COSA Evaluation Results

Evaluation results for COSA version 5.1 against the workflow control-flow patterns

Pattern

Rating

Motivation
Sequence + Directly supported by arcs connecting activities.
Parallel Split + Supported by multiple outgoing arcs from an activity. None of the arcs have transition conditions specified.
Synchronization + Supported by multiple incoming arcs to an activity. None of the arcs have transition conditions specified.
Exclusive Choice + Supported by multiple outgoing arcs from an activity. All of the arcs have disjoint transition conditions specified.

Simple Merge

+ Supported by multiple incoming arcs to a place.
Multi-Choice + Supported by multiple outgoing arcs from an activity. The arcs may have (possibly overlapping) transition conditions specified.
Structured Synchronizing Merge - Processes are not inherently structured.
Multi-Merge +/- Only safe Petri net diagrams can be used.
Structured Discriminator - The discriminator can be modelled by using true conditions in input arcs and extending the network. Unfortunately, the resulting diagram is too complex.
Arbitrary Cycles + Supported. Any graph structure is allowed.
Implicit Termination - Not supported, explicit termination is needed.
Multiple Instances without Synchronization + COSA has a three level workflow model, i.e., workflow, flow, and activity. Flows (i.e., workflow instances) can be grouped in one workflow and share information. This combined with a trigger mechanism to create new flows is a possible solution where folders are used to facilitate shared access to common data.
Multiple Instances with a Priori Design-Time Knowledge - There is no means of denoting that an activity should be executed multiple times.
Multiple Instances with a Priori Run-Time Knowledge - There is no means of denoting that an activity should be executed multiple times.
Multiple Instances without a Priori Run-Time Knowledge - There is no means of denoting that an activity should be executed multiple times.
Deferred Choice + Supported by multiple outgoing arcs from a place.
Interleaved Parallel Routing + Directly supported through places and also an optional setting of the workflow engine.
Milestone + Directly supported through places.
Cancel Activity + Supported by removing tokens from input places.
Cancel Case - Only supported through an API call.
Structured Loop - There is no means of specifying repeated execution of an activity or set of activities.
Recursion + Recursive definition of process models can be achieved using triggers or the activ_run tool agent.
Transient Trigger + Supported through trigger construct in synchronous mode.

Persistent Trigger

 + Supported through trigger construct in asynchronous mode.
Cancel Region +/- Achievable by specifying a shadow cancellation activity for each activity in the cancellation region although the overall diagram is likely to be intractable for anything other than simple process models.
Cancel Multiple Instance Activity - Multiple instance activities are not supported.
Complete Multiple Instance Activity - Multiple instance activities are not supported.
Blocking Discriminator - There is no modelling construct that directly corresponds to this pattern and although the behaviour can be indirectly achieved, the process model required to do is too complex.
Cancelling Discriminator - Similar to WCP28, no direct support.
Structured N-out-of-M Join - There is no modelling construct that directly corresponds to this pattern and although the behaviour can be indirectly achieved, the process model required to do is too complex.
Blocking N-out-of-M Join - Similar to WCP30, no direct support.
Cancelling N-out-of-M Join - Similar to WCP30, no direct support.
Generalised AND-Join - Only safe Petri net diagrams can be used.
Static Partial Join for Multiple Instances - Multiple instance activities are not supported.
Cancelling Partial Join for Multiple Instances - Multiple instance activities are not supported.
Dynamic Partial Join for Multiple Instances - Multiple instance activities are not supported.
Acyclic Synchronizing Merge + The condition on an input arc to an activity can specified such that it will not be considered when the join condition for the activity is evaluated if the branch to which it belongs is not live.
General Synchronizing Merge - No ability to determine when an OR-join should fire based on a complete evaluation of the overall state of the process instance.
Critical Section + Supported through the use of a mutex place to prevent concurrent access to the critical section.
Interleaved Routing + Supported through the use of a mutex place to prevent nominated activities from executing concurrently.
Thread Merge - No ability to merge threads as the process in inherently safe.
Thread Split - No ability to merge threads as the process in inherently safe.
Explicit Termination + Directly supported, a process instance completes when an end activity is reached.

Evaluation results for COSA version 4.2 against the workflow data patterns

Pattern

Rating

Motivation
Task Data + Directly supported by (non-persistent) STD attributes at the activity level
Block Data + Workflows can be nested and attributes of the form INSTANCE.name provide a means of supporting block data
Scope Data - Not supported
Multiple Instance Data + Support for distinct data elements in multiply triggered tasks and tasks with shared sub-workflow decompositions
Case Data + Supported via tool agent INSTANCE (INSTANCE.name).
Folder Data + Fully supported via folders accessible to nominated activities across multiple cases
Workflow Data +/- COSA allows for attributes of the form DEFINITION.name however these are fixed at design time
Environment Data + External data elements can be accessed via DDE, ODBC, XML, OS tool agents
Task to Task + Supported by data sharing (implicit data passing)
Block Task to SubWorkflow Decomposition +/- Supported by data sharing (implicit data passing) but no ability to limit the range of items passed
SubWorkflow Decomposition to Block Task +/- As for Pattern 10
To Multiple Instance Task - Not supported
From Multiple Instance Task - Not supported
Case to Case + Supported via folder data
Task to Environment - Push-Oriented + Supported through tool agents e.g. ODBC
Environment to Task - Pull-Oriented + Supported through tool agents e.g. ODBC
Environment to Task - Push-Oriented + Supported via command line and C/COM/Java APIs
Task to Environment - Pull-Oriented + Supported via command line and C/COM/Java APIs
Case to Environment - Push-Oriented - Not supported
Environment to Case - Pull-Oriented - Not supported
Environment to Case - Push-Oriented + Trigger functions allow process instance and folder data to be set
Case to Environment - Pull-Oriented + Trigger functions allow process instance and folder data to be read

Workflow to Environment - Push-Oriented

 - Not supported
Environment to Workflow - Pull-Oriented - Not supported
Environment to Workflow - Push-Oriented - Not supported
Workflow to Environment - Pull-Oriented + Supported via command line and C/COM/Java APIs
Data Transfer by Value - Incoming +/- Achievable via triggers although limitation on range and typing of parameters passed
Data Transfer by Value - Outgoing +/- As for Pattern 27
Data Transfer - Copy In/Copy Out - Not supported
Data Transfer by Reference - Unlocked + Standard means of data passing
Data Transfer by Reference - With Lock - Not supported
Data Transformation - Input - Not supported
Data Transformation - Output - Not supported
Task Precondition - Data Existence + By specifying transition conditions for tasks based on the CONDITION.TOKEN and STD.exists tool agents, subsequent task invocation can be delayed until required data element is available
Task Precondition - Data Value + By specifying transition conditions for tasks based on the required data values and CONDITION.TOKEN tool agent, subsequent task invocation can be delayed until required data values are met
Task Postcondition - Data Existence - Not supported
Task Postconditon - Data Value - Not supported
Event-Based Task Trigger + Triggers provide direct support for all three Pattern variants
Data-Based Task Trigger + Directly supported by including a transition condition (which may include CONDITION.TOKEN) corresponding to the required data condition on the incoming arc to the task to be triggered
Data-Based Routing + Supported by conditions on input and output arcs. Both exclusive choice and multi-choice supported

Evaluation results for COSA version 4 against the workflow resource patterns

Pattern

Rating

Motivation
Direct Allocation + Directly supported
Role-Based Allocation + Directly supported
Deferred Allocation - Not supported
Authorisation + Distinct authorisation and distribution mechanisms are supported

Seperation of Duties

 +/- Indirectly achievable through user access rights
Case Handling - Not supported
Retain Familiar + Supported via a customised distribution algorithm
Capability Based Allocation + Supported via competency definitions for users, groups and activity definitions.
History Based Allocation +/- Indirectly achievable via a custom (external) distribution algorithm
Organisational Allocation + Directly supported through user/group and user/group script languages.
Automatic Execution + Achievable by assigning work items to internal system users.
Distribution by Offer - Single Resource +/- Non-binding offers not supported but allocated work items can by rejected for reallocation
Distribution by Offer - Multiple Resources + Directly supported for multiple resources via group queues.
Distribution by Allocation - Single Resource + Directly supported
Random Allocation + Directly supported via random function in user/group language
Round Robin Allocation +/- Indirectly achievable via a custom (external) distribution algorithm
Shortest Queue + Supported via a customised distribution algorithm based on the fewwork function
Early Distribution - Not supported
Distribution on Enablement + Standard means of work distribution
Late Distribution - Not supported
Resource-Initiated Allocation +/- The act of a resource reserving a work item on a shared work list has the effect of locking the process instance
Resource-Initated Execution - Allocated Work Item + Resources can initiate allocated work items from their work queues.
Resource-Initiated Execution - Offered Work Item + Supported for work items on shared work queues

System Determined Work Queue Content

 - Not supported
Resource-Determined Work Queue Content + A series of options are provided for configuring views in the worklist handler.
Selection Autonomy + Resources can select any of the work items on their queue to initiate next
Delegation + Resources can manually reroute work items from their work queues
Escalation + Supported via the Target Dates option for processes together with a trigger to reroute the work item
Deallocation + Directly supported through redistribution
Stateful Reallocation + Supported through the reroute function
Stateless Reallocation - Not supported
Suspension/Resumption + Resources can suspend work items currently being executed
Skip + Directly supported via skip option in worklist handler
Redo - Not supported
Pre-Do - Not supported
Commencement on Creation + Supported for tasks initiated via a trigger
Commencement on Allocation - Not supported
Piled Execution - Not supported
Chained Execution - Not supported
Configurable Unallocated Work Item Visibility - Not supported
Configurable Allocated Work Item Visibility - Not supported
Simultaneous Execution + Resources can execute multiple work items simultaneously
Additional Resources +/- Simulation environment provides multiple resource modelling capabilities for a single work item.

Evaluation results for COSA version 5.1 against the workflow exception handling patterns

Pattern

Explanation

Work Item Failure

SRS-CWC-RBK An activity can deal with a detected failure by rolling back work in progress and restarting the activity via the COSA_activity_cancel function.

Work Item Deadline

OCO-CWC-COM A compensating activity can be triggered for an activity that has no reached a specified state by a nominated time.
ACA-CWC-COM A compensating activity can be triggered for an activity that has no reached a specified state by a nominated time.
SCE-CWC-COM A compensating activity can be triggered for an activity that has no reached a specified state by a nominated time.

External Trigger
OCO-CWC-COM A compensating activity can be initiated for an activity via an external trigger.
ACA-CWC-COM A compensating activity can be initiated for an activity via an external trigger.
SCE-CWC-COM A compensating activity can be initiated for an activity via an external trigger.