Attribute-based%20Programming%20for%20Grid%20Services

1
Attribute-based Programming for Grid Services

• Glenn Wasson and Marty Humphrey
• Grid Computing Group
• University of Virginia

2
Programming Grid Services

• How do I write a grid service?
• Do I need to understand the specifications (e.g.
  OGSI, WSDL, XSD)?
• What about the grid plumbing?
• What support does the container provide?
• Goal Make it as easy as writing a
• Web Service

3
Observation

• Difference between a Grid Service and service
  logic is meta-data
• Defines how methods and data are exposed
• Conditions of exposure (policy)
• Annotate service logic with meta-data
• C attributes (can get at runtime)
• Other languages (need pre-processing)

4
Programming Model

• Write Code
• Create service logic
• Annotate Code
• Provide meta-data the container needs to get this
  code running as a Grid Service
• Run Tooling
• e.g. Generate WSDL
• Deploy Service

5
Example Exposing Methods

• OGSIPortType
• OGSIPortType(typeof(FactoryPortType))
• OGSIPortType(typeof(NotificationSourcePortType)
  )
• OGSIPortType(typeof(GridServicePortType))
• public class MyService GridServiceSkeleton
• SoapDocumentMethod
• WebMethod
• SoapDocumentMethod("http//gcg.cs.virginia.edu/
  samples/
• countersubtract",
  Binding"CounterSOAPBinding")
• return XmlElement("returnValue")
• public int subtract(int value)

6
Design and Use of Attributes

• How many attributes are there?
• Tradeoff of attrs vs. of attr parameters
• Try to keep of mandatory attributes low
• Attribute scope
• Class level, method level, member level
• Auto-generation
• E.g. SoapAction names from WebMethod

7
Exposing Data

• SDE
• SDE ("interface",
• typeof(XmlQualifiedName), false,
• MutabilityType.constant, false,
• "1", "unbounded")
• public class GridServicePortType
  GridServiceSkeleton

8
Other Ways to Expose Data

• Get and Set handlers for SDEs
• SDEGet(currentTime)
• public ArrayList getTime(OGSIServiceData sde,
• GridServiceWrapper gsw)
• Member variables as SDEs
• public class SomeServicePortType
  GridServiceSkeleton
• SomeServicePortType()
• SDE
• public int foo

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Service Policy

• Initially security policy
• Integrity(require, body, token1,
  token2)
• Confidentiality(reject, header1,
  token3)
• Message(require, agelt30)
• Token(token1, x509v3, subjectBob Smith,
  CAUVA)
• Token(token2, Kerberosv5ST)
• Token(token3, SecurityContextToken,
• issuerhttp//token.virginia.edu/ mytoken)
• public class Service1 GridServiceSkeleton
• Port type or method policy? SDE policy?
• Deployers policy vs. Programmers policy

10
Future

• Extend programming model
• What functionality lends itself to
  attribute-based programming?
• Refine attribute set
• More intelligent defaults
• More non-class level attributes?
• OGSI.NET website
• http//www.cs.virginia.edu/gsw2c/OGSIdotNet.htm
  l