Pro Java Clustering and Scalability by Jorge Acetozi

Author:Jorge Acetozi
Language: eng
Format: epub
Publisher: Apress, Berkeley, CA

10.3 Message Flow Using a Simple Broker

Figure 10-1 shows the message flow with a simple broker. The figure may be confusing at first glance, but this is exactly the flow that you just learned about.

Figure 10-1.Message flow: simple broker

When you send a frame through WebSocket over STOMP, the message will first reach clientInboundChannel. There, it will be routed to a specific MessageHandler depending on the destination name. If the name starts with /app, then it will route it to the SimpAnnotationMethod message handler (which will eventually call your @MessageMapping annotated method inside the @Controller class). If the name starts with /topic, then it will route it directly to the SimpleBroker4 message handler.

Let’s look at an example of the frame SEND /app/a. First, clientInboundChannel will receive and forward it to the SimpAnnotationMethod message handler. Then, from the @MessageMapping annotated method, the message will be forwarded to brokerChannel. This will send it to the SimpleBroker message handler. This message handler keeps a ConcurrentHashMap with every WebSocket session ID for every connected client and also all the subscriptions in the SubscriptionRegistry (in memory). Then, the message handler uses the WebSocket client ID to forward the message to the corresponding clientOutboundChannel, which will finally send the message to the client.

Note that using the simple broker approach , the subscriptions are kept in memory.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.