A couple years ago, everyone was wildly excited over a handful of promising new XML standards. The pundits were aflutter about "applications as services," where enterprises would lease each other’s server-side apps over the Internet. Soon, companies would plug into each other and do business over the wire, on the fly. You might call Web services the Last Big Thing.

The surprise is that today, in the midst of an IT downturn that has become a way of life, Web services really is changing everything. But rather than creating a web of ad-hoc external connections, enterprises are instead quietly adopting Web services to reduce dependence on proprietary message-oriented middleware (MOM).

Key to this shift is service-oriented architecture (SOA)—that is, making applications inside the enterprise available to other applications by wrapping them in Web services interfaces. MOM from Tibco Software or WebMethods can now connect using Web services protocols much as they would via conventional application adapters, making it conceivable to switch MOM vendors without wreaking infrastructure havoc. Plus, Web services wrappers let enterprise developers create simple app-to-app connections without using commercial middleware at all.

Not that MOM vendors appear seriously threatened. During the past couple years, those companies have been shucking the EAI label in favor of "business integration" to emphasize rules-based process management rather than app connections.

Web services will take about a decade to mature on the business process side. There has been some progress, such as the Business Process Execution Language for Web Services (BPEL4WS). But creating a complete specification for business process integration is incredibly complicated. The idea that the entire industry—including the Microsoft, Java and MOM camps, each with its own agenda—could produce a generic, all-encompassing spec for business integration seems pretty preposterous.

So most customers will keep their commercial integration solutions, with the caveat that SOA can loosen the stranglehold that such solutions have on many large enterprises. Meanwhile, IT managers are tired of hearing about standards wars and highfalutin’ specs, such as BPEL4WS. What they want instead are basic tools to help make Web services truly interoperable across platforms. This is one reason why low-profile startup Systinet is the unsung hero of Web services: The company’s sole product suite, the Web Applications and Services Platform (WASP), provides Java and C++ runtime environments that ensure a fully interoperable SOA. WASP also comes with a UDDI directory that enables developers to publish Web services in a central, inside-the-firewall repository.

Sonic Software offers another interesting approach to SOA. Rather than modifying conventional MOM technology at the edges to accommodate Web services standards, Sonic has created an integration solution built from the ground up on Web services called the Sonic Business Integration Suite. The central component is the Enterprise Service Bus, which combines messaging, distributed transactions, data transformation and intelligent routing to enable applications to "plug in" and interact in a coordinated way.