4 Monitoring Applications
In addition to using HPjmeter when you notice a problem, you can also use it to prevent problems. For example:
•You can use HPjmeter to check the efficiency of your applications, even if you don't notice a problem.
To make it easier to detect problems, you should periodically review key metrics for your application to establish a baseline profile.
To save metrics information to a file that you can review later, see Saving Monitoring Metrics Information (page 38).
•You can check your application after making code or configuration changes to see how performance might have been affected.
NOTE: You cannot use HPjmeter to monitor Java applets in a production environment.
Controlling Data Collection and Display
HPjmeter provides two methods to control how information is collected and displayed.
JVM agent filters. The include and exclude options to the JVM agent allow you to filter metrics by class name.
JVM agent filters are configured when you start the JVM, and cannot be dynamically changed.
Console filters are configured when you open a session with a JVM agent, and can be changed from session to session. With HPjmeter 4.0 and later, these filters can also be changed during a session.
NOTE: In metrics displays, you can see the list of filters in effect while the data was collected, including default agent filters, by clicking the 
icon.
Related Topics
•Setting filters with JVM Agent Options (page 17)
•Setting filters by Setting Monitoring Session Preferences (page 100)
Setting Data Collection Preferences
HPjmeter allows you to control how metrics are collected to give you control over the amount of detail and possible performance impact on your application.
When you open a session between the console and JVM agent, the Session Preferences window lets you select from the available metrics, filters, and alerts.
When you open a session to monitor your applications, you can:
•Specify which metrics to collect.
•Enable alerts to give notifications when specific conditions occur.
•Specify filters to include or exclude specific classes.
Related Topics
•Controlling Data Collection and Display (page 36)
36 Monitoring Applications