There has been some speculation in the press recently around Microsoft's commitment to DSLs now that we are planning on supporting five UML 2.1 diagrams in the Rosario release ( Class, Use Case, Component, Sequence, and Activity diagrams ). Specifically, some articles have been written in a way to lead the reader towards a perception that Microsoft is moving away from DSLs and towards UML. Not at all correct! I wanted to take a moment and set the record straight on this, and start a broader conversation.

Let me first start by making one thing very clear: Microsoft is very committed to our DSL strategy, and in particular to the DSL toolkit that ships as part of the VS SDK. In fact, our UML designers are built on top of that toolkit.

I believe that supporting both approaches to modeling gives developers and Architects alike the "right tool for the right job". For those folks who want to analyze and design their architecture using a standard notation that does not imply an implementation decision, use some UML diagrams. UML is great for describing higher level concepts and for defining the initial glossary that can be used to describe the concepts necessary to facilitate broader communication. For those folks who have decided on an implementation strategy, and do not want to be encumbered by the more general nature of the UML to describe that implementation choice, use DSLs.

In the coming months, you will very likely hear me or others on the team talk about using UML at the "logical" layer and DSLs at the "physical" layer. We are really trying to promote a clean separation between the two approaches, while at the same time, attempt to maintain an understanding of how one can inform the other, and vice versa. In this way, we are hoping to more cleanly support the understanding and intent behind the models at each layer.

So this is not a "DSL vs. UML" conversation. This is a "DSL + UML" conversation. And more importantly, this is about meeting our customers where they are and giving them tools that allow them to get to where they need to be.

The true innovation in this space is going to be how we can seamlessly connect the two approaches, and how we can make modeling more central to a broader range of people.

Stay tuned. :)

Cameron