1. ©Ferenc Vajda 1 Open Grid Services Architecture Ferenc Vajda vajda@sztaki.hu Computer and Automation Research Institute Hungarian Academy of Sciences

2. ©Ferenc Vajda 2 GRID Past: Globus Present: OGSA Future: Semantic Grid “Past is history, future is mystery”

3. ©Ferenc Vajda 3 Roots of OGSA Globus Toolkit: GTPL (Globus Toolkit Public License) GT3: Platform Globus (Commercially supported) “The Anatomy of the Grid” “The Physiology of the Grid” papers by Ian Foster et al. Grid Forum GGF (Global Grid Forum) OGSA Working Group

4. ©Ferenc Vajda 4 Main issues of “The Anatomy of the Grid” -SDK (Software Development Kit) Virtual Organization (VO) Nature of Grid Architecture -Interoperability -Protocol -Services -API (Application Programming Interface)

5. ©Ferenc Vajda 5 -Applications Main issues of “The Anatomy of the Grid” 2. Architecture Description -Fabric: interfaces to local control -Connectivity: communicating easily and securely -Resource: sharing single resources -Collective: coordinating multiple resources

6. ©Ferenc Vajda 6 The layered Grid architecture “The Anatomy of the Grid”

7. ©Ferenc Vajda Main issues of “The Physiology of the Grid” -Business-to-Business (B2B) Computing -Web Services o SOAP o WSDL o UDDI o WSFL o WS-Inspection Grid technologies -Enterprise Computing -Service Providers (SPs) Background -Globus Toolkit

8. ©Ferenc Vajda 8 Building an Open Grid

9. ©Ferenc Vajda 9 Open Standards Building an Open Grid

10. ©Ferenc Vajda 10 Open Standards Open Source Building an Open Grid

11. ©Ferenc Vajda 11 Open Standards Open Source Open Infrastructure Building an Open Grid

12. ©Ferenc Vajda 12 Open Standards Open Source Open Infrastructure Open Grid Credit to Ian Foster Building an Open Grid

13. ©Ferenc Vajda 13 Increased functionality, standardization Time Custom solutions Open Grid Services Arch GGF: OGSI, … (+ OASIS, W3C) Multiple implementations, including Globus Toolkit Web services Globus Toolkit Defacto standards GGF: GridFTP, GSI X.509, LDAP, FTP, … App-specific Services Grid and Open Standards Credit to Ian Foster

14. ©Ferenc Vajda 14 Open Grid Services Architecture -Language interoperability From Web Services Standard interface definition mechanisms -Interface and implementation (multiple protocol bindings) -Local/remote transparency -Service semantics

15. ©Ferenc Vajda 15 Open Grid Services Architecture 2. Further services: resource management, authorization, etc. From Grids Lifecycle management Reliability and security models Discovery

16. ©Ferenc Vajda 16 Open Grid Services Architecture 3. Objective: to integrate services across - distributed - heterogeneous - dynamic virtual organizations Solution: -standard mechanisms for creation, naming, discovery -location transparency, multiple protocol binding -integration with hosting environment

17. ©Ferenc Vajda 17 OGSI Transport Protocol Hosting Environment Host. Env. & Protocol Bindings OGSA Platform services: registry, authorization, monitoring, data access, etc., etc. More specialized & domain-specific services Models for resources & other entities Other models Environment- specific profiles Domain- specific profiles OGSA Platform GWD-R (draft-ggf-ogsa-platform-3) Editors: Open Grid Services Architecture Platform I. Foster, Argonne & U.Chicago http://www.ggf.org/ogsa-wg D. Gannon, Indiana U. OGSA Platform

18. ©Ferenc Vajda 18 Principal elements of OGSA Platform Open Grid Services Infrastructure (OGSI) OGSA Platform Interfaces OGSA Platform Models

19. ©Ferenc Vajda 19 OGSA Platform Profiles Sets of domain-specific services Environment, domain-specific supplements: Protocol bindings Hosting environment bindings

20. ©Ferenc Vajda 20 Open Grid Services Infrastructure Service group Key Features: Grid Service description and instances Service state, metadata and introspection Naming and name resolution Fault model Lifecycle

21. ©Ferenc Vajda 21 OGSI OGSI = Grid Technologies + Web Services In OGSI everything is represented as a Grid service. Service: a network-enabled entity that provides some capabilities through the exchange of messages.

22. ©Ferenc Vajda 22 OGSI Most important components: Grid Service Factory Registry HandleMap

23. ©Ferenc Vajda 23 The Grid Service -Grid service instance A WSDL-defined service that conforms to a set of conventions relating to its interface and behaviors. Description composed of two parts: -Grid service description -Describes a client’s interaction with service instances:syntax and semantics (PortType) -Can be used by any number of Grid service instances

24. ©Ferenc Vajda 24 The Grid Service 2. -Has one or more Grid Service References (GSRs) -Grid service instance -Embodies a state -Has one or more unique Grid Service Handles (GSHs)

25. ©Ferenc Vajda 25 The Grid Service 3. GSR (Grid Service Reference): abstraction for e.g. protocol binding, network address, etc. typed (characterized by the offered capability) interfaces (set of operations) invocation (by sequences of message exchange) created/destroyed (dynamically) GSH (Grid Service Handle): globally unique name

26. ©Ferenc Vajda 26 Factories: Creating Transient Services Factory = Factory interface + implemented service CreateService operation: -creates a requested Grid service -returns a GSH + an initial GSR

27. ©Ferenc Vajda 27 Handles and References -returns a valid GSR GSH: reference for service instance “forever” GSR: changes during lifetime HandleMap: handle-to-reference mapper -takes a GSH

28. ©Ferenc Vajda 28 Registry and Notification Semantics: protocol binding property e.g. SOAP/HTTP protocol Registry: registry interface + service data elements (info about GSH) Notification Subscribe operation NotificationSource interface NotificationSink: message (“keep alive”) “push” model (FindServiceData “pull” model)

29. ©Ferenc Vajda 29 Client runtime architecture Credit to S. Tuecke et al. (Grid Service Specification)

30. ©Ferenc Vajda 30 GSH Resolving Credit to S. Tuecke et al. (Grid Service Specification)

31. ©Ferenc Vajda 31 Open Grid Service Infrastructure Implementation Service data element Other standard interfaces: factory, notification, collections Hosting environment/runtime (“C”, J2EE,.NET, …) Service data element Service data element GridService (required) Data access Lifetime management Explicit destruction Soft-state lifetime Introspection: What port types? What policy? What state? Client Grid Service Handle Grid Service Reference handle resolution Credit to Ian Foster

32. ©Ferenc Vajda 32 1a. Request to Registry for sources of data about “x” 1b. Registry responds with Factory handle 2a. Request to Factory for access to database 2b. Factory creates GridDataService to manage access 2c. Factory returns handle of GDS to client 3a. Client queries GDS with XPath, SQL, etc 3b. GDS interacts with database 3c. Results of query returned to client as XML SOAP/HTTP service creation API interactions RegistryFactory Grid Data Service Client XML / Relationa l database OGSA-DAI (Data Access and Integration

33. ©Ferenc Vajda 33 Security Challenges Integrate Extensible architecture Using existing services Implementation agnostic Interoperate Secure interoperability Publishing QoS Federation Trust Trust relationship Trust establishment Presumed trust Assertions

34. ©Ferenc Vajda 34 Grid Security Requirements Integrity Authentication Delegation Single sign-on Credential lifespan and renewal Authorization Privacy Confidentiality

35. ©Ferenc Vajda 35 Securing infrastructure Grid Security Requirements 2. Policy exchange Secure logging Assurance Manageability Firewall traversal

36. ©Ferenc Vajda 36 Components of Grid Security Model

37. ©Ferenc Vajda 37 Security Architecture Building Blocks

38. ©Ferenc Vajda 38 Security as Service Privacy service Authentication service Identity mapping service Authorization service I/O policy service Credential conversion service Audit service Profile service

39. ©Ferenc Vajda 39 Semantic Grid Ferenc Vajda vajda@sztaki.hu Computer and Automation Research Institute Hungarian Academy of Sciences

40. ©Ferenc Vajda 40 Data/Information/Knowledge Data: observed facts Information: organized and related facts with attributed properties Knowledge: “sum of what is known”: concepts, objects with characteristics, principles, laws, know-how, etc. Semantics: a term used for meaning, interpretation, knowledge through reasoning

41. ©Ferenc Vajda 41 Different Evaluations of the Grid 1. Grid generations To link supercomputer centers (e.g. I-way) Toolkit- and middleware-based (e.g. Globus) Service-oriented (OGSA)

42. ©Ferenc Vajda 42 Different Evaluations of the Grid 2. 2. Based on the technologies used Protocol-based Service-based Semantic Web based 3.Based on application requirements Data/computational Grid Information Grid Knowledge Grid

43. ©Ferenc Vajda 43 Problems Related to Semantic Web Knowledge Evaluation Knowledge Representation Ontologies Agents

44. ©Ferenc Vajda 44 Resource Description Framework (RDF) -Set of triplets: subject, property,object Metadata: structured data about data Resource identification: Universal Resource Identifier (URI) Most common type of URI: Uniform Resource Locator (URL) Qualified URI: URI + fragment identifier Concepts: -Graph model

45. ©Ferenc Vajda 45 RDF 2. SubjectObject Property -Data types: based on XML Schema -Vocabulary: URI-based (Both nodes and arcs)

46. ©Ferenc Vajda 46 RDF 3.

47. ©Ferenc Vajda 47 What is an Ontology? Greek: ontos = being, logos = science world view regarding a domain shared understanding definitions, inter-relationship conceptualization

48. ©Ferenc Vajda 48 What does an Ontology look like? vocabulary of terms specification of their meaning (i.e. definitions) - highly informal (natural language) - semi-informal (restricted, structured form of natural language) - semi-formal (artificial, formally defined language) - rigorously formal (formal semantics, proofs, completeness)

49. ©Ferenc Vajda 49 Use of Ontologies communication (between people and organizations) system engineering (specifications, reusable components) inter-operability (between systems)

50. ©Ferenc Vajda 50 Ontologies Web Ontology Language (OWL) Ontology: defines the terms used to describe and represent an area of knowledge -taxonomy: object classification + relationship among them (properties and inheritance of properties) -inference rules DAML (DARPA = Defense Advanced Project Agency Agent Markup Language)

51. ©Ferenc Vajda 51 Agents Agent: Capability to understand and integrate diverse information resources (based on domain ontologies)

52. ©Ferenc Vajda 52 Agents 2.

53. ©Ferenc Vajda 53 Semantic Web Layers Credit to Berners-Lee (XML2000 address)

54. ©Ferenc Vajda 54 Semantic Grid

55. ©Ferenc Vajda 55 Semantic Grid Basis: Metadata enabled Goal: Grid + Semantic Web Ontologically principled New e-Science infrastructure

56. ©Ferenc Vajda 56 Services e.g. -semantic database integration -semantic workflow description Base services -data/computational services (network access, resource allocation and scheduling, data shipping, etc.) -information services (query processing, event notification, instrumentation management, etc.) Semantic services

57. ©Ferenc Vajda 57 Services 2. -application Knowledge services -acquisition -modeling -publishing, use and maintenance -resource management

58. ©Ferenc Vajda 58 Knowledge Grid Architecture Credit to Carole Goble et al.

59. ©Ferenc Vajda 59 Roles of Ontologies Credit to Carole Goble et al.

60. ©Ferenc Vajda 60 The term ‘ procedure ’ used by one tool is translated into the term ‘ method ‘ used by the other via the ontology, whose term for the same underlying concept is ‘ process ’. procedure viewer translator Ontology method library give me the procedure for… translator here is the METHOD for… procedure = ??? procedure = process give me the process for… here is the process for… METHOD = process ??? = process Roles of Ontologies (Example) Credit to Rokhlenko Oleg

61. ©Ferenc Vajda 61 Knowledge Services Credit to Carole Goble et al.

62. ©Ferenc Vajda 62 Typical Applications Service discovery Knowledge annotation Workflow composition Data interpretation Collaborative science

63. ©Ferenc Vajda 63 Grid Service Discovery Simple discovery attribute-base name lookup type matching Semantic discovery matchmaking based on ontology description

64. ©Ferenc Vajda 64 Brokering vs. Matchmaking

65. ©Ferenc Vajda 65 Grid Service Discovery Framework Ontology based description used by service provider service requester service matchmaker service registry database Matchmaking process comparison: request to registry decision: based on filters information

66. ©Ferenc Vajda 66 Service Description “What the service does”: service profile “How it works”: ServiceModel “How it is used”: ServiceGrounding Description by RDF(S): Resource Description Framework Schema Service profile description (human readable) functionalities functional attributes

67. ©Ferenc Vajda 67 Service Description 2. Credit to DAML-S White Paper

68. ©Ferenc Vajda 68 Filtering Independent filtering is based on context matching syntactic matching - comparison of profiles - similarity matching - signature matching semantic matching

69. ©Ferenc Vajda 69 myGrid project

70. ©Ferenc Vajda 70 Role of Ontologies in myGrid