OGSI on Microsoft .NET
Daragh Byrne, Ally Hume, Mike Jackson
EPCC
http://www.epcc.ed.ac.uk/~ogsanet
ogsanet-queries@epcc.ed.ac.uk
Budapest, Hungary – November 10th-11th 2003
Some slides within this presentation have been graciously contributed by the OGSA-DAI project.
Microsoft is a trademark of Microsoft Corporation.
Overview
MS.NETGrid Project
Web Services, OGSA and OGSI
OGSI on Microsoft .NET – MS.NETGrid-OGSI
Grid Service Demonstrators
Training Courses
Project Goals
Goals:
Engaging and training the UK e-Science community in
OGSI and .NET
Facilitate uptake of .NET for developing Grid services
Achieve via delivery of:
Free-source OGSI implementation on .NET
Free-source Grid service demonstrators
Training materials
Training courses
Project Partners
EPCC:
Project management
Design, development and implementation
Authoring training materials
Delivering training courses
Microsoft Research Limited (Cambridge):
Technical consultancy and expertise
Provision of training materials
NeSC – UK National e-Science Centre:
Production and negotiation of collaboration agreement
Hosting training courses
Project Activities
OGSADAI
e-Science
Application
e-Science
Application
OGSI
Microsoft .NET
OGSI and
Microsoft .NET
OGSI and
Course
Microsoft
.NET
…
OGSI
… …Course
… … and
Microsoft
.NET
…
OGSI
… …Course
… … and
Microsoft
.NET
…
Course
…………
…
…………
Web Services, OGSA and
OGSI
Web Services
Network-enabled application
Exposes a well-defined interface
Stateless:
Born
Services Request
Dies
Accessible using common Internet protocols
HTTP
XML-oriented technology:
Describe services and their interfaces

WSDL – Web Services Description Language
Support messaging

SOAP – Simple Object Access Protocol
WSDL
Web Services Description Language
XML description of Web Services:
Define input and output messages
Define operations in terms of input and output messages
Aggregate operations into portTypes

Application-specific collections of related operations
Combine portTypes with a concrete network protocol and message
format to form a binding
Combine a binding and a network address to define a concrete network
endpoint or port
Aggregate ports into an abstract network endpoint or service
Current W3C version is 1.1
What is OGSA?
Open Grid Services Architecture
Open Grid Architecture + Web Services = Grid Services
Grid Services:
Dynamic
Transient
Stateful – have a finite lifetime
Defined by a well-defined set of interfaces and behaviours
More information from
http://forge.gridforge.org
OGSA Characteristics
Supports:
Resource access
Resources sharing
Service integration
Uniform access to services
Specifies protocols and standards that:
Are:


Implementation-independent
Platform-independent
Support:




Communication
Data access, transfer, translation and transformation
Access and security
Auditing and logging
What is OGSI?
Open Grid Services Infrastructure
Minimum set of standards and behaviours with which Grid Services must
comply
Exploits existing Web Services properties:
Interface abstraction via WSDL portTypes
Web Service protocols
Hosting platform-independent
Extends these to provide for:
State management
Event notification
Service location and access
Lifecycle management
Service data
More information from:
http://forge.gridforge.org
Anatomy of a Grid Service
• Service Data Access
• Lifetime Management
GridService
portType
(required)
Other PortTypes
(Optional)
•Service Creation
•Service Grouping
•Notification
•Handle Resolution
•Other functions e.g:
Handle
Element
Element
Service
Data
Element
Grid Service
Hosting Environment
•Workflow
•Auditing
•Resource Management
Anatomy of a Grid Service
• Service Data Access
• Lifetime Management
GridService
portType
(required)
Other PortTypes
(Optional)
•Service Creation
•Service Grouping
•Notification
•Handle Resolution
•Other functions e.g:
Handle
Service
Element
Element
ElementSet
Data
Implementation
Hosting Environment
•Workflow
•Auditing
•Resource Management
Anatomy of a Grid Service
• Service Data Access
• Lifetime Management
GridService
portType
(required)
Other PortTypes
(Optional)
•Service Creation
•Service Grouping
•Notification
•Handle Resolution
•Other functions e.g:
Handle
Service Data
Service Data
Service Data
Implementation
Hosting Environment
•Workflow
•Auditing
•Resource Management
OGSI PortTypes (1)
GridService
findServiceData
setServiceData
requestTerminationBefore
requestTerminationAfter
destroy
Factory
createService
HandleResolver
findByHandle
ServiceGroup
OGSI PortTypes (2)
ServiceGroupRegistration
add
remove
ServiceGroupEntry
NotificationSource
subscribe
NotificationSubscription
NotificationSink
deliverNotification
WSDL and GWSDL
WSDL 1.1:
Lack of portType inheritance

A portType cannot be defined in terms of an aggregation or extension of
one or more other portTypes
Lack of an open content model

Needed for specifying service data
GWSDL:
portType inheritance
Open content model
Stepping stone to WSDL 1.2
GWSDL => WSDL 1.1:
Flattening the inheritance hierarchy
The “most-derived” portType
WSDL 1.2
Grid Service Identification
Grid Services are identified by means of a
Grid Service Handle (GSH), which is used to find the
Grid Service Reference (GSR) that is unique to an instance of a
Grid Service
A HandleResolver service is used to provide a GSR given a
GSH
GSH:
Type of URI (or URL)
Constant for the lifetime of the Grid Service
GSR:
Representation of the service interfaces

Can be a WSDL document
Can change if the service evolves
OGSI Implementations
Microsoft .NET:
EPCC: MS.NETGridOGSI Release 1.1
University of Virginia: OGSI.NET Release 1.1
Java:
Globus: Globus Toolkit 3 Release 1.0
Unicore
Perl:
University of Manchester: OGSI::Lite
Python:
Lawrence Berkley National Labs: pyGlobus
OGSI on Microsoft .NET
MS.NETGrid-OGSI
Design Dimensions
Use IIS/ASP.NET:
Facilitate speed of development

SOAP and WSDL handling for free!
Industry-standard Web services programming model
Maintain integration with existing technology
Exploit existing knowledge of developers
Utilise .NET class library
Rich framework for XML programming, serialization etc.
Use an object instance to represent a service instance
Creating service object and loading state every request is too
costly:


Performance-wise
Development time-wise
Design Limitations
No rich client-side support:
No Grid service-specific support
But Grid services ARE Web services!
GSH / GSR support
Subset of OGSI portTypes
Security
But can secure using ASP.NET Web Services
Security
No GWSDL
MS.NETGrid-OGSI
Implementation of OGSI on Microsoft .NET
Leverages ASP.NET functionality
Provides support for:
Grid service hosting in ASP.NET Web services
container
GridService portType-related functionality
Factory portType-related functionality
Service data management
Management of persistent and transient services
Client-Service Interaction
C#
Implementation
8. C# method return
Proxy
(from WSDL)
Client
1. C# method call
7. SOAP response
2. SOAP request
HTTP
ASP.NET
Web Service Proxy (.asmx)
3. Grid
Service
ID
C#
Implementation
4. Grid
Service
Object
Reference
5.
Operation
Call
6.
Operation
Return
OGSI Container
Grid
Service
Grid
Service
Grid
Service
Service Lifetime and Naming
Persistent services:
Server-managed services
Necessary for factories, permanent services
Naming

http://host/Ogsi.Container/services/persistent/Som
eServiceFactory.asmx
Transient services:
Client-managed services
Naming

http://host/Ogsi.Container/services/transient/Some
Service.asmx?instanceID=someService1
Service Proxy Model
Service proxy is standard ASP.NET Web service
Created – processes request - dies
Communications layer between client and Grid services:
One proxy type corresponds to one or more Grid services
One instance of a proxy created per service request to .asmx
file
GSH is used by proxy to find Grid service object
Reflection allows invocation of a service method on that object
Operations exposed via WebMethod attributes
SOAP communication and WSDL description for free!
Familiar model to ASP.NET users
Potential for auto-generation of proxy code
Developing a Grid Service
Grid Service Design
What services will your Grid service provide?
What operations will it support?
How are these operations aggregated into
portTypes?
What existing and new portTypes will your
service implement?
No need to write WSDL!
Grid Service Development
Implement the service functionality:
GridServiceSkeleton-derived OR
PersistentGridServiceSkeleton-derived
PortTypeProviders for portTypes
Provide a service proxy class:
Communications layer between clients and services
No original effort required!
Represents the most-derived portType
Inherits from GridServiceInstanceAspProxy (which derives
from ASP.NET class WebService)
Deploy the service:
ASP.NET Web service deployment descriptor (Web.config)
Location of classes and proxies / service lifetime type
Application-specific information
Implement the Service Functionality
MS.NETGrid-OGSI Classes
Inherit from:
GridServiceSkeleton
OR
PersistentGridServiceSkeleton
Hello Service:
public class HelloServiceImpl :
PersistentGridServiceSkeleton
{
. . . . . . . . .
}
GridServiceSkeleton (1)
Implements GridService portType functionality:
findServiceData, setServiceData,
requestTerminationBefore,
requestTerminationAfter, destroy
InstanceServiceDataSet property:
ServiceDataSet for the live running service instance
ServiceDataSet and ServiceData APIs
ServiceParameters property:
General purpose hashtable
Loaded with configuration data from a deployment descriptor
when service is initialised
PortTypeProviders property:
Hashtable containing references to implementations of
portTypes
GridServiceSkeleton (2)
PostCreate method
public abstract class GridServiceSkeleton
{
public virtual void PostCreate()
{
}
}
Can be used for resource acquisition, service data
initialisation, other initialisation:
Called by the container or factory when service is created
Store useful items in ServiceParameters hashtable
Only for objects used by all the portTypes of a service
Implementing PortType Operations
Option 1 - Inheritance:
Provide methods on a GridServiceSkeleton-derived class
Recommended when only one portType is required
Quick and convenient
Option 2 – PortType Providers:
Use IPortTypeProvider implementations
Use OgsiPortType attribute to associate with service class
PortTypeProviders property of GridServiceSkeleton

Maps requests to IPortTypeProvider instances
Modularises portType and service implementations
Inheritance
public class HelloServiceImpl :
PersistentGridServiceSkeleton
{
int i = 0;
// sayHello is an operation on some portType
public string sayHello(string name)
{
return “Hello, “ + name + “ “ + (++i);
}
}
PortType Providers (1)
public class HelloPortType : PortTypeProviderBase
{
int i = 0;
public string sayHello(string name)
{
return “Hello, “ + name + “ “ + (++i);
}
public override void Initialise() { }
}
// Declare service and attach portType using attribute
[OgsiPortType(typeof(HelloPortType),
“http://mydomain.com/NameSpace”, “HelloPortType”]
public class HelloServiceImpl :
PersistentGridServiceSkeleton
{
}
PortType Providers (2)
public interface IPortTypeProvider
{
GridServiceSkeleton ServiceInstance
{
get;
set;
}
void Initialise();
}
Provides for:
Access to service instance
Custom initialisation code – called after the
IPortTypeProvider is created
Attach to service with OgsiPortTypeAttribute
PortTypeProviderBase gives simple implementation
of PortTypeProvider
How PortType Providers Work
Attributes and reflection!
On instantiation of GridServiceSkeleton:
Reflects upon self to get OgsiPortType attributes
Uses the information in the attributes to instantiate
implementation classes
[OgsiPortType(typeof(HelloPortType),
“http://mydomain.com/NameSpace”,
“HelloPortType”]
Stores instances in PortTypeProviders hashtable
Methods can then be called on these instances
Service Data
Named like any XML element:
(namespace, local name)
Represented by an instance of the
Ogsi.ServiceData.ServiceData type
ServiceDataSet type represents the entire
collection of service data for a service
GridServiceSkeleton.InstanceServiceData
Service Data APIs
ServiceDataSet:
Create(XmlQualifiedName name);
Add(ServiceData data);
Contains(XmlQualifiedName name);
Delete(XmlQualifiedName name);
Remove(XmlQualifiedName name);
ServiceData:
Contains System.Object(s)
GetValues() / GetValuesArray()
Value property
SetValues(object [ ])
Callback property for on-demand generation

Uses IServiceDataValuesCallback
Provide a Service Proxy Class
Service Proxies
Communications layer between clients and Grid
service objects
Proxies are Web services
Based on
System.Web.Services.WebService class of
ASP.NET
Allows ASP.NET to forward service requests
to/from Grid service objects:
GridServiceInstanceAspProxy
and
PersistentGridServiceInstanceAspProxy
Proxies and Inheritance
// HelloService.cs
public class HelloService :
PersistentGridServiceInstanceAspProxy
{
[WebMethod]
// Any other ASP.NET attributes
public string SayHello(string name)
{
object [] args = { name };
return (string)
CallMethod(“SayHello”, args);
}
}
GridServiceInstanceAspProxy /
PersistentGridServiceInstanceAspProxy constructor
provides reference to service instance object via container
CallMethod invokes on service instance object
Proxies and PortType Providers
// HelloService.cs
public class HelloService :
PersistentGridServiceInstanceAspProxy
{
[WebMethod]
// Any other ASP.NET attributes
public string SayHello(string name)
{
object [] args = { name };
return (string)
CallMethodOnProvider(“HelloPortType”,
“SayHello”, args);
}
}
Completing the Proxy
Write .asmx file which references proxy type
<%@ WebService
Class=“HelloService"%>
Deploy the Service
Deployment Descriptors and
ASP.NET Web.Config
gridContainer element
Add gridServiceDeploymentDescriptor:
<gridServiceDeploymentDescriptor
asmxFileName=“HelloService.asmx”
serviceClass=“HelloServiceImpl”
assembly=“HelloAssembly”
persistence=“persistent”>
<serviceParameter name=“key” value=“value”/>
</gridServiceDeploymentDescriptor>
Attributes:
asmxFileName - .asmx file for proxy
service – main service implementation class
assembly - service and proxy assembly
persistence - transient or persistent
Provide the Service
Copy assemblies to Ogsi.Container/bin/
directory
Copy .asmx file to:
services/persistent directory
OR
services/transient directory
Grid Service Demonstrators
Grid Service Demonstrators
Representative examples provided with the
MS.NETGrid-OGSI distribution
Basic GridService:
Implements GridService portType
Persistent and transient services available, with
factory
Counter Service:
A simple transient counter service which maintains
state
An associated persistent factory service
A client with a graphical user-interface
OGSA-DAI Grid Data Service (1)
Client
Request
(GDS-Perform document)
Response
(GDS-Response document)
(WebRowSet)
Grid Data Service
SQL Server
Open Grid Services Architecture – Data Access and
Integration
http://www.ogsadai.org.uk
Stripped down from full OGSA-DAI functionality
Service-database communication over ADO.NET
OGSA-DAI Grid Data Service (2)
Training the UK e-Science
Community
Training Courses
“OGSI on Microsoft .NET”
Designed for UK e-Scientists
Four courses each for 25 attendees:
September 9th-10th 2003
November 4th-5th 2003
January 27th-28th 2004
February 2004
e-Science Institute in Edinburgh
http://www.nesc.ac.uk/esi
Course Goals
Introduce / review:
Grid Services
Microsoft .NET
Introduce OGSI on Microsoft .NET
MS.NETGrid-OGSI
Use MS.NETGrid-OGSI:
Develop a Grid Service
Develop a client
Introduce related OGSI on Microsoft.NET work
Course Outline – Day 1
Welcome and Workshop Overview
Grid Services
Web Services and XML
Grids, OGSA and OGSI
Essential Microsoft .NET Concepts
.NET Framework Overview
C# Recap, Assemblies and Using Metadata
ASP.NET
OGSI and .NET
Why OGSI on .NET?
MS.NETGrid-OGSI
Obtaining, installing and testing MS.NETGrid-OGSI
Practical
Course Outline – Day 2
Recap
Developing a Grid Service 1
Practical
Developing a Grid Service 2
Practical
Developing a Grid Service 3
Practical
Miscellaneous:
MS.NETGrid-OGSI Demonstrators
Course Feedback
Discussion
Near Future
Revision of OGSI on .NET container
Facilitating scalability and service persistence
Development of additional Grid service
demonstrators:
Practical demonstration of the utility of OGSI on .NET
Revision of training materials:
Courses and supporting materials on OGSI and .NET
Delivery of additional courses