One of the interesting questions about Oslo is its relationship to DSL Tools. Actually, we should say between Oslo and Software Factories (the marketing side), or between M and DSL Tools (the technical side). Technically it seems there is no link -- which means no integration and no upgrade path. On the marketing side, few people seem to have picked up on the fact that Keith Short, co-author of the Software Factories book, moved to work on Oslo nearly two years ago. Steve Cook and Alan Cameron Wills, co- authors of the DSL Tools book, have also left the team, but for UML and MSF respectively.

Of course, people move around, and it's more interesting to hear what people still in those teams say. An Oslo developer writes:

If I look around, I see people doing [declarative, model-driven programming] today in the form of XML schemas and dialects, various textual reps, and frameworks that encode a domain. We went down that path as well, using visual designers and XML. But at some point the pain was too much :) We evolved our approach into Oslo.

Microsoft's "visual designers and XML" presumably refers to DSL Tools, and the comment about the pain being too much is perhaps at least one answer to the question of why Oslo isn't being billed as an evolutionary step along the Software Factories / DSL Tools path. It sounds more like Microsoft have concluded that their DSL Tools are an evolutionary dead end, have taken a step back, and are now heading down a different path. That's the impression I get from Keith Short's blog entry: "both Oslo and the DSL Toolkit have grown from a common belief" in DSLs.

Microsoft are of course claiming both products will continue to be developed, but losing 3 out of 6 main figures from the DSL Tools team is hardly encouraging. Mind you, I think what is needed is even more radical: both Oslo and DSL Tools should be put on hold until Microsoft have figured out what you need for an industrial strength language for describing modeling languages. The resulting languages and tools have to scale to multiple simultaneous users, multiple representational paradigms (graphical, textual, matrix, tabular), multiple platforms (not very likely that one!), integration between multiple modeling languages and multiple models, and evolution through multiple versions of the languages. There are a few more multi's I could add (look at slide 15 from my keynote to the OOPSLA DSM Workshop), but you get the picture. And if you want more than just the picture, get the tool!