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OGSI for Network Measurement

OGSI for Network Measurement. Keith R. Jackson Lawrence Berkeley National Laboratory krjackson@lbl.gov. Overview. Globus Project / Open Grid Services Architecture (OGSA) OGSI Specification Service Data Elements Service Data Operations Notification Acknowledgements / Contact Information.

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OGSI for Network Measurement

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  1. OGSI for Network Measurement Keith R. Jackson Lawrence Berkeley National Laboratory krjackson@lbl.gov

  2. Overview • Globus Project / Open Grid Services Architecture (OGSA) • OGSI Specification • Service Data Elements • Service Data Operations • Notification • Acknowledgements / Contact Information

  3. Grid Evolution:Open Grid Services Architecture • Refactor Globus protocol suite to enable common base and expose key capabilities • Service orientation to virtualize resources and unify resources/services/information • Embrace key Web services technologies for standard IDL, leverage commercial efforts • Result: standard interfaces & behaviors for distributed system management: the Grid service Courtesy of the Globus Project™

  4. OGSA Structure • A standard substrate: the Grid service • OGSI = Open Grid Service Infrastructure • Standard interfaces and behaviors that address key distributed system issues • Much borrowed from GT abstractions • … supports standard service specifications • Resource mgt, dbms, workflow, security, … • Target of current & planned GGF efforts • … and arbitrary application-specific services based on these & other definitions Courtesy of the Globus Project™

  5. Transient Service Instances • “Web services” address discovery & invocation of persistent services • Interface to persistent state of entire enterprise • In Grids, must also support transient service instances, created/destroyed dynamically • Interfaces to the states of distributed activities • E.g. workflow, video conf., dist. data analysis, subscription • Significant implications for how services are managed, named, discovered, and used • In fact, much of Grid is concerned with the management of service instances Courtesy of the Globus Project™

  6. Standard Interfaces & Behaviors:Four Interrelated Concepts • Naming and bindings • Every service instance has a unique name, from which can discover supported bindings • Lifecycle • Service instances created by factories • Destroyed explicitly or via soft state • Information model • Service data associated with Grid service instances, operations for accessing this info • Basis for service introspection, monitoring, discovery • Notification • Interfaces for registering existence, and delivering notifications of changes to service data Courtesy of the Globus Project™

  7. Open Grid Services Infrastructure Specification

  8. OGSI Grid Service Specification • Defines WSDL conventions and GSDL extensions • For describing and structuring services • Working with W3C WSDL working group to drive GSDL extensions into WSDL • Defines fundamental interfaces (using WSDL) and behaviors that define a Grid Service • A unifying framework for interoperability & establishment of total system properties Courtesy of the Globus Project™

  9. Courtesy of the Globus Project™ OGSI Specification The Specification Defines how Entities can Create, Discover and Interact with a Grid Service GridService (required) … other interfaces … (optional) • Optional: • Service creation- Notification • Registration • Service Groups • + application-specific interfaces • Required: • Introspection (service data) • Explicit destruction • Soft-state lifetime Service data element Service data element Service data element Service Implementation

  10. Courtesy of the Globus Project™ OGSI Specification (cont.) GridService portType • Defines the fundamental behavior of a Grid Service • Introspection • Discovery • Soft State Lifetime Management • Mandated by the Spec

  11. Courtesy of the Globus Project™ OGSI Specification (cont.) Factory portType • Factories create services • Factories are typically persistent services • Factory is an optional OGSI interface (Grid Services can also be instantiated by other mechanisms)

  12. Courtesy of the Globus Project™ OGSI Specification (cont.) Notification portTypes • A subscription for notification causes the creation of a NotificationSubscription service • NotificationSinks are not required to implement the GridService portType • Notification portTypes are optional

  13. Courtesy of the Globus Project™ OGSI Specification (cont.) Service group portTypes • A ServiceGroup is a grid service that maintains information about a group of other grid services • The classic registry model can be implemented with the ServiceGroup portTypes • A grid service can belong to more than one ServiceGroup • Members of a ServiceGroup can be heterogenous or homogenous • Each entry in a service group can be represented as its own service • Service group portTypes are optional OGSI interfaces

  14. Courtesy of the Globus Project™ OGSI Specification (cont.) HandleResolver portType • Defines a means for resolving a GSH (Grid Service Handle) to a GSR (Grid Service Reference) • A GSH points to a Grid Service (GT3 uses a hostname-based GSH scheme) • A GSR specifies how to communicate with the Grid Service (GT3 currently supports SOAP over HTTP, so GSRs are in WSDL format) • HandleResolver is an optional OGSI interface

  15. Courtesy of the Globus Project™ A Service Creation Scenario Registry 1. From a known registry, the client discovers a factory by querying service data Client

  16. Courtesy of the Globus Project™ A Service Creation Scenario Registry Factory 2. The client calls the createService operation on the factory 1. From a known registry, the client discovers a factory by querying service data Client

  17. Courtesy of the Globus Project™ A Service Creation Scenario Registry Factory 2. The client calls the createService operation on the factory 1. From a known registry, the client discovers a factory by querying service data 3. The factory creates a service Client Service

  18. Courtesy of the Globus Project™ A Service Creation Scenario Registry Factory 2. The client calls the createService operation on the factory 1. From a known registry, the client discovers a factory by querying service data 3. The factory creates a service 4. The factory returns a locator Client Service

  19. Courtesy of the Globus Project™ A Service Creation Scenario Registry Factory 2. The client calls the createService operation on the factory 1. From a known registry, the client discovers a factory by querying service data 3. The factory creates a service 4. The factory returns a locator Client Service 5. The client and service interact

  20. Courtesy of the Globus Project™ A Notification Scenario NotificationSource 1. NotificationSink calls the subscribe operation on NotificationSource NotificationSink

  21. Courtesy of the Globus Project™ A Notification Scenario NotificationSource 1. NotificationSink calls the subscribe operation on NotificationSource 2.NotificationSource creates a subscription service NotificationSubscription NotificationSink

  22. Courtesy of the Globus Project™ A Notification Scenario NotificationSource 1. NotificationSink calls the subscribe operation on NotificationSource 2.NotificationSource creates a subscription service 3. Notification Source returns a locator to the subscription service NotificationSubscription NotificationSink

  23. Courtesy of the Globus Project™ A Notification Scenario 4.a deliverNotification stream continues for the lifetime of NotificationSubscription NotificationSource 1. NotificationSink calls the subscribe operation on NotificationSource 2.NotificationSource creates a subscription service 3. Notification Source returns a locator to the subscription service NotificationSubscription NotificationSink 4.b The NotificationSink and Subscription service interact to perform lifetime management

  24. Service Data Elements

  25. Service Data Elements • Standard way to expose a service instance’s state data. • No service data specific operations defined. • No getXXX() or setXXX() functions • GridService portType defines base operations for manipulating Service Data by name • A new child element of portType is defined: serviceData. <gwsdl:portType name="NCName"> * <wsdl:documentation .... /> ? <wsdl:operation name="NCName"> * … <sd:serviceData name="NCName" … /> * <sd:staticServiceDataValues>? <some element>*

  26. SDE Example <wsdl:definitions xmlns:tns=”xxx” targetNamespace=”xxx”> <gwsdl:portType name="exampleSDUse"> * <wsdl:operation name=…> … <sd:serviceData name="sd1" type=”xsd:String” mutability=”static”/> <sd:serviceData name="sd2" type=”tns:SomeComplexType”/> … <sd:staticServiceDataValues> <tns:sdl>initValue</tns:sd1> </sd:staticServiceDataValues> </gwsdl:portType> … </wsdl:definitions>

  27. SDE Schema Elements • maxOccurs = (nonNegativeInteger | unbounded) : default to 1 • This value indicates the maximum number of serviceData element values that can appear in the service instance’s serviceDataValues or the portType staticServiceDataValues. • minOccurs = nonNegativeInteger : default to 1 • This value indicates the minimum number of serviceData element values that can appear in the service instance’s serviceDataValues or the portType staticServiceDataValues. • If the value is 0, then the serviceData element is optional

  28. SDE Schema Elements (cont.) • name = NCName and {target namespace} • The name of the serviceData element must be unique amongst all sd:serviceData and xsd:element declarations in the target namespace of the wsdl:definitions element. • The combination of the name of the serviceData element and the target namespace of the wsdl:definitions element’s targetNamespace attribute forms a QName, allowing a unique reference to this serviceData element. • nillable = boolean : default to false • Indicates whether the serviceData element can have a nil value (that is a value that has an attribute xsi:nil with value=“true”). • For example a serviceData declaration • <serviceDataElement name=”foo” type=”xsd:string” nillable=true” /> • can have a valid SDE value • <foo xsi:nil=”true”/>

  29. SDE Schema Elements (cont.) • type = QName • Defines the XML schema type of the serviceData element value • modifiable = “boolean” : default to false • If true, it is legal for requestors to directly update the serviceData value through the setServiceData operation (see §9.2.2), subject to constraints on cardinality (minOccurs, maxOccurs) and mutability. If false, the serviceData element should be regarded as “read only” by the requestor, though its values may change as a result of other operations on the service’s interface. • mutability = “static” | “constant” | “extendable” | “mutable” : default to extendable • An indication of whether and how the values of a serviceData element can change.

  30. SDE Schema Elements (cont.) • {any attributes with non-schema namespace} • Open content on the attributes of serviceData declaration is allowed. • Content • annotation • This element allows documentation elements to appear as children of a serviceData declaration • Open content element model, meaning elements from any other namespace (besides XML Schema) may appear as child elements of the serviceData element. • A serviceData element extends a restricted of xsd:element to allow open element content model,

  31. Service Data Operations

  32. findServiceData GridService :: findServiceData Query the service data. Input • QueryExpression: The query to be performed. This extensib le parameter MUST conform to an inputElement declaration denoted by one of the findServiceDataExtensibility SDE values. Note: The service infers what to do based on the tag of the root element of this argument. Output • Result: The result of the query. The format of this result is dependent upon the QueryExpression.

  33. findServiceData (cont.) Fault(s) • ExtensibilityNotSupportedFault: Indicates that the service cannot evaluate the QueryExpression because its type is not supported by this service. • ExtensibilityTypeFault: Indicates that the value passed as the QueryExpression violates that value’s type. • TargetInvalidFault: Indicates that one or more of the SDEs that the QueryExpression requires do not exist in this service. • Fault: Any other fault.

  34. setServiceData GridService :: setServiceData This operation allows for the modification of a service data element’s values, if its service data declaration specifies modifiable=”true”. Changing a modifiable service data element implies changing the corresponding state in the underlying service instance. If no service data elements have a modifiable=”true” attribute then setServiceData is essentially disabled. Input • UpdateExpression: The update to be performed. This extensible parameter MUST conform to an inputElement declaration denoted by one of the setServiceDataExtensibility SDE values. Note: The service infers what to do based on the tag of the root element of this argument

  35. setServiceData (cont.) Output • Result: The result of the update. The format of this result is dependent upon the UpdateExpression. Fault(s) • ExtensibilityNotSupportedFault: Indicates that the service cannot evaluate the UpdateExpression because its type is not supported by this service. • ExtensibilityTypeFault: Indicates that the value passed as the UpdateExpression violates that value’s type. • CardinalityViolationFault: Indicates that operation requested would violate the “minOccurs” and/or “maxOccurs” attributes of the service’s SDE(s). • MutabilityViolationFault: Indicates that the UpdateExpression was not consistent with the “mutability” attribute of the service’s SDE(s). • ModifiabilityViolationFault: Indicates that the UpdateExpression was not consistent with the “modifiable” attribute of the services’s SDE(s).

  36. setServiceData (cont.) • TypeViolationFault: Indicates that the UpdateExpression contains values that do not conform to the XSD type of the service’s SDE(s). • IncorrectValueFault: Indicates that the UpdateExpression contains values that are XSD type conformant, but are not acceptable to the service for other reasons. • PartialFailureFault: Indicates that servic e was unable to satisfy all portions of the UpdateExpression. This fault extends FaultType with an element that contains a list of qnames of SDEs from the UpdateExpression that could not be updated. This fault MAY have 1 or more “faultcause” elements that describe in more detail the portions that failed, using any of the fault types allowed by setServiceData. • Fault: Any other fault.

  37. Notification

  38. Notification portTypes • Notification Source • Source of notification messages. May send to multiple sinks • Notification Sink • Receives notification messages from any number of notification sources • Not required to implement the GridService portType • NotificationSubscription • Created from a subscription message and used to manage a subscription

  39. Notification Source SDE’s • notifiableServiceDataName • A set of QNames of service data elements to which a requestor MAY subscribe for notification of changes. <sd:serviceData name=”notifiableServiceDataName” type=”xsd:QName” minOccurs=”0” maxOccurs=”unbounded” mutability=”mutable” modifiable=”false” nillable=”false”/> • subscribeExtensibility • A set of operation extensibility declarations (§7.8) for the subscribe operation. Any conforming inputElement declared by values of this SDE MAY be used by the client as a SubscriptionExpression parameter to the instance’s subscribe operation, and implies the subscription semantics and notification message that result from the subscription. <sd:serviceData name=”subscribeExtensibility” type=”ogsi:OperationExtensibilityType” minOccurs=”1” maxOccurs=”unbounded” mutability=”static” modifiable=”false” nillable=”false”/>

  40. Notification Source SDE’s (cont.) • The NotificationSource portType also includes the following initial service data value elements. <sd:staticServiceDataValues> <ogsi:subscribeExtensibility inputElement=”ogsi:subscribeByServiceDataNames” /> </sd:staticServiceDataValues>

  41. Notification Source Operations NotificationSource :: subscribe Subscribe to be notified of subsequent changes to the target instance’s service data. This operation creates a Grid service subscription instance, which MAY subsequently be used to manage the lifetime and discovery properties of the subscription. Input: • SubscriptionExpression: The subscription to be performed. This extensible parameter MUST conform to an inputElement declaration denoted by one of the subscribeExtensibility SDE values. Note: The service infers what to do based on the tag of the root element of this argument. • Sink : The locator of the notification sink to which messages will be delivered. This locator MAY be to some other service than the one issuing this subscription request, thus allowing for third-party subscriptions. This locator MAY contain only references, thus allowing it to refer, for example, to a Web service that implements the NotificationSink portType but that does not have a handle. • ExpirationTime: The initial time at which this subscription instance should terminate, and thus notification delivery to this sink be halted. Normal GridService lifetime management operations MAY be used on the subscription instance to change its lifetime.

  42. Notification Source Operations (cont.) Output: • SubscriptionInstanceLocator: A locator to the subscription instance that was created to manage this subscription. This subscription instance MUST implement the NotificationSubscription portType. • CurrentTerminationTime: An element of type TerminationTimeType (as defined in §7.6) that gives the NotificationSubscription service's currently planned termination time. The timestamp attribute of this CurrentTerminationTime MUST be the time at which the NotificationSubscription service was created.

  43. Notification Source Operations (cont.) Fault(s): • ExtensibilityNotSupportedFault: Indicates that the service cannot evaluate the SubscriptionExpression because its type is not supported by this service. • ExtensibilityTypeFault: Indicates that the value passed as the SubscriptionExpression violates that value’s type. • TargetInvalidFault: Indicates that one or more of the SDEs that the SubscriptionExpression requires does not exist in this service. • Fault: Any other fault.

  44. Notification Subscription SDE’s • subscriptionExpression The current subscription expression managed by this subscription instance. <sd:serviceData name=”subscriptionExpression” type=”xsd:anyType” minOccurs=”1” maxOccurs=”1” mutability=”mutable” modifiable=”false” nillable=”false”/> • sinkLocator The Grid Service Locator of the Notification sink to which this subscription is delivering messages. <sd:serviceData name=”sinkLocator” type=”ogsi:LocatorType” minOccurs=”1” maxOccurs=”1” mutability=”mutable” modifiable=”false” nillable=”false”/>

  45. Notification Sink Operations NotificationSink :: deliverNotification Deliver message to this service. Input: • Message: An XML element containing the notification message. The content of the message is dependent upon the notification subscription. This operation is input-only, so it does not return an output or faults.

  46. Acknowledgement • Thanks to the Globus project • More information can be found at • http://www.globus.org/ • http://www.ggf.org/ • Email: • krjackson@lbl.gov

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