Pattern 31 (Stateless Reallocation)

FLASH animation of Stateless Reallocation pattern

Description

The ability for a resource to reallocate a work item that it is currently executing to another resource without retention of state.

Example

As progress on the Recondition Engine work item is not sufficient, it has been reallocated to another Mechanic who will restart it.

Motivation

Stateless Reallocation provides a lightweight means of reallocating a work item to another resource without needing to consider the complexities of state preservation. In effect, when this type of reallocation occurs all state information associated with the work item (and hence any record of effective progress) is lost and the work item is basically restarted by the resource to which it is reassigned.

Overview

This pattern is illustrated by the R:reallocation_no_state arc in Figure 6. It has similarities in terms of outcome with Delegation and Escalation patterns in that the work item is restarted except that in this scenario, the work item has already been partially executed prior to the restart. This pattern can only be implemented for work items that are capable of being redone without any consequences relating to the previous execution instance(s).

Context

There are no specific context conditions associated with this pattern.

Implementation

None of the offering examined directly implement this approach to reallocation. It is included in this taxonomy as it constitutes a useful simplication of the Stateful Reallocation pattern.

Issues

None identified.

Solutions

N/A.

Evaluation Criteria

An offering achieves full support if it satisfies the description for the pattern.

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