Annotations - swe574-spring23/SWE574 GitHub Wiki

This page shows a documentation for Web Annotation Data Model.

Introduction

Annotations are used to provide information about a resource or the relationships between resources. Examples include a remark or tag on a single web page or picture, as well as a blog entry on a news story.

An annotation is a group of related resources, like a body and a target, that shows how the body is connected to the target. The exact nature of this relationship depends on the goal of the annotation, but most of the time, the body is "about" the target in some way.

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The Web Annotation Data Model provides an extensible, compatible framework for expressing annotations in a way that makes them easy to share between platforms. This framework allows annotations to be expressed in a way that is rich enough to meet complex requirements but simple enough to support common use cases, like attaching a piece of text to a single web resource.

The main goal of the Web Annotation Data Model is to create a standard model and format for describing annotations so that they can be shared between different systems.

This interoperability can be used to share with others or move private annotations from one device or platform to another. The shared annotations should be able to be added to and used with other collections without losing important information.

The model should be able to handle as many different ways to annotate as possible, while keeping simple annotations easy to use and building on that base to allow for more complex uses.

Framework

Annotation

An Annotation is a Web Resource. Typically, an Annotation has a single Body, which is a comment or other descriptive resource, and a single Target that the Body is somehow "about".

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Bodies and Targets

The Web is distributed, with different systems working together to provide access to content.

Annotations can be used to link those resources together, being referenced as the Body and Target.

The Target resource is always an External Web Resource, but the Body may also be embedded within the Annotation.

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Web Annotation Principles

The Web Annotation Data Model is defined using the following basic principles:

  • An Annotation is a rooted, directed graph that represents a relationship between resources.

  • There are two primary types of resource that participate in this relationship, Bodies and Targets.

  • Annotations have 0 or more Bodies.

  • Annotations have 1 or more Targets.

  • The content of the Body resources is related to, and typically "about", the content of the Target resources.

  • Annotations, Bodies and Targets may have their own properties and relationships, typically including creation and descriptive information.

  • The intent behind the creation of an Annotation or the inclusion of a particular Body or Target is an important property and represented by a Motivation resource.

The following principles describe additional distinctions regarding the exact nature of Target and Body:

The Target or Body resource may be more specific than the entity identified by the resource's IRI alone.

In particular,

  • The Target or Body resource may be a specific segment of the resource.
  • The Target or Body resource may be styled in a specific way.
  • The Target or Body resource may be a specific state of the resource.
  • The Target or Body resource may be included in the Annotation to play a specific role.
  • The Target or Body resource may be any combination of the above.
  • The resource with these constraints is a separate resource from the Annotation, Body or Target, and is called a SpecificResource.
  • The SpecificResource refers to the source resource and the constraints that make it more specific.
  • The identity of the SpecificResource is separate from the descriptions of the constraints.
  • The Body resource may be a choice between multiple resources.

The properties of external resources, such as Bodies and Targets, included in the Annotation document are intended as hints to the client, and are not to be considered authoritative information. This includes properties such as the created time, the creating agent, the modification time, any rights assertions, format, language or text direction of the external resource.

Other Properties

Lifecycle Information

The person, group, or machine that made the annotation or linked resource should get credit for their work, and the time at which those resources were made can be used to sort content and get rid of old or irrelevant information. The person who made the Annotation is also a good way to figure out how reliable it is.

Agents

An IRI might not enough to tell who made an Annotation. Instead, you need more information about them. This includes their real name, account nickname, and email address, as well as whether they are a person, a group, or a piece of software.

Intended Audience

In addition to the agents who create and manage the Annotation and other resources, it is also helpful to know the audience or class of agents who will use the resource. This makes it possible to record the roles (like teacher vs. student) or properties of the class (like the suggested age range) of the audience.

Accessibility of Content

The United Nations says that access to information is a basic human right. Even if there are physical barriers to communication and interaction, the Web can get rid of them. This helps bring people together, but it also makes the information more likely to reach more people.

When a resource is used as the Body or Target of an Annotation, it is helpful to write down the parts of that resource that make it easier for people with different levels of ability to use.

Motivation and Purpose

In many situations, it is important to know why the Annotation was made or why the Textual Body was added to the Annotation, not just the times and people who were involved.

These reasons are given by explaining why the Annotation was made or why the Textual Body was included in the Annotation. This is the "why" instead of the "who" and "when" described in the previous sections.

Rights Information

It is common to attach a license or rights statement to a resource to explain how it can be used. This lets the user use the resource in the right way and also lets some automated systems check to see if the use is allowed.

Since the Annotation, Bodies, and Targets may have been made with different licenses or rights, each can be described separately. A client application that uses an Annotation looks at the rights of resources other than the Annotation itself as helpful hints.

Other Identities

In a system with a lot of different parts, like the Web, information is often copied. It is possible to record more IRIs that also identify the resource in order to track where the Annotation and other resources that are related to it came from.

These could be "permalinks" that can be used again, names given by a client who doesn't know anything about the web, or just the place where the current harvesting system found the resource.

References