Searching Heterogeneous e-Learning Resources

Resource discovery supports the core functions of virtual learning environments and digital repository systems. The function enables existing resources to be identified and re-purposed for teaching. This paper describes the purpose and the development of a search service developed within a project funded by the UK Joint Information Systems Committee (JISC). The search service corresponds to an emerging framework for implementing e-learning web services. It mediates resource discovery among distributed and heterogeneous repositories via a service-oriented approach. This paper provides a review of the elearning technical framework, and discusses the development of the service along with the application scenarios in which it has been deployed. 1. Service-Oriented Approach and e-Learning A main challenge in delivering high quality e-learning has been the provision of an infrastructure that is capable of fulfilling the diverse requirements of educational processes. Current developments of e-learning infrastructures involve an increased adoption of service-oriented and distributed computing technologies. The Grid, for example, has become a prominent area of development. As an advanced form of resources-sharing and service-oriented network infrastructure originally developed for e-science purposes, e.g. the Enabling Grid for E-science (EGEE) project (http://public.eu-egee.org/), it can be harnessed to fulfill the diverse demands of effective e-learning processes. The European Learning Grid Infrastructure (EleGI) project is one such initiative as it aims to investigate and develop software architecture and prototypes underpinned by the Grid for advanced e-learning paradigms such as socio-constructivism [3, 4]. A service-oriented approach in general involves deriving web services from decomposing the functional components of legacy and monolithic systems. For example, intrinsic parts of virtual learning environments (VLEs), student record systems and library management systems may be unbundled and exposed such that a variety of educational processes, particularly those of a cross-organisational nature, can be better facilitated through custom-built platforms that are built upon the “orchestration” of these loosely coupled services, along with any new service components required to enhance the processes. The E-Learning Framework (ELF) ( http://www.elframework.org ) is a collaborative initiative to build a common approach for service-oriented developments [11,12]. It has produced a technical framework identifying a broad set of e-learning services in two categories of functional granularity: Learning Domains Services and Common Services. The former are learning-specific (assessment, course management, resource lists etc.), while the latter identify the underpinning cross-domain support services that are shareable among the learning domain services such as search and authentication. ELF also maps each of the services to the existing or emerging technical standards and interfaces to encourage the adoption of standards and interoperability among the service components. This paper discusses one of ELF’s common services – federated-search and its development within d+, a project funded by JISC [7]. 2. Search Service for Heterogeneous Repositories E-Learning resources can be broadly defined as physical and digital resources that are applicable to course contexts. While some of these resources may include web sites, for example, accessible via search engines such as Google, most reside in digital repositories, VLEs and dedicated portals such as the RDN. Given the widespread use of Google, federated-searching (across multiple data sources simultaneously) is fast becoming the most popular approach to resource discovery available to users. However, unifying accesses to heterogeneous repositories is generally hindered by the information environment that caters for the access to such a diverse range of resources, since the environment is fragmented and typified by widely distributed and autonomously maintained services. These are in effect ‘information ‘islands’, unconnected to an available common source (examples include the list of databases in a digital library [1,2]). Users are confronted with multiple user-interfaces (UI) each requiring familiarisation. Efforts to bridge these information islands remain a challenge due to the heterogeneity of repositories and access methods, where these exist. Although rarely built into the native functionality of most VLEs, federated searching of external resources is essential. For example, the existing digital resources from the library may be searched from within a VLE, repurposed and augmented with annotations, as reading lists for various course context usages. Such cross-domain use scenarios require more fine-grained integration of the heterogeneous systems beyond the shallow UI-level integration such as linking to (framing) the front-page of a library system. The search service should be accessible from within the VLE in a context that is consistent with educational processes, embedded at the appropriate junctures of learning activities and attuned to different learning outcomes as intended by the instructors. For example, a generic search tool that is used for information discovery and therefore suitable for a constructivist learning style may be cumbersome to provide for other e-learning scenarios, e.g. embedding it as a subject of discussion in an online forum. The search service discussed in this paper, the d+ search service, is part of the ELF common services corresponding to the infrastructure-type services which are shareable across e-learning applications. The following ELF common services are related to resource discovery, as described by the ELF initiative: • Search: supports the finding of information resources including learning objects, assets, e-reserves, learning opportunities, funding sources and so on • Federated search: supports the processing of searches that target multiple types of repository, such as a combined search using SRW, XQuery and Z39.50 protocols against repositories supporting a range of different metadata formats, the results from which are then aggregated for presentation to the consumer • Resolver: provides services based on the use of OpenURL (or similar) metadata, including redirection to document delivery services, redirection to online bookshops, to local library services, and other discovery activities The federated search service addresses the fragmentation by focusing on the ‘intrafunction’ interoperability of repositories, i.e. providing a single service-interface search functionality that is interoperable across multiple repositories [2]. It also corresponds to the reference models identified by the IMS Digital Repository Interoperability Specification: search/expose for the searching of metadata [5]. Part of the ELF common services also overlap and correspond to the similar infrastructure-type services of frameworks from other sectors, particularly the digital library field. This includes the shared services of the JISC Information Environment Architecture and the emerging JCSR (JISC Committee For Supporting Research) e-research framework. Since the rationale of deriving these services from these different frameworks is the same, i.e. re-factoring common services that are shareable across applications, it is anticipated that there will be initiatives to harmonise and consolidate the services across these different initiatives such that the common services are shareable not only among applications within a specific domain, but also across the different domains, e.g. providing for a common search service for both e-learning and digital library purposes. This will be a welcome improvement. Academics and learning technologists who build learning environments wish to improve and enhance the learning experience of students by including search options generally only available via library portals, and librarians want to expand the range of content available through their portals in order to bring as much relevant material as possible into scope.