Model driven Architect

[Jignesh Patel]

Hello,
Can anybody explain me by taking a small example, what is model driven architecture.

[Jignesh Patel]

Ok, let me ask this way.

Suppose I am developing a high level design(including component,class and sequence diagrams) in Rational or TogetherSoft for the target system by keeping in mind j2ee.
Will it be consider as a PSM.

Here one more point, since I am not implementing PIM, PIM to PSM transformation is not there. Then will it be considered as MDA?
[ September 02, 2005: Message edited by: Jignesh Patel ]

[Lasse Koskela]

Well, it says here that

Software development in the MDA starts with a Platform-Independent Model (PIM) of an application's business functionality and behavior, constructed using a modeling language based on OMG's MetaObject Facility (MOF). [...] MDA development tools [...] convert the PIM first to a Platform-Specific Model (PSM) and then to a working implementation on virtually any middleware platform: Web Services, XML/SOAP, EJB, C#/.NET, OMG's own CORBA, or others.

In other words, if you don't have a PIM, you're not doing MDA by the spec. Whether your design models constitute a PSM is irrelevant--if it's not part of a full MDA approach, it's just a model. Personally, I am of the opinion that even if you generate the application from your model automatically, it's not MDA--it's just plain old code generation.

[Scott Ambler]

You might find Examining the MDA interesting. It asks a few hard questions about the concept. Are You Ready for MDA? should also be of interest.

- Scott

[Jignesh Patel]

Scott,
I have gone to the "Examining the MDA interesting".and "Are You Ready for MDA?". They both are interesting article, but then I have gone to
http://www.metamaxim.com/download/documents/MDAv1.pdf. In which Ashley McNeile have a different opinion then what you have. He says, "MDA adoption has caught on faster than any other OMG standard." While as a technocrate I realized there are very few people who knows detail about MDA. I agree with you there are very few organization are ready for MDA.

Also I don't know any industrial tool other then ERWIN which implements MDA, especially in Java.

[Scott Ambler]

I'm not in the business of selling people tools, so it shouldn't be surprising that my opinion differs from that of an MDA tool vendor. ;-)

I suspect that the tool vendors may have jumped on the MDA spec very quickly, MDA is a wonderful marketing strategy for them, but as far as practitioner adoption I don't see a lot of uptake out there in the market place. Some people are talking about it, but few seem to be doing it.

At the UML World conference in Austin (June 2005) few people seemed interested in MDA, most thinking that it was little more than I-CASE warmed over. I would have expected people to be excited about MDA, but that didn't seem to be the situation.

How many people do you know who are interested in MDA? I have to think that for every person who can tell you what MDA stands for that you could find 20 who know what the UML is. Or that for every person you know who is taking an MDA approach that you will find 100 people who only model on whiteboards or paper, when they model at all.

In the end, you need to decide if MDA is appropriate for your situation.

- Scott

[JeanLouis Marechaux]

Jignesh,

Some tools on the market are already implementing MDA concepts. For example, check this url.
And I agree with Lasse. You don't do MDA without PIMs.

Scott,
I agree with you, MDA will probably remain hard to understand for some developers. But if tools create PIMs to PSMs transformation, then the learning curve will be less important. We will see what vendors will provide...

Anyway, one key principle of MDA is to decouple the conceptual aspect from the implementation. This is not new. RUP already stresses on that technique for a couple of years now. The RUP logical view is also supposed to be neutrral regarding technologies. So MDA is only bringing normalized transformation on the table, while the concept is existing and widely used across organizations.

Finally, maybe MDA will find its audiance through MDD (Model Driven Development), extending the concepts to MDA later on.

[Jignesh Patel]

Can we consider the class diagram we develop during analyze phase as a PIM.

[Scott Ambler]

If the class diagram doesn't take technology issues, such as the use of Java as your implementation language for example, then it would be part of your PIM. But, class diagrams only show structural aspects of your model, but what about behavioral aspects? You'll likely need activity diagrams for business logic, or some form of scripting language (usually called an action semantic language (ASL) ) to describe business rules. How will you capture user interface requirements? Or timing requirements? Performance requirements? Interesting questions which the MDA tool vendors usually gloss over. In theory MDA is a great vision, but in practice it simply isn't there yet and likely never will be (do some research, the rhetoric of the MDA vendors is very close to the rhetoric of the I-CASE vendors in the 80s, and we all know what happened to them).

There's no standard for ASLs, the end result being that ASLs are one of many issues which cause MDA-based CASE tools to be incompatable with one another. However, the real issue with incompatability is that the tool vendors really aren't motivated to make it easy for you to port your models to a competing vendor.

- Scott

[Stan James]

I agree this sounds like the 80s all over again. Back then Ed Yourdon went to each of the major CASE vendors and asked them to show him how they used their tool to build their tool. Every one said, "Erm, our product is a special case that can't really be done that way". When they start to show us the PIMs for their own products maybe we'll perk up.