Open Grid Services Architecture Ferenc Vajda vajdasztaki hu

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

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

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

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

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 -Applications ©Ferenc Vajda 5

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

Main issues of “The Physiology of the Grid” • Grid technologies -Enterprise Computing -Service Providers (SPs) -Business-to-Business (B 2 B) Computing • Background -Globus Toolkit -Web Services o SOAP o WSDL o UDDI o WSFL o WS-Inspection

Building an Open Grid ©Ferenc Vajda 8

Building an Open Grid Open Standards ©Ferenc Vajda 9

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

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

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

Grid and Open Standards Credit to Ian Foster Increased functionality, standardization App-specific Services Open Grid Services Arch Web services X. 509, LDAP, FTP, … Custom solutions ©Ferenc Vajda 13 Globus Toolkit GGF: OGSI, … (+ OASIS, W 3 C) Multiple implementations, including Globus Toolkit Defacto standards GGF: Grid. FTP, GSI Time

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

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

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

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

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

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

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

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. ©Ferenc Vajda 21

OGSI Most important components: • Grid Service • Factory • Registry • Handle. Map ©Ferenc Vajda 22

The Grid Service • 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 (Port. Type) -Can be used by any number of Grid service instances ©Ferenc Vajda 23 -Grid service instance

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

The Grid Service 3. • 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 • GSR (Grid Service Reference): abstraction for e. g. protocol binding, network address, etc. ©Ferenc Vajda 25

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

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

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

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

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

Open Grid Service Infrastructure Client Introspection: • What port types? • What policy? • What state? Grid Service Handle handle resolution Lifetime management • Explicit destruction • Soft-state lifetime Grid. Service (required) Data access Service data element Other standard interfaces: factory, notification, collections Service data element Grid Service Reference Implementation ©Ferenc Vajda Hosting environment/runtime (“C”, J 2 EE, . NET, …) 31 Credit to Ian Foster

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

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

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

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

Components of Grid Security Model ©Ferenc Vajda 36

Security Architecture Building Blocks ©Ferenc Vajda 37

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

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

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 ©Ferenc Vajda 40

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) ©Ferenc Vajda 41

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 ©Ferenc Vajda 42

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

Resource Description Framework (RDF) • 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 -Set of triplets: subject, property, object ©Ferenc Vajda 44

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

RDF 3. ©Ferenc Vajda 46

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

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) ©Ferenc Vajda 48

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

Ontologies • 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 • Web Ontology Language (OWL) • DAML (DARPA = Defense Advanced Project Agency Agent Markup Language) ©Ferenc Vajda 50

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

Agents 2. ©Ferenc Vajda 52

Semantic Web Layers ©Ferenc Vajda 53 Credit to Berners-Lee (XML 2000 address)

Semantic Grid ©Ferenc Vajda 54

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

Services • 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 e. g. -semantic database integration ©Ferenc Vajda 56 -semantic workflow description

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

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

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

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 Credit to Rokhlenko Oleg concept is ‘process’. Roles of Ontologies (Example) procedure give me the procedure for… viewer translator procedure = here is the process for… ©Ferenc Vajda 60 give me the procedure = ? ? ? Ontology process METHOD = process for… ? ? ? = process translator here is the METHOD for… method library

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

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

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

Brokering vs. Matchmaking ©Ferenc Vajda 64

Grid Service Discovery Framework ©Ferenc Vajda 65 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

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

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

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

my. Grid project ©Ferenc Vajda 69

Role of Ontologies in my. Grid ©Ferenc Vajda 70