Access Windows Performance Monitor counters from Java, Part 2

NSClient4j is a pure Java API that provides simple and quick access to Windows Performance Monitor (WPM) statistics. These statistics prove invaluable for monitoring your Windows servers and providing a baseline for activities such as capacity planning and trouble shooting. Additionally, access to low-level performance or operating statistics can be useful in your low-level code, such as the current rate of GETS against your IIS (Internet Information Server) Web server.

In this article, the continuation of my series on WPM, I present a brief introduction to Java Management Extensions (JMX) and its benefits. I then explain how to implement JMX-based services for NSClient4j and describe different methods for implementing that technology.

Changes in NSClient4j since Part 1

As a brief aside, I want to enumerate some changes and enhancements that have been made in the NSClient4j package since Part 1 of this series:

• The main package name has migrated from com.marketwide.nagios to org.nsclient4j.
• Calls have been added to the NSClient4j class as convenience methods:
  1. getUsedDiskSpace(String diskVol)
  2. getFreeDiskSpace(String diskVol)
  3. getTotalDiskSpace(String diskVol)
  4. getUsedPercentDiskSpace(String diskVol)
  5. getFreePercentDiskSpace(String diskVol)
• To accommodate NSClient4j implementation in the Oracle 9i internal JVM, the source code is now fully supported under J2SE 1.3.
• Additional error handling identifies the cause of any errors emerging from the WPM engine (e.g., "Unrecognized pattern," or "Counter not found"), and the NSClient4JException has been extended to differentiate between transport errors and WPM errors.
• New JMX-based classes provide JMX instrumentation of the WPM engine, which is this article's focus.