An Analysis Pattern for the Request and Allocation of Limited Resources

1. Intent How to allocate a limited number of nonreusable resources between several requests, both fairly and efficiently? 2. Context In many situations the number of available resources is smaller than the requests. For example, tickets for a popular sports game are sold out far before the date of play; a well-paid position in a company may have many applicants; in China, stocks are always sold out when first offered because of their lower price. These are nonreusable resources in that, from the system point of view, there is no provision for the return of the resource and its future allocation. This is in contrast with reusable resources such as vehicles, hotel rooms, and airplane seats, which are returned after use and scheduled to be used again in the future. Allocation of limited nonreusable resources is complicated because of its many possible combinations of operations. Usually, pre-requesting (sending the request and waiting for later allocation) is required, but in some rare cases, a client can acquire resources directly without reservation or wait, e.g., when the resource validity is near expiration. For example, ticket requests for important soccer games are fulfilled after the request is sent; however, one can go t