Pattern 17 (Shortest Queue)

FLASH animation of Shortest Queue pattern

Description

The ability to allocate a work item to a selected resource chosen from a group of eligible resources on the basis of having the shortest work queue.

Example

The Heart Bypass Procedure is allocated to the Surgeon who has the least number of operations allocated to them.

Motivation

Shortest Queue provides a means of allocating work items to resources such that the chosen resource should be able to undertake the work item as soon as possible.

Overview

Shortest Queue distribution provides a means of allocating work items to resources with the intention of expediting the throughput of a process instance by ensuring that work items are allocated to the resource that is able to undertake them in the shortest possible timeframe. Typically the shortest timeframe means the resource with the shortest work queue although other interpretations are possible.

Context

There are no specific context conditions associated with this pattern.

Implementation

In order to implement this distribution method, offerings need to maintain information on the work items currently allocated to resources and make this information available to the work item distribution algorithm. Of the offerings examined, COSA provides the fewwork() function which allows this pattern to be directly realised. iPlanet and Oracle BPEL provide facilities for programmatically extending the work item distribution algorithm and enabling this to be achieved indirectly.

Issues

None identified.

Solutions

N/A.

Evaluation Criteria

An offering achieves full support if it satisfies the description for the pattern. It achieves a partial support rating if the same effect can be achieved through programmatic extensions.

Product Evaluation

To achieve a + rating (direct support) or a +/- rating (partial support) the product should satisfy the corresponding evaluation criterion of the pattern. Otherwise a - rating (no support) is assigned.

Summary of Evaluation