1. 1 Modeling Stateful Resources with Web Services ICE 0534 - Ph.D lecture 20042068 Byung-sang Kim

2. 2 Contents  Introduction  SOA and Services  Motivation  Modeling Stateful Resources in WS  Stateless & Stateful  The WS-Resource Framework Model  Standardization and Implementation  Public Review Specifications  Java WS Core in GT4

3. 3 Service Oriented Architecture (SOA)?  An SOA application is a composition of services  A “ service ” is the atomic unit of an SOA  Services encapsulate a business process  Service Providers Register themselves  Service use involves: Find, Bind, Execute  Most well-known instance is Web Services Service Registry Service Provider Service Consumer FindRegister Bind, Execute

4. 4 Web Services  “ A Web service is a software system designed to support interoperable machine-to-machine interaction over a network. ”  “ It has an interface described in a machine-processable format (specifically WSDL). ”  “ Other systems interact with the Web service in a manner prescribed by its description using SOAP messages, typically conveyed using HTTP with an XML serialization in conjunction with other Web-related standards. ” W3C – Web Services Architecture

5. 5 Grid..?  Flexible, secure, coordinated resource sharing among dynamic collections of individuals, institutions, and resource  How different from distributed computing?  Focused on dynamic, cross-organizational sharing  Internet scale distributed computing  Grid architecture  Protocol architecture by which VO users and resources negotiate, establish, manage and exploit sharing relationships.  A services standards-based open architecture that facilitates extensibility, interoperability, portability and code sharing

6. 6 Motivation (1/2)  Grid  Focus on the sharing multiple sources  Need standard protocol and infrastructure for SOA  WS is good as a Grid infrastructure and standard protocol (OGSA)  But WS  Focus on the interoperability between services  Does not care current status of the services and their entities  Need Service that acts upon stateful resources  Provides access to, or manipulates a set of logical stateful resources

7. 7 Motivation (2/2)  Building large-scale systems by composition of many heterogeneous components demands that we extract and standardize common patterns  Use WS-Addressing for referring to resources, with extensions for stability  Define resource lifetime management interfaces  Define resource inspection and monitoring interfaces  Define base fault representation & groups  WSRF is just a start to WS Distributed Management (WSDM) defining resource management framework (probably) on WSRF

8. 8 Grid Services as an extension of WS  Resource management protocol  Resource framework in WSDL Remote Job Execution Resource Discovery & Monitoring Data Transfer & replication Security Grid Stuff WSDL / XML SOAP / HTTP TCP / IP Internet WSRF Web Services OGSA OASIS

9. 9 Modeling Stateful Resources with Web Services

10. 10 State ?  Service’s Internal data  Attributes which are needed to persist across multiple invocation  Web Service’s internal data  Attributes which are needed to maintain for multiple clients  Attributes which are needed to deal with the dependencies among multiple services  Service’s status at system level  Service’s life time, system workload, disk information

11. 11 Stateless Web Service

12. 12 Stateful Web Service

13. 13 Web Services and Stateful Resources  “ State ” appears in almost all applications  Data in a purchase order  Current usage agreement for resources on a grid  Metrics associated with work load on a Web server  There are many possible ways Web services might model, access and manage state  The WS-Resource Framework proposes to standardize this capability for Web services

14. 14 Modeling Stateful Resources  A stateful resource is something that exists even when you're not interacting with it.  E.g. database backend service  Stateful resources have properties that define state  these properties are how you interact with them  Properties have values  Add/remove/change properties and values dynamically  WSRF Specification:  a WS-Resource is the combination of a Web service and a stateful resource on which it acts. Web Service + WSRF = Stateful Resources = WS-Resource

15. 15 Interface Web Service The WS-Resource framework model Web Service WSDL Run-time environment Source : www.ibm.com

16. 16 Interface Web Service message Invoking a Web Service address Endpoint Reference Run-time environment The WS-Resource framework model Source : www.ibm.com

17. 17  What is a WS-Resource  Examples of WS-Resources :  Physical entities (e.g.. processor, communication link, disk drive) or Logical construct (e.g.. agreement, running task, subscription)  Real or virtual  Static (long-lived, pre-existing) or Dynamic (created and destroyed as needed)  Simple (one), or Compound (collection)  Unique - Has a distinguishable identity and lifetime  Stateful - Maintains a specific state that can be materialized using XML  May be accessed through one or more Web Services resource The WS-Resource framework model Source : www.ibm.com

18. 18 context Interface Web Service message id message Using a Web service to access a WS-Resource id address resource Run-time environment Endpoint Reference The WS-Resource framework model Address Resource id Source : www.ibm.com

19. 19 context Interface Web Service message id message Using a Web service to access a WS-Resource id address resource Endpoint Reference The WS-Resource framework model Run-time environment Source : www.ibm.com

20. 20 Interface Web Service message Creating / Locating a WS-Resource address Endpoint Reference resource Endpoint Reference Web Service either locates or creates a WS-Resource addres s id The WS-Resource framework model Run-time environment Source : www.ibm.com

21. 21  WS-Resource Properties  Resource state and metadata “ Projected ” as an XML document  Query and Set operations  WS-Resource LifeTime  Explicit destruction or “ Soft state ” time-to-live  Provides for cleanup of resource instances resource 5A34C1DE03 Power6.2 400 256 1 The WS-Resource framework model Source : www.ibm.com

22. 22 WS-Notification  Asynchronous WS resource state handling  WS-Notification  Loosely coupled, asynchronous messaging in a Web services context  Standardizes the role of Brokers, Publishers, Subscribers and Consumers  Provides two forms of publish/subscribe: direct publishing and brokered publishing

23. 23  Subscriber indicates interest in a particular “ Topic ” by issuing a “ subscribe ” request  Broker (intermediary) permits decoupling Publisher and Subscriber  “ Subscriptions ” are WS-Resources  Various subscriptions are possible  Publisher need NOT be a Web Service  Notification may be “ triggered ” by:  WS Resource Property value changes  Other “ situations ”  Broker examines current subscriptions  Brokers may  “ Transform ” or “ interpret ” topics  Federate to provide scalability Broker Subscriber WS-Notification Publisher subscribe SS S notify

24. 24 Standardization & Implementation

25. 25 Current public review specifications (still on going):  http://www.oasis-open.org/committees/tc_home.php?wg_abbrev=wsrf http://www.oasis-open.org/committees/tc_home.php?wg_abbrev=wsrf  WS-Resource specification WS-Resource specification  WS-ResourceProperties (WSRF-RP) specification WS-ResourceProperties (WSRF-RP) specification  WS-ResourceLifetime (WSRF-RL) specification WS-ResourceLifetime (WSRF-RL) specification  WS-ServiceGroup (WSRF-SG) specification WS-ServiceGroup (WSRF-SG) specification  WS-BaseFaults (WSRF-BF) specification WS-BaseFaults (WSRF-BF) specification  WS-Resource WSDL WS-Resource WSDL  WS-ResourceProperties (WSRF-RP) WSDL WS-ResourceProperties (WSRF-RP) WSDL  WS-ResourceLifetime (WSRF-RL) WSDL WS-ResourceLifetime (WSRF-RL) WSDL  WS-ServiceGroup (WSRF-SG) WSDL WS-ServiceGroup (WSRF-SG) WSDL  WS-BaseFaults (WSRF-BF) WSDL WS-BaseFaults (WSRF-BF) WSDL  WSN (WS-Notification) also can refer in  http://www.oasis-open.org/home/index.php http://www.oasis-open.org/home/index.php

26. 26 Service Composition Transports Messaging Description Quality of Experience (QoX) WS-Service Group WS-Resource Properties WS-Resource Lifetime WS-Base Faults WS-Notification HTTP/HTTPS SMTP RMI / IIOP XSD WSDL SOAP XMLWS-Addressing WS-Renewable References WS-Metadata ExchangeWS-Policy JMS WS-Security WS-Reliable MessagingWS-Transaction BPEL4WS How these proposals relates to other Web services standards

27. 27 WS-Resource  http://docs.oasis-open.org/wsrf/rpw-1 http://docs.oasis-open.org/wsrf/rpw-1  describes the relationship between a Web service and a resource in the WS-Resource Framework.  WS-Resource Access Pattern,  an abstract concept of how resources are accessed through Web services,  the means by which WS-Resources are referenced.

28. 28 WS-RP (ResourceProperty)  http://docs.oasis-open.org/wsrf/rpw-1 http://docs.oasis-open.org/wsrf/rpw-1  Web Services Resource Properties 1.2 (Public Review Draft 01, 10 June 2005)  Resource Property defined by the state model  A piece of information  Reflect a part of the resource’s state, meta-data, manageability information  Resource properties Document  Logical composition of resource property elements  Resource property Element  XML representation of a resource property  Child of the root element of a resource properties document  XML global element definition and unique Qname  Resource Property Value  Value(s) associated with a resource property

29. 29 WS-RP (simple example) … … Resource property element declarations Resource properties document  The resource properties document associated with GenericDiskDrive  Defines the GenericDiskDrive portType

30. 30 WS-RP (simple example) … <wsdl:portType name="GenericDiskDrive" wsrf-rp:ResourceProperties="tns:GenericDiskDriveProperties" > … … Association of resource properties document to a portType  The resource properties document associated with GenericDiskDrive  Defines the GenericDiskDrive portType  The association of the resource properties document with the portType defines the type of the WS-Resource.

31. 31 WS-RP (simple example) … <wsrp:GetMultipleResourceProperties xmlns:tns="http://example.com/diskdrive" …> tns:NumberOfBlocks tns:BlockSize tns:StorageCapability …  The request message used to retrieve two resource property elements from the WS-Resource that implements the GenericDiskDrive portType:

32. 32 WS-RP (simple example)  A sample response to the simple get request: … <wsrf-rp:GetMultipleResourcePropertiesResponse xmlns:ns1="http://example.com/diskdrive" xmlns:ns2="http://example.com/capabilities"...> 22 1024 true 42 …

33. 33 OGSA, WSRF, GT4 Relationship

34. 34 Java WS Core in GT4  A component in GT4 functionality  An implementation of the Web Services Resource Framework (WSRF) and the Web Service Notification (WSN) family of standards.  It provides APIs and tools for building stateful Web services.  An Implementation of the 2004/06 OASIS WSRF and WSN working draft specifications  Basic HTTP/1.1 client & server support  JNDI based registry based on the JNDI service in Apache Tomcat

35. 35 Java WS Core  Visit following link for more information  http://www.globus.org/toolkit/docs/4.0/common/javawscore/ http://www.globus.org/toolkit/docs/4.0/common/javawscore/ Any questions for WSRF ?