Core: Key Concepts

Overview
Interdependence with other components

Overview

The following figure illustrates the GT3 core architecture. Core components are represented by a white background.

The core component of the Globus Toolkit version 3 contains the basic infrastructure needed for building grid services. In particular, it is comprised of the following major subcomponents:

OGSI Spec Implementation	An implementation of the OGSI Specification , i.e., an implementation of all OGSI specified interfaces.
Security Infrastructure	This subcomponent provides support for message level security, authentication and gridmap based authorization. The message level security implementation provides session (GSI-SecureConversation) as well as per-message (GSI-SecureMessage) based security. More information can be found here
System level services	System level services are OGSI-compliant grid services that are generic enough to be used by all other grid services. Currently the toolkit contains three system level services:
	Ping service	Used to "ping" a hosting environment.
	Logging Management Service	Allows you to modify log filters and to group existing log producers into more easily manageable units at run time.
	Management Service	Provides an interface for monitoring the current status and load of a grid service container and to cleanly shut down a container. It also allows you to activate and deactivate service instances.
	Note: The Admin Service (which formerly contained the ping and shutdown services) was deprecated in GT 3.2.

More information can be found in the GT3 Core white paper

Interdependence with other components

GT3.2 Core itself depends on and is required by a number of other components.

The components GT3.2 Core depends on are:

• A hosting environment that provides traditional web server functionality, such as a transport mechanism, e.g. HTTP.
  
  GT3.2 ships with lightweight embedded and standalone hosting environments, but will also work with a standard Java Servlet Engine, e.g. Tomcat, and EJB application servers, e.g. JBOSS or Websphere.
  
• A web service engine which is responsible for implementing XML Messaging.
  
  GT3.2 currently depends on the Apache Axis project for this component.

Components that require GT3.2 Core are:

• The base service component which contains the higher level services such as the WS GRAM (program execution) and Reliable File Transfer services that ship with GT3.2.
  
• User-defined services. This term denotes services outside of the toolkit that are developed on top of any subset of GT3.2 components ,including the base services.