I recently had a conversation with a new client and they asked a very common question about integrating ERP systems through SOA:

I manage the ERP applications within my organization and I would like to integrate our processes into enterprise-wide business processes, how should I start to define my architecture and provide our organization the ability to start with a small SOA-based integration or ERP connectivity initiative and to move to a larger enterprise-wide, multi-domain project?

The reality is before you can implement SOA, you’ve got to lay the groundwork: a service bus where your services will managed, a service registry for identifying services, a security framework to manage access to your services, a solid understanding of your business processes, an enterprise architecture showing your eventual enterprise-wide goals. 

If you put these pieces in place you will “service enable” your enterprise and get you ready to start implementing your SOA.

It sounds like a lot, but we typically have the infrastructure installed and configured in less than a month.  It depends on the unique needs of each enterprise. 

http://www.consultems.com/technology/soa-integration/soa-integration.htm

Let me know if you have anymore questions.