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Modeling Stateful Resources with Web Services

Modeling Stateful Resources with Web Services. ICE 0534 - Ph.D lecture 20042068 Byung-sang Kim. Contents. Introduction SOA and Services Motivation Modeling Stateful Resources in WS Stateless & Stateful The WS-Resource Framework Model Standardization and Implementation

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Modeling Stateful Resources with Web Services

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

  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. 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 Find Register Service Consumer Service Provider Bind, Execute

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

  9. Modeling Stateful Resources with Web Services

  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. Stateless Web Service

  12. Stateful Web Service

  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. Modeling Stateful Resources Web Service + WSRF = Stateful Resources = WS-Resource • 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.

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

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

  17. The WS-Resource framework model Source : www.ibm.com • 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) orDynamic (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

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

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

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

  21. The WS-Resource framework model Source : www.ibm.com • 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 cleanupof resource instances resource <ProcessorProperties> <ProcID>5A34C1DE03</ProcID> <ProcArchitecture>Power6.2</ProcArchitecture> <ProcSpeedMIPS>400</ProcSpeed> <ProcCacheMB>256<ProcCache> <ProcRunning>1</ProcRunning> </ProcessorProperties>

  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. Subscriber Broker WS-Notification • 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 subscribe notify notify notify subscribe S S S Publisher notify

  24. Standardization & Implementation

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

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

  27. WS-Resource • 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. WS-RP (ResourceProperty) • 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. WS-RP (simple example) • The resource properties document associated with GenericDiskDrive • Defines the GenericDiskDrive portType <wsdl:definitions … " …> … <wsdl:types> <xsd:schema targetNamespace="http://example.com/diskDrive" ... > <!-- Resource property element declarations --> <xsd:element name="NumberOfBlocks" type="xsd:integer"/> <xsd:element name="BlockSize" type="xsd:integer" /> <xsd:element name="Manufacturer" type="xsd:string" /> <xsd:element name="StorageCapability" type="xsd:string" /> <!-- Resource properties document declaration --> <xsd:element name="GenericDiskDriveProperties"> <xsd:complexType> <xsd:sequence> <xsd:element ref="tns:NumberOfBlocks"/> <xsd:element ref="tns:BlockSize" /> <xsd:element ref="tns:Manufacturer" /> <xsd:any minOccurs="0" maxOccurs="unbounded" /> <xsd:element ref="tns:StorageCapability“ minOccurs="0“ maxOccurs="unbounded" /> </xsd:sequence> </xsd:complexType> </xsd:element> … </xsd:schema> </wsdl:types> Resource property element declarations Resource properties document

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

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

  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" ...> <ns1:NumberOfBlocks>22</ns1:NumberOfBlocks> <ns1:BlockSize>1024</ns1:BlockSize> <ns1:StorageCapability> <ns2:NoSinglePointOfFailure>true</ns2:NoSinglePointOfFailure> </ns1:StorageCapability> <ns1:StorageCapability><ns2:DataRedundancyMax>42 </ns2:DataRedundancyMax></ns1:StorageCapability> </wsrf-rp:GetMultipleResourcePropertiesResponse> …

  33. OGSA, WSRF, GT4 Relationship

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

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