Grid Services B.Ramamurthy 12/28/2018 B.Ramamurthy

Material The presentation is based on the two main publications on grid computing given below: The Physiology of the Grid, An Open Services Architecture for Distributed Systems Integration, by Ian Foster, Carl Kesselman, Jeffrey Nick, and Steven Tuecke, 2002. The paper explains how a grid functions and how grid technologies can be implemented and applied. URL:http://www.globus.org/research/papers.html 12/28/2018 B.Ramamurthy

Open Grid Services Architecture Builds on concepts and technologies from the Grid and Web services communities. Defines a uniform exposed service semantics. Defines standard mechanisms for creating, naming, and discovering transient grid service instance; Provides location transparency and multiple protocol bindings Supports integration with underlying native platform facilities. Defines WSDL definition for creating sophisticated distributed system including lifetime management, change management, and notification. It also supports authentication, authorization, and delegation. 12/28/2018 B.Ramamurthy

Contents of the paper Describes the nature of the services that respond to the protocols. Explains how grid technologies can be aligned with web services technologies. Discusses commercial applications rather than the scientific and technical applications. (e-business rather than e-science) OGSA defines the interfaces to the services. 12/28/2018 B.Ramamurthy

The Need The world wide web began as a technology for scientific collaboration and was adopted for e-business. Grid may lead to a similar revolution. Two emerging technologies that support this are the enterprise computing and service providers. 12/28/2018 B.Ramamurthy

An Open Grid-services Architecture Service orientation and virtualization: A service is a network-enabled entity provides some capability. Virtualization allows the composition of services to form lower-level resources. WSDL allows for multiple bindings of a single interface, including distributed communication protocols. 12/28/2018 B.Ramamurthy

Service Semantics OGSA defines the semantics of a Grid Service instance: how it is created, how its lifetime is determined, how to communicate and so on. WSDL is used to define standard interfaces that address discovery, dynamic service creation, lifetime management, notification, and manageability. Transient services along with the conventional persistence services. Example: video conferencing, where is QoS is important. Upgradeability: services within a complex distributed system must be independently upgradeable. Needs reliable service invocation and authentication. 12/28/2018 B.Ramamurthy

Role of hosting Environment OGSA does not define the implementation of the services. The hosting environment defines not only implementation programming model, programming language, development tools, and debugging tools but also how an implementation of a Grid service meets its obligations with respect to Grid services semantics. Current implementations are in C, C++ and Fortran with linked libraries. A more sophisticated implementation can be realized by container-component-based hosting environments such as J2ee, websphere, .net and Sun One. 12/28/2018 B.Ramamurthy

Building Virtual Organization Applications create transient services and to discover and determine the properties of available services. OGSA’s Factory, Registry, GridService, and HandleMap interfaces support the creation of transient service instances and the discovery of services associated with a VO. 12/28/2018 B.Ramamurthy

Possible Environments Simple hosting environment: Set of resources located within a single administrative domain. Example: J2ee application server, MS’s .net system, or a Linux cluster. Virtual Hosting environment: VO span heterogeneous, geographically distributed “hosting environments”, a combinations several simple environments. Collective operations: A “virtual hosting environment” that provides VO participants with more sophisticated, virtual “collective” or “end-to-end” services. 12/28/2018 B.Ramamurthy

VO Organization Factory Registry Factory Mapper Service …… Service Hardware 12/28/2018 B.Ramamurthy

Rest of the paper Application example Technical details Network bindings Related work References 12/28/2018 B.Ramamurthy