Performance data classification

PMI provides several different metrics. Each of these metrics is classified into one the following five types to provide some standardization within the infrastructure. This classification is based on J2EE management specifications and is important to understand when developing a monitoring tool.

• Count statistic

  Specifies standard count measurements. It consists of a single numeric value and is used to represent data such as counts and sizes. Examples of count statistics include number of times beans were created, number of calls retrieving an object from the pool, and used memory in the JVM runtime.

• Boundary statistic

  Specifies standard measurements of the upper and lower limits of the value of an attribute. This classification is currently not being used by PMI.

• Range statistic

  Specifies standard measurements of the lowest and highest values an attribute has held as well as its current value. These values can be used for obtaining the number of concurrent invocations to a call method, average number of threads in a pool, or the number of requests that are concurrently processed by the ORB.

• Bounded range statistic

  Extends the Range statistic and Boundary statistic interfaces and provides standard measurements of a range that has fixed limits. Examples of use of the Bounded range statistic interface are the number of free connections in the J2C pool, total memory in JVM runtime, and average number of threads in pool.

• Time statistic

  Specifies standard timing measurements for a given operation. Examples of time statistics are average response time in milliseconds on the bean methods (home, remote, local) and average connection time in milliseconds until a connection is granted.

The performance data classifications have been redefined since the WAS V5 release in order to comply with the J2EE Management Specification. The former classifications (Numeric, Statistical, Load and Group) as well as the new classifications will still be available from the PMI Client API for compatibility reasons.

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