Well, we have been live on R12.1 for a full month now. We made it through our first month end and now we are days away from closing out the year. While no upgrade is void of significant issues I would have to say ours has played out better than I could have hoped. Really, from an operations standpoint, the only major issues we had were getting our custom interfaces to work properly (which brings me to the topic of this post).
My new personal opinion is that (Upgrade + Interfaces) = (Potato Chips + Bubble Gum). What I mean is that the upgrade by itself is a very good thing and our custom interfaces by themselves really are superb but when you combine them together its like chewing bubble gum while eating potato chips, they just don't go well together.
We have three major interfaces that we maintain, all on the operations side. Two of the three interfaces were created to link a third party solution into oracle applications. In those two cases we were only able to test that information was put into and taken out of the interface tables the same way it was before the migration. As much as you try and replicate these interfaces without being able to test the process all the way through from beginning to end it becomes very difficult to verify that your solution will process correctly post upgrade. To complicate matters even more, our two third parties didn't have test instances available in which we could validate our code pre migraiton.
Here we are now, four weeks later and we are hoping that we've gotten the last 'glitch' resolved with our interfaces. It's been a hectic and very busy month essentially 'testing' our updated code in our production instance but we might finally be on our way to wrapping things up.
The lesson learned: things are sure easier when you don't have custom interfaces. To me it drives home the idea that its better to have a single fully integrated ERP system then it is to have a multiple systems trying to interface with each other. Granted, the price is very different between the cost of those two solutions unless you add in the cost of hiring developers to maintain and constantly monitor your code. For me, I'm taking the integrated system any day of the week.
