Grid Workflow A __Grid Workflow__ is a workflow within a [Grid Computing] environment. 1.1 Distinction to "normal" Workflows Grid Workflows differ from "normal" workflows, such as business workflows or IT workflows, mainly in the following sense: - __Stateful/stateless__: Activities of Grid workflows are often related to ~~stateful services~~ (workflow of [Grid Service]s), whereas other workflows are mostly related to the invocation of ~~stateless services~~ (workflow of [Web Service]s) - __Reliability__: In a computing Grid resources may fail during the runtime of the workflow. This must taken into account by advanced workflow fault management techniques (e.g. workflow checkpointing and recovery, monitoring) - __Performance__: One objective of Grid computing is to provide high performance computing power. Therefore Grid Workflows have to deal with resource brokerage, scheduling (load balancing), and distributed applications (parallel computing) 1.1 Definition by the Workflow Managment Coalition The Workflow Management Coalition [WfMC] defines ~~workflow~~ as "The automation of a business process, in whole or part, during which documents, information or tasks are passed from one participant to another for action, according to a set of procedural rules". In the context of Grid computing the term workflow usually concerns the automation of distributed IT processes. 1.1 Definition by the [OGSA]-WG glossary __Workflow__ is a pattern of business process interaction, not necessarily corresponding to a fixed set of business processes. All such interactions may be between services residing within a single data center or across a range of different platforms and implementations anywhere. __Choreography__ describes required patterns of interaction among services and templates for sequences (or more structures) of interactions. __Orchestration__ describes the ways in which business processes are constructed from Web services and other business processes, and how these processes interact. 1.1 Related Within a Web service operation, external applications may be invoked. An execution of an activity is called an activity instance. The Web service operations invoked in activity instances are called invoked applications of activities. An invoked application can be considered as a set of code regions. A code region is a sequence of program statements. Code regions can be entire program units (functions or subroutines), loops (do while, for), function calls. __Workflow constructs__ are certain sub-regions of the workflow that can be used as common control structures, such as sequence, choice, split/join, and iteration. Not every sub-region of a workflow may constitute a reasonable workflow construct. 1.1 References and Links - {link:TWiki MyGrid|http://twiki.mygrid.org.uk/twiki/bin/view/Mygrid/WorkflowDefinitions} - http://en.wikipedia.org/wiki/Workflow 2005-09-08 07:32:12.412 2005-03-17 12:11:27.44