Oxite Review – Part 2

In Part 1, we covered some overall, general aspects of Oxite (as a sample application, as an OSS project, etc) as well as the lack of tests and the problematic domain and persistence strategy.

In this part, dig a little deeper and get into some particular aspects of the application design of the application outside of the domain model.  In this part, I plan on covering:

• High Coupling, Low Cohesion
• Lack of Dependency Injection and IoC causes cascading design problems
• Incorrect layering and slicing of abstractions
• The Provider Anti-Pattern

High Coupling, Low Cohesion

The concepts of Loosely Coupled, Highly Cohesive code (Jeremy has a great article on MSDN which you should stop now and go read), are not new even to the OO design world.  Unfortunately we don’t hear much about it in the .NET space for some reason.  I say unfortunately because they are two extremely important concepts  around OO design. As the title of this section implies, the Oxite object design is, generally speaking, not loosely coupled or highly cohesive. There are some decent abstractions and quite a few classes are cohesive to various extents (some good, some OK, some not so good, etc).  However, some classes are particularly egregious and I want to call them out as a big warning to anyone designing an application in the same manner as Oxite.  The BaseController class is extremely coupled to just about every part of the system.  It is not cohesive at all as its functionality basically equals that of a “Utility” class. It has everything and the kitchen sink in it.  As best I can tell, it does the following things:

• Loads the current user object from the membership provider (coupled to MembershipRepository directly)
• Maintains a list of feeds to be displayed on the view/page
• Sets up the RSS/ATOM Feed list for a given view/action
• Sets up the view/page title, checks for admin permissions, sets up the OpenSearch properties
• Handles “Not Found” scenarios
• Handles file/binary download scenarios
• Handles XML result scenarios
• Handles Feed (RSS/ATOM) result scenarios
• Generates the ATOM/RSD link tags on the page
• Handles RSD-xml requests
• Handles Localization of strings
• Handles localized Date/Time conversions

Lack of Dependency Injection, IoC

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Incorrect Layering of Abstraction

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The Provider Anti-Pattern

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