Java Annotation Processor for GWT Async Services

GWT-RPC

The client side of the GWT-RPC mechanism requires an asynchronous variant of the service interface. An example synchronous service from the official documentation:

package com.google.gwt.sample.stockwatcher.client;

import com.google.gwt.user.client.rpc.RemoteService;
import com.google.gwt.user.client.rpc.RemoteServiceRelativePath;

@RemoteServiceRelativePath("stockPrices")
public interface StockPriceService extends RemoteService {

  StockPrice[] getPrices(String[] symbols);
}

... must be turned into ...

package com.google.gwt.sample.stockwatcher.client;

import com.google.gwt.user.client.rpc.AsyncCallback;

public interface StockPriceServiceAsync {

  void getPrices(String[] symbols, AsyncCallback<StockPrice[]> callback);
}

in order to have a type which fits the asynchronous (callback-based) programming model of the client. This annotation processor can make this transformation automatically, and therefore has the following benefits:

• no longer requires developers to hand-code async services,
• no longer requires manual intervention to generate async services using IDE facilities,
• no longer requires to keep the generated sources under version control,
• is not tied to a specific build tool (as opposed to GWT Maven Plugin, for instance).

Usage

Every service interface annotated with @RemoteServiceRelativePath has its async variant generated automatically. If this annotation is absent, async service generation can be turned on using @AsyncService:

import net.omikron.apt.gwt.AsyncService;

@AsyncService
public interface MyService { ... }

Dependency Metadata

Grab the most recent release from JitPack. An complete Gradle configuration is shown below:

repositories {
  mavenCentral()
  maven { url "https://jitpack.io" }
}

apply plugin: 'java'

dependencies {
  compileOnly 'com.github.fact-finder.apt-gwt-async:apt-gwt-async-annotation:1.0.0'
  annotationProcessor 'com.github.fact-finder.apt-gwt-async:apt-gwt-async-processor:1.0.0'
}