When using the stickynotes app, instead of curl, the notes bucket is marked as being handled by the ‘notes’ module. When objects are stored in the notes bucket, functions from this module are called, and it is one of those functions that adds the reverse link to the groups object.

If you wanted to do the same with just curl, you’d need to execute something like:

> curl -X PUT -H “content-type: application/json” http://127.0.0.1:8098/jiak/notes –data “{\”bucket_mod\”:\”notes\”}”

Assuming you’re using the stickynotes riak config file, and therefore have the stickynotes ebin in your code path, and the notes and groups atoms exist, riak will make the calls you expect, and notes:affect_write/4 will add that reverse link for you.

HOWEVER, the curl command described required that you pull the latest riak (as of this evening). I just patched a bug while writing this reply. If it’s inconvenient for you to update riak, you can get the same effect by typing the following two lines at the erlang shell running riak (assuming you used the debug-fresh.sh script):

> {ok, C} = riak:local_client().
> C:set_bucket(<>, [{bucket_mod, notes}]).

“…I can now use the Jiak utility jaywalker to get all of the notes in the todo group with a single query:
$ curl http://127.0.0.1:8098/jiak/groups/todos/notes,_,_”

But at this point, I received an empty “results” list, as I’ve shown, instead of receiving “all of the notes” as it is stated. Did I misunderstand this sentence?

Your first curl command creates the “todos” item in the “groups” bucket.

Your second curl command creates the “blog” item in the “notes” bucket. You’ve added a link in the “notes/blog” item that points to the “groups/todos” item.

Your third curl command asks Riak to start at the “groups/todos” item and follow all “notes” links it has. The “groups/todos” item has no links at all, so Riak finds nothing to give you.

Your final curl command asks Riak to start at the “notes/blog” item and follow all “groups” links it has. It has one link (the one you added in the second curl command), so it follows that one, finds the “groups/todos” item and returns it to you.

Make sense?

$ sudo ./start-fresh.sh config/riak-demo.erlenv
$ curl -X PUT -H “Content-type: application/json” http://127.0.0.1:8098/jiak/groups/todos -d “{\”bucket\”:\”groups\”,\”key\”:\”todos\”,\”object\”:{\”name\”:\”todo\”},\”links\”:[]}”
$ curl -X PUT -H “Content-type: application/json” http://127.0.0.1:8098/jiak/notes/blog -d “{\”bucket\”:\”notes\”,\”key\”:\”blog\”,\”object\”:{\”text\”:\”finish blog post\”,\”x\”:0,\”y\”:0,\”z\”:0,\”color\”:\”green\”},\”links\”:[[\"groups\",\"todos\",\"open\"]]}”
$ curl http://127.0.0.1:8098/jiak/groups/todos/notes,_,_
{“results”:[[]]}
$ curl http://127.0.0.1:8098/jiak/notes/blog/groups,_,_
{“results”:[[{"object":{"name":"todo"},"vclock":"a85hYGBgzGDKBVIsjGWr2jOYEhnzWBk4EqKO8GUBAA==","lastmod":"Mon, 26 Oct 2009 18:01:44 GMT","vtag":"23zAcKJCpRQzn8HKxdy5jh","bucket":"groups","key":"todos","links":[]}]]}

Based on your instructions and from my understanding of links the results for the 4th and 5th commands seem to be switched. Did I miss something?

I still miss those ordinary 1,2,3… ids like the known @@identity or SEQUENCE, but I admit that they might be non-adequate to the volatile networking multi-node environment with no master node in it.

There is currently nothing in the dets_backend watching for a potential overflow, but limit-checking code could be added.

…or you could choose among the other available backends.