The Enterprise Library application blocks help address the common problems that developers face from one project to the next. They are designed to encapsulate the Microsoft recommended best practices for .NET applications. In addition, they can be added to .NET applications quickly and easily. For example, the Data Access Application Block provides access to the most frequently used features of ADO.NET 2.0 in simple-to-use classes, thus boosting developer productivity. It also addresses scenarios not directly supported by the underlying class libraries.

Different applications have different requirements, and you will not find that every application block is useful in every application that you build. Before using an application block, you should have a good understanding of your application requirements and of the scenarios that the application block is designed to address.

Enterprise Library 3.0–April 2007 contains the following general purpose application blocks:

Caching Application Block. Developers can use this application block to incorporate a local cache in their applications.
Cryptography Application Block. Developers can use this application block to incorporate hashing and symmetric encryption in their applications.
Data Access Application Block. Developers can use this application block to incorporate standard database functionality in their applications.
Exception Handling Application Block. Developers and policy makers can use this application block to create a consistent strategy for processing exceptions that occur throughout the architectural layers of enterprise applications.
Logging Application Block. Developers can use this application block to include standard logging functionality in their applications.
Policy Injection Application Block. Developers can use this application block to implement interception policies that can be used to streamline the implementation of common features, such as logging, caching, exception handling, and validation, across an application.
Security Application Block. Developers can use this application block to incorporate authorization and security caching functionality in their applications.
Validation Application Block. Developers can use this application block to create validation rules for business objects that can be used across different layers of their applications.
Enterprise Library also includes a set of core functions, including configuration, instrumentation, and object builder services. These functions are used by all other application blocks.

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