Sending a SyncRequest from within a SyncRequest and getting a response

Hey!

I’m in a situation where I would need this to work:

1. Client sends a SyncRequest to Server
2. Server requires more info and therefore sends a SyncRequest back to Client
3. Client replies with a SyncResponse including the requested info
4. Server replies to the original SyncRequest (from step 1)

Basically: client -> server (extra: -> client -> server) -> client, if that makes sense.

To explain it better, here is some code to illustrate what I’d want to do (fiddle):

using System.Text;
using WatsonTcp;

const string host = "127.0.0.1";
const int port = 1337;

var server = new WatsonTcpServer(host, port);
var client = new WatsonTcpClient(host, port);

server.Callbacks.SyncRequestReceived += request =>
{
    Console.WriteLine(2);
    var response = server.SendAndWait(1000, request.IpPort, "hello from server!");
    
    Console.WriteLine(4);
    return new SyncResponse(request, response.Data);
};

client.Callbacks.SyncRequestReceived += request =>
{
    Console.WriteLine(3);
    return new SyncResponse(request, "hello back from client!");
};

server.Events.MessageReceived += (_, _) => { };
client.Events.MessageReceived += (_, _) => { };

server.Start();
client.Connect();

Console.WriteLine(1);
var response = client.SendAndWait(1000, "hello from client!");

Console.WriteLine("client received response: " + Encoding.UTF8.GetString(response.Data));
Console.ReadKey(true);

However, this is the output I am getting from this exact code:

1
2
3
Unhandled exception. System.TimeoutException: A response to a synchronous request was not received within the timeout window.

As you can see, the client does not seem to be sending a response back, or at least the server isn’t letting me know about it (stuck at step 3). If I was to guess, and without having read the entire codebase, I would assume this is the intended behavior and is due to a lock() or SemaphoreSlim somewhere, preventing concurrent requests/responses?

This would make sense as otherwise, it would mean multiple different data could be received concurrently, mixing everything up. Hopefully I’m not saying sh*t here. Please, correct me if so 😅 Always looking to get more knowledge!

Considering I am right (and even if I am not), then how would I go about getting this to work?

What I thought of is: Instead of sending a SyncRequest back from within a SyncRequest, what I could do is make the server reply right away with a SyncResponse saying something along the lines of "hey! more data is required! please come back with a new SyncRequest containing it!", but that is pretty inconvenient and would not work well with my current structure. My question here really is about (issue title): “Sending a SyncRequest from within a SyncRequest and getting a response”, without getting blocked.

So, what can/should I do? Is that even possible at all or should I completely forget about it and instead go with the idea above?

[jchristn]

Thanks Matt! Will be moving over to the other issues shortly! Cheers

[Laiteux]

Anyway, everything now seems to work just fine. I’ll close this issue so we can move to the next one whenever you have some time.

Thanks a lot for your time collaborating on this, it is very much appreciated. Please keep up the good work! (: