
SDF4WS |
org.kepler.domains.SDF4WS |
The SDF4WS is an SDFDirector for the domain of WebServices. SDF4WS
provides the abilty to monitor WebService actors in a workflow, catching
their exceptions and error messages.
Additional domain-specific operations can be "three re-trials" of failing web
services before finally switching to another server providing
the same service (if available) OR determining if the web service operation
failure was caused due to invalid user input or internal web service errors.
Based on the Director for the synchronous dataflow (SDF) model of computation.
SDF4WS overview
The Synchronous Dataflow(SDF) for Web Services director, like its parent SDF Director
supports the efficient execution of Dataflow graphs that
lack control structures.
SDF4WS is a director made specifically for web services with added functionality.
This director catches possible exception from Web Service incase of a scenario
and hence failures in web service access.
More SDF Director Information
Dataflow graphs that contain control structures
should be executed using the Process Networks(PN) domain instead.
SDF allows efficient execution, with very little overhead at runtime. It
requires that the rates on the ports of all actors be known before hand.
SDF also requires that the rates on the ports not change during
execution. In addition, in some cases (namely systems with feedback) delays,
which are represented by initial tokens on relations must be explicitly
noted. SDF uses this rate and delay information to determine
the execution sequence of the actors before execution begins.
Schedule Properties
- The number of tokens accumulated on every relation is bounded, given
an infinite number of executions of the schedule.
- Deadlock will never occur, given an infinite number of executions of
the schedule.
Class comments
An SDFDirector is the class that controls execution of actors under the
SDF domain. By default, actor scheduling is handled by the SDFScheduler
class. Furthermore, the newReceiver method creates Receivers of type
SDFReceiver, which extends QueueReceiver to support optimized gets
and puts of arrays of tokens.
Actors are assumed to consume and produce exactly one token per channel on
each firing. Actors that do not follow this convention should set
the appropriate parameters on input and output ports to declare the number
of tokens they produce or consume. See the
Author(s): Nandita Mangal
Version:$Id: SDF4WS.java,v 1.3 2006/03/30 18:06:17 mangal Exp $
Pt.Proposed Rating:Green (neuendor)
Pt.Accepted Rating:Green (neuendor)