SAP Web Dispatcher Cache Test

The SAP Web dispatcher can be configured in such a way that the contents (static and dynamic) are stored in the cache, and the next request to this page can be satisfied quickly from the cache. The SAP Web dispatcher normally forwards incoming requests to an Internet Communication Manager (ICM), which is responsible for Web requests in SAP NetWeaver AS. The advantage of caching in the Web dispatcher over caching in the ICM is that the cache is located at the initial access point where all the requests arrive, and therefore all backend servers activated later and their network connections are offloaded. Caching is deactivated in the SAP Web Dispatcher by default. You need to activate caching by specifying a URL prefix and cache directory in the parameter icm/HTTP/server_cache_0 in the Web Dispatcher profile with which the SAP Web Dispatcher was started.

This test monitors the cache of the SAP Web Dispatcher and reports the total size of all cache entries, the total number of cache entries etc. Using this test, administrators can easily detect the number of invalid entries and remove them from the cache. This way, administrators can analyze how quickly the cache processes the requests. In the process, the test points to poor cache usage and processing bottlenecks, and reveals if the cache is poorly sized.

Target of the test : A SAP Web Dispatcher

Agent deploying the test : An internal agent

Outputs of the test : One set of results for the SAP Web Dispatcher being monitored.

Configurable parameters for the test
Parameter Description

Test period

How often should the test be executed

Host

Specify the host for which the test is to be configured.

Port

The port number at which the specified host listens. The default is 2375.

WEB Dispatcher DIR

Specify the full path to the directory where the target SAP Web Dispatcher is installed.  Ensure that the location specified contains the sapwebdisp and wdispmon executables.

Profile File

Specify the full path to the profile file with which the target SAP Web Dispatcher was started. The default name of the profile is sapwebdisp.pfl.

Timeout

Specify the time for which the eG agent should wait for collecting the required metrics. By default, this is 60 seconds

Detailed Diagnosis

To make diagnosis more efficient and accurate, the eG Enterprise embeds an optional detailed diagnostic capability. With this capability, the eG agents can be configured to run detailed, more elaborate tests as and when specific problems are detected. To enable the detailed diagnosis capability of this test for a particular server, choose the On option. To disable the capability, click on the Off option.

The option to selectively enable/disable the detailed diagnosis capability will be available only if the following conditions are fulfilled:

  • The eG manager license should allow the detailed diagnosis capability
  • Both the normal and abnormal frequencies configured for the detailed diagnosis measures should not be 0.
Measurements made by the test
Measurement Description Measurement Unit Interpretation

Total entries

Indicates the total number of entries in the cache.

Number

A high value is desired for this measure.

Invalid entries

Indicates the number of expired or invalidated entries in the cache.

Number

If there are too many invalid entries, it indicates that the cache has become stale. If the value of this measure is gradually increasing, then it indicates that the cache is not sized adequately. The appropriate cache needs to be resized using the icm/HTTP/server_cache_<x>/max_entries and icm/HTTP/server_cache_<xx>/size_MB parameters

Percentage invalid entries

Indicates the percentage of expired or invalidated entries in the cache.

Percent

This measure is the ratio of the Invalid entries to Total entries measure.

A low value is desired for this measure.

Size

Indicates the total size of all cache entries in the cache.

KB