Chapter 10. PublishSubscribe Systems


Chapter 10. Publish/Subscribe Systems

In This Chapter

  • Publish/Subscribe Using Callback Contracts

  • Publish/Subscribe Using MSMQ Pragmatic Multicasting

  • Publish/Subscribe Using Streaming

In "publish/subscribe systems[…]processes can subscribe to messages containing information on specific subjects, while other processes produce (i.e. publish) such messages" (Tannenbaum and van Steen 2002, 701). Publish/subscribe systems are required in many scenarios. In the financial industry, subscriptions to prices are needed. Subscriptions to sensor data and to information about other equipment are required in manufacturing. In computer systems administration, the administrators need to subscribe to information about the security and states of the systems.

Web Services Eventing and Web Services Notification are competing protocols pertinent to publish/subscribe systems. Both specify formats for subscription messages and for publication messages. Neither format is likely to become very important until at least both International Business Machines (IBM) and Microsoft endorse just one of the protocols.

The Web Services Notification specification provides a handy description of some of the various ways in which publishers can provide updates to subscribers (Graham, Hull and Murray 2005, 24). In push-style notification, subscribers send subscription messages to publishers, who then send publication messages to the subscribers. In pull-style notification, subscribers send subscription messages to publishers, who send publication messages to a pull-point that is known to the subscribers, from which the subscribers retrieve the publication messages. In brokered notification, subscribers send subscription messages to brokers, who retrieve publication messages sent by publishers and make them available to the subscribers.

There are various ways of constructing publish/subscribe systems with the Windows Communication Foundation. This chapter describes several of them.




Presenting Microsoft Communication Foundation. Hands-on.
Microsoft Windows Communication Foundation: Hands-on
ISBN: 0672328771
EAN: 2147483647
Year: 2006
Pages: 132

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