Summary

As you can tell, WebSphere 4 and 5 are similar in their baseline architectures. WebSphere 5 has, however, a different underlying technology in the areas of high availability and distributed platforms. Cells and DRS are two key examples of the advanced features of WebSphere 5.

This isn't to say, however, that WebSphere 4 doesn't stand up in the areas of high availability and redundancy ”quite the contrary. As you'll see during later chapters, WebSphere 4 can function within about 90 percent of the high-availability capability of WebSphere 5.

If you're thinking about upgrading from WebSphere 4 to 5 based on some of the points in this chapter, my recommendation is this: Unless you have a compelling reason to do so, such as the need to take advantage of newer J2EE component technologies or there's a licensing or support complication in not upgrading, then stay where you are on version 4. IBM continues to support WebSphere 4 by releasing new versions, fixing bugs , and adding features.

This chapter has given you a good foundation of the major components within both versions of WebSphere. The chapter has summarized each of the components discussed in later chapters. It's these areas or components within WebSphere that allow you to tweak, tune, and optimize the environment to achieve a highly stable, robust, and high-performing environment. Use this chapter as a reference while you explore the performance and optimization capabilities of WebSphere.