagicOnion.Server.HttpGateway
public class Startup
{
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    // This method gets called by the runtime. Use this method to add services to the container.
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddControllersWithViews();

        services.AddGrpc(); // MagicOnion depends on ASP.NET Core gRPC service.
        services.AddMagicOnion();
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }

        app.UseRouting();

        app.UseEndpoints(endpoints =>
        {
            endpoints.MapMagicOnionHttpGateway("_", app.ApplicationServices.GetService<MagicOnion.Server.MagicOnionServiceDefinition>().MethodHandlers, GrpcChannel.ForAddress("https://localhost:5001"));
            endpoints.MapMagicOnionSwagger("swagger", app.ApplicationServices.GetService<MagicOnion.Server.MagicOnionServiceDefinition>().MethodHandlers, "/_/");

            endpoints.MapMagicOnionService();
        });
    }
}

Open http://localhost:5000, you can see swagger view.

image

Advanced

MagicOnionOption

MagicOnionOption can pass to MagicOnionEngine.BuildServerServiceDefinition(MagicOnionOptions option).

Property Description
IList<MagicOnionFilterDescriptor> GlobalFilters Global MagicOnion filters.
bool EnableCurrentContext Enable ServiceContext.Current option by AsyncLocal, default is false.
IList<StreamingHubFilterDescriptor> Global StreamingHub filters. GlobalStreamingHubFilters
IGroupRepositoryFactory DefaultGroupRepositoryFactory Default GroupRepository factory for StreamingHub, default is ``.
bool IsReturnExceptionStackTraceInErrorDetail If true, MagicOnion handles exception ownself and send to message. If false, propagate to gRPC engine. Default is false.
MessagePackSerializerOptions SerializerOptions MessagePack serialization resolver. Default is used ambient default(MessagePackSerializer.DefaultOptions).

Internal Logging

IMagicOnionLogger is structured logger of MagicOnion internal information.

Implements your custom logging code and append it, default is NullMagicOnionLogger(do nothing). MagicOnion has some built in logger, MagicOnionLogToLogger that structured log to string log and send to Microsoft.Extensions.Logging.ILogger. MagicOnionLogToLoggerWithDataDump is includes data dump it is useful for debugging(but slightly heavy, recommended to only use debugging). MagicOnionLogToLoggerWithNamedDataDump is more readable than simple WithDataDump logger.

Raw gRPC APIs

MagicOnion can define and use primitive gRPC APIs(ClientStreaming, ServerStreaming, DuplexStreaming). Especially DuplexStreaming is used underlying StreamingHub. If there is no reason, we recommend using StreamingHub.

// Definitions
public interface IMyFirstService : IService<IMyFirstService>
{
    UnaryResult<string> SumAsync(int x, int y);
    Task<UnaryResult<string>> SumLegacyTaskAsync(int x, int y);
    Task<ClientStreamingResult<int, string>> ClientStreamingSampleAsync();
    Task<ServerStreamingResult<string>> ServertSreamingSampleAsync(int x, int y, int z);
    Task<DuplexStreamingResult<int, string>> DuplexStreamingSampleAync();
}

// Server
public class MyFirstService : ServiceBase<IMyFirstService>, IMyFirstService
{
    // VisualStudio 2017(C# 7.0), Unity 2018.3 supports return `async UnaryResult` directly
    // I recommend disable async-warning on project level. <NoWarn>1998</NoWarn>
    public async UnaryResult<string> SumAsync(int x, int y)
    {
        Logger.Debug($"Called SumAsync - x:{x} y:{y}");

        return (x + y).ToString();
    }

    // VS2015(C# 6.0), Unity 2018.2 use Task
    public async Task<UnaryResult<string>> SumLegacyTaskAsync(int x, int y)
    {
        Logger.Debug($"Called SumAsync - x:{x} y:{y}");

        // use UnaryResult method.
        return UnaryResult((x + y).ToString());
    }

    public async Task<ClientStreamingResult<int, string>> ClientStreamingSampleAsync()
    {
        Logger.Debug($"Called ClientStreamingSampleAsync");

        // If ClientStreaming, use GetClientStreamingContext.
        var stream = GetClientStreamingContext<int, string>();

        // receive from client asynchronously
        await stream.ForEachAsync(x =>
        {
            Logger.Debug("Client Stream Received:" + x);
        });

        // StreamingContext.Result() for result value.
        return stream.Result("finished");
    }

    public async Task<ServerStreamingResult<string>> ServertSreamingSampleAsync(int x, int y, int z)
    {
        Logger.Debug($"Called ServertSreamingSampleAsync - x:{x} y:{y} z:{z}");

        var stream = GetServerStreamingContext<string>();

        var acc = 0;
        for (int i = 0; i < z; i++)
        {
            acc = acc + x + y;
            await stream.WriteAsync(acc.ToString());
        }

        return stream.Result();
    }

    public async Task<DuplexStreamingResult<int, string>> DuplexStreamingSampleAync()
    {
        Logger.Debug($"Called DuplexStreamingSampleAync");

        // DuplexStreamingContext represents both server and client streaming.
        var stream = GetDuplexStreamingContext<int, string>();

        var waitTask = Task.Run(async () =>
        {
            // ForEachAsync(MoveNext, Current) can receive client streaming.
            await stream.ForEachAsync(x =>
            {
                Logger.Debug($"Duplex Streaming Received:" + x);
            });
        });

        // WriteAsync is ServerStreaming.
        await stream.WriteAsync("test1");
        await stream.WriteAsync("test2");
        await stream.WriteAsync("finish");

        await waitTask;

        return stream.Result();
    }
}

Client sample.

static async Task UnaryRun(IMyFirstService client)
{
    // await(C# 7.0, Unity 2018.3)
    var vvvvv = await client.SumAsync(10, 20);
    Console.WriteLine("SumAsync:" + vvvvv);
    
    // if use Task<UnaryResult>(Unity 2018.2), use await await
    var vvvv2 = await await client.SumLegacyTaskAsync(10, 20);
}

static async Task ClientStreamRun(IMyFirstService client)
{
    var stream = await client.ClientStreamingSampleAsync();

    for (int i = 0; i < 3; i++)
    {
        await stream.RequestStream.WriteAsync(i);
    }
    await stream.RequestStream.CompleteAsync();

    var response = await stream.ResponseAsync;

    Console.WriteLine("Response:" + response);
}

static async Task ServerStreamRun(IMyFirstService client)
{
    var stream = await client.ServertSreamingSampleAsync(10, 20, 3);

    await stream.ResponseStream.ForEachAsync(x =>
    {
        Console.WriteLine("ServerStream Response:" + x);
    });
}

static async Task DuplexStreamRun(IMyFirstService client)
{
    var stream = await client.DuplexStreamingSampleAync();

    var count = 0;
    await stream.ResponseStream.ForEachAsync(async x =>
    {
        Console.WriteLine("DuplexStream Response:" + x);

        await stream.RequestStream.WriteAsync(count++);
        if (x == "finish")
        {
            await stream.RequestStream.CompleteAsync();
        }
    });
}

Zero deserialization mapping

In RPC, especially in real-time communication involving frequent transmission of data, it is often the serialization process where data is converted before being sent that limits the performance. In MagicOnion, serialization is done by my MessagePack for C#, which is the fastest binary serializer for C#, so it cannot be a limiting factor. Also, in addition to performance, it also provides flexibility regarding data in that variables of any type can be sent as long as they can be serialized by MessagePack for C#.

Also, taking advantage of the fact that both the client and the server run on C# and data stored on internal memory are expected to share the same layout, I added an option to do mapping through memory copy without serialization/deserialization in case of a value-type variable.

Especially in Unity, this is can combinate with MessagePack.UnityShims package of NuGet.

// It supports standard struct-type variables that are provided by Unity, such as Vector3, and arrays containing them, as well as custom struct-type variables and their arrays.
// I recommend doing this explicitly using [StructLayout(LayoutKind.Explicit)] to accurately match the size.
public struct CustomStruct
{
    public long Id;
    public int Hp;
    public int Mp;
    public byte Status;
}
 
// ---- Register the following code when initializing.
 
// By registering it, T and T[] can be handled using zero deserialization mapping.
UnsafeDirectBlitResolver.Register<CustomStruct>();
 
// The struct-type above as well as Unity-provided struct-types (Vector2, Rect, etc.), and their arrays are registered as standards.
CompositeResolver.RegisterAndSetAsDefault(
    UnsafeDirectBlitResolver.Instance,
    MessagePack.Unity.Extension.UnityBlitResolver.Instance
    );
 
// --- Now the communication will be in the format above when they are used for transmission.
await client.SendAsync(new CustomStruct { Hp = 99 });

Nothing needs to be processed here, so it promises the best performance theoretically possible in terms of transmission speed. However, since these struct-type variables need to be copied, I recommend handling everything as ref as a rule when you need to define a large struct-type, or it might slow down the process.

I believe that this can be easily and effectively applied to sending a large number of Transforms, such as an array of Vector3 variables.

Experimentals

OpenTelemetry

MagicOnion.OpenTelemetry is implementation of open-telemetry/opentelemetry-dotnet: OpenTelemetry .NET SDK, so you can use any OpenTelemetry exporter, like Prometheus, StackDriver, Zipkin and others.

See details at MagicOnion.Server.OpenTelemetry

License

This library is under the MIT License.