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

2. 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

3. 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

4. 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

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

6. 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)

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

8. 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

9. 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

10. Requesting a service

11. 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

12. GSH e GSR GSH1 GSR1 GSH2 GSR2 WSDL URI Grid Service Document Instance
WSDL
Document 1
Grid Service
Instance 1
Client
GSH2
GSR2
URI
WSDL
Document 2
Grid Service
Instance 2

13. 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.

14. 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).

15. 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.

16. 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).

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

18. 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

19. 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, …)

20. 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

21. 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)

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

23. 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

24. Grid Service = Interfaces + Service Data
Counter value
cpuLoad

25. 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,…

26. 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, …)
Grid Service
XML-DB portType
Relational-DB portType …
Grid Data Service

27. 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

28. 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

29. 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

30. 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

31. 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

32. Registration Grid Service Registry portType User Application
Service Provider

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

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

35. Registration Grid Service Registry portType User Application GSH 1
Service Provider

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

37. Registration Grid Service Registry portType User Application
Service Provider

38. Transients Database Services

39. 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

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

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

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

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

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

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

46. 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)