Not sure about fusion, and it seems the installed base is not that big just yet.
For R12 from 11i, there are changes in the data model (e.g. vendors and banks are stored in TCA, invoices uses lines besides distributions) and some new core modules are added (payments, tax, SLA) so you might need to review that to better understand the application inner workings. More GUI is moved to OAF from Forms, but the later is still majority. Something that is mostly migrated are reports which now are being converted to BI Publisher.
About middleware, it depends on how big is your team and how many integrations are there to work with. If the team is big there will likely be different people for middleware and core oracle applications. SOA/BPEL are not par of the application technology stack per se, yet it is now more prevalent for integrations vs. old point to point ones.
Thanks a lot...
Can you please tell me going forward what r the skills required for R12 or Fusion ?
11i and R12 skills are nearly the same
Fusion is something completely different
SOA,BPEL,JSM are not directly related to eBS/APPS
You can setup SOA so work with eBS, but it's not very common
But still not clear what r the required technical skills for Fusion ?
Middleware fusion is basically software that connects applications to a database. Middleware Fusion, or Weblogic, sets on top of the database and different software such as SOA(Service-Oriented Architecture, OBIEE, ODI, etc is installed on top of Weblogic. I am not sure what JSM is and I can tell you BPEL is apart of SOA. All these things can connect to Oracle EBS if the company wants them to. Our company has SOA, OBIEE, and other products on top of different Weblogic Servers, and these applications connects to the server that Oracle EBS is on and use data from EBS. But yes, as stated before EBS and Middleware fusion are two totally different beast.
A middleware admin is suppose to do the middleware work but in our shop we don't have that luxury so we do it all. Jack of all trade environment, master of none but learn something new everyday and I'm extremely marketable because I dibble in so much. But I would not recommend you learn all. Way too much and can be extremely overwhelming, stick with R12, that is what I love the most!
Hope that helps