Comparison between Server-side object model/Client object model/REST API(s) and Decision Matrix on what to use when

Server-Side Object Model	Client Object Model	REST API(s)
·         Most extensive set of options to customize SharePoint 2010 ·         Any Components consuming server-side object model needs to be deployed on the server ·         Slower Performance than Client OM and REST API(s) ·         Synchronous ·         Documentation: o   Class Library	·         Client OM APIs are wrappers around a custom Web service that calls the server-side object model. ·         Better Performance than server-side OM ·         Asynchronous ·         Execute calls in a batch of commands ·         Limited options/types as compare to server-side OM ·         Designed to be used in the remote client –side components ·         Documentation: o   Client Class Library o   ECMAScript Library	·         Limited set of REST interfaces ·         Supports JSON(JavaScript Object Notation),Atom and AtomPub standards ·         Based on ADO.NET Data Services ·         Eliminated the need for intermediate layers between client and server by mapping  Read, create, update, and delete operations directly to GET, POST, PUT, and DELETE HTTP verbs ·         Interoperable ·         Documentation: o   REST Interface

 

 Decision Matrix:

 

Reference: http://msdn.microsoft.com/en-us/sharepoint/ff462048