GT3 Index Services Lecture for Cluster and Grid Computing, CSCE 490/590 Fall 2004, University of Arkansas, Dr. Amy Apon

References w.html WooKang.ppt indexgrid/?ca=dgr-lnxw02IndexGT3

GT3 Index Services GT3 provides an “index services” as a higher level service to access service data provided with a Grid Service Service data can include both hardware and software details of service Can be state information or service metadata

"Information service, implemented as the Index Service, is one of the GT3.2 Base Services. It collects, aggregates, and queries Service Data; monitors data feeds; and creates Service Data dynamically on demand. It can be used to index Service Data carrying state information from multiple grid service instances for use in resource discovery, selection and optimization." - IBM

Derived from The Globus Toolkit 3 Programmer’s Tutorial” by Borja Sotomayor, 2004, page 65. addListener to subscribe notifyChange when change occurs deliverNotification to notify subscribers

GT3 Index Service From “Grid Computing” by J. Joseph and C. Fellenstein, page 340.

Index Service key capabilities (1) An interface for connecting external Service Data Provider programs to service instances –The Index Service provides a standard mechanism for dynamic generation of service data via external programs. –These external provider programs can be the core providers that are part of GT3 or user- created, custom providers.

Index Service key capabilities (2) A generic framework for aggregation of service data –Service data coming in from various Service Data Provider programs can be aggregated in different ways and indexed to provide efficient query processing. –The Index Service also provides a standard mechanism for registration, polling, and notification/subscription of service data.

Index Service key capabilities (3) A Registry of Grid services –A set of available Grid services is maintained in a Registry. –A Registry allows for soft-state registration of Grid services, in that a set of services can be registered and periodically updated as required. –A Registry then can be used to support query

Index Service key capabilities (4) A dynamic data-generating and indexing node, suitable for use in a hierarchy or federation of services –The Index Service combines ServiceDataProviderExecution components with DataAggregation and ServiceGroup components to create a dynamic data-generating and indexing node, similar in concept to an MDS2 hierarchical GIIS. –Index Services can be combined in a variety of topologies, useful in building Virtual Organizations.

Aggregator Mechanism (caching here) Provider Mechanism Java Provider Grid Service Grid Service Grid Service Index Service User Service Data Service Data Service Data Notification Message Existence Notification Message Service Data Service Data Collective Layer Resource Layer Registry Mechanism GSH GT3 Index Service

Interfaces and Functions Factory –Used to create a new Grid service instance via its CreateService operation. –A Factory returns a Grid Service Handle (GSH) as described below –It maintains a set of Service Data Elements that can be queried.

Interfaces and Functions Grid Service Handle (GSH) –Returned by the Factory create operation. –A GSH is a URL used to globally name a Grid service instance for all time. –A GSH must be converted to a Grid Service Reference in order to use the service.

Interfaces and Functions Grid Service Reference (GSR) –Describes how a client can communicate with a Grid service instance. –The HandleMap interface allows a client to map from a GSH to a GSR. –While the GSH represents name only, the GSR includes binding information for transport protocol and data encoding format.

Interfaces and Functions Query –Provides extensible query language support. A Grid service instance maintains a set of Service Data Elements. The FindServiceData operation from the GridService interface is used to query this information. NotificationSource interface used for client subscription Can use push or pull The ogsi-find-service-data command is a command line client to the query interface.

Interfaces and Functions Registry –Supports discovery by returning the GSHs of a set of Grid services. –A Registry allows for soft-state registration of Grid services –That is, a set of Grid services can periodically register their GSHs into a Registry service to allow for discovery of services in that set.

Interfaces and Functions Notification –Used for client subscription, to register interest in a service. –It sends notification messages about registered topics. –These topics can be linked to arbitrary values (state values) generated by a service at runtime or linked to a service data element. –The NotificationSink interface is used for asynchronous delivery of notification messages; it can be applied to dynamic discovery/registration services, monitoring, application error notification, etc.

Summary of Interfaces&Functions Grid service instance is created by the Factory interface The Factory interface returns a GSH to identify the service. The GSH is converted to a GSR (which includes binding information) so that the service can be used.

Summary of Interfaces&Functions Service instances can be identified in a Registry, which can be used to support query or other operations on a given service. The Notification interface provides for subscription to and delivery of notification messages regarding service-related events. Project idea: Set up a Registry and demonstrate the use of it in a substantial way