api-guidelines/execution/batch-operations.md

Batch Operations

When a client needs to submit a number of similar requests for different resources, as long as the operations on each resource are the same and the resources are “similar,” you can combine them into a single operation on a collection resource

– RESTful Web Services Cookbook

Processing Similar Resources

An operation that needs to process several similar resource in bulk SHOULD use a collection resource with the appropriate HTTP Request Method. When processing existing resource the request message body MUST contain the URLs of the respective resources being processed.

Example

Create Multiple Orders at Once

POST /orders
Content-Type: application/json

{
  "order": [
    {
      "item_count": 42
    },
    {
      "item_count": 2
    }
  ]
}

Update Multiple Orders at Once

NOTE: The self link relation clearly identifies the existing resource being edited.

PATCH /orders
Content-Type: application/json

{
  "order": [
    {
      "_links": {
        "self": { "href": "/order/1"}
      },
      "item_count": 42
    },
    {
      "_links": {
        "self": { "href": "/order/2"}
      },      
      "item_count": 2
    }
  ]
}