Are you still considering rolling out a major Enterprise Service Bus (ESB) stack — you know, the kind that involves a massive initial investment and takes 8+ months to deploy? This wasteful approach was a major factor in doomed corporate SOA initiatives that were common between 2003 and 2009. During this same period, clever architects ignored large vendor promises and realized that you simply cannot buy your way into an agile enterprise SOA. They instead focused on the tasks at hand, integrating existing IT assets, following SOA principles, using existing tools and adding lightweight strategic and specialized infrastructure to help them along the way. The winning enterprise SOA initiatives are the ones who made sure that the SOA was operational as it evolved.

SOA Gateways gained popularity in recent years as a lightweight ESB that can span departmental boundaries. Like software ESBs, SOA Gateways can translate data formats, route content, service-enable data sources and switch between transport protocols. But SOA Gateways have a number of significant advantages over traditional software ESBs. For example, they scale easily and accommodate high volume traffic environments owing to their specialized acceleration of message validation, routing and translation. Also, SOA Gateways offer comprehensive security and identity federation features built in so they can be deployed at the service zone perimeter (think DMZ).

Looking back, the pattern of using an SOA Gateway to integrate and service-enable existing IT assets has been a large success. Because of the appliance form factor and the configure, not code approach, the cost of integration and the time to react to new requirements both shrunk considerably. And with a focus increasingly shifting towards cloud computing, this ability to quickly accommodate new integration mechanisms has already paid off for those who invested in the lightweight, agile solution. This is especially the case for those who opted for the virtual appliance form factor.

I like to refer to this pattern as the Enterprise Service Gateway (ESG). That is, the ability to execute integration, transformation and security using a specialized gateway appliance as opposed to coding using traditional software ESB frameworks.

From http://francoislascelles.sys-con.com/node/1776653