Prof S.Ramachandram Dept of CSE,UCE Osmania University OGSA Prof S.Ramachandram Dept of CSE,UCE Osmania University

Major Goals Identify the use cases that can drive the OGSA platform components Identify and define the core OGSA platform components Define hosting and platform-specific bindings Define resource models and resource profiles with interoperable solutions

More specific goals Facilitating distributed resource management across heterogeneous platforms Providing seamless QOS delivery Building common base for automatic management solutions Providing common infrastructure blocks to avoid stovepipe solution towers Open published interfaces and messages Industry-standard integration solutions including web services Facilities to accomplish seamless integration with existing It resources where resources become on-demand services/resources Providing more knowledge-centric and semantic orientation of services

Functional requirements of OGSA Discovery of resources Instantiating new service Service-level management to meet user expectations Enabling metering and Accounting to quantify resource usage into pricing units Monitoring resource usage and availability Managing service policies Providing service grouping and aggregation to provide better indexing and information Managing end-to-end security Servicing life cycle and change management Failure management Provisioning Management Workload management Load balancing to provide a scalable system

Classification of Functions Basic functions Security functions Resource Management functions System properties

OGSA platform components Layers Native platform services and transport mechanisms OGSA hosting environment OGSA transport and security OGSA infrastructure( OGSI) OGSA Basic Services (meta-os and domain services)

Open Grid Service Architecture Three principal elements of OGSA: OGSI, OGSA services, OGSA applications OGSA main architecture

OGSA - Definition The Open Grid Services Architecture (OGSA) defines mechanisms for creating, managing, and exchange information among entities called Grid Services Grid Service instance: (persistent or transient) service that conforms to a set of conventions (expressed as WSDL interfaces, extensions, and behaviors) for such purposes as lifetime management, discovery of characteristics, notification, and so forth, described from a WSDL PortType PortType: a WSDL element that describes a collection of message signatures (operation elements) that define the abstract interface of the Web Service Grid Service instances are made accessible to client applications through the use of a GSH and a GSR GSH (Grid Service Handle): URI (uniform resource identifier) that identifies in univocal way a instance, directs to a GSR GSR (Grid Service Reference): WSDL document that contains information about the location of the instance

OGSI OGSI: provides a uniform way for software developers to model and interact with grid services by providing interfaces for discovery, life cycle, state management, creation and destruction, event notification, and reference management

Requesting a service

Important OGSI concepts and interactions service factory create service service requester grid service handle resource allocation service data, keep-alive, notifications, service invocation service discovery register service service instances service registry

GSH e GSR GSH1 GSR1 GSH2 GSR2 WSDL URI Grid Service Document Instance www.pc2.it/gsr1 WSDL Document 1 Grid Service Instance 1 Client GSH2 GSR2 URI www.pc3.it/gsr2 WSDL Document 2 Grid Service Instance 2

Naming Because Grid services are dynamic and stateful, we need a way to distinguish one dynamically created service instance from another. Thus, we need a naming scheme for Grid service instances.

Naming OGSI defines a two-level naming scheme for Grid service instances based on simple, abstract, long-lived Grid service handles (GSH). GSH can be mapped by handle resolution services to concrete but potentially short-lived Grid service references (GSR).

Naming A GSH is a globally unique name that distinguishes that specific Grid service instance from all other Grid service instances that have existed, exist now, or will exist in the future. A GSH is represented using a Uniform Resource Identifier.

Naming A GSH carries no protocol- or instance-specific information such as network address or supported protocol bindings. All other instance-specific information is encapsulated into a single abstraction called a Grid service reference (GSR).

Naming Resolve (GSH) handle resolver client time<T time>T GSR1 migrate service instance service instance at time T

Grid Service PortTypes (1) A Grid Service can implement following PortType: GridService: encapsulates the root behavior of the component model HandleResolver: mapping form a GSH to a GSR NotificationSource: allows clients to subscribe to notification messages NotificationSubscription: defines the relationship between a single NotificationSource and NotificationSink pair NotificationSink: defines a single operation for delivering a notification message to the service instance that implements the operation Factory: standard operation for creation of Grid Service instances Registration: allows clients to register and unregister registry contents Il testo va cambiato. Tipo: Un grid service puo’ implementare i seguenti portTypes:..... La tabella puo’ essere sostituita da una descrizione a bullet

Grid Service PortTypes (2) (required) …other interfaces… (opzional) Service data access Explicit destruction Soft-state lifetime Standard: Notification Authorization Service creation Service registry Manageability Concurrency + application-specific interfaces Implementation Qui la figura sarebbe piu efficace se vewngono messi tutti i porTypes; il colore rosso va cambiato perche’ nn si vede Hosting environment/runtime (“C”, J2EE, .NET, …)

WSDL Extensions OGSA architecture introduced WSDL extensions to allow Grid Service implementation New WSDL elements: serviceData: represents properties of the service’s state that may be externally queried serviceDataDescription: formal description of serviceData elements Convention on portType name: naming conventions and immutability of portType names Grid Service Reference Grid Service Handle

ServiceData Concept (1) Service data: to support discovery, introspection, and monitoring of Grid Service instanceò it refers to descriptive information about Grid Service instance, including Meta-Data: information about the service instance State Data: runtime properties of the service instance Each Grid Service instance has an associated set of SDEs (each one is represented in XML by a serviceData element)

ServiceData Concept (2) serviceData elements samples: Instance’s data which value can change at runtime

ServiceData Concept (3) Each Grid Service instance is associated with a set of SDEs. This set is modelled as a serviceDataSet: serviceData cpuSpeed with relative description: type, value serviceData configuration with relative description

Grid Service = Interfaces + Service Data Counter value cpuLoad

Example of Grid Service : DB Service A DBaccess Grid Service has at least two portType GridService DBaccess Each has any serviceData GridService: base informations, lifetime informations,… DBaccess: kind of database, query languages supported, current load,…

Example of Grid Service : DB Service The UK e-Science Institute collaborate in the OGSA Project, and it implemented a Grid Data Service, a Grid Service with portType to work with many database (relational, XML-DB, …) http://umbriel.dcs.gla.ac.uk/NeSC/general/ Grid Service XML-DB portType Relational-DB portType … Grid Data Service

GridService portType: operations FindServiceData: query the service data RequestTerminationAfter: request that the termination time of this service be changed RequestTerminationBefore: request that the termination time of the service be changed Destroy: explicity request destruction of this service FindServiceData(lifetime) Client

Factory portType It is used by a client to create an instance of a Grid Service It is a Grid Service that must implement the Factory portType, which provides a standard WSDL operation for creation of Grid Service instances The used operation is: CreateService Grid Service Counter Factory La grafica del servizio si deve uniformare a quella di prima. User Application Service Provider

Factory portType It is used by a client to create an instance of a Grid Service It is a Grid Service that must implement the Factory portType, which provides a standard WSDL operation for creation of Grid Service instances The used operation is: CreateService Grid Service Counter Factory La grafica del servizio si deve uniformare a quella di prima. CreateService User Application Service Provider

Factory portType It is used by a client to create an instance of a Grid Service It is a Grid Service that must implement the Factory portType, which provides a standard WSDL operation for creation of Grid Service instances The used operation is: CreateService Grid Service Counter Factory La grafica del servizio si deve uniformare a quella di prima. CreateService User Application Counter Service Provider

Registration A registry is a Grid Service that maintains a collection of GSH, with policies associated with that collection. Clients may query the registry to discover what services are available The registration portType allows clients to register and unregister registry content The registry makes available a WS-Inspection document (defined with the Web Services Inspection Language – WSIL) to aid in discovery of the services in that registry

Registration Grid Service Registry portType User Application Service Provider

Registration Grid Service Registry portType User Application RegisterService(locator 1) User Application Service Provider

Registration Grid Service Registry portType User Application GSH 1 RegisterService(locator 1) User Application GSH 1 Service Provider

Registration Grid Service Registry portType User Application GSH 1 Service Provider

Registration Grid Service Registry portType User Application GSH 1 UnregisterService(GSH 1) User Application GSH 1 Service Provider

Registration Grid Service Registry portType User Application Service Provider

Transients Database Services

Notification The purpose of the notification is to deliver interesting messages from a notification source to a notification sink Notification source: sender of the notification messages Notification sink: Grid Service instance that receives notification messages from any number of sources Notification message: XML element sent from a notification source to a notification sink Subscription expression: XML element that describes what messages should be sent from the notification source to the notification sink

Notification portTypes NotificationSource portType Subscribe NotificationSubscription portType: used from Clients to manage the subscription (lifetime and others properties) NotificationSink portType deliverNotification

USE CASE OF NOTIFICATION Grid Service Notification portType User Application X=0 Service Provider serviceData

USE CASE OF NOTIFICATION Grid Service Notification portType User Application Subscribe(x=1, sink, exp time) X=0 Service Provider serviceData

USE CASE OF NOTIFICATION Grid Service Notification portType User Application X=0 Service Provider serviceData

USE CASE OF NOTIFICATION Grid Service Notification portType User Application X=1 Service Provider serviceData

USE CASE OF NOTIFICATION Grid Service Notification portType User Application DeliverNotification(x=1) X=1 Service Provider serviceData

HandleResolver portType A Handle Resolver is a Grid Service instance that implements the HandleResolver portType FindByHandle: returns a serviceLocator, which contains one or more GSR (Grid Service Reference) for a GSH (Grid Service Handle)