The first requirement for (re)use of a digital learning resource is that it be able to work in as many relevant computing environments as possible. Issues that impact reusability include:
- Software that behaves differently (or does not run) on different platforms. (“Platform” is used to denote a combination of hardware, operating system and software environment.)
- Web content that behaves differently in different browsers and operating systems.
- Java applets that behave differently on different platforms.
- Specialized plug-ins that are available for a limited number of platforms.
Since digital learning resources run on desktop and notebook computers , these issues are unavoidable. Nonetheless, it is possible to achieve a reasonable degree of cross-platform functionality. Web content authoring tools can be configured to produce HTML that runs fairly well in most browsers, and many Java applets work quite well on different platforms. Word processors, spreadsheets and image editors have versions that run on a variety of platforms and can convert files back and forth without too much loss of functionality. Formats such as Flash, PDF or QuickTime™ can be read using free plug-ins that are readily available and install themselves when needed (if an Internet connection is present).
Granularity Impact on Interoperability
The meaning of "interoperability" of a digital learning resource depends on the granularity † of the resource in question.
Interoperability for a raw media file means the ability of others to open it, possibly edit it, and certainly display it. Interoperability for a course refers to its ability to run in a variety of learning environments as well as to the ability of an instructor to modify or select parts of its contents for reuse.
The following table shows how the types of standards and products vary with granularity:
Standards and Characteristics of Dominant Products as a Function of Granularity
Characteristics of Dominant Products
| Content Asset †
||Text and pure HTML are standardized formats for content assets, although HTML produced by most authoring tools is not standards conformant. XHTML is an improvement.
Interoperability is improved by associating appropriate metadata to a content asset.
|Content assets are usually edited and displayed using common authoring suites, plug-ins and browsers. For widest use, it is best when no plug-in is needed, or when a plug-in is freely available, automatically downloaded and widely in use, e.g. Flash™ or Acrobat Reader™. Products, plug-ins and formats can be community-specific, as in those needed to produce and display MathML.
|Information Object †
||Information objects are similar to content assets. For applets, Java™ is considered a standardized format by some, although it has many platform and versioning issues. There are specification and standards that specifically address test questions.
||Information objects are similar to content assets in that they generally require a single application to edit and a single plug-in or application to display. The products involved are usually not specific to learning, although it is possible to use learning-specific authoring tools to produce information objects. Look for products whose output can be edited by more commonly available tools.
|Learning Object †
||SCORM † and IMS † specifications are relevant to learning objects. Learning objects whose structure is expressed in XML, even if proprietary, can usually be transformed for use in other environments. Metadata is always important.
||Working with learning objects may require authoring and editing tools that are built for that purpose. As with information objects, the output is paramount for interoperability. On the delivery side, learning objects that are not tracked require standard server technology, but if data is to be exchanged between the learning object and the delivery system, then products like course management systems and learning management systems must be used to have any degree of interoperability. Assessment engines are also important for learning objects that include quizzes.
|Learning Component †
||Learning components are similar to learning objects.
||Learning components are similar to learning objects although they may rely more on course management technology. If a learning component (e.g. a course) can only run on a particular course management system, it is not very interoperable.
|Learning Environment †
||The standards relevant to learning environments are those relevant to IT infrastructure.
||Learning environments must integrate with registrar systems, library information systems, content and knowledge management systems, etc.