The SOA tool kit

The principal layers of an SOA -enabling infrastructure are service brokers, orchestration engines, message-oriented middleware environments and service-level management tools.

Brokering infrastructures encourage reuse by allowing developers to "advertise" their programs' service interfaces in a shared online registry, repository or catalog.

UDDI is the Web services standard, but companies have implemented service-brokering infrastructures on other platforms, such as database management systems.

Orchestration engines encourage reuse by allowing developers to build new services through workflow definitions that connect preexisting services. Developers often use graphical process-definition tools that allow them to specify orchestration tasks, dependencies, and routing and processing steps with flowchart icons. This approach also is called model-driven development. Once defined, these visual process models might be compiled into reusable rule definitions that control the execution of multistep interaction flows, such as those that involve complex transformation and routing rules, across heterogeneous platforms.

MOM environments encourage reuse by providing guaranteed-delivery, event-notification and publish-and-subscribe protocols that bind heterogeneous application endpoints into an enterprise service bus.

Abebooks has deployed Sonic Software's MOM products as the backplane for its SOA environment. "We deploy Sonic MQ everywhere in our intranet," says Abebooks' Jayson Minard. "Sonic MQ supports both asynchronous and synchronous calls between service endpoints and provides pub/sub, message queuing and event notification services. At the edges of our intranet, we use Sonic ESB to wrap shared services with Web services interfaces so that they can be called by our external trading partners."

Service-level management infrastructures encourage reuse by helping companies monitor, optimize, control and integrate their distributed application environments. A more common term for this functionality is Web services management (WSM) tools. WSM infrastructures help companies ensure the performance, reliability, availability, operational management, life-cycle management and security of end-to-end Web services within an SOA environment. However, a growing range of WSM tools also monitor and enforce service levels in environments that implement MOM and other middleware protocols, which is why the broader term "service-level management" is more appropriate than the middleware-specific term "WSM."

Thomson Learning uses Actional's SOAPstation WSM proxies to control XML -based interactions within their SOA environment, according to company Vice President Chris Crowhurst.

Companies can implement SOA without service-level management, but they would be foolish to do so for long. As SOA succeeds, companies will need to ensure 24/7 availability, guaranteed delivery and performance optimization across the service bus, spanning all service endpoints. But, just as important, your company will need to maintain an IT culture that encourages maximum service reuse, through a full slate of SOA-focused training, incentives, tools and practices.