Design Patterns

Refactoring to Patterns provides some of the glue that Design Patterns (GoF) and Patterns of Enterprise Application Architecture (PoEAA is missing. The concept of the book is very simple: to provide examples of how to use design patterns to refactor code. A side product of this is the reader should really have an understanding of the two books previously mentioned before reading this book. If GoF and PoEAA is the bible, then Refactoring to Patterns is the Sunday school teacher. »

I just started using the Policy Injection Application Block from Microsoft’s Enterprise library. At first, I thought it was worthless and overly complex. I was wrong. It is a very powerful programming tool that allows me to develop a lot faster and cleaner. Policy Injection is similar to aspect-oriented programming in that it helps to break away cross-cutting concerns (authorization, logging) from the actual business logic. And yes, I basically copied that from the documentation. »

As most of you know, the data access layer is my favorite application layer to work with. For a while, I worked on my own active record implementation in PHP. After switching to .NET, my outlook has strayed away from the active record pattern though. I like using business entity objects that have no coupling to a database. Instead, I use an object/relational mapper to translate from business entity to persisted database object. »

I recently started a new project here at Webmail.us which will be a .NET based web application. One of the core pieces of .NET web apps is, not surprisingly, ADO.NET. It is Microsoft’s upgrade from ADO, but it is more of a rewrite. Almost everything has been refactored, with many new abstractions and paradigms for how to access data. When I first read about ADO.NET, I was very skeptical. I didn’t understand the need for these complex, hard to understand abstractions like DataTable’s and DataRelation’s and DataSet’s. »

A while back, I posted a review of some existing Active Record implementations. One of those happened to be the Zend frameworks DB portion. I believe that was about the time of version 0.7, and I recently looked on their website and discovered 1.0 had been released. I initially had low expectations, expecting 1.0 to just clean up 0.7 code, with minimal feature additions. After I downloaded it, I found out how wrong I was. »

It has been a while since I have written about, or coded, my Active Record implementation. Basically, I have had too many other things to work on to enhance the functionality of an already working, albeit very beta, design. But, that doesn’t mean I haven’t been thinking of all the features I want to add to it. For many applications, the date created and date modified information for data is very useful, but annoying to set. »

As I have mentioned before, design patterns are one of my favorite areas of computer science. Well, design patterns have a close association with web frameworks, so web frameworks are definitely another favorite area of mine. They both help speed up the development process by providing a structure for applications. Since Ruby on Rails took off a couple years ago, other web frameworks have sprung up in many other languages. None of these have met my needs at Webmail.us. »

One of my favorite design patterns is the Active Record pattern. For those of you who haven’t heard of it, this pattern abstracts database access to a very simplistic level. I first starting playing with my own implementations a couple years ago, but it wasn’t until I used Ruby on Rails that I first saw a fully functional implementation. At Webmail.us, I have decided to use my side-project hours to work on my own version of the active record pattern. »