What are best practice for packaging and deploying j2EE apps to iAS?

Question

We've been running a set of J2EE applications on a pair of iAS SP1b for about a year and it has been quite stable.
Recently however we have had a number of LDAP issues, particularly when registering and unregistering applications (registering ear files sometimes fails 1st time but may work 2nd time). Also We've noticed very occasionally that old versions of classes sometimes find their way onto our machines.
What is considered to be best practice in terms of packaging and deployment, specifically:
1) Packaging - using the deployTool that comes with iAS6 SP1b to package is a big manual task, especially when you have 200+ jsp files. Are people out there using this or are they scripting it with a build tool such as Ant?
2) Deploying an existing application to multiple iAS's. Are you guys unregistering old application then reregistering new application? Are you shutting down iAS whilst doing the deployment?
3) Deploying ear files can take 5 to 10 mins, is this normal?
4) In a clustered scenario where HTTPSession is shared what are the consequences of doing deployments to data stored in session?
thanks in asvance for your replies
Owen

Answer 1

You may want to consider upgrading your application server environment to a newer service pack. There are numerous enhancements involving the deployment tool and run time layout of your application that make clear where you're application is loading its files from.
If you've at a long running application server environment, with lots of deployments under your belt, you might start to notice slow downs in deployment and kjs start time. Generally this is due to garbage collecting in your iAS registry.
You can do several things to resolve this. The most complete solution is to reinstall the application server. This will guarantee a clean ldap registry. Of course you've got to restablish your configurations and redeploy your applications. When done, backup your application server install space with the application server and directory server off. You can use this backup to return to a known configuation at some future time.
For the second method: <B>BE CAREFUL - BACKUP FIRST</B>
There is a more exhaustive solution that involves examining your deployed components to determine the active GUIDS. You then search the NameTrans section of the registry searching for Applogic Servlet *, and Bean * entries that represent your previously deployed components but are represented in the set of deployed GUIDs. Record these older GUIDs, remove them from ClassImp and ClassDef. Finally remove the older entries from NameTrans.
Best practices for deployment depend on your particular environmental needs. Many people utilize ANT as a build tool. In later versions of the application server, complete ANT scripts are included that address compiling, assembly and deployment. Ant 1.4 includes iAS specific targets and general J2EE targets. There are iAS specific targets that can be utilized with the 1.3 version. Specialized build targets are not required however to deploy to iAS.
Newer versions of the deployment tool allow you to specify that JSPs are not to be registered automatically. This can be significant if deployment times lag. Registered JSP's however benefit more fully from the services that iAS offers.
2) In general it is better to undeploy then redeploy. However, if you know that you're not changing GUIDs, recreating an existing application with new GUIDs, or removing registered components, you may avoid the undeploy phase.
If you shut down the KJS processes during deployment you can eliminate some addition workload on the LDAP server which really gets pounded during deployment. This is because the KJS processes detect changes and do registry loads to repopulate their caches. This can happen many times during a deployment and does not provide any benefit.
3) Deploying can be a lengthy process. There have been improvements in that performance from service pack to service pack but unfortunately you wont see dramatic drops in deployment times.
One thing you can do to reduce deployment times is to understand the type of deployment. If you have not manipulated your deployment descriptors in any way, then there is no need to deploy. Simply drop your newer bits in to the run time space of the application server. In later service packs this means exploding the package (ear,war, or jar) in to the appropriate subdirectory of the APPS directory.
4) If you've changed the classes of objects that have been placed in HTTPSession, you may find that you can no longer utilize those objects. For that reason, it is suggested that objects placed in session be kept as simple as possible in order to minimize this effect. In general however, is not a good idea to change a web application during the life span of a session.