SOA power

As Bruce Silver points out in Intelligent Enterprise, companies need business process management (BPM) to be agile.

"But to achieve agility without breaking the bank, you can't simply rip and replace," he adds. "You must break down legacy stovepipes into modular components that can be reused in multiple business processes. That's precisely the promise of a new style of software development called service-oriented architecture. With SOA, applications are no longer built as monoliths. Instead, they're composed by assembling modular services."

Where do services come from? According toSilver's excellent new primerlinkingSOA toBPM, services emerge from several places:

Coding from scratch:"Today, application servers from infrastructure vendors such as IBM, Microsoft, BEA and Oracle compete largely on the basis of their tools for rapidly creating custom code that can be deployed as reusable Web services."

Wrapping existingsystems:Leveraging middleware components known as"integration adapters," one can "wrap" existing systems,"exposing their functionality as Web services without custom code."

Buying themfrom the enterprise application vendors: "New versions of enterprise apps such as SAP and Siebel are being packaged as collections of native Web services, ready for out-of-the-box orchestration."

Accessingthird-party services: Using registries, services can be accessed on the Web.

Finally, one can "combine services implemented in all of these ways in an orchestrated business process. That's the power of SOA."