Enabling Grids for E-scienc E The Web Services

Enabling Grids for E-scienc. E The Web Services Resource Framework and Globus Toolkit version 4 Mike Mineter National e-Science Centre, Edinburgh www. eu-egee. org INFSO-RI-508833

Acknowledgements: some slides are from Enabling Grids for E-scienc. E http: //www. nesc. ac. uk/action/esi/contribution. cfm? Title=385 INFSO-RI-508833 2

Goal of presentation Enabling Grids for E-scienc. E • An orientation to – Web Services and to their role in Grid computing – Implementation in Globus Toolkit 4 • No prior knowledge assumed INFSO-RI-508833 4

Outline Enabling Grids for E-scienc. E • “ Web Services are the way to build Grids” • Web Services • Relevance of Web Services to Grids • Extending WS for grids • Globus Toolkit 4 INFSO-RI-508833 5

October 2001 View Enabling Grids for E-scienc. E Web Services • Commerce • Standards • Tools Grid Technology Grid Services • Research driven • Data-intensive • Compute intensive • Collaboration – sharing of resources - Trust: opening resources infrastructure for the information society INFSO-RI-508833 7

Dynamic composition Enabling Grids for E-scienc. E Client Registry Service Service A Service INFSO-RI-508833 Service B Service 11

Using service B from service A Enabling Grids for E-scienc. E service B service A: consumes B Messages Web services container O/S A INFSO-RI-508833 Web services container TCP/IP messages O/S B 12

Using service B from service A Enabling Grids for E-scienc. E These messages define service B service A: consumes B Messages Web services container O/S A INFSO-RI-508833 Web services container TCP/IP messages O/S B 13

HTTP and HTTPS Enabling Grids for E-scienc. E • Commonly used for WS - original purpose: carry HTML • HTTP request methods • GET : specify a URL • service key-value pairs POST: A: • Defaults for B client to port 80 • HTTPS: encrypts / decrypts service B Messages Web services container http, https O/S A INFSO-RI-508833 TCP/IP messages O/S B 14

XML – usual basis for messages Enabling Grids for E-scienc. E XML e. Xtendable Markup Language • Human readable (sort of) – so not tied to one architecture service A: • Extendable: can define new data client for B types, belong to “namespaces”, expressed by schemas service B Messages Web services container XML Web services container http, https O/S A INFSO-RI-508833 TCP/IP messages O/S B 15

WSDL -1 Enabling Grids for E-scienc. E service A: consumes B Service B is described by WSDL, “Web Service Description Language”. Includes: • Where: “ end point” URL where B receives messages service B • What: Message definitions • How: “Bindings” to use service Messages Web services container XML Web services container http, https O/S A INFSO-RI-508833 TCP/IP messages O/S B 16

WSDL -2 Enabling Grids for E-scienc. E • API’s are derived from the WSDL by tools • Developer adds code for specific client service B service A: • NO API LIBRARY SUPPLIED consumes B API’s for B Messages Web services container XML Web services container http, https O/S A INFSO-RI-508833 TCP/IP messages O/S B 17

SOAP Enabling Grids for E-scienc. E XML-based messaging protocol Header: extendable for security, accounting, Body: message content service B service A: consumes B API’s for B Messages Web services container SOAP Web services container http, https O/S A INFSO-RI-508833 TCP/IP messages O/S B 18

(JAVA) Web Services Enabling Grids for E-scienc. E WSDL for B Insert the web into the invoke and into the return A B invoke B. Op (a, b) return c Java program with 2 classes INFSO-RI-508833 A Bstub Stack invoke Bs. Op (a, b) return c … Op(a, b) Soap envelope HTTP message Sk Stack eleton … Web … Consumes B (client) Ret(c) Soap envelope HTTP message … B invoke B. Op (a, b) return c Provides B (server) 22

WS-I core of Web Services Enabling Grids for E-scienc. E • WS-I (Interoperability) delivers practical guidance, best practices and resources for developing interoperable Web services solutions. • http: //www. ws-i. org/ Open standards: • SOAP: protocol for message passing • Web Service Description Language: to describe services • UDDI: Universal Description, Discovery and Integration • WS-Security: incorporates security INFSO-RI-508833 23

Outline Enabling Grids for E-scienc. E • “ Web Services are the way to build Grids” • Web Services • Relevance of Web Services to Grids • Extending WS for grids • Globus Toolkit 4 INFSO-RI-508833 24

Web services and Grids Enabling Grids for E-scienc. E Web Services • Short-lived Interactions Grids • Persistence – – – • “call-return” interaction INFSO-RI-508833 Infrastructure Computation Data People • also, event-driven interaction 25

Grids – and resources Enabling Grids for E-scienc. E Auth. N and Auth. Z Client Registry Service Service Resources INFSO-RI-508833 30

A bit of history Enabling Grids for E-scienc. E • “Open grid services architecture” OGSA– proposed in 2001 • Open Grid Services Infrastructure – Globus Toolkit 3 resulted – Specified in 2003 • Then in January 2004 – OGSI to be replaced by emerging WS-RF (Web Services Resource Framework) • NOTE: – OGSA still under development (GGF) • Imbalances in OGSI that are addressed by WS-RF (OASIS) – WS community not engaged – Over O-O, megalithic INFSO-RI-508833 31

What is WSRF? Enabling Grids for E-scienc. E • Grid Services = Web Services + Stateful resources (WSRF) + Event-driven client activation (Notification) WSRF - A stateful (WS) resource … • Holds persistent state – Like an object in an object-oriented architecture WS-N -The Notification-based Interaction pattern – Event Driven • Subscribe to a “Special Offers” Notification Service • Notification Service sends a communication to me, I can reply with “buy it”. INFSO-RI-508833 32

The WS-Resource framework model § 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) resource • 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 © 2004 IBM Corporation © 2004 University of Chicago 36

The WS-Resource framework model Using a Web service to access a WS-Resource Endpoint Reference id Resource id Address Run-time environment message © 2004 IBM Corporation © 2004 University of Chicago message id Interface address resource Web Service contex t 37

The WS-Resource framework model Using a Web service to access a WS-Resource Endpoint Reference id Run-time environment message id Interface address resource Web Service resource context © 2004 IBM Corporation © 2004 University of Chicago 38

The WS-Resource framework model § WS-Resource Properties • Resource state and metadata “Projected” as an XML document • Query and Set operations § WS-Resource Life. Time • Explicit destruction or “Soft state” time-to-live • Provides for cleanup of resource instances resource <Processor. Properties> <Proc. ID>5 A 34 C 1 DE 03</Proc. ID> <Proc. Architecture>Power 6. 2</Proc. Architecture> <Proc. Speed. MIPS>400</Proc. Speed> <Proc. Cache. MB>256<Proc. Cache> <Proc. Running>1</Proc. Running> </Processor. Properties> © 2004 IBM Corporation © 2004 University of Chicago 40

WS-Notification § Subscriber indicates interest in a particular “Topic” by issuing a “subscribe” request Subscriber subscribe § Broker (intermediary) permits decoupling Publisher and Subscriber notify § “Subscriptions” are WS-Resources • Various subscriptions are possible § Publisher need NOT be a Web Service Broker notify subscribe § Notification may be “triggered” by: S • WS Resource Property value changes • Other “situations” § Broker examines current subscriptions § Brokers may S S Publisher notify • “Transform” or “interpret” topics • Federate to provide scalability © 2004 IBM Corporation © 2004 University of Chicago 41

Bringing it All Together Scenario: Resource management & scheduling Grid “Jobs” and “tasks” Scheduler Local processor manager J J Other kinds modeled using isalso are also of resources are a is “front-ended” with Grid WS-Resources and “modeled” as WS-Resources J Web Service A Web service interface Service Scheduler Resource Properties Level Notification Blades R R R WS-Resource used A Service Level to “model” physical Agreement processor resources is modeled. Cluster as a Storage WS-Notification can be WS-Resource used to “inform” the Lifetime of SLA R R R scheduler WS-Resource when Resource tied Properties “project” to the duration processor utilization processor status (like changes of the utilization) agreement © 2004 IBM Corporation © 2004 University of Chicago 42

GT 4 -view of OGSA and WSRF -1 Enabling Grids for E-scienc. E Diagram from Globus Alliance INFSO-RI-508833 47

Enabling Grids for E-scienc. E Diagram from Globus Alliance INFSO-RI-508833 48

GT 4 – Specific Components Specific Component = Deployable Service Generic Component = Can be part Of any service 49

Further reading Enabling Grids for E-scienc. E • • http: //www. globus. org/wsrf/ http: //gdp. globus. org/gt 4 -tutorial/ http: //gsbt. sourceforge. net/content/view/14/31/ http: //www-128. ibm. com/developerworks/edu/gr-dw-greclipseide-i. html INFSO-RI-508833 50

Summary Enabling Grids for E-scienc. E • Current way people try to create grid middleware is using Service Oriented Architectures based on WS • An abundance of standards is en route • Extensions to WS-I to manage stateful resources are in WS-RF framework • Implementation based on WS-RF and OGSA is in Globus Toolkit 4 INFSO-RI-508833 51