Bulk Collection Manipulation through a REST (RESTful) API

Question

I\'d like some advice on designing a REST API which will allow clients to add/remove large numbers of objects to a collection efficiently.

Via the API, clients need

Answer 1

You could introduce meta-representation of existing collection elements that don't need their entire state transfered, so in some abstract code your update could look like this:

{existing elements 1-100}
{new element foo with values "bar", "baz"}
{existing element 105}
{new element foobar with values "bar", "foo"}
{existing elements 110-200}

Adding (and modifying) elements is done by defining their values, deleting elements is done by not mentioning it the new collection and reordering elements is done by specifying the new order (if order is stored at all).

This way you can easily represent the entire new collection without having to re-transmit the entire content. Using a If-Unmodified-Since header makes sure that your idea of the content indeed matches the servers idea (so that you don't accidentally remove elements that you simply didn't know about when the request was submitted).