2002 Technology of the Year: Publish/subscribe technology

In the realm of message-oriented middleware, publish/subscribe technology has long been taken for granted. Tibco's early pub/sub innovations became a standard feature of IBM's MQSeries, Microsoft's MSMQ, and the Java Message Service (supported by IBM, Sonic, Sun, BEA, and others). It was inevitable that pub/sub would play a role in the emerging architecture of loosely coupled Web services, and in 2002 that happened on many fronts.

Free IT resource TechNet: More ways to know it, share it, and keep it running. Sponsored by Microsoft Free IT resource Attend the SOA Executive Forum: Breaking SOA Bottlenecks SOAExecForum.com/may2007 Sponsored by InfoWorld

Sonic Software, a leading JMS provider, teamed up with XMethods, an online Web services lab, to offer an alternative interface to XMethod's XSpace, a shared database. This service, described in WSDL, was previously accessible only via SOAP over HTTP, but the Sonic/XMethods demonstration opened a JMS channel to XSpace. Along with JMS point-to-point messaging, developers were able to register for notification of XSpace events using the publish/subscribe mode of JMS.

A new breed of middleware vendors brought pub/sub messaging down to the desktop. With Kenamea and KnowNow, you can subscribe a spreadsheet cell to a topic that's managed out in the cloud. An event published to that topic —such as an inventory update — automatically updates the spreadsheet. It's true that you could do this kind of thing a decade ago, using NetDDE (Network Dynamic Data Exchange) on your Windows for Workgroups LAN. But pub/sub at Internet scale is far more compelling.

With the introduction of Macromedia's Flash Communication Server MX, the Flash 6 player also entered the world of desktop pub/sub. The server supports pub/sub event distribution networks that can be wired up one-to-one or one-to-many. Events can be produced by audio and video streams, but also by any of the GUI widgets in the Flash player's suite.

The Web services stack doesn't yet specify a pub/sub model, but Microsoft's WS-Routing trial balloon and Sonic Software's proposal to weave JMS support into the Apache Axis engine are steps in that direction.

Meanwhile, another kind of pub/sub technology enjoyed skyrocketing popularity in 2002: the RSS (Rich Site Summary) news-feeds that Weblogs publish and to which RSS news-readers subscribe. A mailing list is monolithic, and subscribing is a binary decision. Weblogs are granular, and subscribing is a game of multiple choice. Since every subscriber can also be a publisher, filtering and aggregation of information events happens in an easy and natural way.

Prediction for 2003: Interapplication and interpersonal pub/sub will grow even closer.