Atrium Integrator is your best bet unless you have a slew of developers ready to write API calls and who also understand web services.
AI is part of Atrium Core even though it is a separate installer...you do not need a separate license and it can handle all the data transformations you have listed and is very scalable.
Thanks for your reply! I will dig into the AtriumIntegrator7.6.04_UsersGuide right now to find out the best practice I could do.
My another concern is that the current BMC CDM doesn't fit our requirements very well. Potentially we have to create new regular classes (many and maybe each with over 100 or even 200 attributes) to extends the current BMC CDM classes (mostly are BMC_Settings). Can Integrator overcome this ugly design to have a good performance as you mentioned "very scalable" (any potential risks)?
I know the federation will be ideal way to tackle this ugly guy but we couldn't.
Seamless Technologies has a product called the SeamlessData Pump that can handel your requirement ... you can find more information at www.seamlessti.com/products ... or contact me directly at firstname.lastname@example.org. We are a BMC partner of 17 years and our products are certified by BMC.