Components and Their Caches (SAP Library

Components and Their Caches

Use

Many caches are used in Knowledge Management in order to ensure that the system performs well. It is important that you configure the caches correctly after they have been created.

This section lists the technical components of Knowledge Management that use caches. As well as a short explanation of the caches, this section also includes a recommendation for configuration in a standard scenario.

Integration

Components other than caches also influence performance. The processor performance and main memory structure of the portal server, the available bandwidth, user figures, and the number of documents managed all influence the performance of the portal.

Features

The configuration of a cache used in Content Management comprises various parameters (see Caches). The optimal values for these attributes depend on the following factors:

● How many entries are written to the cache and in what time frame?

● How large are the cache entries?

● For how long do the entries need to be current?

● What is the effect of the performance of the components that use the cache?

● How much main memory is available in the system?

The caches listed below are memory caches that are stored in the main memory of the portal server.

ACL Security Manager

The ACL security manager uses a cache in which access control lists (ACLs) that are valid for resources are stored. Since ACLs are inherited, it is possible for there to be an entry in the cache for every resource of the underlying repository. ACLs are cache entries that need little memory space (only a few KB). The ACL security manager is used constantly, so the cache should be large.

ca_rsrc_acl (Effective ACL Cache)

Parameter	Setting	Additional Comments
Restart Lifetime on Access	Not activated
Singleton	Activated	More than one ACL security managers can use a cache.
Assumed Entry Size	0	This value is not used if the maximum size of a cache is set to unlimited (Maximum Cache Size = 0).
Capacity	This value depends on the number of frequently used resources within the repositories that are assigned to the ACL security manager.
Default Time-to-Live	Between half an hour and several hours	The cache is checked for expired entries within a CM installation, so this value cannot be too high.
Maximum Cache Size	0 (unlimited)	The actual size of the ACLs is not defined.
Maximum Entry Size	0 (unlimited)

You select the cache ca_rsrc_acl in the configuration of repository managers under Content Management → Repository Managers in the parameter ACL Manager Cache.

(JDBC) ACL Manager

The (JDBC) ACL manager uses two caches. One of the caches is for ACLs; the other for permissions and object types. The ACL cache contains entries for every ACL that is used by the system. The cache for permissions contains only a few entries. The entries are mainly static.

ACLs are cache entries that need only a little memory space (only a few KB). Permissions and object types need very little memory space (less than 1KB). The ACL manager is used constantly, so the cache should be large.

ca_cm_rep_acl, ca_cm_srv_acl (ACL Cache)

Parameter	Setting	Additional Comments
Restart Lifetime on Access	Not activated
Singleton	Activated	More than one ACL manager can use a cache.
Assumed Entry Size	0	This value is not used if the maximum size of a cache is set to unlimited (Maximum Cache Size = 0).
Capacity	This value depends on the number of frequently used resources with ACLs within the repositories that are assigned to the ACL manager.
Default Time-to-Live	Between half an hour and several hours	The cache is checked for expired entries within a CM installation, so this value cannot be too high.
Maximum Cache Size	0 (unlimited)	The actual size of the ACLs is not defined.
Maximum Entry Size	0 (unlimited)

You select the caches ca_cm_rep_acl and ca_cm_srv_acl in the configuration of the ACL manager under Content Management → Utilities → ACL Managers in the parameter ACL Cache.

ca_cm_rep_acl_perm, ca_cm_srv_acl_perm (Cache for Permissions)

Parameter	Setting	Additional Comments
Restart Lifetime on Access	Not activated
Singleton	Activated	More than one ACL manager can use a cache.
Assumed Entry Size	0	This value is not used if the maximum size of a cache is set to unlimited (Maximum Cache Size = 0).
Capacity	100
Default Time-to-Live	Between half an hour and several hours	The cache is checked for expired entries within a CM installation, so this value cannot be too high.
Maximum Cache Size	0 (unlimited)
Maximum Entry Size	0 (unlimited)

You select the caches ca_cm_rep_acl_perm and ca_cm_srv_acl_perm in the configuration of the ACL manager under Content Management → Utilities → ACL Managers in the parameter Permission Cache.

Application-Defined Properties

The application property service uses two caches to store the properties of resources. One cache is for storing user-dependent properties. The second cache is used to store user-independent properties. Entries can be medium-sized or small depending on the number of properties and their content.

ca_props_1, ca_props_2 (Caches for Application-Defined Properties)

Parameter	Setting	Additional Comments
Restart Lifetime on Access	Not activated
Singleton	Activated
Assumed Entry Size	0	This value is not used if the maximum size of a cache is set to unlimited (Maximum Cache Size = 0).
Capacity	This value depends on the number of frequently used resources with application-defined properties within the repositories that are assigned to the application property service.
Default Time-to-Live	Between half an hour and several hours	The cache is checked for expired entries within a CM installation, so this value cannot be too high.
Maximum Cache Size	0 (unlimited)	The actual size is not defined.
Maximum Entry Size	0 (unlimited)

The caches ca_props_1 and ca_props_2 for the application property service are already selected under Content Management → Repository Services → Application Properties Service.

URL Access For Content

The utility URL access for content uses its cache to store the content of external link resources. These entries may need a large amount of memory space.

ca_contentaccess (Cache for URL Access for Content)

Parameter	Setting	Additional Comments
Restart Lifetime on Access	Not activated
Singleton	Activated
Assumed Entry Size	0	This value is not used if the maximum size of a cache is set to unlimited (Maximum Cache Size = 0).
Capacity	The value depends on the number of frequently used external-link resources.
Default Time-to-Live	Between half an hour and several hours	The cache is checked for expired entries within a CM installation, so this value cannot be too high.
Maximum Cache Size	0 (unlimited)	The actual size of the content is not defined.
Maximum Entry Size	0 (unlimited)

The cache ca_contentaccess is already selected under Content Management → Utilities → URL Access for Content.

CM Repository Manager

A CM repository manager uses two other caches as well as the ACL cache.

CM Cache

This cache stores the names of resources, and properties and locks.
No content is stored in the cache.

ca_cm (CM Cache)

Parameter	Setting	Additional Comments
Restart Lifetime on Access	Not activated
Singleton	Activated
Assumed Entry Size	0	This value is not used if the maximum entry size is set to unlimited (Maximum Entry Size = 0).
Capacity	This value depends on the number of frequently used resources within the repository.
Default Time-to-Live	Between half an hour and several hours	The cache is checked for expired entries within a CM installation, so this value cannot be too high.
Maximum Cache Size	0 (unlimited)	The actual size of the mappings is not defined.
Maximum Entry Size	0 (unlimited)

You can normally select the cache ca_cm under Content Management → Repository Managers → CM Repository.

Cache for Small Content

This cache is used by a CM repository manager for content smaller than 32 KB.

ca_cm_content (Cache for Small Content)

Parameter	Setting	Additional Comments
Restart Lifetime on Access	Not activated
Singleton	Not activated
Assumed Entry Size	0	This value is not used if the maximum entry size is set to unlimited (Maximum Entry Size = 0).
Capacity	This value depends on the number of frequently used resources within the repository.
Default Time-to-Live	Between half an hour and several hours	The cache is checked for expired entries within a CM installation, so this value cannot be too high.
Maximum Cache Size	0 (unlimited)	The actual size of the mappings is not defined.
Maximum Entry Size	0 (unlimited)

You can normally select the cache ca_cm_content under Content Management → Repository Managers → CM Repository.

Web Repository Manager

The content of resources (Web sites) is stored in the cache of a Web repository manager. The entries can be medium-sized or large, but are usually small and need little memory space (10 – 20 KB).

Web repository cache

Parameter	Setting	Additional Comments
Restart Lifetime on Access	Not activated
Singleton	Activated	More than one Web repository can use a cache.
Assumed Entry Size	10 KB
Capacity	This value depends on the number of frequently used resources within the repository.
Default Time-to-Live	1-2 hours
Maximum Cache Size	This value depends on the amount of memory space required by the cache.
Maximum Entry Size	10 KB

You should create a separate cache for each Web repository. You then select the cache in the configuration of the Web repository manager under Content Management → Repository Managers → Web Repository.

WebDAV Repository Manager

Resources are stored in the cache of a WebDAV repository manager. The cache entries need little memory space.

WebDAV repository cache

Parameter	Setting	Additional Comments
Restart Lifetime on Access	Not activated
Singleton	Activated
Assumed Entry Size	0	This value is not used if the maximum size of a cache is set to unlimited (Maximum Cache Size = 0).
Capacity	This value depends on the number of frequently used resources within the repository.
Default Time-to-Live	This value depends on the usage of the connected WebDAV server. Choose a few minutes if changes are often made by other clients.
Maximum Cache Size	0 (unlimited)	The actual size of the mappings is not defined.
Maximum Entry Size	0 (unlimited)

You should create a separate cache for each WebDAV repository. You then select the cache in the configuration of the WebDAV repository manager under Content Management → Repository Managers → WebDAV Repository.

Navigation Point Cache

This cache contains navigation points of the flexible user interface. The entries in the cache are user-specific. A cache entry for storing user-specific navigation points is created for every user. If the entries in the cache become obsolete, for example, because of a timeout, the user interface no longer displays the old navigation points.

nm (Navigation Point Cache)

Parameter	Setting
Restart Lifetime on Access	Activated
Singleton	Activated
Assumed Entry Size	0
Capacity	5000
Default Time-to-Live	Half an hour (1800 seconds)
Maximum Cache Size	0 (unlimited)
Maximum Entry Size	0 (unlimited)

The cache nm is used internally by the system. It does not need to be specified in the configuration of other components.

Object Type Handler Cache

This cache is used by the object type handler service. It stores the URIs of resources that have object type definition files and whose object type definition files have already been found.

oth (Object Type Handler Cache)

Parameter	Setting	Additional Comments
Restart Lifetime on Access	Activated	Prevents entries from being deleted from the cache whilst they are still being used.
Singleton	Activated
Assumed Entry Size	0	This value is not used if the maximum size of a cache is set to unlimited (Maximum Cache Size = 0).
Capacity	This value depends on the number of frequently used resource URIs within the entire CM.
Default Time-to-Live	Half an hour (1800 seconds)	The cache is checked for expired entries within a CM installation, so this value cannot be too high.
Maximum Cache Size	0 (unlimited)	The actual size of the mappings is not defined.
Maximum Entry Size	0 (unlimited)

The cache oth is already selected under Content Management → Global Services → Object Type Handler Service.

Rendering Cache

This cache is used by the KM user interface (see Debugging Settings). Various interface-related objects and settings are stored temporarily in it.

rendering (Rendering Cache)

Parameter	Setting	Additional Comments
Restart Lifetime on Access	Activated	Prevents entries from being deleted from the cache whilst they are still being used.
Singleton	Activated
Assumed Entry Size	0	This value is not used if the maximum size of a cache is set to unlimited (Maximum Cache Size = 0).
Capacity	5000
Default Time-to-Live	Half an hour (1800 seconds)	The cache is checked for expired entries within a CM installation, so this value cannot be too high.
Maximum Cache Size	0 (unlimited)	The actual size of the mappings is not defined.
Maximum Entry Size	0 (unlimited)

The cache rendering is already selected under Content Management → User Interface → Debugging Settings.

Control Status Service Cache

The control status service allows rendering components (for example, controls) to persistently store structured data using HTTP request cycles and to access it. This data is stored temporarily in the corresponding cache.

css (Status Cache)

Parameter	Setting	Additional Comments
Restart Lifetime on Access	Activated	Prevents entries from being deleted from the cache whilst they are still being used.
Singleton	Activated
Assumed Entry Size	0	This value is not used if the maximum size of a cache is set to unlimited (Maximum Cache Size = 0).
Capacity	The capacity should be three times as large as the number of users who work simultaneously within a 10-minute timeframe on a portal node.	Increase this value if you receive error messages (for example, Cache Expired) when working with iViews (this includes navigating, sorting, and copying objects) that are based on the flexible user interface. However, you should note that a too high capacity can lead to out-of-memory errors.
Default Time-to-Live	Half an hour (1800 seconds)	The cache is checked for expired entries within a CM installation, so this value cannot be too high.
Maximum Cache Size	0 (unlimited)	The actual size of the mappings is not defined.
Maximum Entry Size	0 (unlimited)

The cache css is already configured and is used internally by the system.

XSLT Pipeline Processor Cache

The XSLT pipeline processor uses this cache to store temporarily data structures that are used for XML transformations (see Pipeline Add-Ons).

ca_pipeline (XSLT Pipeline Processor Cache)

Parameter	Setting
Restart Lifetime on Access	Not activated
Singleton	Activated
Assumed Entry Size	0
Capacity	50
Default Time-to-Live	0
Maximum Cache Size	0 (unlimited)
Maximum Entry Size	0 (unlimited)

The cache ca_pipeline is already selected under Content Management → Global Services → Pipeline Add-Ons → XSLT Pipeline Processor.

Cache for XML Forms List Entries

This cache temporarily stores list entries that are used in the preview of news items, for example, in the news browser. A list entry corresponds to an element in the cache.

ca_xmlforms_renderlistitems (Cache for XML Forms List Entries)

Parameter	Setting	Additional Comments
Restart Lifetime on Access	Not activated
Singleton	Activated
Assumed Entry Size	0	This value is not used if the maximum size of a cache is set to unlimited (Maximum Cache Size = 0).
Capacity	100	Raise this value if you use a large number of news items in your scenario and want to display them in list entries as a preview.
Default Time-to-Live	0 (unlimited)
Maximum Cache Size	0 (unlimited)	The actual size of the mappings is not defined.
Maximum Entry Size	300000

The cache ca_xmlforms_renderlistitems is used internally by the system. It does not need to be specified in the configuration of other components.

Classification Cache

This cache stores temporary application data of the classification inbox and taxonomy query builder. This data is needed for the reconstruction of the user interface (see Classification Inbox and Taxonomy Query Builder).

classification (Classification Cache)

Parameter	Setting	Additional Comments
Restart Lifetime on Access	Activated
Singleton	Activated
Assumed Entry Size	0	This value is not used if the maximum size of a cache is set to unlimited (Maximum Cache Size = 0).
Capacity	20	Raise this value if more than 20 content managers use the classification inbox or taxonomy query builder in your scenario at the same time.
Default Time-to-Live	Half an hour (1800 seconds)
Maximum Cache Size	0 (unlimited)	The actual size of the mappings is not defined.
Maximum Entry Size	0 (unlimited)

The cache classification is used internally by the system. It does not need to be specified in the configuration of other components.

TREX Caches

The component Search and Classification (TREX) uses several caches. For more information, see TREX Caches.

Activities

To create a memory cache or to change the configuration of an existing one, launch the KM configuration and choose Content Management → Utilities → Caches → Memory Caches.

You can determine a more precise value for the capacity of a cache by using the cache monitor.

Recommendations for Cache Configuration in a Standard Scenario

The table below contains recommendations for the cache configuration for a normal KM implementation. If you access particular repositories (for example, a Web repository) often, you should modify the listed values accordingly. The cache monitor helps you to do this.

Cache	Technical Name	Restart Lifetime on Access	Singleton	Assumed Entry Size	Capacity	Default Time to Live	Max Cache Size	Max Entry Size
Effective ACL cache	ca _rsrc_acl	-	Activated	0	10000	1800	0	0
ACL Cache	ca_cm_rep_acl ca_cm_srv_acl	-	Activated	0	10000	1800	0	0
Cache for permissions	ca_cm_rep_acl_perm ca_cm_srv_acl_perm	-	Activated	0	100	1800	0	0
Cache for application-defined properties	ca_props_1 ca_props_2	-	Activated	0	10000	1800	0	0
Cache for URL access for content	ca_contentaccess	-	Activated	0	500	1800	0	0
CM Cache	ca_cm	-	-	0	5000	1800	0	0
Cache for small content	ca_cm_content	-	-	0	10000	1800	0	0
Web repository cache	Not normally defined	-	Activated	10000	10000	7200	10000000	10000
WebDAV repository cache	Not normally defined	-	Activated	0	1000	1800	0	0
Navigation point cache	nm	Activated	Activated	0	5000	1800	0	0
Object type handler cache	oth	Activated	Activated	0	5000	1800	0	0
Rendering cache	rendering	Activated	Activated	0	5000	1800	0	0
Control status service cache	css	Activated	Activated	0	500	1800	0	0
XSLT pipeline processor cache	ca_pipeline	-	Activated	0	50	0	0	0
Cache for XML forms list entries	ca_xmlforms_ renderlistitems	-	Activated	0	100	0	0	300000
Classification Cache	classification	Activated	Activated	0	20	1800	0	0
TREX administration cache	trexadmin	-	Activated	0	100	300	0	0
TREX memory cache	trexmemory	-	Activated	0	100	300	0	0