Introduction
SharePoint 2010 introduces an overhaul of the MOSS 2007 Shared Service Provider (SSP). It is such a significant paradigm change that those who are responsible for implementing SharePoint must understand architecting to a different level.
MOSS 2007 had the SSP. The SSP encapsulated Search, Excel Calculations Services, user profiles, and the business data catalog. This is a "box" of services. This box was limited because you could not break it apart. One of the reasons it was limited was the fact that the services within affected the whole farm. If Accounting wished to use Excel Calculation Services, the whole farm was affected, even those not using it. In addition, writing an integrated custom service was out of the question.
SSPs are gone in SharePoint 2010. Microsoft has taken the SSP concept and built a new service application infrastructure that is flexible, extensible, and scalable:
Flexible: Services can be segmented to a particular group of users providing security boundaries...