One area is the use of what the Java world calls "containers." According to Sun, "J2EE containers provide for the separation of business logic from resource and lifecycle management, which means that developers can focus on writing business logic -- their value add -- rather than writing enterprise infrastructure."

One example often cited is the Enterprise JavaBeans container, which can handle (when implemented correctly) distributed communication, threading, scaling, transaction management, and so on.

Freedom of choice
Because J2EE is a published standard, many vendors (such as IBM) are implementing to that standard. That said, your freedom begins and ends with your platform choice. Like all development environments, once you've chosen one and built into it sufficiently, you're in, dude. You're in.

The key to getting certified by Sun as compatible is that vendors can build whatever implementation (the internal guts) they want, but the standards and the APIs must remain absolute. This, of course, is where Microsoft is managing to regularly tick off the Java community, and where many other vendors find themselves trying to keep standard, while supporting diverging implementations.

To be sure, true, standard J2EE is a locked-in spec. So if you're building to J2EE, theoretically, your code can be moved from any one J2EE implementation to any other. This is theory, however, because once you start knitting in other custom implementations, systems, add-ons, hacks, and what-not, you're staying pretty much on platform.

Simplified connectivity
SOAP, JAX-RPC, and XML-RPC notwithstanding, J2EE has a pile of services for talking to other systems, such as Web clients, cell phones, PDAs, and other devices. I'm still not sure there's a future for the Java ring, and Java apps running on my Tungsten T3 are spectacularly crappy, but there is something to be said for solid, spec'd out connectivity to other systems.

Here's what Sun says:

J2EE offers Java Message Service for integrating diverse applications in a loosely coupled, asynchronous way. The J2EE platform also offers CORBA support for tightly linking systems through remote method calls. In addition, the J2EE platform has J2EE Connectors for linking to enterprise information systems such as ERP systems, packaged financial applications, and CRM applications.

When all is said and done, J2EE is a language and a set of APIs like any other. However, since it's decades more modern than C, controlled by standards bodies and disciplined corporations rather than a bunch of open-source guys like PHP, and built to handle server loads, it's a pretty good foundation for Web application environments like WebSphere.

Do me a favor. If you've got experience using J2EE with WebSphere or any interesting stories to tell, send me a note with some details. I can be reached at david@ZATZ.com.

Dan Velasco is a Senior Technical Editor for WebSpherePower Magazine and DominoPower Magazine. He's a Sun Certified Java Programmer, Sun Certified Web Component Developer and an IBM Certified Solution Developer for WebSphere Studio V5.0. He's also a Principal CLP Application Developer (R4, R5 and ND6) as well as a CLP System Administrator (R4 and R5). You can reach him via email at dvelasco@webspherepower.com or on the Web at http://DanVelasco.com.