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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