Jaguar: Java Components and Transactions

Developers interested in the pending Enterprise JavaBeans specification (still under development at the time of this writing) can get an inkling of its final form thanks to Powersoft's Jaguar CTS (component transaction server). The general-availability version of Jaguar was released last fall and, according to Jaguar engineers, tracks closely the Enterprise JavaBeans specification. That specification promises to extend JavaB eans' distribution capabilities into the realm of transaction coordination.

Jaguar is middleware, an application server. Components installed in Jaguar become usable across whatever network the Jaguar server is connected to (which can include the Internet). And the diversity of components that Jaguar supports is eye-opening: A single Jaguar server can juggle JavaBeans, classes, ActiveX controls, and even DLLs.

If component diversity is Jaguar's proudest trait, transaction management is its strongest muscle. In many ways, Jaguar is like Microsoft's Transaction Server. It removes from the developer any concern for transaction management details. Any component installed in the server is a candidate for participation in a transaction. More important, no component in a transaction need concern itself with the behavior of other components in regards to their effect on the transaction -- Jaguar handles all that.

Here's an example. Suppose you have three components -- A, B, and C -- that you want to use in a transaction. Jaguar provides a small but versatile API that components call in order to keep the server informed of each component's transaction state. So, if components A and B succeed, while component C fails, the Jaguar server aborts the overall transaction and deals with the dirty work of issuing rollbacks on whatever database resources A and B were communicating with.

As mentioned, Jaguar is not limited to Java components. A Jaguar component can as easily be a C/C++ DLL or an ActiveX control. So, a client-side application written in Java can not only remotely invoke a JavaBean or class, it can as easily invoke a C/C++ routine in a DLL, or an ActiveX control. (Similarly, a Jaguar client could be an ActiveX control, calling a JavaBean or a C/C++ DLL.)

Jaguar comes with the necessary tools for generating the stub files needed for a Java client to communicate with a Jaguar component (regardless of the component's species). The stub files contain "mim ic" methods that appear to the Java client application as the methods of the remote component. Within the stub is the code that establishes a session with the Jaguar server and commands the server to instantiate the actual component. The stub also handles the client end of marshalling the data between the client and the Jaguar server.

Pricing for Jaguar starts at $135 per seat. However, developers can get a jump-start on working with Jaguar by purchasing the $295 software development kit. This is a fully functioning Jaguar system whose only limitation is the number of simultaneous connections allowed. (For details, check the Jaguar site at http://www.powersoft.com/products/jaguar .)