Grid, Web services and Taverna

Machiel Jansen

Richard Holland

The Problem

Requirement:

• Build a WebService which submits job on the Grid pretty easily• It must be user and programmer friendly.

• Do it for a java programmer

• Adapt Taverna in such a way that it can use a Web Service which uses the Grid.• It must be user friendly

Problem: Grid authentication

• On the Life Science Grid every user needs a grid certificate (X509).

• The certificate functions

as a passport.

• In order to use resources (possibly) all around the world your delegate your credentials for a limited amount of time to the Grid middleware. During that time the Grid middleware can work on your behalf.

This is called a proxy certificate.

Problem with webservices and Grid

• Your Grid certificate consists of two files: A public and private part. If a web service wants to submit jobs to the Grid it needs a user certificate.

• You cannot send the Web Service your credentials. Instead you have to delegate them. This is done by public and private key cryptography. This is needed to make things safe.

• Then how you do delegate your credentials to the Web Service?

Solution: MyProxy

• MyProxy is an applications which stores credentials and deals out short lived proxy certificates.

• You delegate your certificate to the store and lock it with username and password. You can send around this username/password combination to the WebService

• The WebService then contacts the MyProxy server and gets a proxy server with your username and password. The WebService will now submit jobs on your behalf to the Grid.

The scenario

Client

Web Service

MyProxy

WMS

Usernamepassword

Proxycertificate