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

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)