This is a complicated question, so let me give you the scenario:
- There are one or more HATS applications that are to implement WEL to a z/OS host using DCAS
- These HATS applications may be in one or more EAR files
- These HATS applications will be installed in at least two clusters, Test and Production.
- The Test cluster will likely have only one WAS server
- The Production server will likely have two or more WAS servers
There are actually several questions, but to simplify them lets assume that there are two HATS applications and they are each in their own EAR file.
- How many DCAS connections will exist on each server? I assume two, one from each EAR file.
- How many client certificates must there be? I assume three, one for each WAS server.
Now assume that I place both HATS applications in the same EAR file, let's answer the same two questions:
- How many DCA connections will exist on each server? I assume one, and that both WAR files will share the same connection
- How many client certificates must there be? I assume this is the sam, three, one for each WAS server.
In general I normally package a HATS application into its own EAR file so that I only affect a single application when it is upgraded. If I have more than WAR per EAR, then I must regression test each WAR before deploying. If I package multiple WARs per EAR I save on disk space (a minor savings), but I will also save on Virtual memory (may become more significant in a loaded environment). Separate packaging also allows me to migrate the applications to new maintenance levels individually. What I don't have a handle on at this time is what is the impact on the WAS server of having multiple DCAS connections.
Any experiences or comments are appreciated.