Model Driven Architecture..Huh! What is that?

As you all would have noticed, lately I have been pondering a lot about architecture, design and the way software development can be made easier for the software community. Well, this led to me Model Driven Architecture. Now, you would wonder-what is different about Model Driven Architecture? After all, all software starts with design where you develop a sort of model of the end software.

First let me try to explain a problem which we software developers face almost everyday-CHANGING TECHNOLOGY. First there was VB, then came VB.NET, first there was remoting, then came web services. Each time a new technology comes into the market, lot of rework needs to be done. Add to this the plethora of rapidly changing requirements and the ability that your software needs to interact with other systems and you get a fairly complex scenario which haunts you everyday. I on a personal basis hate the client asking me to change the application so that his application can run on Oracle database as well.

Allow me to explain a little more, Model Driven Architecture is a new way of writing just what you thought-“Specifications”. Here, no technology is taken into consideration. So, what do you exactly write? You develop a platform independent base UML model aptly called Platform Independent Models (PIMs). You are not supposed to concentrate on the language to be used or the database on which the software will run or the number of frigging threads the application will spawn. You concentrate only on the functionality and the end behavior of the application. There is no relation what so ever with the implementation details.

So, what is the benefit of this sort of architecture?

With today’s fast changing technology environment, lots of new platforms and infrastructure are coming into the market. Now what happens to your existing applications? If your applications have been written solely targeted towards a particular platform or infrastructure, then they become redundant-right? So, that means you lose all your investment that you have been putting into technology hoping for a better tomorrow. Now, that’s a really scary situation. This is where Model Driven Architecture steps into the picture.

MDA is already being projected as the next big step to be taken by the software industry. At the heart of the MDA development is UML, which involves developing models in order to develop your application. So, during the analysis of the requirements, UML is used to develop a model in a standard way which acts like a blueprint for your application. But you would be wondering how can just developing a model, lead to the development of the entire application. So, here in order for the application to be targeted towards a particular platform or infrastructure, the Platform Independent Model needs to be converted into a Platform Specific Model (PSM). So, if you wish to put it into simple words, a PIM sits at the center of the application and then a PSM is written around the PIM. The PSM can be written in any technical language-be it CORBA, or .NET or JAVA. The business functionality and the behavior of an application are etched into the PIM and the UI and the UI components are written in any available language.

It is then the responsibility of the platform specialists to convert the model into one targeted towards a specific platform like CCM, EJB or MTS. Standardized tools are used in order to do this conversion from PIM to PSM. This is one area where a lot of scope is still there for research and development due to the fact that although the tools being used today use standard mappings to do the conversion, there is still a lot of human intervention involved. So, this is a sort of developing art which needs some hand-holding even today.

The next step is the actual generation of the code. Finally, the software developers would have heaved a sigh of relief here-after all what will they do if everything is done by the model. The actual code generation will involve generating a lot of configuration files, interface files and so on. If the models generated using UML are complete or encompass the entire functionality of the application, there will be lesser work to do during the PSM conversion phase and the better the application nitty-gritty’s and runtime behavior have been handled in the PSM, the lesser code will have to generated.

This type of architecture is still in its infancy stage right now and if you expect that you can generate all your code using models TODAY, then you are probably mistaken. MDA offers just another layer of reusability below the development tools which we all are already using these days. This art of architecture still has to grow a lot before we start searching for expert UML modelers rather than expert C# developers.