Category:Service Descriptions

Overview
A service description is a high level description of some aspect of e-assessment functionality.

Service descriptions are primarily used in the reference model to match up software components (especially web services) with domain behaviour.

For example, a service description may be called “Author Item Service”. The reference model allows you to
 * examine the internal functionality (behaviour) which this service description encapsulates (e.g. does it include tagging of items?) - thereby allowing you to gauge how closely it matches your understanding of "authoring items".
 * see what other FREMA components are related to this service description (see below)
 * in particular, via the Gap Analysis Tool, determine which, if any, software components satisfy this service description. If there's a match, then you can download and reuse existing software (thus saving time and effort).

Note that a service description
 * is not executable programming code (such as Java)
 * can be expressed in either
 * an informal language (e.g. Structured English)
 * or a more formal description language such as WSDL (Web Services Description Language).

How service descriptions emerge in the reference model
If you examine the FREMA Ontology Diagram, you'll see that Service Description is connected to several other components, in particular


 * Software (code)
 * Use Case (behaviour)
 * Service Description (behaviour)
 * Pattern (behaviour)

Therefore, a service description is a means of interrelating code and behaviour.

Service descriptions emerge in FREMA via two main routes:


 * 1) Bottom up approach - a service description can be created for any existing web service. It specifies the public methods (and their interfaces) exposed by that web service.
 * 2) Top Down approach – modelling e-assessment behaviour (e.g. deriving use cases) leads to the generation of generic service descriptions, which represent actual behaviour practiced in the domain.

Attributes
Name – name of service description - describe the functionality as fully as possible – e.g. “Tagging QTI v1.2 items with LOM metadata”. Don’t put “service description” in the text of this attribute

Version – the version number or code e.g. 2.0 (don’t prefix with “v” or “version”)

Description – high level overview of the web service.

Related Components and Associations
The following table identifies the other components to which Service Description is associated. Click on an association below to find out more information.

How to create a new Service Description
You create a new service description to represent either
 * the explicit functionality exposed by an existing software component
 * generic functionality derived from high level behaviour (e.g. use case, pattern)

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