Reactive Distributed Applications with Vert.x
8 likes2,623 views
Vert.x is a toolkit for building distributed, reactive systems using a non-blocking model on the JVM. It offers components for various communication protocols and supports multiple programming languages, allowing seamless messaging and robust handling of failures. Key features include an event bus for inter-component communication, clustering capabilities, and mechanisms for managing scalability and reliability.
Reactive Distributed Applications with Vert.x
- 14. ASYNCHRONOUS & NON-BLOCKING // Synchronous development model X x = doSomething(a, b); // Asynchronous development model - callback variant doSomething(a, b, // Params ar -> { // Last param is a Handler<AsyncResult<X>> // Result handler }); // Asynchronous development model - future variant Future<X> future = doSomething(a, b); future.setHandler( ar -> { /* Completion handler */ });
- 16. VERT.X HELLO WORLD Vertx vertx = Vertx.vertx(); vertx.createHttpServer() .requestHandler(request -> { // Handler receiving requests request.response().end("World !"); }) .listen(8080, ar -> { // Handler receiving start sequence completion (AsyncResult) if (ar.succeeded()) { System.out.println("Server started on port " + ar.result().actualPort()); } else { ar.cause().printStackTrace(); } });
- 18. EVENT LOOPS
- 19. VERT.X ASYNC HTTP CLIENT HttpClient client = vertx.createHttpClient( new HttpClientOptions() .setDefaultHost("localhost") .setDefaultPort(8081)); client.getNow("/", response -> { // Handler receiving the response // Get the content response.bodyHandler(buffer -> { // Handler to read the content }); });
- 24. POINT TO POINT vertx.eventBus().send("address", "message"); vertx.eventBus().consumer("address", message -> {});
- 26. REQUEST / RESPONSE vertx.eventBus().send("address", "message", reply -> {}); vertx.eventBus().consumer("address", message -> { message.reply("response"); });
- 27. FROM LOCAL TO CLUSTERED Vert.x instances form a cluster The event bus is distributed on all the cluster members Vertx.clusteredVertx(new VertxOptions(), result -> { if (result.failed()) { System.err.println("Cannot create a clustered vert.x : " + result.cause()); } else { Vertx vertx = result.result(); // ... } });
- 34. MANAGING FAILURES Distributed communication may fail AsyncResult lets us manage these failures: doSomethingAsync(param1, param2, ar -> { if (ar.failed()) { System.out.println("D'oh, it has failed !"); } else { System.out.println("Everything fine ! "); } });
- 35. MANAGING FAILURES Adding timeouts vertx.eventbus().send(..., ..., new DeliveryOptions().setSendTimeout(1000), reply -> { if (reply.failed()) { System.out.println("D'oh, he did not reply to me !"); } else { System.out.println("Got a mail " + reply.result().body()); } });
- 36. CIRCUIT BREAKER
- 37. CIRCUIT BREAKER cb.executeWithFallback(future -> { // Async operation client.get("/", response -> { response.bodyHandler(buffer -> { future.complete("Ola " + buffer.toString()); }); }) .exceptionHandler(future::fail) .end(); }, // Fallback t -> "Sorry... " + t.getMessage() + " (" + cb.state() + ")" ) // Handler called when the operation has completed .setHandler(content -> /* ... */);
- 47. SCALING HTTP