Dotnet Enterprise Library

Enterprise Library has 8 parts namely,Data Access Application blocks, caching application blocks, logging application blocks, Exception handling application blocks, security application blocks, cryptography application block, validation application block, policy injection application block.

It is not a pattern, it is not part of dot net framework, Its not an application framework. This is not a Microsoft framework, it is community project with source code.

Choose DataAccessApplicationBlocks when DB operations are standard and doesn't need any customization, need an easy way to switch between databases, portable code for multiple data sources.

Exception shielding in Exception Blocks helps prevent web service from disclosing internal information in case of errors.

Download latest enterprise library from below location.

You can use more then one application blocks with combination.
http://www.microsoft.com/downloads/details.aspx?FamilyId=90DE37E0-7B42-4044-99BE-F8ECFBBC5B65&displaylang=en

you can find all the releases of enterprise library in the below link
http://msdn.microsoft.com/en-us/library/cc467894.aspx

Consistency, easy of use, extensibility and integration are the main goal features of Enterprise Libraries.

Refer to below excellent article on application blocks, consider reading this before implementing.
http://msdn.microsoft.com/en-us/library/cc816060.aspx

Happy Learning !!!