EM2: An Environment for Editing and Management of Educational Metadata
Internet-based education and training offer many potential benefits specific to adult learners with emphasis given to learner-centred and self-directed instruction models empowered by web-based educational resources. Indeed, the recent growth of the World Wide Web (WWW) has greatly increased the amount of information and educational resources available to the education community.
The full exploitation of this mass body of knowledge resources available on the Web, can be, however, compromised, by the difficulty in describing, classifying and maintaining those resources in such a way that they can be retrieved in an “educationally efficient and effective way”. Today, the web community has embraced the collection and use of metadata to characterise and index educational resources, which lead to semantically more accurate retrieval of information than search engines. In general sense, metadata is information about data. In the context of resource discovery, descriptive metadata is a characterisation that aims to represent the intellectual content of the resource. The most popular technology for representing metadata is XML (eXtensibleMarkup Language, http://www.w3.org/TR/REC-xml).
Educational metadata (EMD) are attracting increasing attention in this context, since they facilitate the description of educational resources, so that they can be easily retrieved (Duval et al, 1999; Greenberg, 1999; Burda & Hilier, 2000). A number of international efforts have been initiated during the past few years, aiming to define EMD specifications for the common description of educational resources. These specifications include fields that are considered necessary for the description of educational resources – such as the type of the resource (i.e. whether it is an experiment, simulation, questionnaire, assessment, etc), the target learner age, difficulty level, estimated learning time, etc – as opposed to “general purpose” meta-data standards (e.g. the Dublin Core, http://purl.oclc.org/dc), or standards that have been developed for different fields of knowledge (e.g. geo-spatial meta-data standards, http://badger.state.wi.us/agencies/wlib/sco/metatool). The most well-known international EMD standardisation initiatives are the IEEE LTSC (http://ltsc.ieee.org), IMS (http://www.imsproject.org), AICC (http://www.aicc.org), ARIADNE (http://ariadne.unil.ch), and CEN / ISSS (http://www.cenorm.be/isss/Workshop/lt/) (Bacsich et al, 1999).
This paper describes the difficulties raised in retrieving educational resources from the Web and discusses the current state-of-the-art in educational metadata technologies and the advantages of their use. The most popular software tools for managing XML metadata files are presented and their limitations on the educational sector are discussed. The paper proposes EM2, an educational metadata management tool, to support editing and management of educational metadata documents, which are represented in XML. EM2 aims to facilitate the improvement of search, accessibility and navigation of educational resources and to promote the usability of educational metadata specifications.
At present, learners often have full-time jobs while pursuing professional and personal development. Consequently, working and learning are no longer exclusive activities. Learning through the Web allows new forms of education to be offered by corporations and higher education institutions to a diverse and distributed population of learners. Educational metadata is a proposed possible solution aiming to overcome the problems arising in most e-learning environments, related to relevant information retrieval and access to education resources based on user’s specific needs.
Metadata can be used for a number of e-learning scenarios (Figure 1). Each scenario of use may address different dimensions in terms of the:
In the next section a typical scenario of use of educational metadata is described by focusing on the above mentioned dimensions.
Vertical Learning Portals (VLP) provide a possible solution for web-based learning that responds to the needs of the learners for adaptive, resource-based and collaborative learning. In its simplest form, a learning portal is a web site that offers a broad range of resources and makes it easier for users to locate online information. More involved vertical learning portals provide personalised access to academic courses, tutorials, training programs, e-books, on-line tests (Sampson et al, 2002c).
The users involved in this scenario can be divided in three categories:
Metadata technology can be important for delivering intelligent, adaptive and personalised services through learning portal. Educational metadata, when created by the owner of the resource allows semantic and relevant retrieval of information. Hence, educational metadata provides Learning Portals with the means to offer learners the information they need according to their demand, skills and learning style. The technology used to describe the metadata and the metadata specification in this scenario is also dependent on the metadata-editing tool.
The following list summarises the addressed dimensions in this scenario.
A software tool to address all the users of this scenario should provide both metadata authoring and metadata management features. Some of the most common tasks that the users of a vertical learning portal perform are summarised in Table 1. Figure 2 presents a typical UML diagram from the VLP manager operations.
Table 1. Tasks performed by the users of vertical learning portal perform
2.2. Discussion on the Scenario of Use
Other scenarios of use can involve the deployment of metadata technologies to describe the e-content of an on-line library, a virtual university, a virtual museum, as well as research papers in a repository of publications addressing the needs of researchers in different fields etc. Although the dimensions in each scenario are different there are common limitations on each one of them. The quality of the metadata depends on the software tool chosen to be used for creating the educational metadata. It should be easy to use and provide a number of proposed metadata specifications since, in the majority of scenarios, it is addressing non computer literate people and without prior knowledge on the metadata technologies.
Consequently the software application is of great importance on providing metadata that can improve the effectiveness and the quality of information retrieval (Curtis et al, 1999). Studying the above scenarios we conclude that an educational metadata application tool should provide the user with the following features (Figure 3):
In the next section a number of available software tools are outlined. The paper focuses on applying the existing tools on the above scenarios of use, and presents their limitations on supporting all the requirements mentioned.
The need for creating and managing metadata had lead to the development of numerous software tools addressing the needs of metadata editors and managers/administrators of metadata repositories. Commercial and freeware tools are available for creating, changing, validating and managing metadata documents.
Currently a wide range of components related to XML, are available. Some of these components are:
The available software tools that support the metadata technologies and the metadata specifications are combinations of the above components and can be divided into two major categories:
3.2. Discussion on Limitations
Each of these tools can provide functionalities for meeting specific requirements, however a number of limitations come across when applying them in the above described scenarios.
The first category of tools in mainly focused on XML technologies and the main disadvantages are:
The solution that would apply better to the educational community for creating and managing educational metadata documents would lie on the second category of tools. The main characteristics of the second category are the focus on educational metadata and the user-friendly interface, however they fall short on functionality compared to the users needs derived from the scenarios.
Currently, it appears that we are lacking a toolkit that covers all the above mentioned design considerations. Most of the educational metadata tools are limited only to metadata authoring and they do not provide validation or support of any metadata specification. In addition they do not provide management of resources and “translation” to other specifications.
Table 2 summarises the features of the main educational metadata tools mentioned above, compared to the requirements concluded on the previous section.
Table 2. Features of some educational metadata tools
In the next section, EM2, an educational metadata management tool, that falls in the second category of metadata tools, but combines functionality features of the first category of applications, is described. The proposed educational metadata tool, satisfies all the required functions summarised in table 2.
The back-end users of a web-based educational environment need an educationally oriented application, which can be used by metadata non-experts and can provide authoring and management features. Study of the described scenarios suggests that there is a need for an easy to use tool, which is focused on educational metadata (to meet the needs of metadata editors) and which allows document management features (to meet the needs of metadata repository managers). In more detail, the application should meet the following set of criteria:
At present there are various tools available as mentioned in the previous section, that support one or combination of the above criteria. However, they are either educationally oriented, user-friendly but too simple allowing only limited features, or they are very general complex tools, allowing editing and management but address only to advanced users. As a result, there is no available tool to meet the needs of both managers/administrators of a metadata resource repository and editors of metadata documents. At present back-end users should use either a combination of the available tools or a single tool but minimise their expectations on usability and functionality.
The current version of EM2 is an educational metadata editor providing an easy way for characterising educational resources (creation and modification) based on three main metadata specifications (DC, IMS, LOM). The offered features are limited compared to the criteria mentioned above. The proposed tool EM2 meets all the above criteria and is an attempt to build some bridges between the current players in this field (editors, managers) drawn from higher education, companies, etc. and the metadata specifications initiatives.
Extension of the previous EM2 versions (Papaioannou et al, 2001) allows the toolkit to be used by a wide range of services. Based on the above mentioned design considerations, the new version of EM2 can support all the requirements extracted by the scenario analysis:
In this section the architecture of EM2is described. The components, their relationship to each other, the environment and the principles guiding the design of the EM2 architecture are outlined.
The aim of EM2 application is to provide a tool targeted to a wide range of educational metadata editors/managers, which overcomes the limitations of the existing metadata tools.
As it has been mentioned in the previous section, the system must satisfy the following functional requirements:
In terms of non-functional requirements the system should meet the following principles:
Figure 7 presents the EM2 architecture diagram showing the structural components of the system and their interconnection paths. Components can be passive or active, created at system start up or be created and deleted at any time at runtime, and they can be system specific or be reusable repository components. Interconnection between components is modelled by associations (directed arrows). The direction of each association shows which component initiates communication. These associations can represent direct connections or they can also be used to abstract away details of more complex connection and communication patterns (e.g. indirect communication based on events). Interfaces are shown by the round interface symbol and by adding dependency arrows between the interfaces and the components using them.
Figure 7 presents a view of each component of the EM2 application at the highest level of abstraction. Each of the components is described in the following sections of this paper in more detail.
The components of this architecture can be grouped into two different layers.
Every metadata XML file is accompanied by a DTD or an XML Schema file (http://www.w3c.org). The purpose of a DTD (Document Type Definition) is to define the legal building blocks of an XML document. It defines the document structure with a list of legal elements. XML Schema contains all the information of a DTD and additional information such as the type of the elements. A DTD or XML Schema file can be declared in the XML document, or as an external reference. To store and manipulate all these different type of files EM2 tool is using a number of repositories:
Associations between the repositories, the databases and the XML files are achieved by using the DOM (http://www.w3c.org). The XML Document Object Model (DOM) is a programming interface for XML documents. It defines the way an XML document can be accessed and manipulated. The objective for the XML DOM has been to provide a standard programming interface to a wide variety of applications. The XML DOM is designed to be used with any programming language and any operating system. With the XML DOM, a programmer can create an XML document, navigate its structure, and add, modify, or delete its elements. The DOM represents a tree view of the XML document. The document element is the top-level of the tree. This element has one or many child nodes that represent the branches of the tree and are associated to the elements of the XML file. A program called XML parser can be used to load an XML document into the memory of the computer. When the document is loaded, its information can be retrieved and manipulated by accessing the DOM. In addition by accessing the DOM any format of files can be generated (XML files, DTD, XML Schema and DB XML files) as shown graphically (Figure 8) and therefore one format can be converted to another through DOM.
The EM2 tool uses DOM to generate XML files, DTDs, and XML Schema files (e.g. generate unknown DTD from an XML file through DOM). In more detail the tool uses two different document object models. The first one is generated from the XML file, when the user opens an existing or creates a new XML file. The second DOM is generated from DTD or XML Schema files and it contains additional to the structure information (e.g. multiplicity, element type etc). The following diagram (Figure 9) illustrates how the associations (shown in Figure 8) between the two DOM models and the repositories are implemented in the EM2 tool.
The XML Editor provides the interface for creating a new XML file or loading and modifying existing ones. These components and their associations are represented in Figure 7.
Create a new XML file (Figure 10): When the user creates a new metadata file, one educational standard must be specified from a list, which contains all the available educational specifications that are stored in the repositories as DTD or XML Schema files. Therefore the associated DTD or XML Schema of the new XML file is loaded into the DTD or XML Schema editor respectively. A user-friendly interface provides a graphical representation of the selected metadata file in tree view and a number of panels for completing the values of the metadata file. At the same time the DTD or XML Schema editor provide a graphical representation of the DTD or XML Schema respectively. The output of this operation is a new XML file stored into the "XML file repository" and into the "XML file database".
Open an existing file (Figure 11): When the user opens an existing file, a selected file stored in the "XML file repository" or in a specified directory is loaded into the XML editor. The graphical representation of the XML file is shown together with the panels, where the user can modify the values. If the DTD or XML Schema of the XML file is known it can be retrieved and loaded to the respective editors. The outcome of this operation is a new XML file stored in the "XML file repository". If DTD or XML Schema is not specified (shown with grey arrows in Figure 11), the tool can automatically create a new DTD or XML Schema to associate it with the current XML file and loads it into the DTD or XML Schema Editors. The outcome of this operation is a new XML file stored in the "XML file repository" together with a DTD or XML Schema stored into the respective repositories.
Modify the structure of a loaded DTD or XML Schema (Figure 12): The user can change the structure of a DTD or XML Schema when it is loaded in the respective editors. The new DTD or XML Schema can be saved as new educational metadata standard and stored in the repository. Therefore it can be available for retrieval the next time the user wishes to create a new metadata file according to this standard. The outcome of this operation is a new DTD or XML Schema stored in "DTD repository" or "XML Schema repository" respectively. (Figure 12 is an extension of both Figures 10 and 11.)
The "Map generator" and the "mapping" components allow the user to convert XML files from one educational standard to another (Figure 13).
The "Map generator" component requires as input two XML files. For example if the user creates the IMS to LOM mapping then an IMS XML file and a LOM XML file are required. Both these XML files are created and completed by the user into the "XML Editor" with unique values for each element and the generated XML files are stored into the "XML file repository". The outcome of this operation is a map. The generated map is stored into the "Map database".
In more detail, this operation retrieves all the elements of the first XML file that have the same values with certain elements of the second file and generates a table, which contains all the corresponding elements between the two files. This table is the "map" between the two educational metadata specifications.
To convert one XML file from a certain metadata educational standard to another the map between these files should exist into the "Map Database". The inputs to the "Mapping" component are the XML file for conversion and the map. The XML file and the map are stored in the respective repositories and the user specifies them. The outcome of this component is a new XML file of the required educational metadata standard and it is stored into the "XML file repository".
The "Validation" component of the EM2 tool provides two different types of XML file validation: structure validation and data validation.
Structure validation checks if the XML files conform to the element structure and hierarchy of the associated DTD or XML Schema files. On the other hand data validation checks if XML files conform to the associated XML Schema (if any) in terms of data type. To achieve validation, two different document object models are required, which have been explained in a previous section (5.2.2).
When an XML file is loaded into the "XML Editor" (either in "Create" or "Open" mode) the corresponding DTD or XML Schema is loaded into the respective editor. In the memory two different DOMs are generated. The DOM generated from the XML file, and the DOM generated from the DTD/XML Schema file. These two DOM are compared to define to define if the loaded XML file is valid. When the user modifies the structure of the loaded XML file, the corresponding DOM is modified as well. The XML file DOM is compared to the DTD/XML Schema DOM to define whether the XML file is valid or not. If the XML file has been modified and it does not conform to the DTD/XML Schema the tool prompts the user to either correct the XML file or modify the corresponding DTD/XML Schema. The following diagram shows is a flow chart of the described process (Figure 7). The output of this component is a validated XML file that is stored in the "XML file repository" and in case the DTD/XML Schema are modified, a new DTD/XML Schema stored in the respective repositories.
The Wizard is an interface component offering a user-friendly
environment for the novice user. The wizard is a layer between the user
and the "XML Editor" (Figure 7). The component provides the
available features of the "XML Editor" but with some restrictions.
It does not allow modification of the XML file structure and therefore
the modification of the DTD and the XML Schema files are restricted. The
aim of the wizard is to encrypt the complicated operations of the EM2
and provide an interface where the user just completes values in a number
of fields. It provides guidance for creating XML files that conform to
"Management" is a user interface component allowing manipulation of multiple XML files. The component and the "XML files database" are associated, which allows retrieve, update and sorting of XML files by their element values. The Management interface will provide the user with a graphical representation of all the XML files stored in the repositories. The user will be able with simple commands (sort by, update, select, edit etc.) or with graphical features (e.g. drag and drop) to manage the available XML files.
The EM2 tool is under development in Microsoft Windows NT platform, by using Java programming language. An advantage of Java is interoperability; therefore the tool is not platform dependent. The following list provides all the system requirements necessary for using EM2.
It is widely accepted that use of metadata can improve the efficiency and the effectiveness of information retrieval from the web. In addition, it can provide the means for customised retrieval, based on users knowledge and preferences. This paper focused on the educational community and outlined a number of reasons that make the use of educational metadata essential in e-learning environments. It described the main design considerations that should be satisfied to provide an effective metadata management tool in the context of web-based life-long learning framework.
The proposed EM2 architecture promotes the use of educational metadata specifications. It offers features such as the creation and modification of educational metadata, data and structure validation, support of emerging XML technologies, support of any learning standard or specification, mapping between specifications and creation of these maps. Finally, it provides metadata management features, enabling the user to manipulate (update, edit, sort, search, etc) existing metadata documents.
EM2 can be used as a standalone tool in real-world scenarios mentioned in section 2, or it can be integrated to more complex e-learning scenarios. In particular, EM2 has been developed to provide the basic educational metadata management component of the European IST projects KOD (“Knowledge-on-Demand”) (Sampson et al, 2002a) and NEMO (“Non Excluding Models for Web-based Education”). Future work on EM2 development includes the use of a deductive object-oriented database system to facilitate data storage, efficient information retrieval and management. The use of the object-oriented database model for XML document storage provides a number of advantages as opposed to the relational database model (Sampson et al, 2002b). In addition, external agents can access and benefit from the EM2 services in an automated way, without the need for human participation. An agent-based architecture for the invocation of services from the EM2 is proposed (Manouselis & Sampson, 2002). This approach uses wrapper agents to utilise the validation and translation services of the EM2 tool, without encapsulation of the whole EM2 application into the agent’s knowledge base. Such features can be proven extremely useful in applications, such as the validation of large numbers of educational metadata content packages or the translation of such packages to another standard.
The work presented in this paper is partially funded by the European Commission Information Society Technologies (IST) Programme through the IST-1999-12503 “Knowledge on Demand”, and the IST-2000-25308 NEMO “Non Excluding Models for Web-based Education” Projects.
The authors would like to acknowledge the support of their colleagues, Dr. CharalamposKaragiannidis and Mr. AthanasiosPapageorgiou, at the initial stages of this work.
Bacsich, P., Heath, A., Lefrere, P., Miller, P., & Riley, K. (1999).The Standards Fora for Online Education, D-Lib Magazine, 5 (12).
Bourda, Y., & Hilier, M. (2000). What Metadata and XML can do for Learning Objects.WebNet Journal: Internet Technologies, Applications & Issues, 2 (1).
Cutris, K., Foster, P., & Stentiford, F. (1999).Metadata
– The Key Content Management Services. In Proceedings of 3rd
IEEE Metadata Conference,
Duval, E., Vervaet, E., Verhoeven, B., Hendrikx, K., Cardinaels, K., Oliviι, H., Forte, E., Haenni, F., Warkentyne, K., Forte, M.W., & Simillion, F. (1999).Managing Digital Educational Resources with the ARIADNE Metadata System. Journal of Internet Cataloging, 3 (2-3).
Greenberg, J. (1999). Metadata and Organising Educational Resources on the Internet.Journal of Internet Cataloging, 3 (1).
Heery, R. (1996). Review of Metadata Formats.Program, 30 (4).
Manouselis, N., & Sampson, D. (2002). Cooperative Learning e-Content Management Systems using Wrapper Agents. CERTH-ITI-ASK Internal Technical Report (available from the authors).
Papaioannou, V., Karadimitriou, P., Papageorgiou, A.,
Karagiannidis C., & Sampson, D. (2001).From Educational Metadata Authoring
to Educational Metadata Management.In Proceedings IEEE Computer Society
International Conference on Advanced Learning Technologies.
Sampson, D., Karagiannidis, C., Schenone, A., & Cardinali, F. (2002a). Knowledge-on-Demand in e-Learning and e-Working Settings.Educational Technology & Society Journal, 5 (2).
Sampson, D., Vassiliades, N., & Vlahavas,
Sampson, D., Karagiannidis, C., & Cardinali, F. (2002c). An Architecture for Web-based e-Learning promoting Re-usable Adaptive Educational e-Content. Educational Technology & Society Journal, 5 (4).
Steinacker, A., Ghavam, A., & Steinmetz, R. (2001).Metadata standards for web-based resources.IEEE Multimedia Journal, 8 (1).
Tozer, G. (1999). Metadata Management for Information Control and Business Success.Artech House.
Weibel, S. (1995). Metadata: The Foundations of Resource Description, D-Lib Magazine, 1 (1).
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