Delivery Context Ontology

1.1 Overview

The DeliveryContext Ontology provides a formal model of the characteristics of the environment in which devices interact with the Web or other services. The Delivery Context includes the characteristics of the Device, the software used to access the service and the Network providing the connection among others.

The Ontology captures the Context of Use in which a user is interacting with a particular computing platform in a given physical environment in order to achieve an interactive task.

The Ontology is formally specified in the Web Ontology Language [OWL]. It defines a normative vocabulary of terms (classes, properties and instances) that models the different Properties, Aspects and Components (Aspect instances) of a Delivery Context.

1.2 Motivation

The Delivery Context is an important source of information that can be exploited to create context-aware applications, thus providing a compelling user experience. Particularly, it can be used to adapt web content & applications to make them useable on a wide range of different devices with different capabilities.

The Ontology represents a normative, common understanding about the Delivery Context. As such it can be used as a normative reference to create specific Vocabularies, while at the same time enabling the interoperability between them.

The Delivery Context Ontology itself constitutes a vocabulary of terms and can be used in conjunction with generic APIs for retrieving Context Properties, such as [DCCI].

1.3 Understanding the Delivery Context Ontology

It is recommended to be familiar with RDF, OWL and ontologies in general before reading this specification. The [RDF-Primer] and the [OWL-Guide] are two documents which might be helpful for this purpose.

The model represented by the ontology is essentially hierarchical. At the top of the hierarchy is the DeliveryContext class, which gives access to the current UserAgent, NetworkBearer, Device, RuntimeEnvironment and pysical Environment, which are the essential elements of any Delivery Context. Each of these elements are represented by classes which have different properties that model their specific characteristics and Components.

There are a number of generic properties which domain and / or range has been left deliberately open in order to maximize reuse and genericity. For example, the Object Property common:supports, is devoted to convey what it is supported (formats, fonts, features, etc.) by any Delivery Context Entity. As such it can be used with both entities that are currently modelled within the Ontology or new entities that might appear in the future (Ontology extensions).

The UWA Working Group intends to publish tutorial materials related to this specification, containing at least:

• Diagrams that will facilitate the comprehension of the Ontology Terms and its relationships.
• Example instances that will illustrate how the Ontology works in practice.
• Guidelines for creating Vocabularies based on the Ontology.
• Guidelines for extending the Ontology with new terms.
• Examples that will illustrate how to obtain derived Properties. For instance, how to determine whether a mobile phone is in roaming or not.
• Examples of use of the Ontology in conjunction with Context APIs, particularly the [DCCI].
• Examples of use of the Ontology in combination with other widely-used Ontologies, such as [FOAF].

1.4 Scope

The Delivery Context Ontology is aimed at providing a formal and universally accepted model of the Delivery Context. As such it is not intended to model properties which can be application or domain dependent. For instance, there are a number of properties that can be derived from the properties explicitly modelled by the Ontology.

On the other hand it is noteworthy to remark that certain facets of the Context of Use are not covered by this specification. Specific examples are the User Context or a full description of the physical environment (temperature, noise, light ...). It is expected that such descriptions will be included in future versions of this specification.

2 Reading the Recommendation

This section is normative.

3.1 Definition

This section is normative.

The ontology is formally specified in OWL [OWL]. The documentation of the different ontology terms has been automatically generated from the OWL file.

The ontology conforms to the OWL-DL expressivity. This allows it to be used within appropriately written reasoning systems.

3.2 URI

This section is normative.

The ontology URI is http://www.w3.org/2007/uwa/context/deliveryContext.owl .

3.3 Namespaces

This section is normative.

The table below describes the different namespace URIs defined by the Ontology. Namespaces allow to create groups of terms.

3.4 Term Groups

This section is normative.

For modularity reasons, the Ontology has been splitted into the following groups of terms:

• Common
• Hardware
• Java
• Location
• Main
• Network
• Push
• Software
• Web Browsing

3.5 Measurement Units Representation

This section is informative.

A number of properties in the Ontology represent physical magnitudes. The same magnitude, for instance "length", can be measured using different units ("meters", "inches", "feet", "milimeters", etc), yielding to different numeric values depending on the unit used. However, from a conceptual point of view, all of these values are (or should be) actually equivalent.

RDF nor OWL supports to tag a literal value with its measurement unit. In other words, RDF literal nodes can represent discrete numeric values, such as "10" or "9.81", but a literal node does not capture the unit used to express the value. On the other hand, the problem of ontological modelling of measurement units is still open to debate and goes beyond the scope of this specification. For example, the [MUO Ontology] is a recent proposal for modelling measurement units using OWL.

In this version of the Ontology, each Property that represents a magnitude has to be expressed normatively in a single unit. This solution is simple and at the same time maximizes interoperability. However, it is also recognized that this approach might not be suitable in all scenarios, due to both practical (some scales are more conveniently captured using certain units) and cultural reasons. Therefore, it is expected that, once a Measurement Units Ontology is widely adopted (and standardized), future versions of this specification will allow to represent magnitudes using different units.

3.6 Instances

This section is informative.

Only a minimum set of instances has been declared as normative in this specification. This has been done for simplicity and maintainability reasons. On the other hand it is important to remark that Vocabularies based on the Ontology may define their own normative instances for representing specific values within their respective domains. For example, the [DDR Core Vocabulary] enumerates different instances for image formats or markup languages.

Nonetheless, the main OWL file (distributed as a companion resource), contains a number of utility instances that can come in handy for Ontology users or implementors. Instances for character sets, MIME Types, network technologies and formats, among others, are included.

In addition, example instances (under the http://www.example.org namespace) are also distributed with the only purpose of illustrating how the Ontology works in practice.