Apache Synapse: 'intermediary' or 'bus'?

In recent times, there has been an abundance of contention and confusion within the industry over the exact purpose and benefits of enterprise service buses, or ESBs. Some say its a quick on ramp to SOA, others say its a distraction. A big problem is the proliferation of ESBs from a variety of different vendors -- requiring a new phase of integration projects, defeating the purpose of SOA.

In hopes of averting this tangle, the Apache Software Foundation has unveiled its latest project, called Synapse, which essentially is an open-source ESB that proponents hope will bring standardization and commonality to budding SOAs that require a mediation framework, as well as the vendor product sets that can make it happen.

I caught up with Infravio's Miko Matsumura, who has been active in the Synapse project, to see how Synapse may alleviate the fear and loathing around ESBs. (Infravio is contributing code to Synapse). He points out that while Synapse does many ESB-like things, the working committee has side-stepped that term, as well as the term "broker."

Synapse, he says, "does intend to be a fully functional Web service intermediary, but we punted on the ESB question. The problem is so many companies have jumped in and said, 'My thing is an ESB.' Well, if this is an ESB, and the other one is an ESB, and this is an ESB, then what's the common denominator here, and how did they all get to be ESB? We're avoiding that whole name game, and using more neutral terminology. 'Intermediary' has the least political implications. 'Broker' is slightly more flavored, while 'ESB' has a very sharp, nutty flavor."

WSO2, a new startup whose founders have deep roots in Apache, is spearheading the initiative. Vendors supporting or contributing code to Synapse include some leading ESB vendors, including Blue Titan, Iona, and Sonic Software, as well as Infravio.

Synapse is also designed to work with the Apache Axis toolkit to serve as an intermediary within an SOA. "This intermediary is designed to function along core Web service standards, such as WSDL, WS-Addressing, WS-Policy, WS-Security, WS-and ReliableMessaging," says Matsumura. "It will be a ubiquitous part of the future of Web services runtime."

The role of the intermediary is to "sit in the middle and perform three principle functions. One is dynamic load balancing and dynamic routing, tied to the loose-coupling paradigm," he adds. The second role is data transformation, and the third is systems management. "If you don't use an intermediary, you're basically doing point-to-point Web services connections, not SOA. For SOA, you need some kind of overview of what your services are, and achieving reuse of those services, using registry and policies. An intermediary is an important piece of the puzzle."

Gartner analysts have also weighed in on Synapse, noting that "real-world" Synapse technology is likely to start becoming available on the market sometime next year. "The Synapse product offering will initially be targeted at providing an embeddable ESB core that the partners can extend with proprietary capabilities or integrate into their 'closed-source' products. The Apache Software Foundation's involvement gives the project credibility, but Synapse will face challenges in getting vendors with different agendas to cooperate on the same platform."