[ckan-dev] Future of VDM

David Read david.read at hackneyworkshop.com
Wed Jun 12 14:06:47 UTC 2013


VDM's code is rather complex and off-putting, I'm afraid. Although it
works fine for one-many relations, the abstraction of many-many
relations didn't always fit CKAN's needs. No-one has had the interest
of getting stuck in to improve it and CKAN has ended up avoiding these
parts of vdm. So there's been less and less use of vdm and the code
remaining needs an overhaul, if not general rethink.

David

On 12 June 2013 14:14, Martin Häcker <spamfaenger at gmx.de> wrote:
> Hi there,
>
> I'm currently considering to use VDM to add versioning to one of my applications. As CKAN is (afaik) the biggest user of vdm, I'd love to get some hints from you about it's applicability and it's future (as there hasn't been a lot of commits on github to it's codebase recently).
>
>
> Some of the questions I'm trying to answer are these:
> - Whats the current status and future of vdm (I haven't found anything starting from the repository or the documentation).
> - The repo is fairly low trafic, last patches have been a few months ago and most of the activity was 2011
> - Whats the Story with SQLAlchemy 0.8 compatibility? Right now its limited to 0.7. Why is that and what would be required to go to 0.8?
> - Say we are managing Questions and Users. We would like to query SQLAlchemy for all Questions created (not edited) by a specific User. How would the vdm model answer a question like that? Looking at the DDL it issues, that seems like something that would be hard to get fast.
> - Could the same model classes sometimes be used with and without vdm attached? We use our model in different contexts, some will just read in the whole object graph and then detach it from the database. Here we don't want to get any additional overhead from the revisions. As far as I see it, we should be just fine with ignoring it as long as we ensure that we don't follow the relations it creates.
>
> Most pressing of course would be the question about the future of VDM - I've heard that you may be considering to replace it with something different once you get around to it. If so, what would that be and why?
>
> Many thanks in advance and best regards,
> Martin Häcker
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