I would like to share some (personal) pitfalls I came across when creating the demo REST with dojo and PHP: Demo of a dgrid observing changes to the JsonRest store:

• dojo/store/Observable only works correctly when the object has an id. Unfortunately, dojo/store/Memory.add(object) does not add the id to the object when creating it (as of 1.7.1) .  See bugs http://bugs.dojotoolkit.org/ticket/12835 and http://bugs.dojotoolkit.org/ticket/14281. For a fix see changeset http://bugs.dojotoolkit.org/changeset/27072/dojo
• Observable does neither work correctly (for the reason above?) with a dojo/store/JsonRest nor a dojo/store/Cache, but that doesn’t really matter, because you can use it directly with the dojo/store/Memory instead.
• As stated in the docs, but easily missed: dojo/store/Cache automatically adds all returned objects from get() and query() calls to the cache, but only get() uses the cache, whereas query() directly uses the master store. If you want the query to come from the cache, directly call query() on the caching store, e.g. dojo/store/Memory.
• In the demo, the PHP script responds to the GET 2 by returning a Json object with id 2 and to a GET 2/ by returning an array of objects with parent id 2. If you want to query the Memory store for 2′s children, you have to provide an object as an argument, e.g. storeMemory.query({parId: 2}), whereas the JsonRest store expects a string e.g. storeJsonRest.query(’2/’);
• JsonRest store’s methods do not return the same types as Memory store, which can be confusing…
  storeMemory.add(newObject) returns the id
  storeJsonRest.add(newObject) returns the response from the server (or rather a Deferred providing it)
  …, but makes sense, because it can save an extra round trip to the server.