Glossary

Copyright: 2010 University of Southampton, IT Innovation Centre

Introduction

This document explains the terms used in the software and documentation.

Authorisation
When an entity wants to share their access to a resource with someone else, they create an Authorisation and give this to their delegate. This allows them to manage and revoke access as needed.
Consumer <X>
An <X> that an organisation is providing to a customer (seen from the point of view of the organisation). For example, a Consumer Service is a service which you host and allow your customers to use.
External Resource
Resources provided by a Supplier SLA (i.e. where the Resource Manager is a customer of another organisation).
In-house Resource
A resource provided directly by a Service Hosting Container.
Promise
An expectation of a result at some point in the future. When a new object is requested in the graphical client, the client immediately (without waiting for a reply) displays the promise of the new object with a "*" after it (e.g. "Swirl job *"). When the Swirl service responds with the address of the new job, the promise is resolved. Alternatively, the promise may be broken. Promises can be used in place of actual resources in many places (for example, you can tell a job input to copy from a promise of another job's output).
Resource
A resource is some ability available to a service provider. Resources are registered with the Resource Manager.
Resource Manager
The Resource Manager keeps track of the organisation's Resources (in-house and external). The SLA Service uses the Resource Manager to create new Service Instances needed by the Consumer SLAs it provides.
Service Hosting Container
A hosting container is used to create and manage instances of a service. Normally, only the service administrator has access to the hosting container itself. Hosting containers create and manage Service Instances, and can be registered with a Resource Manager. For example, a Swirl Hosting Container manages Swirl Services.
Service Instance
A service is something given to a customer, typically through an SLA. A service may manage Tasks. For example, a Swirl service creates and manages Swirl jobs. A service instance may be created manually by the service administrator, or automatically by the Resource Manager.
Service Manager
Monitors commitments (agreed Consumer SLAs), potential commitments (Consumer SLA Templates) and Resources to determine whether the service provider is likely to be able to meet their commitments.
Service Registry
A Service Registry holds a set of services and allows clients (Workflow Services) to find them by submitting queries. The Resource Manager tries to ensure that the registry always holds enough services to meet the organisation's requirements.
SLA
A Service Level Agreement (SLA) is an agreement between two organisations (a customer and a provider) describing the service that will be delivered to the customer. An SLA typically includes pricing terms, limits on usage, guarantees about availability and performance, and so on. A user may propose an SLA, based on an SLA Template. If accepted, the Resource Manager is used to create Service Instances to meet the requirements of the SLA, and these services are made available to the customer. The provider hosts an "SLA" object which represents this agreement. The SLA object aggregates usage over all its services, and may change the access control policy of these services to enforce the terms of the SLA.
SLA Template
An SLA Template is an offer made by a service provider to potential customers. A template will typically offer access to one or more Services and will detail the costs, performance and usage limits of the service. A template is typically published in a public registry.
Supplier <X>
An <X> that an organisation is receiving from a supplier (seen from the point of view of the organisation). For example, a Supplier Service is a service which one of your suppliers hosts and allows you to use.
Task
A context within a service. Services can often perform several tasks at once. For example, an aircraft cleaning service may allow the user to schedule and track the cleaning of several aircraft at once.
Workflow
A workflow is a computer program that makes use of other services, using the Service Registry to locate suitable resources.