Flutter stomp client cant connect with spring stomp client

Question

I,m new in Flutter. I'm trying to connect to spring websocket which uses stomp but the connection fails. I'm using stomp_dart_client 0.3.3. Spring sever is working fine. I'm able to see the messages on the browser.

This is my spring implementation:

Spring config class:

@Override
public void configureMessageBroker(MessageBrokerRegistry config) {
    config.enableSimpleBroker("/topic");
    config.setApplicationDestinationPrefixes("/app");
}

@Override
public void registerStompEndpoints(StompEndpointRegistry registry) {
    registry.addEndpoint("/gs-guide-websocket").withSockJS();
}

Spring controller:

@MessageMapping("/hello")
@SendTo("/topic/greetings")
public Greeting greeting(HelloMessage message) throws Exception {
    Thread.sleep(1000); // simulated delay
    return new Greeting("Hello, " + HtmlUtils.htmlEscape(message.getName()) + "!");
}

Flutter implementation:

StompClient stompClient = StompClient(
        config: StompConfig(
          url: 'ws://10.0.2.2:7000',
          onConnect:(ss, dd)=> ss.subscribe (
            destination: '/topic/greetings/gs-guide-websocket',
            callback: (StompFrame frame) {
              print(frame.body);
            },
          ),
          onWebSocketError: (dynamic error) => print(error.toString()),
          onStompError: (d) => print("stomp error"),
          onDisconnect: (d)=> print("disconnect"),
        ));

   stompClient.activate();

   stompClient.subscribe (
        destination: '/topic/greetings',
        callback: (StompFrame frame) {
          print(frame.body);
          List<dynamic> result = json.decode(frame.body);
          return result;
        },
    );

this is the error:

E/flutter (30825): [ERROR:flutter/shell/common/shell.cc(213)] Dart Error: Unhandled exception:
E/flutter (30825): NoSuchMethodError: The method 'subscribe' was called on null.
E/flutter (30825): Receiver: null
E/flutter (30825): Tried calling: subscribe(callback: Closure: (StompFrame) => List<dynamic>, destination: "/topic/greetings", headers: null)
E/flutter (30825): #0      Object.noSuchMethod (dart:core-patch/object_patch.dart:53:5)
E/flutter (30825): #1      StompClient.subscribe (package:stomp_dart_client/stomp.dart:74:21)
E/flutter (30825): #2      _MyHomePageState._receivedMessage (package:tutorial_projecect/main.dart:154:16)
E/flutter (30825): #3      _MyHomePageState.build (package:tutorial_projecect/main.dart:90:41)
E/flutter (30825): #4      StatefulElement.build (package:flutter/src/widgets/framework.dart:4619:28)
E/flutter (30825): #5      ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4502:15)
E/flutter (30825): #6      StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:4675:11)
E/flutter (30825): #7      Element.rebuild (package:flutter/src/widgets/framework.dart:4218:5)
E/flutter (30825): #8      StatefulElement.update (package:flutter/src/widgets/framework.dart:4707:5)
E/flutter (30825): #9      Element.updateChild (package:flutter/src/widgets/framework.dart:3201:15)
E/flutter (30825): #10     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:5837:14)
E/flutter (30825): #11     Element.updateChild (package:flutter/src/widgets/framework.dart:3201:15)
E/flutter (30825): #12     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4527:16)
E/flutter (30825): #13     Element.rebuild (package:flutter/src/widgets/framework.dart:4218:5)
E/flutter (30825): #14     StatelessElement.update (package:flutter/src/widgets/framework.dart:4583:5)
E/flutter (30825): #15     Element.updateChild (package:flutter/src/widgets/framework.dart:3201:15)
E/flutter (30825): #16     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:5837:14)
E/flutter (30825): #17     Element.updateChild (package:flutter/src/widgets/framework.dart:3201:15)
E/flutter (30825): #18     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:5837:14)
E/flutter (30825): #19     Element.updateChild (package:flutter/src/widgets/framework.dart:3201:15)
E/flutter (30825): #20     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4527:16)
E/flutter (30825): #21     StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:4675:11)
E/flutter (30825): #22     Element.rebuild (package:flutter/src/widgets/framework.dart:4218:5)
E/flutter (30825): #23     StatefulElement.update (package:flutter/src/widgets/framework.dart:4707:5)
E/flutter (30825): #24     Element.updateChild (package:flutter/src/widgets/framework.dart:3201:15)
E/flutter (30825): #25     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:5837:14)
E/flutter (30825): #26     Element.updateChild (package:flutter/src/widgets/framework.dart:3201:15)
E/flutter (30825): #27     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:5837:14)
E/flutter (30825): #28     Element.updateChild (package:flutter/src/widgets/framework.dart:3201:15)
E/flutter (30825): #29     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4527:16)
E/flutter (30825): #30     StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:4675:11)
E/flutter (30825): #31     Element.rebuild (package:flutter/src/widgets/framework.dart:4218:5)
E/flutter (30825): #32     StatefulElement.update (package:flutter/src/widgets/framework.dart:4707:5)
E/flutter (30825): #33     Element.updateChild (package:flutter/src/widgets/framework.dart:3201:15)
E/flutter (30825): #34     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4527:16)
E/flutter (30825): #35     Element.rebuild (package:flutter/src/widgets/framework.dart:4218:5)
E/flutter (30825): #36     StatelessElement.update (package:flutter/src/widgets/framework.dart:4583:5)
E/flutter (30825): #37     Element.updateChild (package:flutter/src/widgets/framework.dart:3201:15)
E/flutter (30825): #38     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4527:16)
E/flutter (30825): #39     StatefulElement.performRebuild (package:flutter/src/widgets/framework.dart:4675:11)
E/flutter (30825): #40     Element.rebuild (package:flutter/src/widgets/framework.dart:4218:5)
E/flutter (30825): #41     StatefulElement.update (package:flutter/src/widgets/framework.dart:4707:5)
E/flutter (30825): #42     Element.updateChild (package:flutter/src/widgets/framework.dart:3201:15)
E/flutter (30825): #43     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:5837:14)
E/flutter (30825): #44     Element.updateCh

Answer 1

Firstly.

Your original post should use stompClient.subscribe in the onConnect callback. If you subscribe before connected, the client object is null.

Secondly.

Since you changed a lib. You should show your new code. I have tried both lib. And stomp: ^0.8.0 gives

java.lang.IllegalArgumentException: Invalid character found in method name [STOMP0x0aaccept-version:1.20x0a0x0a...]. HTTP method names must be tokens

Still struggle to make it work...

Answer 2

After some investigation and retries I found the issue. registerStompEndpoints should not return SockJs.

And i have used another stomp lib: stomp: ^0.8.0

@Override
public void registerStompEndpoints(StompEndpointRegistry registry) {
    registry.addEndpoint("/gs-guide-websocket");
}

Answer 3

Pulling this back to the original post which mentioned stomp_dart_client, I struggled to find working examples for this on the internet and Stack Overflow, so here's my solution that may help.

I am using RabbitMQ with the Web STOMP plugin: https://www.rabbitmq.com/web-stomp.html , publishing JSON packets onto a queue called "ping". The examples and the documents for stomp_dart_client were not clear regarding how to connect to a secure session, to which I have resolved by adding authentication within the header:

import 'dart:convert';

import 'package:stomp_dart_client/stomp.dart';
import 'package:stomp_dart_client/stomp_config.dart';
import 'package:stomp_dart_client/stomp_frame.dart';

dynamic onConnect(StompClient client, StompFrame frame) {
  client.subscribe(
      destination: 'ping',
      callback: (StompFrame frame) {
        var jsonData = json.decode(frame.body);
        print(jsonData);
      });
}

final stompClient = StompClient(
    config: StompConfig(
        url: 'ws://x.x.x.x:15674/ws',
        onConnect: onConnect,
        onWebSocketError: (dynamic error) => print(error.toString()),
        stompConnectHeaders: {
      'login': 'someuserlogin',
      'passcode': 'somepassword'
    },
));

void main() {
  stompClient.activate();
}