function createEventStream(stream, parser, model) {
    var eventStream = new EventUnmarshallerStream({
        parser: parser,
        eventStreamModel: model
    });

    var eventMessageChunker = new EventMessageChunkerStream();

    stream.pipe(
        eventMessageChunker
    ).pipe(eventStream);

    stream.on('error', function(err) {
        eventMessageChunker.emit('error', err);
    });

    eventMessageChunker.on('error', function(err) {
        eventStream.emit('error', err);
    });

    return eventStream;
}
What is necessary to create an event stream in node?
 - http response stream
 - parser
 - event stream model