Design and Reusability of Learning Objects in an Academic Context: a new Economy of Education?

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Overview

These design principles are intended to govern the development of an architecture for a distributed learning object repository network (DLORN). The purpose of the principles is to guide the description of the components employed, the standards followed, and the principles governing the operation of the network.

These principles are in one sense descriptive and in another sense prescriptive. They are descriptive in the sense that they attempt to capture the essential elements of what is likely to be the most successful system for the distribution and use of learning materials on the internet. They are prescriptive in the sense that they are intended to inform the development of such a network.

Open Standards

The protocols used by components of the components of DLORN to communicate with each other and with external systems are described, documented, and freely available to the public at large. The purpose of this principle is to encourage the development of complimentary systems that may interact with and support the functionality of DLORN.

For example, a DLORN should embody interoperability with other networks and systems that are being developed by libraries and museums worldwide. In other words, the DLORN is not a network with own proprietary communication protocols open to only repositories within system but can operate with others outside systems such as the Open Knowledge Initiative (OKI; http://web.mit.edu/oki/) and to be aware of other communications protocols, such as Z 3950 (Miller, 1999), to augment its own information objects with those from other collections.

Royalty-free Standards

The standards developed or used by DLORN shall be royalty-free. The purpose of this standard is to ensure that there is no a priori overhead cost incurred by agencies wishing to offer services compatible with DLORN. Imposing an a priori cost immediately poses a barrier to small and medium sized enterprises that may wish to participate and it biases the network toward the provision of commercial content only.

Enable, Don’t Require
Where possible, DLORN will not require adherence to a particular constraint, but rather, will allow users of the system to exercise options among various models. The design of the system will be to allow systems that exercise different options to interoperate and to work within the same space.
This principle is essentially based on the idea of defining different levels of compliance required for interoperability within the network as a whole than would be required by specific instances of the system. At the network level, a minimal standard is desired in order to achieve the widest functionality possible. One way of stating this is to require interoperability at the syntactical level only, without stipulating as to the content being exchanged.
This need must be balanced against the need for a more robust interoperability, one that requires a common understanding of meaning as well as sentence structure. Although interoperability is possible, if the agreement consists of syntactic structures only, such interactions are functionally meaningless. Greater agreement is desired, and the greater the level of semantic agreement within two systems, the greater the interoperability.
In practice, what this means is that although the network as a whole imposes no prior semantic restrictions, in order to use the network it is necessary that some semantical agreement is required for two instances to interoperate within this framework. In other words, though the network imposes no restrictions on how something is described, evaluated, valued, or transacted, entities within the network must define how these are to be described. [1]

Open-Source Infrastructure Layer

The infrastructure layer is the set of components that provides end-to-end functionality for DLORN. It is described in the paper Distributed Learning Object Repository Network Infrastructure Layer (forthcoming). The set of components in the infrastructure layer will be developed and distributed as royalty-free open source software. The purpose of this principle is to demonstrate functionality without requiring financial advances, and to provide a base of functional components on which other services and applications may be developed.

Open or Proprietary Service Layer

Over and above the infrastructure layer it is hoped and anticipated that third parties will develop components with increased functionality, offering an improvement in design or services over and above the functionality provided by the infrastructure layer. Such components may be developed as free and open applications, or they may embody commercial and proprietary components. The purpose of this principle is to enable the development of commercial applications that generate a revenue stream for software developers and service providers.

Component Based Architecture

The DLORN is to be designed not as a single software application, but rather, as a set of related components, each of which fulfills a specific function in the network as a whole. This enables users of the DLORN to employ only those parts of DLORN that suit their need, without requiring that they invest in the entire system. It also allows for distributed functionality; a user of DLORN may rely on a third party to provide services to users. The purpose of this principle is to allow for specialization. Additionally, it allows users of DLORN to exercise choice in any of a variety of models and configurations.

Distributed Architecture

Any given component of DLORN may be replicated and offered as an independent service. Thus, it is anticipated that there will be multiple instances of each component of the DLORN infrastructure. The purpose of this principle is to provide robustness. Additionally, it is to ensure that no single service provider or software developer may exercise control over the network by creating a bottleneck through which all activities must pass.

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