How bulk requests run

This page explains in which order the server runs the operations of a bulk request (RFC 7644 §3.7), and how it resolves the references between them.

The order of the operations

A bulk request holds several operations. An operation can reference a resource that a POST of the same request creates, with a bulkId: value (RFC 7644 §3.7.2). For instance, a request can create a user and a group, and add the user to the group.

The server runs the operations in the order of the request, except that a POST runs before the first operation that references it. The response lists the results in the order of the request.

The server computes this order before it runs anything, in a BulkPlan. The plan does no input or output: the synchronous and the asynchronous handlers run the same plan with the same loop. It walks the references without recursion, so a long chain of references cannot exhaust the Python stack.

The references

The storage creates the resource of a POST, and gives its id. The server then replaces each bulkId: reference with this id, before it passes the next operations to the storage:

• in the path of an operation, such as /Groups/bulkId:qwerty;

• in every value of the data of an operation, at any depth, such as the value of a group member.

A reference is a whole value, such as bulkId:qwerty. The storage never receives it. When the POST of a reference failed, or when no POST of the request has its bulkId, the operation fails with a 409.

Circular references

Two operations can reference each other: group A has group B as a member, and B has A. Per RFC 7644 §3.7.1, the server “MUST try to resolve circular cross-references between resources in a single bulk job but MAY stop after a failed attempt and instead return HTTP status code 409 (Conflict)”.

scim2-server answers 409 to the operations of the cycle.

Authorization

The server authorizes each operation on its own, with authorize(). The server first resolves the references of the operation, so authorize() receives the id of the resource the operation acts on. The server then authorizes the operation, before it reports the validation errors of the operation. A refused client gets a 403, even when its data is invalid, and learns nothing about the expected data. An operation on an endpoint that serves no resource type fails with a 400, without authorization.

Failures

A failed operation does not fail the request. Its result carries a status and an error, and the next operations run. fail_on_errors caps the number of failures the client accepts. Once it is reached, the remaining operations do not run, and the response lists the results of the operations that ran.

A failed operation keeps the location of its resource, when it has one. Per RFC 7644 §3.7.3, every result has a location, except the result of a failed POST.

The limits

The ServiceProviderConfig announces two limits: max_operations and max_payload_size. A request beyond either limit fails as a whole, with a 413. The service checks the size of the body it receives. WSGIApplication and ASGIApplication also stop reading the body of a bulk request beyond the limit, so that a large body does not fill the memory first.