When organizations such as Goodwill decide to integrate via Web services, they're connect- ing disparate systems by follow-ing a common set of standards that govern the Web. "Open source is good about building to standard," Michelson says. So adopters of the Web services approach aren't locked into a vendor's proprietary links.
Those standards continue to evolve and include WS-Security, Web Services Description Language, WS-Reliability, and others coming out of the IETF and W3C standards bodies.
In addition to JBoss and WSO2, other open source middleware stacks include LogicBlaze Fuse and IBM's Gluecode. IBM acquired Gluecode to compete with JBoss and the popular LAMP stack: Linux, Apache Web Server, MySQL database, and the Perl, Python, and PHP scripting languages.
Middleware vendors Sun Microsystems and BEA Systems also have managed to keep a foot in the open source waters. Sun makes several pieces of its Java Enterprise System freely available, while offering technical support for a fee.
Bill Roth, BEA Systems' VP of WebLogic tools, says there's no need to choose strictly between commercial or open source code. His company is broadening WebLogic to work with different types of open source code, such as PHP applications. It's demonstrated PHP running on WebLogic Application Server and expects to have PHP support built into its tools and server offerings for developer test drives by year's end.
At Optaros, open source middleware customers are most likely to go with JBoss Enterprise Middleware Suite, LogicBlaze Fuse, WSO2 Tungston, and MuleSource's Mule, an enterprise service bus that's landed early customers in financial services, Michelson says. Ross Mason, a lead developer of Mule, says "less code is better for performance," thus Mule is a small, high-performance messaging core to which modules may be added to connect to specific systems, such as IBM's WebSphere MQ or Tivoli systems management.
Mule supports Web Services Business Process Execution Language, allowing applications to be connected to particular business processes via Web services.
As open source choices in middleware proliferate, it might seem too cluttered a field from which to choose. But Goodwill's Bergman says finding technical support is one of the strengths of the open source route.
"When we had a problem and were under the gun, we would open up the development effort to the open source community and find we'd have it solved over the weekend," he says, referring to an issue that involved customizing the Liferay portal's directory.
Open source certainly isn't the best choice in every integration project. But when Web services are in the game, open source is ready to play.