Custom PMI API
PMI can be extended using the Custom PMI API to create application specific statistics. For example, a stock trading application can use Custom PMI API to create business specific statistics like "number of stock sell transactions" and "number of stock buy transactions".
Note that PMI provides detailed performance data about various runtime and application components. Starting with WAS Version 6.0, PMI offers approximately 180 or more performance statistics. Before creating new statistics, it is important to make sure that the same data is not captured by PMI already.
With WebSphere PMI, application developers can add their own application-specific instrumentation. The Custom PMI API simplifies the process of "PMI enabling" an application by providing an easy to use API. The statistics created via the Custom PMI can be accessed via the standard PMI and JMX interfaces that are used by monitoring tools including the Tivoli Performance Viewer.
PMI instrumentation is based on the Java EE 1.4 standard. As a result, Custom PMI supports all the Statistic types defined in the JSR-77 Performance Data Framework...
- CountStatistic
- TimeStatistic
- RangeStatistic
- BoundedRangeStatistic
Custom PMI does not support user-defined Statistic types.
Key features of Custom PMI...
- Create a custom Stats or PMI (Stats is Java EE terminology) module using an XML template.
- Used by the application to instrument code.
- Statistics in the custom Stats module can be accessed via the standard PMI and JMX interfaces that are used by monitoring tools, including the Tivoli Performance Viewer.
- PMI instrumentation is based on the Java EE 1.4 standard.
- Custom PMI does not support user-defined Statistic types.
PMI is for appserver performance monitoring, and the data collected by PMI is used to tune the appserver resources such as pools, queues, and caches, etc. Since performance instrumentation and statistics can have considerable impact on the appserver performance, it is necessary that every statistic added via Custom PMI is relevant towards solving a performance problem. When designing statistics, consider the following issues:
- Significance of the statistic with respect to solving performance problems.
- Relevance to tuning or configuring the application.
- Avoiding data redundancy and unnecessary frequent data updates.
Subtopics
Example: Implement custom PMI