Sun Microsystems Portal Server 6 2005Q1, Руководство по планированию

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Working with Portal Server Building Modules
Chapter 5 Creating Your Portal Design 97
The session repository is provided by the application server software. Portal Server
is running in an application server. Portal Server supports transparent failover on
application servers that support HttpSession failover. See
Appendix C, “Portal
Server and Application Servers” for more information.
With session failover, users do not need to reauthenticate after a crash. In addition,
portal applications can rely on session persistence to store context data used by the
checkpointing. You configure session failover in the
AMConfig.properties
file by
setting the
com.iplanet.am.session.failover.enabled property
to
true
.
The Netlet Proxy cannot support the transparent failover scenario because of the
limitation of the TCP protocol. The Netlet Proxy tunnels TCP connections, and you
cannot migrate an open TCP connection to another server. A Netlet Proxy crash
drops off all outstanding connections that would have to be reestablished.
Building Module Constraints
The constraints on the scalability of building modules are given by the number of
LDAP writes resulting from profile updates and the maximum size of the LDAP
database. For more information, see
“Directory Server Requirements” on page 98 .
If the analysis at your specific site indicates that the number of LDAP write
operations is indeed a constraint, some of the possible solutions include creating
building modules that replicate only a specific branch of the directory and a layer
in front that directs incoming requests to the appropriate instance of portal.
Deploying Your Building Module Solution
This section describes guidelines for deploying your building module solution.
Deployment Guidelines
How you construct your building modue affects performance. Consider the
following recommendations to deploy your building module properly:
• Deploy a building module on a single machine.
NOTE
If the LDAP server crashes with the
_db
files in the
/tmp
directory,
the files are lost when the server restarts. This improves
performance but also affects availability.