How can I implement Pre- and Post-Commit Hooks in Riak?

Question

There is but scant information on the web as to how to actually implement these features of Riak besides this blog post and a few others. Are any client libraries (ripple etc.) capable of receiving messages via the hook so that working with the changed data in the app (i.e. outside of Riak) becomes possible? Thanks.

Answer 1

It's not possible to have Riak call back into your application, however if you use the "returnbody" option when storing, you'll get back the value that was actually stored as modified by pre-commit hooks.

Post-commit hooks are run asynchronously after the object is stored and so should not be used to modify the stored object. One way you might get "messages via the hook" would be to have your post-commit hook post messages to RabbitMQ (or some other queue), which your application could then consume and do its own processing.

I hope that gives you an idea of where to start. In the meantime, we'll add some examples to that wiki page.