Brief about SSP (MOSS - Shared Service Provider)

What is SSP: Shared Services Providers act as more than an intermediary between web applications and sensitive services. By creating a Shared Services Provider (SSP) you can create an interface, or a mediator, that retrieves the information you need from the sensitive service and places it in a database for query by the appropriately authorised web applications.

Best example to elaborate use of SSP is list of users/profiles. SSP can import all the users and their information from Active Directory (AD) once and make it available to other web applications. So here web applications can consume the date from SSP instead of managing a copy of identical data locally.

Some key aspects of SSP that I learned are mentioned below.

• SSP offers five services
  

1. Business Data Catalog (BDC)
   
2. Office SharePoint server search
   
3. Excel Services
   
4. User Profile Application
   
5. Session State
   

• When you configure SSP, it creates two databases
  
  • SSP Service Database (SharedServices_DB) à For SSP configurations
    
  • SSP Search Database (SharedServices_Search_DB) à For storing search results of users.
    

Recommended Guidelines for SSP

1. It's recommended to create different application pool for SSP web application.
   
2. Not recommended to use same web application for hosting both SharePoint sites and SSP sites. (backup strategy)
   
3. Its good practice to create new application for hosting my sites. Using same web application for both my site and SSP will cause problems while backup.
   
4. SSP creates two databases, it is good practice to use different SQL instance for these databases rather using same SQL server for SharePoint sites.
   

Also you can refer to very good article/post on SSP by sharepoint MVP.
http://msmvps.com/blogs/shane/archive/2007/06/29/what-is-a-shared-service-provider.aspx

Hope you find it useful, cheers.