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Concurrency control

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Note

The Cloud Partner Portal APIs are integrated with and will continue working in Partner Center. The transition introduces small changes. Review the changes listed in Cloud Partner Portal API Reference to ensure your code continues working after transitioning to Partner Center. CPP APIs should only be used for existing products that were already integrated before transition to Partner Center; new products should use Partner Center submission APIs.

Every call to the Cloud Partner Portal publishing APIs must explicitly specify which concurrency control strategy to use. Failure to provide the If-Match header will result in an HTTP 400 error response. We offer two strategies for concurrency control.

  • Optimistic - The client performing the update verifies if the data has changed since it last read the data.
  • Last one wins - The client directly updates the data, regardless of whether another application has modified it since the last read time.

Optimistic concurrency workflow

We recommend using the optimistic concurrency strategy, with the following workflow, to guarantee that no unexpected edits are made to your resources.

  1. Retrieve an entity using the APIs. The response includes an ETag value that identifies the currently stored version of the entity (at the time of the response).
  2. At the time of update, include this same ETag value in the mandatory If-Match request header.
  3. The API compares the ETag value received in the request with the current ETag value of the entity in an atomic transaction.
    • If the ETag values are different, the API returns a 412 Precondition Failed HTTP response. This error indicates that either another process has updated the entity since the client last retrieved it, or that the ETag value specified in the request is incorrect.
    • If the ETag values are the same, or the If-Match header contains the wildcard asterisk character (*), the API performs the requested operation. The API operation also updates the stored ETag value of the entity.

Note

Specifying the wildcard character (*) in the If-Match header results in the API using the Last-one-wins concurrency strategy. In this case, the ETag comparison does not occur and the resource is updated without any checks.