Network Deployment (Distributed operating systems), v8.0 > Monitor > Monitor overall system health > Develop your own monitoring applications
Retrive performance data with PerfServlet
The PerfServlet 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 servlet provides a way to use an HTTP request to query the performance metrics for an entire WAS administrative domain. Because the servlet provides the performance data through HTTP, issues such as firewalls are trivial to resolve.
The PerfServlet provides the performance data output as an XML document, as described in the provided document type description (DTD). In the XML structure, the leaves of the structure provide the actual observations of performance data and the paths to the leaves that provide the context.
The PerfServlet is a sample monitoring tool that uses WAS administration and monitoring interfaces to expose performance data. Using the PerfServlet is not intended for real-time performance monitoring in production environments or for use in large topologies. For these environments you should use the Tivoli Performance Viewer or ITCAM (IBM Tivoli Composite Application Manager) for WAS.
Specific best practices for the PerfServlet are the following:
- PerfServlet overhead: The PerfServlet is not designed to run concurrently. Being a single threaded servlet, it would collect the data sequentially from available servers. This single threaded operation can cause higher response times when the PerfServlet is used in larger deployments.
- PerfServlet in large deployments:
- By default, when the PerfServlet is first initialized, it retrieves the list of nodes and servers within the cell in which it is deployed. Because collecting this data costs in system processing time, the PerfServlet holds this information as a cached list.
To force the servlet to refresh its configuration, you can use the option "refreshconfig=true". However, using this option is not recommended unless required, because this option adds extra overhead to the PerfServlet processing.
- Use option, node and server, if you are looking for a specific server's performance data.
- PerfServlet response time: The PerfServlet responsiveness depends on the following factors:
- Numbers of application servers that exist in the cell.
- Number of resources configured in the cell (including applications).
- PerfServlet alternative: If you are looking for an alternative to using the PerfServlet to capture data programmatically, refer to the Perf MBean programming interfaces documentation, which exists in the Reference > Programming Interfaces > MBean interfaces section of the WAS information center..
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Start with version 6.0, the PerfServlet in WAS uses the JMX Perf MBean interface to retrieve the PMI data and outputs an XML document that uses the Java EE 1.4 Performance Data Framework to describe the statistics. The PerfSerlvet in can also provide an output that is compatible with the PerfServlet 5.0.
To provide PerfServlet 5.0 compatible output it uses the PMI client interface.
The performance servlet .ear file PerfServletApp.ear is located in...
WAS_HOME/installableApps, where WAS_HOME is the installation path for WAS.Start with version 6.1, enable application security to get the PerfServlet working. The performance servlet is deployed exactly as any other servlet.
To use it, follow these steps:
Procedure
- Deploy the servlet on a single application server instance within the domain.
- After the servlet deploys, you can invoke it to retrieve performance data for the entire domain. Invoke the performance servlet by accessing the following default URL:
http://hostname/wasPerfTool/servlet/perfservlet
Results
The performance servlet provides performance data output as an XML document, as described by the provided document type definition (DTD). The DTD is located inside the PerfServletApp.ear file.
Related
PerfServlet input
PerfServlet output
Application security