Another Rational Application Developer tool is the XML editor and perspective that can be used to properly create and maintain valid XML files. An XML validator ensures that the XML is in a valid format and can be useful in fixing files that have become incorrectly formatted. The Rational Application Developer can import application client JAR, EJB JAR, EAR, and WAR files, which can be helpful in problem determination. Sometimes, it is important to be able to view the code of the application that you are deploying. These tools can take the place of a decompiler because they can import an archive file into an editable project. 21.8 Tivoli Performance Viewer Tivoli Performance Viewer is a tool that is integrated in the Administrative Console. It is used to look for bottlenecks in WebSphere for z/OS configuration. Tivoli Performance Viewer can be used to fine-tune the performance of an enterprise system by optimizing resources. You can view the current performance activity of a server using the Tivoli Performance Viewer. With Tivoli Performance Viewer, administrators and programmers can monitor the current status of WebSphere Application Server. Because the collection and viewing of data occurs in the application server, performance is affected. To minimize performance impacts, monitor only those servers with activity that needs investigation. 21.8.1 Setting up Tivoli Performance Viewer To use Tivoli Performance Viewer with WebSphere for z/OS V6, you must set it up by selecting Monitoring and Tuning Performance Viewer Current Activity server in