Jason Bloomberg, senior analyst with ZapThink LLC, said that while adapters have a role to play in SOA it’s mostly for tactical deployments, not a core piece of SOA. He said that users need to be careful of what they’re buying when they go ESB shopping.

“As for ESBs, the market is still confused by the fact that the products that call themselves ESBs are still quite diverse in capability,” he said. “As a result, when customers say they want an ESB, they could mean very different things. What we’re seeing is that there’s a spectrum of approaches among the various SOA infrastructure products — some labeled ESB, some not. At one extreme are the tightly coupled EAI products with service interfaces, like SeeBeyond and webMethods. A bit less extreme are the application server-based ESBs like the IBM ESB and BEA’s AquaLogic service bus. In the middle is a product like the Sonic ESB, which does have the messaging infrastructure, but takes a more service-oriented approach to distributing the service containers than the ones mentioned above.

“At the opposite end of the spectrum would be peer-to-peer approaches linking intelligent Service endpoints, but the SOA marketplace is far from ready for this approach. Moving into the center from that extreme are the distributed intermediary approaches, like Blue Titan, SOA Software and also what companies like Cisco are envisioning. Then closer to the middle from them would be Cape Clear’s approach, which allows for, but doesn’t require a message transport.”

“Fundamentally, we see the middleware-centric ESBs of the first group as being in a transitional market,” Bloomberg said. “As companies eventually get wise that they just don’t need more middleware. After all, they already have a boatload of middleware and if they get more than one ESB, then they’ll need more middleware just to connect up their middleware. Eventually, the [network-base] distributed intermediary approach will gain ground, as this approach is more cost-effective, flexible, scalable and architecturally elegant than the middleware-centric approach.”

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