An example demonstrating how Server Sent Events (SSE) Jersey support can be used to create a message aggregating and streaming resource. The example also demonstrates how to consume data provided by a Twitter Streaming API using Jersey ChunkedInput client-side support.
The example consists of a Swing GUI client application and a server-side application deployed on a Grizzly container.
The Swing client application opens in a single window split into multiple configuration panels. The top-left panel allows to select which aggregators should be executed. It is possible to select a twitter message aggregator and/or a fake test message aggregator. The panel below provides means for adding new keywords tracked by the Twitter message aggregator (if enabled). All actively tracked keywords are listed in the right-side list box which supports removal of the keys using a Delete key on your keyboard. The last panel in the Swing client window contains a Start/Stop button for starting or stopping the selected aggregators as well as a text area for displaying the messages that the aggregators have sent to the message aggregating resource deployed on the server-side of the application.
The server side part of the application consists of a message aggregating JAX-RS resource and a simple HTML page that includes a browser SSE client written in Javascript as well as a basic CSS stylesheet. The SSE Javascript client connects to the JAX-RS message aggregating resource and transforms the streamed message data into HTML code that is rendered by the browser. The mapping of the URI path space of the server-side part of the application is presented in the following table:
| URI path | Resource class | HTTP methods |
|---|---|---|
/aggregator-api/message/stream | MessageStreamResource | GET, PUT |
Application is programmatically configured to run on Grizzly container under base paths aggregator and aggregator-api.
Before running the example, you need to copy the twitter-api.properties file available in the root directory of this example to your user home directory. Once done, you need to edit the file in your user home directory and provide a valid twitter account credentials. This step is necessary as the Twitter streaming API is protected using HTTP Basic Authentication mechanism and only an authenticated twitter account owner can access the API. The TwitterAggregator class in the example will use the credentials provided in the file to access the Twitter Streaming API.
Once you have set up your Twitter credentials, you're ready to run the example. You can run the example by executing a main class via maven as follows:
mvn clean compile exec:java
This deploys the current example as well as it starts the Swing client application. You should be able to see the main Swing application window open as you run the application as well as you should see the note in the command line stating that the Grizzly container has started and the server side part of the application has been deployed.
After successful deployment, you should be able to access the browser SSE client page at
To see the raw SSE event stream, you may also point your browser directly at the
Note that you first need to start the message aggregators via the Swing client application in order to be able to receive any SSE events from the message streaming resource.