JMX interface is part of the J2EE specification and the recommended way to gather WebSphere performance data. PMI data can be gathered from the J2EE
managed object MBeans or the WebSphere PMI Perf MBean. While the J2EE MBeans provide performance data about the specific component, the Perf MBean acts as a gateway to the WebSphere PMI service, and provides access to the performance data for all the components.
Performance Servlet
Performance Servlet provides a way to use an HTTP request to query the PMI data for the entire WebSphere Application Server administrative domain.
Since the servlet provides the performance data through HTTP, issues such as firewalls are trivial to resolve. The performance servlet outputs the PMI data as an XML document.
PMI client API (deprecated)
PMI client API provides a wrapper class to deliver PMI data to a client. The PMI client API uses the JMX infrastructure and the Perf MBean to retrieve the PMI data. PMI client provides the data using a WebSphere Application Server-specific data structure that was introduced in version 4.0.