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This is an implementation of the event bus bridge that allows Java applications to send and receive event bus messages using the SockJS websocket sub-protocol.The API mimics the one used invertxbus.js.Internally, vert.x is used for websocket communication to the SockJS service that governs which event bus addresses are available.

If you would like to send or received messages on the Vert.x event bus using SockJS/websocket communication.

EventBusBridge is the main class to use. Start with the connect method and take it from there.

Call the static connect method with an URI and a connection handler.

You should not be using the EventBusBridge instance returned by connect beforeisOpen returns true.The best way to guarantee this is to access the EvenBusBridge inside the connection handler.

Here's an example that opens a connection to the Vert.x event bus via the SockJS service, registers a message handler and publishes a text message.

EventBusBridge.connect(URI.create("http://localhost:8765/bridge"),eb -> {eb.registerHandler("test",msg -> {System.out.println("I gots a message:" +msg);     });eb.publish("test","hello");});

For this example to work, a SockJS service needs to run on the server side that allows incoming and outgoing messages on thetest address.Here's an example:

vertx =Vertx.vertx();Routerrouter =Router.router(vertx);// events specific to THOPs are made available over the bridgeSockJSHandlersockJSHandler =SockJSHandler.create(vertx);BridgeOptionsoptions =newBridgeOptions();options.addOutboundPermitted(newPermittedOptions().setAddress("test"));options.addInboundPermitted(newPermittedOptions().setAddress("test"));sockJSHandler.bridge(options);router.route("/bridge/*").handler(sockJSHandler);vertx.createHttpServer().requestHandler(router::accept).listen(8765, (res) -> {System.out.println("I'm here to serve");});

Registering handlers comes in two flavorsEventHandler andMessageHandler.EventHandler in addition to the message payload also gives you access to theEventBusBridge instance which might be more convenient in some cases.Here's an example that shows the difference:

eb.registerHandler("test",msg -> { ... } );eb.registerHandler("test", (msg,eventBus) -> { ... });

While Vert.x supports arbitrary message types on the event bus, this bridge only supports plain text and JsonObjects as message payload.Accessing the payload as JsonObject is a bit cumbersome as the type of the message parameter must be specified:

eb.registerHandler("test", (EventBusBridge.EventBusMessage<JsonObject>msg) -> {assertEquals("world",msg.body().getString("hello"));});eb.publish("test",newJsonObject().put("hello","world"));

For convenience,msg.asJson() will return anMessage<JsonObject> so the code above can be simplified like this:

eb.registerHandler("test",msg -> {assertEquals("world",msg.asJson().body().getString("hello"));});eb.publish("test",newJsonObject().put("hello","world"));

There are some gotchas when using lambda expressions and unregistering handlers for messages.For example, this will fail:

eb.registerHandler("test",this::myHandler):eb.unregisterHandler("test",this::myHandler);

since the compiler will create different lambda classes for each occurrence ofthis::myHandler!

In order to make the most common de-registration case simple (de-register after receiving a message),the message object has an unregister method that will unregister the current handler.

eb.registerHandler("test",msg -> {System.out.println("Got your message. Now leave me alone!");msg.unregister(); });

Note one important caveat which is thatmsg.unregister will only work correctly if used while the handler is being called.

v1.1 addedconnect methods to specify the host and port to connect to as well as the URL to retrieve.To connect via aproxyHost atproxyPort, call

EventBusBridge.connect(proxyPort, proxyHost, url, eb -> {...}, options);

Make sure the URL is an absolute URL in this case.

v1.2 added support for SSL.Use ahttps URL or pass your ownnew HttpOptions().setSsl(true) options.Depending on your needs, specify a trust store. Check the Vert.x docs for details.

1.2 - support for SSL. Usenew HttpOptions().setSsl(true).setVerifyHost(false) if you need to connect to a server with a self-signed certificate. See EventBusBridgeSSLTest.Tested with Vert.x 3.0.0 and 3.1.0

Since it is early days, download the git project and runmvn jar:jar to get something you can add to your Java project.The latest build is available here(https://drone.io/github.com/saffron-technology/vertx-eventbusbridge/files)

Open a ticket or send an email to jochen.bedersdorfer (at) intel (dot) com

Licensed under Apache License 2.0. See LICENSE file