Deprecated

This project has been deprecated in favour of the EventSource support provided by Elemental2. Elemental2 is closer to the browser, future compatible and easier to maintain.

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gwt-eventsource

A simple library to provide eventsource support to GWT.

Quick Start

The simplest way to use the library is to add the following dependency into the build system. i.e.

<dependency>
   <groupId>org.realityforge.gwt.eventsource</groupId>
   <artifactId>gwt-eventsource</artifactId>
   <version>1.0</version>
   <scope>provided</scope>
</dependency>

Then you add the following snippet into the .gwt.xml file.

<module rename-to='myapp'>
  ...

  <!-- Enable the eventsource library -->
  <inherits name="org.realityforge.gwt.eventsource.EventSource"/>
</module>

Then you can interact with the EventSource from within the browser.

final EventSource eventSource = EventSource.newEventSourceIfSupported();
if ( null != eventSource )
{
  eventSource.setListener( new EventSourceListenerAdapter() {
    @Override
    public void onOpen( @Nonnull final EventSource eventSource )
    {
      // Connected!
    }

    @Override
    public void onMessage( @Nonnull final EventSource eventSource,
                           @Nullable final String lastEventId,
                           @Nonnull final String type,
                           @Nonnull final String data )
    {
      //Handle message
    }
  });
  eventSource.connect( "http://example.com/someurl.ext" );
  ...
  // Optionally listen to messages on message type other than "message"
  eventSource.subscribeTo( "someMessageType" );
}

This should be sufficient to put together a simple EventSource application.

A very simple example of this code is available in the gwt-eventsource-example project.

Appendix

• Mozilla Using server-sent events
• W3C: Server-Sent Events