There has been a great deal of discussion on the need to better align business with IT in order to successfully implement service-oriented architectures (SOAs).

While many developers agree an SOA should ultimately cater to the needs of the business, there are differing opinions on how exactly this should occur.

Should a top-down, business-centric approach be employed or a bottom-up approach, in which the Business Unit (BU) is more reactive and sensitive to the realities of IT?

In John Crupi's Weblog, the chief technology officer of enterprise Web services practice at Santa Clara, Calif.-based Sun Microsystems Inc., said that SOA is a business-driven architectural style, and for it to be successful, it must employ a "top-down" approach.

The BU should own the business drivers, use-cases and processes, according to Crupi. It is then IT's job to implement the BU requirements and own the service definitions.

Crupi advised against using a "bottom-up" approach to SOA development, in which existing systems are simply wrapped using Web services to create a service layer.