LWC2014: wrap-up

It’s a wrap!

The Language Workbench Challenge, co-located with the Code Generation conference at the Churchill College, Cambridge, UK, once again was a very nice day featuring demos of 7 language workbenches and their newest features. But above all it was joy to meet all the participants and “non-challenging” attendees and exchange knowledge, views and experiences.

LWC 2014 organisers, speakers and delegates
LWC 2014 organisers, speakers and delegates


The LWC 2013 had a record number of participants. There were three problems associated with this:

  1. It was a challenge to give each participant a respectful amount of presentation and demo time. It was equally hard to properly evaluate all workbenches in their own right as well as against each other, tallying their strengths and weaknesses.
  2. Some of the contributions definitely stretched the idea of a language workbench: some were not quite a workbench (in the sense of an integrated tool), others were not quite “language-y” (e.g., the contents of a database is not prose per se).
  3. It is an indication of significant fragmentation in a field that can hardly be considered to be large enough for that.

Because of the first two reasons, the program committee decided to draft up selection criteria. Participants were asked to submit a short report explaining their (future) implementation of the assignment, also addressing why they were fulfilling these criteria.

After an initial misunderstanding was rectified in the assignment’s text, this turned to work out quite well: this year we had a smaller number of candidates (7), which were all promoted to participants based on their reports. Although 5 of these had participated in previous years, there were also two new ones, showing that the selection criteria weren’t inhibitive.

For space reasons, we’ll defer discussing all contributions to the next blog.


This year’s assignment consisted of a base part and a focus assignment. The base part was essentially the same as last year: the implementation of a Questionnaire Language (QL) and a styling language for that (QLS).

We (i.e., the program committee) had provided a reference implementation of an example questionnaire using HTML5 based on a simple questionnaire framework to avoid that participants had to spent a lot of effort on creating that themselves. In practice, this meant that participants could either interpret or generate code from the model in a very straightforward way, requiring a minimum amount of effort. The use of the reference implementation/framework was optional but we were happy to see that most participants have used it and that it indeed had allowed them to focus on the essence of implementing the languages.

The focus assignment consisted of two parts: one focusing on “groupware” capabilities that allow models to be worked on by various people, and one focussing on “scalability” in the sense that one could work (either alone or as a team) on large models. These topics touch on concepts like version control (including “semantic”/language-aware diffing), model persistence and performance. For the latter part, we asked for the implementation of a binary search in questionnaire form.

Persistence of large-scale models

After the last presentation, we had an in promptu presentation by Jürgen Mutschall from MetaModules on persistence of large models. During this he demonstrated a system which held the complete Kepler code base, with parsed Java code viewed as a model, in a database which then could be used to inspect, reason about and manipulate (such Refactoring) it. It was interesting to see the good ‘ole JEE stack being used for model storage and to see it perform really well.

Hands-on session and group discussions

A large part of the afternoon was given over to a hands-on session where attendees could look at the language workbenches and discuss possibilities etc. Although this part was not structured, it certainly led to interesting discussions.


In order to have a good assignment for the LWC 2015 edition we held a little “Agile-style” brainstorm on what subjects  could be interesting. The list we came up with (in no particular order): 

  • Evolution
  • Autotesting
  • Interchange
  • Life Cycle Management
  • Mixing of different notations
  • What is a language workbench?
  • Business users?
  • Interpretation vs. generation
  • Debugging on the model level

Also, the question was raised whether it would be possible to focus on ‘addressing a question rather than building a lot of stuff’.

All of these suggestions, and more ideas, will be taken into consideration for LWC 2015.

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