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XML and Content Reuse Systems for Instructional Design Part I: Introduction to XML and Repository Technologies

by Henry Meyerding

January 19, 2004


by Henry Meyerding

January 19, 2004

The promise: "Write it once, use it many times." Here's a high-level overview of content reuse and the technology involved.

XML as a content reuse methodology is a very complex and technical topic. Instructional designers seeking to discover the impacts of XML technology on the field of instructional design are very often frustrated by the available technical white papers which usually fail to speak to the practical needs of instructional design.

This three-part series is written for experienced instructional designers who wish to understand content reuse in an XML environment. These articles describe XML and discuss how XML can be used in an instructional design setting to manage and facilitate the definition, use, and distribution of learning objects. This first article explains the basic underlying concepts at a non-technical level and relates those concepts to instructional design processes. The second article discusses taxonomies, processes and tools that can be used in conjunction with different source repositories. The final article describes different implementations and how to determine the return on investment for content reuse systems.

XML and Content Reuse Systems for Instructional Design


“Write it once... use it many times.”

This simple statement describes the function and attraction of extensible markup language (XML) as an authoring methodology.

In its simplest form, a learning object is discrete information that speaks to a specific learning objective. That being said, learning objects are not simple things, but are complex constructs of information, presentation and interaction. Designers traditionally have seen themselves as artisans who create unique learning tools for each new learning situation. They have been very slow to make the transition in their thinking to a systematized approach to the development and delivery of learning. They have also spent long weary years learning how to use particular tools and will resist giving up their hard-earned virtuosity, even when the tools in question are obviously a barrier to meaningful improvement.

At the same time, the enterprises for which most instructional designers work have been under increasing pressure to provide training more efficiently. Training departments that are unwilling or unable to deliver substantial increases in efficiency risk being replaced by outside contracting firms that promise to deliver these efficiencies.

XML has become a standard means of information interchange within the computer industry. Using XML to create and manage learning objects is not just a theory, but has a long track record of use in the real world. It offers greater efficiency without reducing the quality of the training deliverables.

But working within an XML environment requires a change in perspective. Instead of approaching each task as the resolution to a specific obstacle to learning for a specific audience, the designer must analyze the task in a wider context. With whom does this audience share this learning requirement? How can this learning obstacle be resolved for all students, not just the students involved in the immediate situation? If this objective does not apply to other groups, are there components within it that do apply to a wider audience? What existing training can be pulled into this task and modified to work, without affecting the quality of the learning? What other training is relevant to the content currently under development? How can these new content objects be fitted to other uses?

Some experienced designers, who are more used to routine and repetitive iterations of vast waves of training materials, may find very little in the previous paragraph that speaks to their job description. Their organizations have identified deliverable requirements, methodologies and audiences for them and the designers are charged with producing the required quantity of training that meets a relatively low quality standard. The attractive feature of XML to these designers is that it offers a way to respond to practically impossible demands for training with substantially less drudgery, thus allowing designers to build at a higher standard of quality, which is (or which should be) always on the nice-to-have list.

Instead of being a creative artist fashioning unique responses to specific learning requirements, the designer becomes a production professional who analyzes the learning needs of a specific group as those needs relate to the generalized requirements of the entire learning community. The importance of designers clearly understanding the capabilities and rationale behind the content reuse system cannot be stated strongly enough.

The changeover into an XML content development and production environment really represents the same quantum leap in capability as was achieved by replacing typewriters with word processing on computers. Managers must be evangelists of XML technology’s liberating capabilities and they must be zealous in training their staffs to understand these capabilities. There has never been a system so good that it could not be rendered totally ineffective by resistant participants!

One of the incidental benefits of operating in an XML learning object environment is that designers are exposed to content created by other designers much more than in traditional project environments. Properly managed, the specialized understanding of different teams is more effectively shared, and the quality of the output is increased.


Before launching into a discussion of XML in more depth, it is important to understand some of the terminology that will be used throughout this series of articles.

Attribute — The characteristic of an XML element that defines the content. Example: If the elements are class, type, and color; corresponding attributes might be toy, rubber ball, and red.

Chunking — The process by which legacy content is tagged for inclusion in the content database.

Content — Content is information. It may take the form of text, graphics, audio, or video.

Database — A hierarchical distribution of data arranged in relationships that provide quick access to information of interest.

Document — Strictly speaking, when working in XML there is only one super document that contains all the content. This content fits into a common structure. We extract pieces of this super-document and publish it as document instances, which may be either static or dynamic.

Dynamic Instance — When publishing a document instance, it may contain information that changes continuously. In defining the document publication instance, it may be desirable that every time a user opens the instance they see the most recently updated information. This contrasts with static instance.

Element — An XML element is a definition for content. Any piece of content may be defined by one or several elements. Examples: class, type, and color.

HTML — Hypertext Markup Language — developed from SGML as a means of conveying information on the Web.

Learning Object — A functional component of training curriculum; a building block. Each learning object generally addresses a specific learning goal. Just how specific a goal varies from system to system.

Legacy Content — Content, usually in electronic form, such as text, graphics, audio or video that has been developed outside of an XML content environment. Legacy content often resides in short-lived proprietary formats, which make reuse or conversion problematical.

Metalanguage — The language that is used to talk about (expressions of) another language, the object language. XML contains and identifies content, but the XML is not the content.

Parse — To divide into components from a larger set based upon some identifying feature or content.

SCORM — Sharable Courseware Object Reference Model — A set of specifications for developing, packaging and delivering high-quality education and training materials whenever and wherever they are needed.

Static Instance — When publishing a document instance, it may serve as a standard or reference. In defining the document publication instance, it may be desirable that users see a single, unchanging document, until any changes have been approved by a ruling/governing body. This contrasts with dynamic instance.

SGML — Standard Generalized Markup Language — the international standard metalanguage for text markup systems.

Taxonomy — a system for naming and organizing things into groups that share similar qualities.

WAP — Wireless Application Protocol — the standard for accessing the internet with wireless devices, e.g. mobile phones. (Not to be confused with Wireless Access Point hardware.)

XML — eXtensible Markup Language — developed as a more manageable subset of SGML.

The next section introduces XML and discusses some of the features of XML that make it particularly appropriate for learning object development and learning content reuse.

XML basics

What is XML? The typical definition of eXtensible Markup Language (XML) says:

“XML is a new World Wide Web Consortium (W3C4) specification. XML is a pared-down version of SGML, designed especially for Web documents. It enables developers to create their own customized tags to provide functionality not available through HTML.” (Harry Newton, Newton ’s Telecom Dictionary, 17th Edition.)

This definition provides a lot of information about XML, but it doesn’t help us understand much about XML and its capabilities. XML was designed as a database metalanguage. It was designed as a means of structuring content so it could be put into and be retrieved from a database in a form that was useful for content reuse. Information content can be text, graphics, audio, video, or complex constructs of all these learning components.

The principal difference between XML and HTML is that XML uses “smart tags.” Smart tags convey information about the content they contain. Because of this, you can use the structure you create to put your content into an easily retrievable form. One exciting aspect of XML is the ability to define your content your way, creating custom tags for different kinds of instructional objects such as objectives, test questions, feedback and other common training content components.

Your content management system reads the smart tags and parses your content into useful chunks that you can assemble into subsequent documents. When you need the same (or similar) content, you construct a query of your content database. You then review the resulting content and if it matches your current need, you use it. If you find nothing useful, you add new content for your current document — and for future use.

By using smart tags, it is also possible to define very specific criteria for making recursive changes. A branding change, which might take weeks to implement across an entire curriculum, can be implemented in minutes. Editorial and style changes can be very exactly implemented in the precise circumstances defined by the editors. Legal reviews can be conducted on exemplar text, which is then recursively edited throughout the content library.

Each of the content elements is consistently tagged so that it fits together with other elements to form consistent document instances. In other words, each content object contains an introduction, main matter, illustrations (if any), conclusion and transitions. Several content objects are aggregated to form a document instance. Given a different use, it may be necessary to slightly modify some of the introductory or transitional materials. You also can structure your learning objects so that they can be specifically relevant to different user groups or to audiences of different aptitudes. The next document instance you require may contain the same content objects, which have been modified, just a little here and there, to meet the requirements of the different audience.

The process of defining these structural components is analogous to creation of animation cells from layers. Each layer contains a different quality of information pertaining to the same object. These objects are then added together to produce an instance of learning delivery. (See Figure 1.)


block diagram how XML is parsed into content

Figure 1: Source content is transformed into document instances or learning delivery instances through the XML object components. (FM = FrameMaker document, WAP = Wireless Application Protocol document).


There are three main components of XML objects with which instructional designers need to be concerned: XML, DTD and XSLT.

The XML file contains the content, just the content and only the content. The Document Type Definition (DTD) specifies how the XML is structured.

The XML Style sheet (XSLT) contains all the formatting information for the output document instance.

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