signalr_client #

A Flutter SignalR Client for ASP.NET Core.
The client supports the following transport protocols:

• WebSocket
• Service Side Events
• Long Polling

The client supports the following hub protocols:

• Json
• MessagePack Since I can't find a MessagePack library that support the current flutter version.

Examples #

• Integration test app - To see how a client calls various hub functions.

Getting Started #

Add signalr_client to your pubspec.yaml dependencies:

...
dependencies:
  flutter:
    sdk: flutter

  signalr_client:
...

Usage #

Let's demo some basic usages:

1. Create a hub connection: #

// Import the library.
import 'package:signalr_client/signalr_client.dart';

// The location of the SignalR Server.
final serverUrl = "192.168.10.50:51001";
// Prints log messages to the console.
final logger = ConsoleLogger();
// Creates the connection by using the HubConnectionBuilder.
final hubConnection = HubConnectionBuilder().withUrl(serverUrl).configureLogging(logger: logger).build();
// When the connection is closed, print out a message to the logger.
final hubConnection.onclose( (error) => logger.log(LogLevel.Information, "Connection Closed"));

2. Calling a Hub function: #

Assuming there is this hub function:

public string MethodOneSimpleParameterSimpleReturnValue(string p1)
{
  Console.WriteLine($"'MethodOneSimpleParameterSimpleReturnValue' invoked. Parameter value: '{p1}");
  return p1;
}

The client can invoke the function by using:

  final result = await hubConnection.invoke("MethodOneSimpleParameterSimpleReturnValue", args: <Object>["ParameterValue"]);
  logger.log(LogLevel.Information, "Result: '$result");

3. Calling a client function: #

Assuming the server calls a function "aClientProvidedFunction":

  await Clients.Caller.SendAsync("aClientProvidedFunction", null);

The Client provides the function like this:

  
  hubConnection.on("aClientProvidedFunction", _handleAClientProvidedFunction);

  // To unregister the function use:
  // a) to unregister a specific implementation:
  // hubConnection.off("aClientProvidedFunction", method: _handleServerInvokeMethodNoParametersNoReturnValue);
  // b) to unregister all implementations:
  // hubConnection.off("aClientProvidedFunction");
  ...
  void _handleAClientProvidedFunction(List<Object> parameters) {
    logger.log(LogLevel.Information, "Server invoked the method");
  }

A note about the parameter types #

All function parameters and return values are serialized/deserialized into/from JSON by using the dart:convert package (json.endcode/json.decode). Make sure that you:

• use only simple parameter types

or

• use objects that implements toJson() since these method is used by the dart:convert package to serialize an object.

Flutter Json 101:

• flutter.io
• json.encode
• json.decode