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WEBSPHERE PORTAL V6.1 TUNING GUIDE
Managing the Retrieval of User Attributes
A user directory doesn’t just contain a user’s ID and password; it also contains a number of
other pieces of information – attributes – about the user. A directory server can contain a lot
of attributes for each user, so if every reference to a user required retrieving all of these
attributes, this would impose a performance penalty on both the Portal server node(s) and
the directory server node(s).
Therefore WebSphere Portal attempts to optimize the loading of these attributes. Two sets
of user attributes are defined: the base set of attributes, and the minimum set of attributes.
Depending on what action caused the user to be retrieved from the directory, either the base
or the minimum set of attributes will be retrieved. Typically, the base set of attributes will be
loaded when the user is retrieved; for example, this is what occurs when a user logs in. If the
user was looked up when searching for users, then the minimum set of attributes will be
loaded. For example, this can occur when searching for users to assign access to a page.
By default, WebSphere Portal defines the user attribute sets as follows:
•
Base set: the following attributes are in the base set:
o uid
o cn
o sn
o preferredLanguage
o ibm-primaryEmail
o givenName
o displayName
•
Minimum set:
o uid
o cn
What happens if additional attributes are needed? For example, consider a portlet which
requires the user attribute
countryName
. Assume that the user in question was looked up on
login, so the base set of attributes was retrieved. The attribute
countryName
isn’t in the base
set, so the full user record – with all of its attributes – will be retrieved from the directory
server at that point. This will require a second request to the directory server. Also, since all
user attributes are retrieved on the second request, this can end up consuming more
memory on the WebSphere Portal server.
This provides an important performance tuning point to both improve response times and
reduce load on the directory server. If a user attribute will commonly be needed, then it
should be included in the base set of attributes so that it’s retrieved on the initial lookup,
eliminating the need for a second request. However, if an attribute is only needed
infrequently, consider leaving it out of the base set of attributes, so that it’s not retrieved for
all users.