Common Execution Architecture

1
Common Execution Architecture

• Paul Harrison
• IVOA Interoperability MeetingCambridge MA23-28
  May 2004

2
Introduction

• Common Execution Architecture (CEA)
• An attempt to model how an application is run in
  the Virtual Observatory
• An application is any process that consumes or
  produces data
• Designed primarily to work in web services
  environment
• A set of schema and WSDL definitions

3
Motivation

• To create a model of an application
• VO infrastructure only has to deal with a single
  application model
• Application writers know how to interface VO
• Provide higher level description than WSDL
• Restrict to manageable subset
• Provide specific semantics for astronomical
  Quantities
• Provide extra information - e.g. Defaults
• Data flow does not necessarily follow call tree
• Asynchronous Operation

4
History

• The desire to be able to create a workflow Engine
  in AstroGrid
• Derived from the Iteration 4 Command Line
  Application Controller experiences.
• It is a work-in-progress
• Will definitely evolve in next few months

5
Application Model
6
Components

• Application
• Command line, web service
• Common Execution Controller
• Controls the application, interacts with the
  other components
• Invoking process
• Workflow, web service, script
• Monitoring Service
• Receives the status messages
• Storage Service

7
Component Interactions

• UML Sequence Diagram
• The monitoring service could be same as invoking
  service
• The only guaranteed status message is the final
  one
• The results of running the application are not
  returned directly to the invoking process. The
  destination is implicit in the specification of
  the output parameters

8
How to use it

• AstroGrid Iteration 5 released at end of month
• Look at test environment!!
• AstroGrid exposes all these components as web
  services
• Workflow is an xml document
• Not limited to using AstroGrid portal
• Script
• Extend existing VO Tools (e.g. Aladin)

9
Deployment Scenario

• UML Diagram
• Command line applications that are wrapped by
  specialized CommonExecutionControllers that make
  a compute farm
• Web services proxy component that can act as an
  adapter between a generic web service and the
  CommonExecutionConnector interface
• Web services proxy can be localised with a web
  service so that the results returned can be
  stored locally thus minimising network traffic

10
How to integrate your Applications

• Command Line Execution Controller already exists
• CEA web service wrapper for UNIX command lines
• Interacts with workflow, MySpace
• Simply a case of configuring the application in
  the registry
• If you want to wrap functionality easy to do by
  extending the CommandLineApplication class.
• Implement the CommonExecutionConnector Interface
  directly.

11
Summary

• CEA creates an environment to send messages to
  and from applications.
• Implemented in AstroGrid Workflow with a CEC for
  Command Line applications
• Configuration only web service.
• Iteration 6 will produce general CEC proxy for
  any web service.
• See maven page
• http//www.astrogrid.org/maven/docs/snapshot/appli
  cations/