Integrated Search in Learning Objects Repositories – Vision or Reality? Tomáš Pitner, Miloš Zikmund

Abstract: The paper present experience and recommendations acquired in development of a meta-search engine enabling searching in multiple learning object repositories including ARIADNE, LeMill, Telmae, and DILLEO. Keywords: learning objects repositories, ARIADNE, LeMill, Telmae, DILLEO, integrated search, meta-search, OpenSearch, Groovy, learning object metadata



Digital learning objects repositories (or libraries) represent a standard instrument for publishing and sharing of learning content having typically the form of learning objects with various pedagogical goals, structure, and size. The IEEE Learning Technology Standards Committee [1] defines a learning object as "any entity, digital or non-digital, that may be used for learning, education or training". The traditional repositories were established and run mostly by large educational institutions or even consortia while nowadays we see a significant development in more community-oriented projects reflecting the current general Web 2.0 trends. However, as the repositories usually tend to be general-purpose, without a specific thematic orientation, the learning process requires more repositories to be searched simultaneously in order to get the relevant learning content. So, we wanted to identify a set of repositories that are relevant in the Czech context (i.e. store high-quality, authoritative learning objects), and to construct a search engine that would search in all of them as “onestop-shop”.



Being in the Czech language context, we included all large Czech repositories (Telmae 1 and distributed DILLEO 2 ) and enriched this set by the European ARIADNE [2], and recent community-oriented LeMill 3 . Not all of these repositories are members of Learning Resource Exchange [3] or similar federation, nor they support OpenSearch 4 or SQI (Simple Query Interface) [4] specific for LO repositories. Thus, we designed and developed an ad-hoc metasearch service being able to access and search just in the selected repositories. The service is called MetaSearch 5 . The implementation revealed a number of issues, which are discussed 1 3 4 5 2

further. The most important lessons learned are formulated as recommendations for implementers of both meta-search engines and the repositories themselves. This meta-search service should be extremely easy-to-use (low number of options or settings while preserving the fine tuning specific for each repository) and fast enough. The option should include the selection of repositories to be searched through, the maximum number of results returned for each repository and constraints to the query (exact phrase, all terms, at least one term). It should also enable to continue browsing the search results on the originating repository. Respecting the growing popularity of OpenSearch (OS) we demanded that the service would offer an OS interface and an OS browser module. We could not rely on a uniform search interfacing with all repositories. Therefore, the architecture comprises of a front-end common for access to all repositories, and modules (methods) specific for each repository. The meta-searcher is implemented in agile Grails6 framework using Groovy 7 dynamic programming language. The user interface of the MetaSearch is depicted in Figure 1 and is equally available also in English and German.

Figure 1. MetaSearch – basic search user interface 3


Lack of an OpenSearch/SQI interface OpenSearch is a standard for simple generic interfacing with (any) search engines while alternative initiatives – such as the SQI mentioned earlier – aim specifically to LO repositories. SQI employs a powerful query language PLQL oriented to LOM metadata thus better targeted to LOs. On the other hand, these activities are limited mostly to learning services and applications and a massive SQI support outside academia is not foreseen yet. REST interface and stateless nature of OpenSearch in contrast to SQI preferring SOAP and stateful communication reduces the burden connected with maintaining session information for each client, and fosters better scalability. Missing (any) web-oriented API If not a standard search API (either OpenSearch or SQI) then at least some API. However, the selected repositories except of ARIADNE have no API at all. Missing API gives the 6 7

system integrator the only remaining option: access the functionality using so-called screenscrapping, i.e. low-level analysis of the end user interface of the service. It means an analysis of the HTML code originally supposed to be interpreted by the browser as a web page and presented to the user. Any integration based on this method is in principle very crisp – any change in the end-user interface (including changes that are even not noticed by a human as the user) can break the integrating application. No uniform metadata set Despite LOM metadata and packaging standards for learning objects, the level of support for precise, uniform, and standardised metadata stored along the learning objects in our selected repositories, varied significantly. MetaSearch have overcome it by providing different search options for each repository. Internationalisation Repositories usually store LOs in more languages. Thus, a UI should be available at least in these languages. Selection of appropriate locales must in some cases be done either by „clicking“ or even setting a user profile which requires registration for a user account, and authentication for each session. Legal issues Although MetaSearch allows finding the desired objects, their usage rights are covered by their respective Terms of use. While ARIADNE and Telmae specify who has the access to the object, DILLEO says whether the object is copyrighted. Only in LeMill, all objects are free to use or licensed under Creative Commons ( However, this holds also for many Web 2.0 services where the user-generated content is substantial [5]. 4


Let us summarise some guidelines and good practices for development of a well interoperable LO repository: • Provide an OpenSearch/SQI interface: An OS plugin is available for most browsers, and it is very easy to install and use for the end user. Moreover, a service accessible via OS can be easily approached from any remote service or application, not just from a browser. • Employ standard metadata: LOM provides a rich and extensible metadata set aimed at learning objects. Using it should be a must for any LO repository. Meta-search using the same set of search criteria based on the same metadata shall provide much more precise results than using plainly the “greatest common denominator” or ignoring some search criteria. • Have an API: Web 2.0 is the mainstream. The portal lists tons of APIs provided by independent services – ranging from small, single purpose web services to giants like Google Search. If a service does not provide an API, it actually does not seriously intent any other use than solely from a web browser. On the contrary, by giving an easy-to-use, well-documented API – either a pure HTTP-based or for an established platform like Java –, one can expect to attract more clients to the repository. • Be resource-oriented: any kind of search is targeted at finding resources, either in their full form or links to them. It exactly corresponds with the principles of the REST architectural style for web applications. Everything is a resource. Each resource is uniquely identified by its URI (usually a URL – i.e. “web location”). To share a web

resource, one can just send this URI and everybody finds it. So, any resource – i.e. learning object – stored in a repository should be addressable from outside by its URI. A result of a search can thus be a list of URIs/links that can be followed to obtain detailed information about the respective LOs. Following the REST style will also pay off in the future when an integrated approach for “write access” i.e. for storing objects into repositories, will be required. Be integration-friendly: the mentioned technological conditions are definitely important. However, to provide the meta-search and other integration efforts a stable and safe legal background, it is necessary to specify Terms of use regulating the use of the service itself but also any 3rd party (=other user) generated content. The latter can well be covered by a Creative Commons license fostering very liberal reuse of the content. Think globally: Having an, at least partially, internationalised service increases the number of potential visitors but also contributors to a LO repository. It is crucial for Web 2.0, community-oriented repositories.

5 CONCLUSION We have shown that an integrated search for learning artefacts stored in heterogenous learning object repositories represents a manifold challenge, despite of the strong effort given to standardisation of learning object metadata and current advances in service-oriented architectures. Although most of the services declare “openness” and adherence to standards, the lack of readily available application programming interfaces (APIs) present in majority of the services makes any integration effort a teaser. In contrast with the Web 2.0 trend with services founding their added value on seamless integration with the others, most of the repositories unfortunately do not pay any attention to real interoperability. This paper tried to improve the situation by sharing our experience and collecting a set of recommendations for developers of future LO repositories. ACKNOWLEDGEMENT The research has been partially supported by the Czech National Programme Information Society, Project No. 1ET208050401 “E-learning in the Semantic Web Context”. REFERENCES [1] IEEE Standard for Learning Object Metadata, available online [2] E. Duval, E. Forte, K. Cardinaels, B. Verhoeven, R. Van Durm, K. Hendrikx, M.W. Forte, N. Ebel, M. Macowicz, K. Warkentyne, F. Haenni. The ARIADNE Knowledge Pool System: a Distributed Digital Library for Education, Communications of the ACM, 44(5):73-78, May 2001. [3] Ternier, S., Duval, E., Massart, D., Campi, A., Guinea, S., Ceri, S.: Interoperability for Searching Learning Object Repositories: The ProLearn Query Language, D-Lib Magazine, Vol. 14, No. 1/2, January 2008 [4] Ternier, S.: Standards based Interoperability for Searching in and Publishing to Learning Object Repositories, PhD Dissertation, Katholieke Universiteit Leuven, 2008

[5] Drášil, P., Pitner, T., Hampel, T., Steinbring, M. Get Ready for Mashability! – Concepts forWeb 2.0 Service Integration. ICEIS, 2008.

Tomáš Pitner, Miloš Zikmund Masaryk University, Faculty of Informatics Botanická 68a, CZ-60200 Brno, CZ Tel. +420-54949 5940, Fax +420-54949 1820 [email protected], [email protected]

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