Adopting an ESB—Or Not
Should services be wrapped into an ESB? Or should they be managed and mediated some other way? Proponents, detractors face off.
But there are those who see ESBs as warmed-over EAI — and feel they defy the open nature of SOA. “EAI is fundamentally different than SOA,” says Anne Thomas Manes, an analyst at Burton Group. “EAI is about bridging business process silos; SOA is about breaking them down.” She has no problem with using an ESB to provision a service, or even to orchestrate fine-grained services into a widely accessible coarse-grained service. But she bridles at the notion of a bus as the gateway to all services, especially when conversion to and from an ESB message transport incurs additional overhead.
Manes also finds fault with the notion that, without an ESB, difficult-to-manage “point-to-point” services are held up as the spaghettilike alternative: Point-to-point is an integration metaphor, whereas the idea of SOA is to expose services that can be reused by many applications or other services. And that needn’t mean lack of control. One alternative to the ESB approach is to use XML appliances — also called gateways — to route messages, handle transformation and mapping, and proxy services so they can be governed and secured effectively.
Eric Knorr is executive editor at large at InfoWorld. Galen Gruman is contributing editor at InfoWorld.
