OData v4变更集行为

Question

I'm implementing an OData v4 Service with WebApi and I also implemented support for OData Changesets using the code from https://damienbod.wordpress.com/2014/08/14/web-api-odata-v4-batching-part-10/

Basically this is working, but now I'm wonder about the correct behaviour when modifying the same entity from multiple requests in one changeset. Consider this example:

Content-ID: 1 - POST ~/Entity
-> Create new Entity.

Content-ID: 2 - PUT ~/Entity($Entity-ContentID1)/Company/$ref?$id=URI
-> Create link from new Entity to existing Company using the ContentID.

Content-ID: 3 - POST ~/Entity($Entity-ContentID1)/ChangeState
-> Execute action to change the state of the newly created Entity.

The ChangetState can only be executed, if a Company is linked. If a client sends all requests in this order and if I execute the requests in order, everything is fine.
But according to the OData Spec , requests in a Changesets are unordered .

What is the expected result if a client sends request 3 before request 2? With my current implementation this changeset will fail, but is this really okay? It's quite hard for me to understand the correct semantic of changesets...

Answer 1

Batch requests are submitted as a single HTTP POST request to the batch endpoint of a service, these requests in a Changeset should be sent to service and proceed in original order.

I think, the spec mean: requests in Changeset will be processed un-order, in our lab, we process with origin order, but different service can use different order, what you concerned is not necessary, client should'n expect same result for a changeset like your scenario, otherwise they should put in different changeset, then the result should be same.