The Definitive Guide to HTML5 WebSocket by Vanessa Wang & Frank Salim & Peter Moskovits

Author:Vanessa Wang & Frank Salim & Peter Moskovits
Language: eng
Format: epub, mobi
ISBN: 9781430247401
Publisher: Apress

Note Not every message broker uses topics and queues. In this chapter, though, we use Apache ActiveMQ, which does support topics and queues.

The more you use WebSocket, the more you may realize that the requirements for building WebSocket-powered applications resemble classic messaging concepts. For example, perhaps you want to extend the reach of your enterprise messaging protocols to the Web by distributing large quantities of messages to a large number of clients. Or, suppose you’re building a collaborative application that requires your WebSocket clients to send and receive data to and from other WebSocket clients. These two examples illustrate messaging applications and WebSocket applications alike. As you will see in this chapter, the two technologies work well together and layering messaging over WebSocket enables you to build powerful messaging applications.

Messaging systems differ in how they integrate with clients. Some, like brokers that support STOMP, offer protocol-level interoperability. Anyone implementing a compatible protocol client can connect to those systems from any platform and language. Others offer APIs that are provided for some select platforms chosen by the system vendor.

The simplest open, widely used protocol for messaging is STOMP: Simple (or Streaming) Text Oriented Messaging Protocol. The most widely used messaging API in the enterprise is JMS: Java Message Service. Unlike STOMP, which promotes interoperability by defining a wire protocol, JMS is just an API. STOMP has been implemented for many different languages; because of its nature as an API, JMS is almost exclusively reigning in the Java world.

A newly standardized open messaging protocol is AMQP: Advanced Message Queuing Protocol. AMQP 1.0 became an OASIS standard in October 2012. Although AMQP was created with wide industry support, whether it can live up to the popularity and success of STOMP and JMS remains to be seen. To learn more about AMQP, see http://amqp.org.

In this chapter we walk through using STOMP over WebSocket (STOMP/WS). But if your interest is JMS or AMQP over WebSocket, there are vendors and projects that can offer you these capabilities. In addition, there are several proprietary pub/sub implementations over WebSocket: some are simple, some more sophisticated. See Appendix B for a list of current WebSocket servers that may have the support you need. The steps in this chapter will hopefully also help give you a general understanding of how pub/sub over WebSocket implementations work.

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