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Explore the architecture of WSRF NET, its compatibility with GT4, attribute-based programming, and implementation details. Evaluate the WSRF approach and its usefulness in programming web services. This open-source implementation of WSRF and WS Notification provides a full set of specifications and enables customization.
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Acknowledgement • Fernando Trigoso
Outline • WSRF.NET Architecture • Attribute-based programming • Compatibility with GT4 • WSRF Issues
Background • WSRF • WS-Resource • WS-ResourceProperties • WS-ResourceLifetime • WS-Notification
WSRF.NET • Open source implementation of WSRF and WS-Notification • Implements full set of specifications • Useful to evaluate the WSRF approach • To make programming WSRF.NET services as easy as programming Web Services
WSRF.NET Architecture • Internet Information Services (IIS) • Internet Server Application Programming Interface (ISAPI) Humphrey, M., & Wasson, G. (2004). Architectural Foundation of WSRF.NET.
WSRF.NET Architecture • ASP.NET with Web Services Extensions (WSE) • Wrapper Web Service automatically created by WSRF.NET Humphrey, M., & Wasson, G. (2004). Architectural Foundation of WSRF.NET.
WSRF.NET Architecture • WS-Resource implemented with ADO.NET • Serialized result returned to client Humphrey, M., & Wasson, G. (2004). Architectural Foundation of WSRF.NET.
WS-Resource • WS-Resource implementation • Ability to query complex states • Ease to access multiple resources • Lookup based on key and state contents
WS-Resource • Portability, scalability and flexibility • No single-point of failure • Efficient expiration check • Provides an interface for customization
Outline • WSRF.NET Architecture • Attribute-based programming • Compatibility with GT4 • WSRF Issues
Declarative & Imperative • Imperative programming • Most common • Methods define behavior of programs • Declarative programming • Declarations define behavior • No need to write instructions • Attributes are used to define behavior [WebMethod] public string Hello() {return “Hello World”;} Wagner, B. (2005). Effective C#.
WSRF.NET Attribute Usage • Attributes easily define: • Resources • Resource Properties • Port Types • Aids development of grid services
[WebMethod] public string Hello() { return “Hello World”; } [WebMethod] public DateTime GetDate() { return DateTime.Now; } Used to create the service logic ASP.NET creates: WSDL document Support to route SOAP requests HTML pages to test web service Security provided by WSE Attributes for Web Service
class PackageService { [Resource] Package pkg; [Resource] PkgRoute route; [Resource] PkgLocation location; … WS-Resource is an abstraction for a collection of state WS-Resource addressed by EPR Resource is the collection of members with [Resource] attribute Attributes for Stateful Resource Wasson, G. (2006). WSRF.NET 3.0 Programmer’s Reference.
class PackageService { [Resource] Package pkg; [Resource] PkgRoute route; [Resource] PkgLocation location; … Resource stored in the database with key: URL + Resource Unique ID EPR in SOAP message contains: <Address> + <ReferenceProperties> Resource loaded from database Values placed in web service’s members Attributes for Stateful Resource Wasson, G. (2006). WSRF.NET 3.0 Programmer’s Reference.
class PackageService { [Resource] Package pkg; [Resource] PkgRoute route; [Resource] PkgLocation location; … WSRF.NET allows customization Just implement IResource Not all web methods require all values Attributes for Stateful Resource Wasson, G. (2006). WSRF.NET 3.0 Programmer’s Reference.
class PackageService { [Resource] Package pkg; [ResourceProperty] public string Sender { get { return pkg.Sender; } } … Resources described in Resource Property Document (RPD) RPD is composed of ResourceProperties All members with [ResourceProperty] define RPD Attributes for Resource Properties Wasson, G. (2006). WSRF.NET 3.0 Programmer’s Reference.
Adding Port Types to the Service [WSRFPortType(typeof(GetResourcePropertyPortType))] [WSRFPortType(typeof(ImmediateResourceTerminationPortType))] public class PackageService { [Resource] Package pkg; … • WSRF defines functions that may be supported • WSRF.NET implements all current specifications • Author’s can reuse them by declaring attributes Wasson, G. (2006). WSRF.NET 3.0 Programmer’s Reference.
Outline • WSRF.NET Architecture • Attribute-based programming • Compatibility with GT4 • WSRF Issues
Compatibility with GT4 • GT4 uses a different version of WS-Addressing than WSE 3.0 • WSRF.NET makes process transparent • GT4 clients can interact with WSRF.NET services and vice versa (being tested) • WSRF.NET cannot send Notifications to both GT4 and WSE 3 services at the same time
WSRF.NET & GT4 B. Sotomayor and L. Childers. Globus Toolkit 4, Programming Java Services. 2006.
Outline • WSRF.NET Architecture • Attribute-based programming • Compatibility with GT4 • WSRF Issues
Stateful vs. Stateless • Service Oriented Architecture • Combines loosely coupled and interoperable services • State clashes with Services Architecture • Bond between client and service • Loose coupling with stateless services • Tighter coupling with stateful services • Proxies mask services as objects
Complexity of Service-Side Code • Importing port types may raise issues • Port types have their own resources • The state and its Resource Property • If one changes the other one has to change • Unintuitive interface: // No WSRF: CheckPackageIn(Package pkg, string location) // WSRF: CheckPackageIn(string location) Humphrey, M., & Wasson, G. (2004). Architectural Foundation of WSRF.NET.
Conclusion • WSRF.NET architecture • Complex application logic requires complex infrastructure • WSRF potential is strong • Decoupling will be difficult • WSRF.NET helps WSRF
References • Architectural Foundations of WSRF.NET by M. Humphrey and G. Wason. • The Open Grid Services Architecture, Version 1.0. I. Foster, H. Kishimoto, A. Savva, D. Berry, A. Djaoui, A. Grimshaw, B. Horn, F. Maciel, F. Siebenlist, R. Subramaniam, J. Treadwell, J. Von Reich. Informational Document, Global Grid Forum (GGF), January 29, 2005.
