JVMTI is a new native programming interface for use by development and monitoring tools. It provides both a way to inspect the state and to control the execution of applications running in the Java virtual machine (VM). JVMTI is intended to provide a VM interface for the full breadth of tools that need access to VM state, including but not limited to: profiling, debugging, monitoring, thread analysis, and coverage analysis tools.
JVMTI will replace the now deprecated JVMPI and JVMDI in the next major release of J2SE.
Refer to the documentation at http://java.sun.com/j2se/1.5.0/docs/guide/jvmti/index.html.