When it comes to legacy systems, one of the most persistent problems is making mainframe applications work with Web applications and other distributed systems. Neon Systems Inc. has launched a noninvasive method of capturing mainframe software events and publishing them to distributed systems.

Shadow Event Publisher lets distributed systems tie into a single interface to receive updates on business processes and business events under way on the mainframe or on multiple mainframes. The software can spot events occurring in the mainframe's IBM's DB2 relational database system, its IMS hierarchical data system, or its CICS transaction environment and report them to the appropriate distributed system.

"You can't ask the distributed parts of an application to ask the mainframe to do something and do it in real time," notes product manager Jeff Overton. Shadow Event Publisher is a substitute for that real-time requesting capability, he says.

Many Web applications are composite applications that tie new business logic to the actions of legacy apps. Without making code changes to the mainframe applications, Shadow Event Publisher can monitor and report events, driving actions in surrounding systems. It communicates with distributed systems using HTTP or through IBM's WebSphere MQ, the former MQ Series middleware.

In the future, composite applications will be built that respond to other applications, based on reported events, said Roy Schulte, a Gartner research fellow, in a July report. "Event-driven applications sense and respond to business events, relevant changes in the state of the world," he wrote in "The Case for Event-Driven Design."

If a time-sensitive event, such as a stock-market fluctuation, affects part of an enterprise, the appearance of that event can trigger responses by other systems. Notice of a sale could trigger a response in an inventory and warehouse system, Overton notes. Or Shadow Event Publisher could be used to spot updates to one database system and then synchronize updates to other related databases, bringing enterprise data closer to real-time operations, he says.

Shadow Event Publisher is available now and can be installed as a broad infrastructure system or as an adapter working with a single mainframe-based system, such as Shadow Event Connect for DB2 or Shadow Event Connect for IMS/DB. As a point adapter, pricing starts around $50,000.