https://nalar.dev/tags/concurrency-control/ Recent content in Concurrency Control on Nalar Hugo en-us Wed, 16 Sep 2026 00:00:00 +0700 https://nalar.dev/http-if-match-turns-representation-state-into-a-write-precondition/ Wed, 16 Sep 2026 00:00:00 +0700 https://nalar.dev/http-if-match-turns-representation-state-into-a-write-precondition/ <p>An HTTP origin can refuse a <code>PUT</code> or <code>DELETE</code> before applying it when the request carries <code>If-Match</code> and the selected representation no longer has an accepted entity tag. The condition converts a representation validator into a write precondition: a client can say that a mutation is valid only against state matching a version it previously observed.</p> <p>This mechanism addresses a specific concurrency boundary. It can prevent one client from silently replacing resource state after another client has changed the selected representation. It does not turn HTTP into a transaction protocol, lock the resource between requests, or guarantee that an entity tag represents every piece of application state involved in a mutation.</p>