Pattern 31 (Stateless Reallocation)
The ability for a resource to reallocate a work item that it is currently executing to another resource without retention of state.
As progress on the Recondition Engine work item is not sufficient, it has been reallocated to another Mechanic who will restart it.
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.
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).
There are no specific context conditions associated with this pattern.
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.
An offering achieves full support if it satisfies the description for the pattern.
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.
|Websphere MQ Workflow||3.4||-||Not supported|
|Oracle BPEL||10.1.2||-||Oracle BPEL PM does not allow task rollback, thus offering no support for this pattern|
|jBPM||3.1.4||-||jBPM does not support this pattern.|
|OpenWFE||1.7.3||-||OpenWFE does not support this pattern. Selecting the "delegate" menu during the execution of a work item results in a stateful reallocation.|
|Enhydra Shark||2||-||Enhydra Shark does not support this pattern. The Reassign button in the Work list Console is currently not enabled.|
Summary of Evaluation