Most new ideas in software developments are really new variations on old ideas. This article describes one of these, the growing idea of a class of tools that I call Language Workbenches - examples of which include Intentional Software, JetBrains's Meta Programming System, and Microsoft's Software Factories. These tools take an old style of development - which I call language oriented programming and use IDE tooling in a bid to make language oriented programming a viable approach. Although I'm not enough of a prognosticator to say whether they will succeed in their ambition, I do think that these tools are some of the most interesting things on the horizon of software development. Interesting enough to write this essay to try to explain, at least in outline, how they work and the main issues around their future usefulness.

When you build a Domain Specific Language (DSL), how do you go about making it executable. This is an easy question to answer for an internal DSL, since they are embedded into real languages. An external DSL needs more work. Here I take a simple DSL example and show a few simple ways to generate code from it.

Using a language workbench is very different to working with traditional Domain Specific Languages. This is an example of building a small but interesting DSL using the JetBrains Meta Programming System (MPS). You can use this to get a feel of what working with language workbenches would be like.

There's been a recent surge in development of tools that allow you integrate between multiple Domain Specific Languages (DSL) - tools that I refer to as language workbenches. Much of the discussion around language workbenches is very similar to the discussion around the Object Management Group's Model Driven Architecture (MDA). In my view the MDA means different things to different people - and this effects how we view the relationship between MDA and language workbenches. Certainly there groups of MDA practitioners who are using MDA ideas to build a language workbench. However my feeling is that the help MDA provides is partial, at best. A broader school of Model Driven Development (MDD) echoes many of these ideas without the links to the MDA standards - this is something that is very much in line with the ideas of a language workbench.

I'm joined by Thoughtworks CTO Rebecca Parsons, who was a contributer to the DSL book, to talk with Markus Völter about DSLs. We talk about what DSLs are, the differences between internal and external DSLs, and when you should (and shouldn't use DSLs).

What's the most common programming language in the world?

Language Workbench is a term I coined in 2005 to describe a new class of software development tool, designed to build software through a rich environment of multiple, integrated, DomainSpecificLanguages. These tools are still quite a way away from being mainstream, but development on them continues and continues to be interesting. They are one of the few things I feel could significantly change the programming landscape.

When I wrote my recent article on Language Workbenches, I decided to separate the section on further reading into my bliki, to make it easier to report updates when new stuff appears.

Model Driven Software Development (MDSD) is a style of software development that considers itself as an alternative to the traditional style of programming. The approach centers itself on building models of a software system. These models are typically made manifest through diagrammatic design notations - the UML is one option. The idea is that you use these diagrams, to specify your system to a modeling tool and then you generate code in a conventional programming language.