Cache Servers (SAP Library - Operating Manual for SAP Content Server)

Cache Servers

Caching

A cache is used to store copies of documents when they are accessed for the first time. As a result, the documents can be accessed again more quickly, since the contents are taken directly from the cache. Caching, however, must not be confused with replication (see below). With caching, the original documents are stored in one location, namely on the content server. The copies in the cache can be replaced with newer content at any time.

Example

Documents are checked in in Walldorf. An employee in South Africa wants to access and display these documents. The transmission time, however, is extremely long and the intercontinental network connections would be overloaded. By using cache servers, the documents are only copied over the connection once.

Caution

Caching is not the same as replication.

These are the main characteristics of caching:

The original document is still located on the content server.
The content server can retrieve the cache content at any time.
Only documents that are actually requested (and therefore genuinely needed) are copied and delivered.

The cache server is used to cache special content server requests. Remote accesses are cached and executed locally. This type of caching is ideal for scenarios in which many different users have joint access to the cache, as the documents only have to be sent once across the wide area network.

Any number of content servers can be installed in different locations. The contents are transferred directly between the client and content server. If the content servers are accessed from different locations that are linked only via a wide area network (WAN), cache servers should be used. Network traffic across the WAN can be reduced to a minimum and performance enhanced by installing at least one cache server at each location.

A client cache is also available on the user's front-end computer.

Purpose

The purpose of the Cache Server is to provide the following benefits:

Seamless, transparent integration into existing content server landscapes
Significant reduction in client response times

As little administration work as possible

Cache servers are used to speed up access to document content. This is particularly useful if the content is required for display in a Web browser, for example. Cache servers can also reduce the network load and thereby enhance performance. It is therefore also a task of the cache to provide the client with documents from a physically close location, even if the content server is located on a different continent.

Cache servers are similar to content servers, but require less administration with the same level of access protection.

Note

The Cache Server only uses HTTP. To make this possible, the SAP Content Server HTTP Interface has been extended (see SAP Content Server HTTP 4.5 Interface). By using cache servers, you are simply extending your existing infrastructure in a transparent way. There is no need to re-structure the existing content server landscape.

Implementation Considerations

The Cache Server is installed as part of the SAP Content Server installation procedure, using the SAP Web Application Server Components CD 2. The installation guide is contained on this CD-ROM in PDF format in the folder \CONTSERV\DOCU. The guide is available in both English and German.