Wednesday, May 23, 2012

Domain Architecture and Middleware Homes Revisited

Over a year ago I wrote a couple important posts about the domain architectures used in Oracle Identity Management deployments.  You can find these posts here and here.
These posts have been very popular.  I’ve received lots of positive feedback on them but also a fair number of questions.  So, I thought that it would be worth revisiting the topic now.

 Let’s Review My First Post
So, the central premise of my first post was that it is a good idea to install products from different distribution packages into different WebLogic domains.  Specifically, I am recommending that customers install the IAM package (OAM,OIM,OAAM) into a separate domain from the IDM package (OID,OVD,OIF).   Same thing goes with products from either package and WebCenter or SOA suite. 
The reason is that it introduces the risk that different components (libraries, jars, utilities), including custom plug-ins, from the different packages that you are installing in the domain might be incompatible and cause problems across your entire domain.
Beyond the risk of such an incompatibility, you also must consider how installing multiple packages into one domain reduces your flexibility to apply patches and upgrades.
The exception to this warning is SOA Suite for OIM. SOA Suite is a prerequisite for OIM and as part of the stack that supports OIM should be installed in the same domain as OIM. However, if you use SOA suite for other purposes, you should consider setting up a separate install for running your own services, composites, BPEL processes etc.
Let’s Review My Second Post
In my second post I discussed whether or not to split up products from the same package into multiple domains.  I argued that while the incompatibility issue isn’t such a big deal but that the additional flexibility of deploying in different domains could still be beneficial.  I did warn though that OIM/OAM/OAAM integration is only supported with all the software running in the same domain.
Advice Revisited
A year and a half later, I still strongly stand by the advice in my posts.  I’ll put it this way, I’ve worked with people who regret deploying multiple packages into one domain for all the reasons I mentioned but all the people I’ve worked with who have gone with a split domain model across packages have been happy and glad they’ve gone that route.
That being said, there are a few clarifications and updates to my advice that I’d like to now make.
It’s About Middleware Homes (Install Locations) Not Just Domains
One thing that I want to make clear is that my advice about separating the products from different packages extends beyond domains to Middleware Homes which are the root directories for the Middleware products that you are installing together.  To avoid the conflicts and restrictions that you can run into by installing multiple packages together you need to install them in separate Middleware Homes, just separate domains is not enough.  It is true that most people just create one domain per Middleware Home but I’ve seen some examples of multiple domains in a Middleware Home recently so I thought this was definitely worth mentioning.
Domain Architecture for OAM/OIM Integration
The limitation that you have to put OAM and OIM in the same domain if you want the integration to work has, shall we say softened.  I would still say putting them in the same domain is the easiest and most tried and true path (the yellow brick road if you will).  However, if you utilize a real OHS based OAM agent rather than the domain agent; you can make the integration work with OAM and OIM in separate domains.  In fact, the most recent IDM EDG for FA includes this option.
Fusion Applications
Speaking of Fusion Apps, I do want to discuss this advice in the context of Fusion Apps.  As I describe here, the IDM build out for Fusion Apps is prescribed very specific process with a specific architecture.  It is very likely you will run into issues deploying Fusion Apps on top of an IDM environment that deviates from this architecture as FA has made certain assumptions about how the IDM environment will be set up.
In the context of the domain discussion, the IDM EDG for FA does steer you down the path of creating one big IDM domain that contains OID, OVD, OAM, OIM, ODSM, and potentially OIF.  This is of course contrary to the advice I’ve been giving.  In the context of FA though I think this is OK.
When using the IDM products with FA you are restricted to very specific versions of the IDM products in the stack, so upgrade flexibility and incompatibility concerns isn’t really an issue.  Also, as I said, the FA provisioning process may be expecting the Oracle IDM/IAM products to be deployed in a single domain.  So, for FA I advice people to follow the EDG and stick with the single domain model or moving forward whatever models are documented in the IDM EDG for FA.

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