OMG issues RFP: concrete syntax for UML action semantics

This is actually old news for many people, but recently I learned (by pure chance) that the OMG issued a RFP for a “Concrete Syntax for a UML Action Language”. Letters of intent are due on December 8th. Submissions, one year after. OMG members only need apply (Aww…). I wonder if anyone in the Eclipse Modeling project is involved in submitting a proposal. Anyone?

Soapbox: since version 1.5, UML has had support for algorithmic behavior specification, commonly called action semantics. It is still hardly used, and most people that consider they know a lot of UML have never noticed it. Some people believe that the lack of an official concrete syntax for action semantics is a barrier to adoption. You see, the OMG defined the semantics and an abstract syntax, but left concrete syntax as an exercise for tool vendors.

As I wrote here before, I don’t really see the value in the OMG godfathering one concrete syntax over all others. Of course, we are talking here about a syntax for human beings, not for tools. Tools certainly don’t need a human-readable concrete syntax, a standard binary or XML format will do. The problem is: we all have our own preferences for what makes a good syntax, and there is no single syntax that will make everybody happy, so we are bound to have multiple concrete syntaxes anyway. We all like interoperability between tools, but when it comes to sugar, we like choice.

But maybe I am wrong. Maybe an OMG-blessed C-like concrete syntax for UML is all that is missing for Executable UML to become mainstream in the software development community. Go figure, we are an amusing bunch. Personally, I don’t care that much. I have been a Java developer for around 12 years now, so I can certainly stand another C-like syntax. We are not talking about a language anyway, it is just a syntax for an existing language, and syntax, a bit like UI, is inherently disposable, if you take it away, the real stuff is still there.

One clear positive outcome of the RFP is that submitters must provide, along with the proposal for a concrete syntax, any changes to fUML* that would be required to support such action language. That will probably help closing some gaps in the UML specification that make it hard to execute if you are stuck with the standard.

There are many other interesting bits in the proposal, but I will leave a more detailed analysis to a future post.

* the Executable UML Foundation Submission says:“Foundational UML Subset (fUML) is that subset of UML required to write ‘programs’ in UML”

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4 thoughts on “OMG issues RFP: concrete syntax for UML action semantics

  1. Doug Schaefer

    October 16, 2008 at 6:48am

    This is great news. While tool vendors could have defined a concrete syntax for action semantics, to my knowledge, no one has. I think it’s time for the OMG to lend a hand and build a community around this so that they do have something.

    I’ve blogged about this in the past, the action semantics are very powerful and are easy to apply to a massively multi-core world. All that’s been missing is a practical way to use them. Hopefully this can help.

  2. rafael.chaves

    October 16, 2008 at 8:14am


    Action semantics is predated by many years by a handful of proprietary action language implementations (Kennedy Carter, Bridgepoint etc). I believe those now are implemented on top of UML action semantics or at least can be exported using UML AS.

    As per practical use for action semantics, I have been busy working on that, more about this here later…


  3. rafael.chaves

    October 14, 2009 at 2:14pm

    Thanks, Stephen. It is an honor to have you posting here. Unfortunately, those URLs are all password protected, so I guess non-OMG members will only be able to see the final spec.

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