C#•2y ago

❔ cannot use InvokeAsync when streaming in signalR

hi i have a streaming channel from client to server using Channel. the stream channel closes when i invoke a method in client from server and wait for response.

4 Replies

sljavad•2y ago

here is my server side code that reads stream:

        public async Task ReplayFromAdminToServer(ChannelReader<int> replay)
        {
            try
            {
                while (await replay.WaitToReadAsync())
                {
                    while (replay.TryRead(out var item))
                    {
                        Console.WriteLine(item);
                    }
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine("EXCEPTION");
                Console.WriteLine(ex.Message);
            }

            Console.WriteLine("END OF ReplayFromAdminToServer");
        }

        public async Task ReplayFromAdminToServer(ChannelReader<int> replay)
        {
            try
            {
                while (await replay.WaitToReadAsync())
                {
                    while (replay.TryRead(out var item))
                    {
                        Console.WriteLine(item);
                    }
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine("EXCEPTION");
                Console.WriteLine(ex.Message);
            }

            Console.WriteLine("END OF ReplayFromAdminToServer");
        }

here is client code that sends stream :

            var channel = Channel.CreateUnbounded<int>();
            await connection.SendAsync("ReplayFromAdminToServer", channel.Reader);
            for (int i = 0; i < 1000; i++)
            {
                await Task.Delay(100);
                await channel.Writer.WriteAsync(i);
                richTextBox1.AppendText(i.ToString()+"\r\n");
            }

            var channel = Channel.CreateUnbounded<int>();
            await connection.SendAsync("ReplayFromAdminToServer", channel.Reader);
            for (int i = 0; i < 1000; i++)
            {
                await Task.Delay(100);
                await channel.Writer.WriteAsync(i);
                richTextBox1.AppendText(i.ToString()+"\r\n");
            }

this code will Invoke StreamHandshake on the server and waits for response :

            var res = await connection.InvokeAsync<bool>("StreamHandshake", "stream_handshake");
            if (res)
            {
                await connection.SendAsync("ImageMessage", "hello");
            }

            var res = await connection.InvokeAsync<bool>("StreamHandshake", "stream_handshake");
            if (res)
            {
                await connection.SendAsync("ImageMessage", "hello");
            }

StreamHandshake method in the server side :

        public async Task<bool> StreamHandshake(string data)
        {
            if (data == "stream_handshake")
            {
                try
                {
                    var token = new CancellationTokenSource();
                    var res = await Clients.Caller.InvokeAsync<bool>("stream_handshake", "someData", token.Token);
                    return true;
                }
                catch (Exception ex)
                {
                    Console.WriteLine("EX in StreamHandshake");
                    Console.WriteLine(ex.Message);
                    return false;
                }

            }
            return false;
        }

        public async Task<bool> StreamHandshake(string data)
        {
            if (data == "stream_handshake")
            {
                try
                {
                    var token = new CancellationTokenSource();
                    var res = await Clients.Caller.InvokeAsync<bool>("stream_handshake", "someData", token.Token);
                    return true;
                }
                catch (Exception ex)
                {
                    Console.WriteLine("EX in StreamHandshake");
                    Console.WriteLine(ex.Message);
                    return false;
                }

            }
            return false;
        }

my stream channel closes when code reaches to line await Clients.Caller.InvokeAsync<bool>("stream_handshake", "someData", token.Token); it invokes a method in the client and waits for response , but the porgram will not continue from this line when client returns the response. here is stream_handshake listener in client side:

            connection.On<string, bool>("stream_handshake", async (input) =>
            {
                return true;
            });

            connection.On<string, bool>("stream_handshake", async (input) =>
            {
                return true;
            });

it just return true , but server side will not get it and stream closes. is this a problem in signalR ? should i open issue in github ?

Accord•2y ago

Looks like nothing has happened here. I will mark this as stale and this post will be archived until there is new activity.

sljavad•2y ago

FYI, i opened an issue for this you can follow it on github https://github.com/dotnet/aspnetcore/issues/46503

GitHub

[SignalR] Cannot use InvokeAsync While there is an stream ongoing i...

Is there an existing issue for this? I have searched the existing issues Describe the bug i have an stream from client to server using SignalR. stream channel closes and completes when i invoke a c...

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ cannot use InvokeAsync when streaming in signalR