Microsoft enterprise library aspect oriented programming

Its need is to access data, it has a contract defined by data access methods, it shields application from changes from database and DB from business rules. Typically a data access layer will not even be aware of how the UI works. There exist a whole bunch of concerns which can't be separated.

These are cross cutting concerns. A change in these means a change across the application. When we write code to access DB we only write in data access layer, however code to write trace logging is written across the application. If due to some reason, we have been tracing only methods names and one fine day plan to start tracing method input parameters and return type code changes must be made across the application.

Unfortunately the cross cutting concerns are the ones which end up being least thought through in the application, think about how often in a design do we think about our exception hierarchy? AOP or Aspect oriented programming is a mechanism using which cross cutting concerns can be developed separately and then combined with executing code of different layers.

As it is obvious, we can have two types of AOP frameworks, one which hook up to the code at run time, others which modify the code at design time.

I find the term aspect oriented programming a bit confusing and would rather call it "Entangled Concern Separation Pattern". There are a whole bunch of AOP frameworks that exist. Microsoft Download Manager. Manage all your internet downloads with this easy-to-use manager.

It features a simple interface with many customizable options:. Download multiple files at one time Download large files quickly and reliably Suspend active downloads and resume downloads that have failed. Yes, install Microsoft Download Manager recommended No, thanks. What happens if I don't install a download manager? Why should I install the Microsoft Download Manager? In this case, you will have to download the files individually.

You would have the opportunity to download individual files on the "Thank you for downloading" page after completing your download. Files larger than 1 GB may take much longer to download and might not download correctly. You might not be able to pause the active downloads or resume downloads that have failed.

Microsoft Enterprise Library is a collection of reusable application blocks designed to assist software developers with common enterprise development challenges. Details Note: There are multiple files available for this download. NET application development—logging, caching, cryptography, exception handling and more. The latest version of the Enterprise Library is 5. Unity is one of the Enterprise Library application blocks.

Also available for Silverlight, Unity is essentially a DI container with additional support for an interception mechanism through which you can make your classes a bit more aspect-oriented. The core idea of interception in Unity is enabling developers to customize the chain of calls that it takes to invoke a method on an object. In other words, the Unity interception mechanism captures calls being made to configured objects and customizes the behavior of the target objects by adding some extra code before, after or around the regular execution of methods.

Interception is essentially an extremely flexible approach to add new behavior to an object at run time without touching its source code and without affecting the behavior of classes in the same inheritance path. Unity interception is a way to implement the Decorator pattern, which is a popular design pattern devised to extend the functionality of an object at run time as the object is used.

A decorator is a container object that receives and maintains a reference to an instance of the target object and augments its capabilities toward the outside world. The Interception mechanism in Unity 2. Furthermore, interception works regardless of the way in which the object is instantiated, whether the object is created through the Unity container or is a known instance.

In the latter case, you can just use a different, completely standalone API. If you do so, however, you lose the configuration file support.

Figure 1 shows the architecture of the interception feature in Unity, detailing how it works on a particular object instance not resolved through the container. The figure is just a slightly reworked version of a figure you find in the MSDN documentation. The interception subsystem is made of three key elements: the interceptor or proxy ; the behavior pipeline; and the behavior or aspect.

At the two extremes of the subsystems you find the client application and the target object—that is, the object being assigned additional behaviors not hardcoded in its source code. Once the client application is configured to use the interception API of Unity on a given instance, any method invocation goes through a proxy object—the interceptor.

This proxy object looks at the list of registered behaviors and invokes them through the internal pipeline. Each configured behavior is given a chance to run before or after the regular invocation of the object method. The proxy injects input data into the pipeline and receives any return value as initially generated by the target object and then further modified by behaviors. The recommended way of using interception in Unity 2.

In Unity 2. The container needs to find information about types to intercept and behaviors to add. This information can be added either using fluent code or via configuration. I find configuration to be particularly flexible, as it lets you modify things without touching the application and without any new compile step.

The purpose of this script is extending the configuration schema with new elements and aliases that are specific to the interception subsystem.

Another due addition is the following:. The interface type IBankAccount is mapped to the concrete type BankAccount this is the classic job of a DI container and associated with a particular type of interceptor. Unity offers two main types of interceptors: instance interceptors and type interceptors.

For now, suffice it to say that an instance interceptor creates a proxy to filter incoming calls directed at the intercepted instance. Type interceptors, instead, just mock the type of the intercepted object and work on an instance of a derived type. For more information on interceptors, see msdn. The interface interceptor is an instance interceptor limited to act as the proxy of only one interface on the object.