While the .NET platform provides a powerful set of tools and
libraries to build robust applications, I am always amazed by the additional
free add-ons provided by Microsoft. In my opinion, the most notable is the Enterprise
Library. This set of application blocks developed by the patterns and
practices group utilizes best practices for solving common problems. The
result is less development time and subsequent costs. In this week’s column, we
take a closer look at the Enterprise Library.

Overview

This is Microsoft’s follow-up to its initial offering of the
individual components contained in the Enterprise Library. The previous
incarnations were designed as well as released separately. The problem with
this approach was that each application block included its own code for tasks
common across all application blocks. This redundancy has been resolved with
the Enterprise Library. It brings each application block together into a
cohesive unit. Each application block uses similar design patterns as well as
sharing deployment and configuration requirements. It includes the following
seven application blocks:

  • Caching: Allows developers to
    incorporate a local cache in their applications.
  • Configuration: Allows applications
    to read and write configuration information.
  • Cryptography: Allows developers to
    include encryption and hashing functionality in their applications.
  • Data Access: Allows developers to
    incorporate standard database functionality in their applications.
  • Exception Handling: Allows
    developers and policy makers to create a consistent strategy for
    processing exceptions that occur throughout the architectural layers of
    enterprise applications.
  • Logging and Instrumentation: Allows
    developers to incorporate standard logging and instrumentation
    functionality in their applications.
  • Security: Allows developers to
    incorporate security functionality in their applications. Applications can
    use it in a variety of situations, such as authenticating and authorizing
    users against a database, retrieving role and profile information, and
    caching user profile information.

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The Enterprise Library is downloaded in a single
self-installing executable. Therefore, you can install and compile the library
with one click of your mouse. The result includes the library components as
well as a slew of QuickStarts that include samples
that clearly demonstrate each application block’s usage. It is a great way to
get a better idea of how or where to use them.

In addition, each application block utilizes instrumentation
through performance counters, event log entries, and WMI (Windows
Management Instrumentation) events so you can easily monitor an application as
well as diagnose possible problems.

Installation and setup

Once you download and install the Enterprise Library, a
whole new set of tools are available on your computer. Note that you can choose
application blocks during installation so you only install what is necessary.
The default installation directory is c:\Program Files\Microsoft Enterprise
Library with a Microsoft patterns & practices entry added to the All
Programs menu in Windows. This menu provides access to each application block
as well as the QuickStarts samples. In addition,
tools are available to install/uninstall related services, work with the
security database console, view documentation, and work with the configuration
GUI.

The application blocks maintain related data in XML
configuration files: web.config (Web application) or app.config (desktop application). Previous versions of the
application blocks forced you to work with these files by hand via your
favorite editor. While this is still possible, the latest version includes a
visual interface to make such changes.

Note: The
performance counters and Instrumentation are enabled by default, but to make
sure everything is registered, you’ll need to run the Install Services script
from the Start Menu or run installutil over each
assembly. It is easy to disable instrumentation if you are deploying to an
environment where the instrumentation (via a project’s conditional compilation properties),
but it requires the code to be recompiled.

Deployment

The assemblies produced by compiling the installed version
of the Enterprise Library source code are not strong named. As a result, they
cannot be installed in the GAC (Global Assembly Cache), nor will they have the
other benefits associated with strong named assemblies.

The application blocks may be compiled and deployed in an
application’s directory structure. This simplifies deployment because you can
install the entire application, including the application block assemblies, on
the target computer by using the xcopy command.

However, if multiple applications on the same computer use
Enterprise Library application blocks, you must install a copy of the
assemblies in each application’s folder hierarchy. If you do have multiple
applications, you can sign the assemblies with a strong name key. As a result,
you can then place the assemblies in the GAC and use it for deployment. In
summary, you must consider several issues when deploying the application:

  • Unless
    the Enterprise Library dll files are stored in
    the GAC, they must be distributed in the application’âs bin directory.
  • While
    the app.config or web.config
    should be deployed just fine, the other config
    files require some manual steps; you must copy them manually to the
    application Bin directory. By default they are created and deployed to the
    application root directory.

Strengthen your applications

The Enterprise Library provides a powerful set of add-ons
for the .NET Framework. It offers a set of well-designed and thoroughly tested
application blocks that can be used to strengthen current or future
applications. You can easily implement logging and caching as well as simplify
database connections and exception management.

These are just a few of the features available via the
Enterprise Library. If you haven’t done so already, download and install it.
Next week, we put portions of the library to work in sample applications.

Miss a column?

Check out the .NET Archive, and catch up on the most recent editions of Tony Patton’s column.