JMeter WebSockets Publish/Subscribe - scripting aschronous responses - websocket

Question

We have built a publish/subscribe model into our application via WebSockets so users can receive "dynamic updates" when data changes. I'm now looking to load test this using JMeter.
Is there a way to configure a JMeter test to react to receipt of a WebSocket "published" message and then run further samplers i.e. make further web requests?
I have looked at plugin samples, but they appear focused on request/reply model (e.g. https://bitbucket.org/pjtr/jmeter-websocket-samplers) rather than publish/subscribe.
Edit:
I have progressed a solution for this using the WebSocketSampler - an Example JMX file can be found on BitBucket which uses STOMP over WebSockets and includes Connect, Subscribe, Handle Publish Message and Initiate JMeter Samplers from that.

Answer 1

It is a misunderstanding that the https://bitbucket.org/pjtr/jmeter-websocket-samplers/overview plugin only supports request-response model conversations.
Since version 0.7, the plugin offers "single read" and "single write" samplers. Of course, it depends on your exact protocol, but the idea is that you could use a "single write" sampler to send a WebSocket message that simulates creating the subscription and then have a (standard JMeter) While loop in combination with the "single read" samplers, to read any number of messages that are being published.
If this does not satisfy your needs, let me know and i'll see what i can do for you (i'm the author of this plugin).

Answer 2

I had the system with STOMP. So the clients executed the HTTP messages and they got the actual state via asynchronous WebSockets with this subscribe model. To emulate this behaviour I wrote a class which via JMeterContext variable could exchange data with Jmeter threads (import part you can find by yourself import org.springframework.*):
public class StompWebSocketLoadTestClient {
public static JMeterContext ctx;
public static StompSession session;
public static void start(JMeterContext ctx, String wsURL, String SESSION) throws InterruptedException {
WebSocketClient transport = new StandardWebSocketClient();
WebSocketStompClient stompClient = new WebSocketStompClient(transport);
ThreadPoolTaskScheduler threadPoolTaskScheduler = new ThreadPoolTaskScheduler();
threadPoolTaskScheduler.initialize();
stompClient.setTaskScheduler(threadPoolTaskScheduler);
stompClient.setDefaultHeartbeat(new long[]{10000, 10000});
stompClient.setMessageConverter(new ByteArrayMessageConverter());
StompSessionHandler handler = new MySessionHandler(ctx);
WebSocketHttpHeaders handshakeHeaders = new WebSocketHttpHeaders();
handshakeHeaders.add("Cookie", "SESSION=" + SESSION);
stompClient.connect(wsURL, handshakeHeaders, handler);
sleep(1000);
}
The messages were handled in this class:
private static class MySessionHandler extends StompSessionHandlerAdapter implements TestStateListener {
private String Login = "";
private final JMeterContext ctx_;
private MySessionHandler(JMeterContext ctx) {
this.ctx_ = ctx;
}
#Override
public void afterConnected(StompSession session, StompHeaders connectedHeaders) {
session.setAutoReceipt(true);
this.Login = ctx_.getVariables().get("LOGIN");
//System.out.println("CONNECTED:" + connectedHeaders.getSession() + ":" + session.getSessionId() + ":" + Login);
//System.out.println(session.isConnected());
**//HERE SUBSCRIBTION:**
session.subscribe("/user/notification", new StompFrameHandler() {
#Override
public Type getPayloadType(StompHeaders headers) {
//System.out.println("getPayloadType:");
Iterator it = headers.keySet().iterator();
while (it.hasNext()) {
String header = it.next().toString();
//System.out.println(header + ":" + headers.get(header));
}
//System.out.println("=================");
return byte[].class;
}
#Override
public void handleFrame(StompHeaders headers, Object payload) {
//System.out.println("recievedMessage");
NotificationList nlist = null;
try {
nlist = NotificationList.parseFrom((byte[]) payload);
JMeterVariables vars = ctx_.getVariables();
Iterator it = nlist.getNotificationList().iterator();
while (it.hasNext()) {
Notification n = (Notification) it.next();
String className = n.getType();
//System.out.println("CLASS NAME:" + className);
if (className.contains("response.Resource")) {
///After getting some message you can work with jmeter variables:
vars.putObject("var1", var1);
vars.put("var2",String.valueOf(var2));
}
//Here is "sending" variables back to Jmeter thread context so you can use the data during the test
ctx_.setVariables(vars);
n = null;
}
} catch (InvalidProtocolBufferException ex) {
Logger.getLogger(StompWebSocketLoadTestClient.class.getName()).log(Level.SEVERE, null, ex);
}
}
});
}
In Jmeter testplan, after Login stage I just added a Beanshell sampler with login/password and session strings and Jmeter thread context:
import jmeterstopm.StompWebSocketLoadTestClient;
StompWebSocketLoadTestClient ssltc = new StompWebSocketLoadTestClient();
String SERVER_NAME = vars.get("SERVER_NAME");
String SESSION = vars.get("SESSION");
String ws_pref = vars.get("ws_pref");
ssltc.start(ctx,ws_pref+"://"+SERVER_NAME+"/endpoint/notification- ws/websocket",SESSION);
Further is possible to use all incoming via Websockets data with simple vars variable:
Object var1= (Object) vars.getObject("var1");

Answer 3

Basically, JMeter is not suited well for async type of interaction with system under test.
Though (virtually) everything is possible with Scripting components (post processors, timers, assertions, perhaps samplers, seems to look most useful in your case) and JMeter Logic Controllers.
Like, you may line up your "further samplers", covered in If blocks, analyze the "receipt of a WebSocket published message" and set the flag variables/other parameters for If blocks.
And you may even sync threads, if you need it, check this answer.
But tell you what - that pretty much looks like a lot of handwritten stuff to be done.
So it make sense to consider the whole custom handwritten test harness too.