Knowledge Technologies March 2001 DataChannel, Inc Preserving Process Hyperlink-Based Workflow Representation W. Eliot Kimber, DataChannel, Inc

Knowledge Technologies March 2001 DataChannel, Inc Agenda The Problem Workflow Analysis Model Workflow Document DTDs Workflow Processing Model Conclusions

Knowledge Technologies March 2001 DataChannel, Inc The Problem Dissatisfaction with existing workflow solutions WfMC abstract model just not right Feels like people are just not thinking about the problem in the right way: –Too simple –Too complicated –Too implementation specific

Knowledge Technologies March 2001 DataChannel, Inc “Workflow Is An Application of Hyperlinks” I Have been saying for years that workflow is just behavior applied to hyperlinks Never put this to the test Could be totally of full of it Finally have the motivation and tools to put it to the test

Knowledge Technologies March 2001 DataChannel, Inc The Question Does using hyperlinks to model and implement workflow actually add value? If so, what are the implementation implications?

Knowledge Technologies March 2001 DataChannel, Inc The Approach Define abstract data model for workflows Map abstract model to hyperdocument- based implementation model Implement behaviors for links to make workflows active

Knowledge Technologies March 2001 DataChannel, Inc Workflow Analysis Model Workflow can be modeled as transition graph between states Two forms of workflow: –Workflow templates: define abstract process –Concrete workflows: bind process to objects and users Concrete workflows generated from workflow templates

Knowledge Technologies March 2001 DataChannel, Inc Abstract Workflow

Knowledge Technologies March 2001 DataChannel, Inc Key Concepts Workflow aggregates states States related to possible next states States have precondidtions and postconditions Conditions relate to properties of information objects, workflows, and information management systems

Knowledge Technologies March 2001 DataChannel, Inc States and Conditions Preconditions define rules for entry into a state Postconditions must hold when in state

Knowledge Technologies March 2001 DataChannel, Inc Concrete Workflows Extends abstract workflows by: –Binding states to information objects –Adding concept of “agent” –State transitions become first-class objects –Adding promotion action InformationObjects are the things managed through the workflow Agents set property values and promote objects from state to state.

Knowledge Technologies March 2001 DataChannel, Inc Concrete Workflow Class

Knowledge Technologies March 2001 DataChannel, Inc State Transition Class

Knowledge Technologies March 2001 DataChannel, Inc Promotion Action

Knowledge Technologies March 2001 DataChannel, Inc Summary of Abstract Models Model feels pretty good Could be implemented fairly directly as normal engineering exercise Would still need way to persist and interchange workflow templates Would not leverage existing information management functionality

Knowledge Technologies March 2001 DataChannel, Inc Link-Based Implementation Have standards for writing down hyperlinks in XML: –HyTime –Xlink Have existing link management systems Should be able to use generic link management functions to make “workflow documents” active Should be easier than one-off implementation of abstract model (maybe)

Knowledge Technologies March 2001 DataChannel, Inc Basic Approach Use XML documents to define workflows: –States are normal elements –State transitions are hyperlinks For workflow templates must: –Declare information object classes –Declare relevant properties of information objects, workflow instances, and information management systems.

Knowledge Technologies March 2001 DataChannel, Inc Approach (Cont.) Concrete workflows are separate documents Objects are progressed through workflow by traversing state transition links Change in workflow state results in new version of workflow document Documents could be literal or “virtual” (DOM or grove only)

Knowledge Technologies March 2001 DataChannel, Inc Workflow Template DTD

Knowledge Technologies March 2001 DataChannel, Inc Property Declarations

Knowledge Technologies March 2001 DataChannel, Inc State Template

Knowledge Technologies March 2001 DataChannel, Inc State Transition

Knowledge Technologies March 2001 DataChannel, Inc Workflow Template Refinements

Knowledge Technologies March 2001 DataChannel, Inc Workflow Template DTD Summary Workflow template documents define abstract processes Not bound to any implementation Can be interchanged Can include arbitrary information Can serve as primary process documentation (e.g., ISO 9000 documentation) Relatively simple to create Purely declarative

Knowledge Technologies March 2001 DataChannel, Inc Review: Abstract Hyperlink Model

Knowledge Technologies March 2001 DataChannel, Inc Concrete Workflow DTD

Knowledge Technologies March 2001 DataChannel, Inc Transition Links

Knowledge Technologies March 2001 DataChannel, Inc State Element Type

Knowledge Technologies March 2001 DataChannel, Inc Concrete Workflow DTD Refinements

Knowledge Technologies March 2001 DataChannel, Inc Concrete Workflow DTD Summary Here, links are from objects to potential states All preconditions and post conditions provided by workflow template ManagedObject elements serve as proxies for real managed objects A concrete workflow document reflects the state of the workflow at a given point in time Still completely declarative May be underspecified wrt agents and tasks

Knowledge Technologies March 2001 DataChannel, Inc Concrete Workflow Document Processing Model Traversal from managed object to potential state causes promotion of object to new state If traversal succeeds, a new version of the workflow document is created reflecting the movement Preconditions checked on traversal start Postconditions checked on traversal completion

Knowledge Technologies March 2001 DataChannel, Inc Example: Part 1 Time T [0] MyCWF.xml, v0: entity1 ent1 state1 state2

Knowledge Technologies March 2001 DataChannel, Inc Example: Part 2 Time T [1] MyCWF.xml, v1: entity1 state1 state2

Knowledge Technologies March 2001 DataChannel, Inc Making It Active: Activity Policies If traversal is promotion, have to hook the traversal action HyTime concept of “activity policies” provide standardized way to model these hooks Activity policies bind actions to nodes and agents The “policy” can be any script or program component Provides a single point of integration Requires appropriate link management infrastructure

Knowledge Technologies March 2001 DataChannel, Inc Traversal Actions Two relevant traversal actions: –Traverse from node –Traverse to node Traverse-from policies check preconditions for target anchor Traverse-to policies check post conditions for target anchor Traverse-to policies can also perform actions that cause post conditions to be true

Knowledge Technologies March 2001 DataChannel, Inc Traversal With Policies Managed Object State Transition Link ManagedObjects PotentialState ?? Traverse-From PolicyTraverse-To Policy

Knowledge Technologies March 2001 DataChannel, Inc Agents Set Properties Agents set the properties checked by preconditions and post conditions Agents may be humans or software components Tasks are represented by actions agents must perform to set states to satisfy preconditions or post conditions

Knowledge Technologies March 2001 DataChannel, Inc Tasks are Implementation Details Tasks and their supporting software are always system specific Will change as information management system changes and as technology evolves Processes may not change over long periods of time (decades) Activity policy approach clearly separates the abstract workflow from implementation details User interfaces may present a task-primary view of workflow

Knowledge Technologies March 2001 DataChannel, Inc Some Interesting Characteristics of Workflow Documents If documents are versioned, maintains complete historical record of the process activity Workflow documents are system independent Reduces implementation task to a scripting exercise (given appropriate infrastructure)

Knowledge Technologies March 2001 DataChannel, Inc Conclusions Overall model is sound Seems to be pretty easy to implement Use of documents to model workflows feels appropriate Need more implementation experience to really prove value Need to think more about modeling relationships to users, groups, and tasks Good potential synergy with versioned document management systems It helps to have a sophisticated link management system handy.