Working with Portal Server Building Modules
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.
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.
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.
Chapter 5 Creating Your Portal Design 97
