Oct 09, 2002
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.
The model envisioned by these principles, a network model, may be contrasted with what may be called the silo model for the distribution of learning resources. In the silo model, separate repositories – one for each corporation, school district, college system or university – is envisioned. These silos are fed by publishers who, often on the basis of separate licensing agreements, distribute bundles of learning content to be stored in the silo for later use.
While the silo model is suitable for large institutions and clearly defined vertical markets, it creates barriers to the access to learning materials by individuals and small or medium sized enterprises. The silo model also poses a barrier to new or small content vendors, who must negotiate separate contracts with each silo, often against the provisions of previously signed contracts. The silo model therefore increases the cost and restricts the choice of learning materials for all users and especially for small users.
- 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.
- 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, DonÂ’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. Typically, this means that there are no prior semantic restrictions: no restrictions on how something is described, evaluated, valued, or transacted. Where restrictions come into play, they are syntactic restrictions, intended to create a common basis for communication, and where possible, multiple syntaxes are supported.
- 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.
- Open Access
Any provider of learning materials may prepare and distribute learning materials through DLORN. Though DLORN will support the registration and indexing of various providers, this registration will be free and optional. The purpose of this principle is to ensure that providers are not faced with a priori ‘membership fees’ or similar tariffs in order to gain access to potential purchasers. This does not preclude restrictions, tariffs or controls on specific instances of a DLORN component. However, in any case where a restricted component, such as a for-profit metadata repository, exists, an equivalent unrestricted component, such as a public metadata repository, will also exist.
- Open Market
There will be no prior restraint imposed on the distribution model selected by participants in DLORN. Specifically, DLORN will accommodate free content distribution, co-op or shared content distribution, and commercial fee-based content distribution. The purpose of this principle is to ensure fair and open competition between different types of business models, to ensure that users of DLORN are not ‘locked in’ to the offerings provided by certain vendors, to provide the widest possible range of content options, and to ensure that prices charged for learning content most accurately reflect the true market value of that content.
- Standards Tolerance
DLORN imposes no prior restraint on the metadata standards used by participants to describe given resources or services. Metadata repositories are tolerant of different standards employed by different providers of learning materials. Metadata repositories also (attempt to) provide output in the standard requested by users of the system. This means, for example, that a vendor may elect to employ IEEE-LOM to describe its learning materials, while a consumer may request information in the form of the CanCore profile. Standards tolerance extends to the description of digital rights, classification and taxonomies, and evaluation and annotation. The purpose of this principle is to enable an inclusive marketplace, to reduce risk by vendors when metadata standards are selected, and to enable the development of vendor-specific or custom metadata for particular uses.
- Multiple Channels
The description of DLORN will include descriptions for communication using multiple channels or multiple modes of communication. For example, DLORN will enable requests using web services such as XML-RPC or SOAP, gateway interfaces such as HTTP-POST, and harvesting protocols such as OAI. The purpose of this provision is to enable redundancy in the system. It is also to reduce the liability of the network should any given standard become a royalty-based standard. It is also to provide software developers the greatest range of options for the creation of new services.
- Multi-Party Metadata
Multiple parties may provide metadata describing a given learning resource. There is no prior restraint exercised by providers of learning materials on evaluations, appraisals, comments and other fair descriptions of their learning material. The purpose of third party metadata may be to provide alternative classification schemes, to indicate certification compliance, or to provide independent assessments and evaluations of learning resources. The purpose of this principle is to ensure that potential users of learning resources to obtain neutral descriptions of that material. It is also to create an environment for the creation of optional but value-added third party services for which fees or other costs may be charged.
- Integration with the Semantic Web
DLORN should be considered as an implementation of and an extension of the semantic web. This means that DLORN metadata data and services would be available to the semantic web as a whole. It also means that DLORN can and should incorporate elements of the semantic web, such as sector-specific ontologies, into its own design. The purpose of this principle is to ensure that DLORN is capable of the widest reach possible. It is also to reduce the duplication of effort between developers working in specific domains and educators working in the same domain.
- Multiple Data Types
No prior restrictions are imposed on the data types to be transported through DLORN. This includes but is not restricted to various content formats, proprietary or otherwise, such as HTML, and the like. This provision is also intended to allow learning resources that are not learning objects, as variously defined, to circulate through the system. For example, academic papers distributed through the Open Archives Initiative, news articles distributed through various vendors, conference, class or seminar registration and information may also be distributed through DLORN. The purpose of this proposal is to enable any learning resource, including in-person learning services, to be accessed, and not merely a specific subset of learning resources.
- Simple Digital Rights Management (DRM)
The principle behind fee-based and subscription-based transactions is that it should be easier to buy material than to steal it. Thus where possible, the acquisition of rights and the exchange of funds will be automated. The purpose of this principle is to reduce transaction and clearance costs for purchasers of learning materials.
- Brokered DRM
Transactions within DLORN are brokered. That is, typically, a given provider of learning materials will work with a single agent who sells to multiple purchasers, and a given user will work with a single agent who conducts transactions with multiple vendors. Vendors and users may select from any number of brokering services, so that no single transaction agent controls the network. Vendors and purchasers may act as their own agents. A vendor or purchaser may elect to employ multiple agents. Agencies acting on behalf of, say, a provincial department of education, may act as agents for a given populations, such as the students of that province. The purpose of this provision is to eliminate the need for the creation of multiple accounts, to allow users to user resources from multiple vendors, and to provide a choice of agents, and therefore a greater likelihood of trust.
- Permission Based
This principle states in effect that users of the system own their own personal data. The userÂ’s agent operates on behalf of the user, and releases information or money only with the agentÂ’s explicit consent. The purpose of this principle is to engender trust in the system and to ensure privacy when dealing with multiple agencies.
