see also Workflow Description Languages
Our definition
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.
In
K-Wf Grid the workflow model is based on
Petri nets. A Petri net consists of two basic elements:
transitions (rectangle) and
places (circle). Transitions and places are connected with each other by directed
edges (arcs). Transitions are related to activities, whereas places store the state of the workflow by means of
tokens.
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.
In K-Wf Grid every
activity (synonyms:
task, job) has a specific level of abstraction ranging from abstract to concrete. An abstract activity contains a very brief description of the task and cannot be executed automatically in the real world without further refinement, whereas a concrete activity is mapped to a specific instance of a Web Service operation. Only concrete activities can be directly executed automatically in the real world.
Within a Web service operation, external applications (e.g. flood forecasting simulation) written in C/C++/Fortran 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.
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.
TWiki MyGrid
BPMN
b_bprimal