PerfServlet output

The PerfServlet input and output is used for simple end-to-end retrieval of performance data that any tool, provided by either IBM or a third-party vendor, can handle.

The performance servlet .ear file PerfServletApp.ear is located in the WAS_HOME/installableApps directory. The PerfServlet 6.0 provides output using the J2EE 1.4 Performance Data Framework. By default, the PerfServlet output is in 6.0 format. PerfServlet can provide the output in 5.0 format using the version parameter:

http://hostname/wasPerfTool/servlet/perfservlet?version=5

PerfServlet 5.0 output details: The following section describes the PerfServlet 5.0 output. There are three types of leaves or output formats within the XML structure: PerfNumericInfo, PerfStatInfo, and PerfLoadInfo.

PerfNumericInfo

When each invocation of the performance servlet retrieves the performance values from Performance Monitoring Infrastructure (PMI), some of the values are raw counters that record the number of times a specific event occurs during the lifetime of the server. If a performance observation is of the type PerfNumericInfo, the value represents the raw count of the number of times this event has occurred since the server started. This information is important to note because the analysis of a single document of data provided by the performance servlet might not be useful for determining the current load on the system. To determine the load during a specific interval of time, it might be necessary to apply simple statistical formulas to the data in two or more documents provided during this interval.

The PerfNumericInfo type has the following attributes:

time

Timeime when the observation was collected (Java System.currentTimeMillis)

uid

Specifies the PMI identifier for the observation

val

Specifies the raw counter value

The following document fragment represents the number of loaded servlets. The path providing the context of the observation is not shown:

<numLoadedServlets> 
     <PerfNumericData time="988162913175" uid="pmi1" val="132"/>
</numLoadedServlets> 

PerfStatInfo

When each invocation of the performance servlet retrieves the performance values from PMI, some of the values are stored as statistical data. Statistical data records the number of occurrences of a specific event, as the PerfNumericInfo type does. In addition, this type has sum of squares, mean, and total for each observation. This value is relative to when the server started.

The PerfStatInfo type has the following attributes:

time

Timeime when the observation was collected (Java System.currentTimeMillis)

uid

Specifies the PMI identifier for the observation

num

Specifies the number of observations

sum_of_squares

Sum of the squares of the observations

total

Sum of the observations

mean

Specifies the mean (total number) for this counter

The following fragment represents the response time of an object. The path providing the context of the observation is not shown:

<responseTime> 
     <PerfStatInfo mean="1211.5" num="5" sum_of_squares="3256265.0" 
                   time="9917644193057" total="2423.0" uid="pmi13"/>
</responseTime> 

PerfLoadInfo

When each invocation of the performance servlet retrieves the performance values from PMI, some of the values are stored as a load. Loads record values as a function of time; they are averages. This value is relative to when the server started.

The PerfLoadInfo type has the following attributes:

time

Timeime when the observation was collected (Java System.currentTimeMillis)

uid

Specifies the PMI identifier for the observation

currentValue

Specifies the current value for this counter

integral

Timeime-weighted sum

timeSinceCreate

Specifies the elapsed time in milliseconds since this data was created in the server

mean

Specifies time-weighted mean (integral/timeSinceCreate) for this counter

The following fragment represents the number of concurrent requests. The path providing the context of the observation is not shown:

<poolSize> 
     <PerfLoadInfo currentValue="1.0" integral="534899.0" mean="0.9985028962051592" 
                   time="991764193057" timeSinceCreate="535701.0" uid="pmi5"/>
</poolSize> 

Reference topic