Contention occurs when a resource request that is not compatible with the existing entries on the resource request queue is added to the queue.

Contention is handled by both XES and the exploiting user. XES recognizes the contention; the user resolves the contention through its contention and notify exits.

When XES recognizes contention, it selects one of the connected users to manage the resource and assigns management responsibilities to that user. The user selected is not necessarily a requestor of the resource. (Note that the application should make no assumptions regarding where contention management will occur.) XES passes the resource request and the associated resource request queue to the contention exit of the selected user. The contention exit's purpose is to resolve the contention based on the user's defined protocols. Subsequent requests for the “in contention” resource are presented to the selected user's contention exit in time-of-arrival sequence. XES ensures that at most one new request at a time is presented to the contention exit.

Once a user is selected to manage the resource, that user remains the manager of the resource until the contention is resolved. If the selected user should disconnect or abnormally terminate while still the manager of the resource in contention, then XES assigns management responsibilities to another connected user.