1 / 28

Lectures 5,6 – Workflows and Internet Process Coordination

Lectures 5,6 – Workflows and Internet Process Coordination. Middleware: the glue for network computing Workflows and Internet Workflows Enabling Technologies Static/Dynamic workflows Tasks and Events Transition Systems Workflow Patterns Liveness Deadlocks. Workflows.

oona
Télécharger la présentation

Lectures 5,6 – Workflows and Internet Process Coordination

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Lectures 5,6 – Workflows and Internet Process Coordination • Middleware: the glue for network computing • Workflows and Internet Workflows • Enabling Technologies • Static/Dynamic workflows • Tasks and Events • Transition Systems • Workflow Patterns • Liveness • Deadlocks

  2. Workflows • Informal definition. • Traditional applications: • Office automation and document processing • Factory automation • Business • Internet workflows, iWM. • Examples • Service grids • Computational grids

  3. Enabling technologies

  4. Areas involved in iWM

  5. Lifecycle of a workflow • Creation – process definition • Process verification • Cases • Workflow enactment • The Workflow Management Coalition • Multibillion $ industry • Workflow Reference Model

  6. Static/dynamic workflows • Static workflows • Dynamic workflows • Exception handling • Reversibility.

  7. Workflow enactment • Case: a particular instance of a workflow • Workflow enactment engine performs a coordination function • Tasks/Activities and Events.

  8. Transition systems • A directed graph: • Nodes the states of the system • Edges events • Two distinguished states: • Initial state – no incoming edge • Goal/termination state – no outgoing edge • Example: laptop assembly. States labeled by the events causing the transition.

  9. Algorithm to construct the transition system from the event-task graph • 1. Construct the set of E of individual events: E={1,2,3,4,5,6,7,8,9} • 2. Split it into equivalence classes based upon the causality relationship: E1 = {1,2,3,4,9} E2 = {1,5,6,7,8,9} The two sets are not disjoint!!

  10. Algorithm to construct the transition system from the event-task graph • 3. Add to E all feasible combinations of events. Each feasible combinations contains one event from each class. Example: [2,5], [3,5] are feasible combinations [2,3] is not a feasible combination

  11. Algorithm to construct the transition system from the event-task graph • 4. Construct the set of states S. • Initially S contains only the initial state. • Construct the set of all events feasible in that state. • For each event in that state label the state reachable when the event occurs. • Add the new state to S • Repeat the process for every state in S.

  12. Choices

  13. Liveness

  14. Basic workflow patterns • Sequence • AND-split • Synchronization • XOR – spli • XOR – merge • OR – split • Multiple merge • Discriminator • N out of M join • Deferred choice

  15. Resources and deadlocks

  16. Agents and workflow enactment • Hybrid systems: some tasks carried out by computers, others by humans. • Why use agents for workflow enactment?

More Related