Pushing Messages to a Flow form a Message Source
After generating a piece of information for the flow, the source uses the SourceCallback to send the information to the flow. Returning to the minimalistic HTTP listener example:
public class HttpListener extends Source<InputStream, HttpRequestAttributes> {
@Override
public void onStart(SourceCallback<InputStream, HttpRequestAttributes> sourceCallback) throws MuleException {
httpServer = serverProvider.connect(); (1)
server.listen(path).onRequest(request -> { (2)
Result<InputStream, HttpRequestAttributes> result = requestToResult(request); (3)
sourceCallback.handle(result); (4)
});
}
}| 1 | The example uses the ConnectionProvider to obtain an HttpServer. The typical connection provider most already configured the server with the proper host and port. |
| 2 | HTTP requests are pushed into the server by the remote clients, and the HttpServer component will notify the source of every request. The source then uses the SourceCallback to push the message into the flow. |
| 3 | The message is represented by leveraging the same Result object that operations use to communicate complex outputs. See Result for more information. |
| 4 | The example uses the handle(Result) method in the SourceCallback to pass the message. |
Threading Model
Once the Result object is passed to the SourceCallback through the handle(Result) method, message processing occurs asynchronously in a different thread than the one invoking the method.
The next step explains how to catch the result of the Flow processing and optionally send a response.