SAP Web Dispatcher Cache Performance Test

In SAP Web Dispatcher, cache instances temporarily store frequently requested static or dynamic content at the edge layer, reducing the load on backend SAP systems and improving response times for end users. The Web Dispatcher cache works by keeping copies of HTTP/HTTPS responses in memory or on disk, based on configured cache rules, such as URL patterns, expiration times, and cache control headers. When properly configured, the cache significantly reduces round trips to backend SAP systems, lowering CPU utilization and improving application performance. However, issues such as low cache hit ratios, restrictive cache rules, insufficient memory allocation, frequent invalidations, or dynamic URLs with unique query strings can prevent the cache from serving requests efficiently, resulting in higher response times and increased backend processing. To help administrators pinpoint such issues, eG Enterprise offers the SAP Web Dispatcher Cache Performance test, which delivers instance-level visibility into cache behavior.

For each cache instance available in the target SAP Web Dispatcher, this test reports the status of the cache handler. This test also helps measure the cache hits and cache accesses to each cache instance and thus identify the cache instance that is handling maximum HTTP traffic. This test also helps administrators identify inefficient caching patterns on each cache instance by analyzing the metrics offered. This way, the cache instances can be optimized while maintaining correct application behavior and system stability.

Target of the test : A SAP Web Dispatcher

Agent deploying the test : An internal/remote agent

Outputs of the test : One set of results for each cache instance in the target 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 Disp URL	By default, the eG agent connects to the SAP Web Dispatcher Admin Login URL to collect the required metrics by scraping the URL. Therefore, specify the full path of the SAP Web Dispatcher Admin Login URL against this text box. For example, your specification can be: https://<SAP Web Dispatcher Host>:<SAP Web Dispatcher Port>/sap/wdisp/admin/public/default.htm.
Separate Login Page	A separate login page may appear in your environment if the target SAP Web Dispatcher cannot authenticate you via HTTP authentication or if HTML FORM-based authentication is enabled or session-based authentication is enforced. By default, this flag is set to Yes indicating that a separate login page appears to access the target SAP Web Dispatcher. If your environment invokes a pop up window for login in order to access the target SAP Web Dispatcher, then, set this flag to No.
Web Disp Username, Web Disp Password and Confirm Password	To enable the test to access the SAP Web Dispatcher Admin Login URL and collect the required metrics, you need to configure the Web Disp Username and Web Disp Password parameters of the test with the credentials (i.e., name and password) of a user with monitor privilege. To know more on how to create a new user, refer to Creating a New User with Monitor Privilege. Confirm the Web Disp Password by retyping it in the Confirm Password text box.

Measurements made by the test

Measurement

Description

Measurement Unit

Interpretation

Cache handler status

Indicates the current status of the cache handler that manages this cache instance.

The values reported by this measure and its numeric equivalents are mentioned in the table below:

Measure value	Numeric Value
Active	0
Inactive	1

Note:

By default, this measure reports the Measure Values listed in the table above to indicate the current status of the cache handler on each cache instance. The graph of this measure however, is represented using the numeric equivalents only.

Cache size

Indicates the size of this cache instance.

Cache memory occupied

Indicates the memory occupied by this cache instance.

Cachable access rate

Indicates the rate at which HTTP requests could be cached on this cache instance during the last measurement period.

Accesses/min

This measure is derived using the formulae:

(Cacheable requests / Total HTTP requests) × 100

Compare the value of this measure across cache instances to identify the cache instance on which maximum number of HTTP requests could be cached.

Cache hits

Indicates the percentage of requests are serviced from this cache instance.

Percent

A high value is desired for this measure.

Compare the value of this measure across cache instances to identify the cache instance that is servicing maximum percentage of requests. This can help administrators identify inefficient cache instances.

Cache misses

Indicates the percentage of requests that could not be serviced from this cache instance.

Percent

A low value is desired for this measure.

Compare the value of this measure to figure out the cache instances that are inefficient.

Cache hits in memory cache

Indicates the percentage of responses that were serviced from the memory (RAM) of this cache instance.

Percent

Unfound object list access rate

Indicates the rate at which HTTP cache accesses referenced to objects that were missing from this cache instance during the last measurement period.

Accesses/min

A high value of this measure suggests that the cache instance is either:

Not storing content effectively (due to improper cache configuration, such as low TTL or incorrect cache control headers).
The cache is frequently invalidated or evicted, leading to more cache misses.
The objects being requested are dynamic or unique, making them unsuitable for caching.

Unfound object hits rate

Indicates the rate at which HTTP cache accesses that were successfully recognized as missing by the Unfound Object List (UOL) of this cache instance during the last measurement period.

Hits/min