Do you use MDA/MDD/MDSD, any kind of model-driven approach? Will it be the future?

Question

Programming languages had several (r)evolutionary steps in their history. Some people argue that model-driven approaches will be The Next Big Thing. There are tools like openArchitectureWare, AndroMDA, Sculptor/Fornax Platform etc. that promise incredible productivity boosts. However, I made the experience that it is either rather easy in the beginning to get started but as well to get stuck at some point when you try something that was unanticipated or pretty hard to find enough information that tells you how to start your project because there may be a lot of things to consider.

I think an important insight to get anything out of model-driven something is to understand that the model is not necessarily a set of nice pictures or tree model or UML, but may as well be a textual description (e.g. a state machine, business rules etc.).

What do you think and what does your experience tell you? Is there a future for model-driven development (or whatever you may want to call it)?

Update: There does not seem to be a lot of interest in this topic. Please let me know, if you have any (good or bad) experience with model-driven approaches or why you think it's not interesting at all.

Answer 1

Disclaimer: I am a developer of business applications. The following view is certainly shaped by my experiences in trenches of enterprise IT. I am aware, that there are other domains of software development. Especially in industrial and/or embedded systems development the world might look different.

I think MDSD is still too much tied to code generation.

Code generation is only useful, when your code contains a lot of noise and/or is very repetitive. In other words, when your code can not mainly focus on the essential complexity, but is polluted with accidental complexity.

In my opinion the trend in current platforms and frameworks is exactly to remove accidental complexity and letting the application code focus on essential complexity.

So these new platforms/frameworks take a lot of the wind out of the sails of the MDSD movement.

DSLs (textual ones) are another trend that tries to enable the sole focus on essential complexity. While DSLs can be used as source for code generation, they are not primarily tied to code generation. DSLs (especially internal DSLs) basically let it open to be interpreted/executed at runtime. [runtime code generation is somewhere in between].

So even if DSLs are often mentioned together with MDSD, I think they are really an alternative to MDSD. And given the current hype, they also take the momentum out of the MDSD movement.

If you have reached the goal of ultimately removing accidental complexity out of your code (I know this is fictitious), then you have arrived at a textual model of your business problem. This cannot be further simplified!

Nice boxes and diagrams do not offer another simplification or elevation of the abstraction level! They may be good for visualization, but even that is questionable. A picture is not always the best representation to grasp complexity!

Further more, the current state of the tooling involved in MDSD adds another level of accidental complexity (think: synchronization, diffing/merging, refactoring ...) which basically nullifies the ultimate goal of simplification!

Look at the following ActiveRecord model, as an illustration of my theory:

class Firm < ActiveRecord::Base
   has_many   :clients
   has_one    :account
   belongs_to :conglomorate
end

I dont think that this can be any more simplified. Also any graphical representation with boxes and lines would be no simplification, and would not offer any more convenience (think about layouting, refactoring, searching, diffing ...).

Answer 2

Model Driven development has been around for a very long time.

The most succesfull of the early attempts was James Martins Integrated Engineering Facility" which is still around and marketed by CA under the seriously uncool "Coolgen" brand name.

So why didnt it take over the world if it was so good?

Well these tools are good at making the simple stuff simpler, but, they dont make the hard stuff any easier, and in many cases make the hard stuff harder!

You can spend hours trying to persuade a graphic 4GL modeling language to "do the right thing" when you know that coding the right thing in Java/C/SQL or whatever would be trivial.