IEEE TCDL Bulletin
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TCDL Bulletin
Current 2006
Volume 3   Issue 1


G-Portal – A Cross Disciplinary Digital Library Research Program from Singapore

Ee-Peng Lim, Jun Zhang, Yuanyuan Li, Zhe Wang1
Chew-Hung Chang, Kalyani Chatterjea2
Dion Hoe-Lian Goh, Yin-Leng Theng3

1School of Computer Engineering
2National Institute of Education
3School of Communication and Information
Nanyang Technological University, Singapore



G-Portal is a digital library research program supported by the Center for Research in Pedagogical Practices (CRPP) of Singapore's National Institute of Education (NIE). The program aims to develop a digital library portal for harnessing distributed geography learning objects and providing the essential tools to support active learning. The G-Portal team consists of researchers from the Education, Computer Science, and Information Science disciplines. The team has so far realised a Java-based portal for managing, visualizing and sharing metadata of geography objects, as well as using them to support various learning activities. This article summarizes the main accomplishments of the research program and its impact on geography education. The future research directions of G-Portal and the associated challenges will also be highlighted.


1. Introduction

The ways that average and expert users find information, and study and disseminate it, have changed significantly in the last decade due to the pervasive use of the World Wide Web. Today, instead of sending information via email or snail mail, for easy dissemination information resources are frequently posted on the Web in various forms, including web pages, document files, spreadsheets, and even blogs. This has certainly made the Web the largest source of information, and probably the most popular one as well, assisted by easy-to-use web search engines and browsers. From the perspective of education, the Web represents an exciting medium for supporting learning activities both within and outside classrooms. On the other hand, educators realise that many web sites contain learning objects of high educational value (Sumner and Marlino, 2004). Learning objects here refer to carefully edited and organized text, HTML, and other multimedia objects that can be used directly or indirectly in the learning process. For example, web pages and image files from a web site documenting environmental issues related to water conservation can be considered as learning objects. Once created, learning objects can be made available on the Web. Web sites can also be designed such that educational software tools can be activated to support a variety of learning tasks. These learning tasks can range from having closely guided instructions to being completely open-ended. As the Web also serves as a global network of servers for user communities to create and share learning objects, these objects may be organized in some manner to allow users to take some control of these learning objects, choosing ways of organising and using them, creating new ones and even developing their own learning strategies.

Using the Web as a learning platform poses a few challenges to researchers from the education, computer and information science disciplines. While education is a highly established discipline, research on learning effectiveness within the Web environment is still in the nascent stage. Computer and information scientists have contributed significantly to web browsing and searching software, but they have few clues about the software functions needed to enhance learning, especially learning in specialized subject domains.

The G-Portal digital library research program, which began in 2001, aims to address the above challenges by developing a digital library portal for harnessing distributed learning objects and provide the essential tools to support active learning (Liu et al., 2003) (Liu et al., 2004). The research program focuses on the geography domain, which requires content rich media including maps, images, text and other data collected from geographical environment. The G-Portal research team consists of members from the education, computer and information science disciplines, and G-Portal research activities can be divided into two complementary tracks:

  1. Design and implementation of the G-Portal digital library portal with learning support functions; and
  2. Deployment of G-Portal digital library portal in geography education.

In the following sections of this article, we report the work done in these two tracks, highlighting the research issues involved and the approaches taken to address them. Long-term research directions will also be described.

2. Design and Implementation of G-Portal

The G-Portal web portal design can be divided into database and software aspects. The former supports flexible representation and storage of metadata and their organisation, while the latter provides a set of functionalities that allow heterogeneous web learning objects to be utilized in learning activities.

2.1 Metadata for heterogeneous geography learning objects

Unlike proprietary learning objects, learning objects on the Web are created by different users for different purposes, including those that are non-educational. In G-Portal, metadata records are constructed for heterogeneous geography objects that allow them to be organised for various learning tasks. A G-Portal metadata record consists of a set of mandatory metadata elements required for uniform metadata identification, visualization and display, and optional metadata elements for storing task- and topic-specific description of learning objects.

For easy metadata sharing and manipulation, metadata schemas can be defined with appropriate mandatory and optional elements, and every metadata record is created using a metadata schema as the template. Every metadata schema must provide a mandatory source metadata element to allow metadata records to be linked to their corresponding learning objects. Figure 1(a) shows a G-Portal metadata record defined for a web page that contains a photo image of a beach headland (see Figure 1(b)). Metadata records can be associated with spatial geometrical shapes for them to be displayed on the G-Portal map interface as shown in Figure 2.

Image showing (a) a metadata record and (b) ther associated raw web object

Figure 1. (a) Metadata Record of Headland 5 (b) Raw web object


Screen shot of G-Portal Client Interface

Figure 2. G-Portal Client Interface

2.2 Metadata organised by learning activities

G-Portal allows a set of metadata records to be organized according to how they are to be used in learning tasks and by the topic to which they belong. These are known as organization by task and organisation by topic, respectively.

A project in G-Portal refers to a collection of metadata records constructed to support a learning activity. For example, Figure 2 depicts a project (called "ECP Project"), which consists of a collection of metadata records about the physical structures and beach water level measurements (also called profiles) taken at the East Coast Beach of Singapore. The project has been used in a geography course to evaluate the extent and cause of beach erosion.

The set of metadata records belonging to a project can be determined when the project is created, or can be added after project creation. Within a project, metadata records can be further organized into layers, each of which represents a subset of metadata records that are displayed as a group. For example, Figure 2 depicts a set of beach profiles displayed under the "ECP Profiles" layer, while the physical beach structures are grouped under a different layer.

Metadata records within a project are also organized by topic or category to facilitate metadata-browsing by category. Parent-child relationships among categories can be defined to form a category hierarchy. Unlike many other digital libraries, G-Portal can accommodate different category hierarchies for different learning projects so as to support customizable metadata organization. A metadata record can also be shared among different projects and appear in different categories. This gives much flexibility that cannot be found in traditional digital libraries.

2.3 Creating, querying and visualizing metadata

In G-Portal, multiple users can access a project simultaneously and can collaboratively contribute metadata records to the project. A web form interface is available for these users to add new metadata records for relevant web objects. The created metadata can be accessed online via either queries or browsing using the G-Portal client interface. The client program is a Java applet that runs on almost any PC or workstation. As shown in Figure 2, it has both map-based and classification-based interfaces for browsing metadata. Within the map-based interface, one can perform zooming and panning operations to locate desired metadata records. The client also has a query interface that can handle queries on spatial locations and metadata elements. Once a metadata record is found by query or browsing, its metadata elements can be displayed in either HTML or XML form. In either case, one can follow the source link in the metadata record to view the referenced learning object.

3. Deployment of G-Portal in Geography Education

Using G-Portal in a learning activity involves the following steps:

  1. Construct a project with an initial set of learning objects and their metadata;
  2. Access and view learning objects within the constructed project;
  3. Collaboratively create and share new learning objects and/or their corresponding metadata;
  4. Analyse project content and use them in assignment report preparation.

Next we describe how the above steps were performed when G-Portal was deployed in a nature reserve field study.

The primary objective of the field study is to evaluate the environmental stress of Bukit Timah Nature Reserve1 (BTNR) by taking readings (e.g., humidity level, temperature, root mass, etc.) and photographs at various locations in the reserve and analyzing them. The study was conducted as part of a course conducted at the National Institute of Education2. Firstly, from the scope and objectives of the field study, a new project was created in G-Portal by the professor responsible for the course. The map area to be covered by the study was also determined, and its corresponding background map image was added as the background of the project's map-based interface. In the study, a map showing the trails of BTNR was used as the background image. The stations at which data were to be collected were also indicated on the map. Students were required to form teams, and each team was to collect environmental data (e.g., temperature, humidity, etc.) at designated stations in BTNR. The students were then required to create spreadsheet files and photo images about the data collected at these stations, and construct the respective metadata records. A screenshot of G-Portal's client with this project loaded, as well as its contributed metadata records, is shown in Figure 3.

When the data collection and metadata creation phases were completed, G-Portal was used by the students to query and visualize all the created metadata records in the BTNR project. They could access G-Portal both in the classroom and at home. Since the student teams were assigned different sets of locations (with possibly some overlaps), each student team had to use G-Portal to gain access to the metadata records and web objects created by other teams.

With G-Portal serving as the central web repository of metadata records, it was found that students were able to locate metadata records and their corresponding web objects required for the field study assignment. G-Portal also facilitated collaboration among students, as they could refer to one another's metadata records. This was also reflected in the final study reports prepared by the student teams as they cited web objects created by other teams.

Screenshot showing the G-Portal Client loaded with BTNR metadata records

Figure 3. G-Portal Client loaded with BTNR metadata records

In the above example scenario, all student teams shared the same project to which they contributed metadata. G-Portal can also be used in other learning scenarios where students are expected to create and update their personalized projects. To begin with, a public accessible project may be first created by the course professor to maintain a basic set of metadata records and maps. The G-Portal client allows students to then copy the relevant information from the public project and paste them in their personalized projects. The same operation can be performed on different public projects to reduce the efforts of gathering metadata records for a newly constructed personalized project.

Other than the above-mentioned online Java applet client interface, G-Portal also provides a Java application client interface that can be used when users are offline. This is particular useful (a) when users have no access to Internet, or (b) when users would like to let others access their projects without involving their user ids and passwords. This application client interface is very similar to the applet version except that this interface can operate on a standalone PC without an Internet connection.

4. Future Research Directions

The G-Portal research program has so far realised a web portal for managing and sharing geography-related metadata records. Sections 2 and 3 above summarized the design of this portal and its deployment in learning activities. As part of our future research, we are extending G-Portal with additional features to support other important steps in learning. These include: (a) reviewing and rating of metadata; (b) interoperability of metadata; (c) harvesting of learning objects and construction of their metadata.

4.1 Metadata review and revision

Compared to raw learning objects, metadata are of better quality, as they are expected to be created by highly qualified human experts. In our proposed meta-portal system, students and community users can create their raw learning objects as part of their learning activities and submit their metadata for these objects to the meta-portal for further sharing. To ensure the metadata quality and to promote cooperation among community members, an open review system for Geography community experts will be required (Ismail et al., 2003). In designing the metadata creation and review process, the collaborative metadata editing and versioning functions will be investigated. The former allows multiple users to jointly construct different elements of metadata records. The latter supports changes to metadata records by maintaining different versions of them.

4.2 Interoperability of metadata

Metadata is a valuable resource for learning. To fully tap into the potential of G-Portal, the metadata resources of G-Portal should be further exchanged with other l the Open Archives Initiative (OAI) protocol (Lagoze et al., 2002) can be extended with flexible metadata formats to support interoperability between G-Portal and other systems. OAI has been implemented for several public domain digital libraries including DLESE and other NSDL (National Science Digital Library) projects ( Because projects and layers are unique features in G-Portal, exchanging these pieces of information via OAI will also be a topic for research.

4.3 Harvesting of learning objects and metadata construction

The current G-Portal digital library largely relies on users to manually identify useful learning objects and create metadata records for them. Although the metadata created are highly relevant to the learning activities, the amount of effort required can be significant. Users are expected to be competent in finding and sometimes creating relevant learning objects themselves and competent in creating metadata records. To address these limitations, future G-Portal research will explore techniques and tools for automatically discovering learning objects and constructing their metadata from the web. For example, we are now investigating the problem of extracting place names from web pages and associating appropriate place names with web pages (Zong et al., 2005). Our future work will focus on uncovering those metadata that are available from public domain web repositories of geography learning objects, including those provided by other digital libraries, e.g., DLESE. Our research will also investigate automatic metadata construction using machine learning techniques.

5. Conclusions

The G-Portal research program represents a multi-disciplinary effort to develop a geography digital library portal for hosting metadata records and providing digital library services over them. The developed software has been put to use already in learning activities such as field studies. This article has described the design and implementation of G-Portal software and its deployment in an example field study. Other than addressing practical issues, research will also have to investigate solutions to new problems as we extend digital libraries with new learning capabilities. Some of these research problems are also highlighted in this article. Geography is a subject that spans across geopolitical boundaries. In the fast developing Asia region, we believe that the G-Portal digital library system can play an important role in gathering metadata about the geography information of the region and making the metadata available for education.


* Bukit Timah Nature Reserve is a national park in Singapore.

+ National Institute of Education is an institute in Nanyang Technological University for teacher trainees.


(Ismail et al., 2003) Dian Melati Md Ismail, Yin Ming, Yin-Leng Theng, Dion Hoe-Lian Goh and Ee-Peng Lim. "Towards a Role-Based Metadata Scheme for Educational Digital Libraries : A Case Study in Singapore", 7th European Conference on Digital Libraries, Trondheim Norway, August 17- 22, 2003.

(Lagoze et al., 2002) Carl Lagoze, Herbert Van de Sompel, Michael Nelson, and Simeon Warner. The Open Archives Initiative Protocol for Metadata Harvesting – Version 2.0, 2002. <>.

(Liu et al., 2003) Zehua Liu, Ee-Peng Lim, Wee-Keong Ng, Dion Hoe-Lian Goh, 2003. "On Querying Geospatial and Georeferenced Metadata Resources in GPortal," ACM/IEEE Joint Conference on Digital Libraries (JCDL2003), Houston, May 27-31 2003.

(Liu et al., 2004) Zehua Liu, Ee-Peng Lim, Yin-Leng Theng, , Dion Hoe-Lian Goh Wee-Keong Ng, 2003. "On Organizing and Accessing Geospatial and Georeferenced Web Resources using the G-Portal System," accepted by the Information Processing and Management Journal, 2004.

(Sumner and Marlino, 2004) Tamara Sumner and Mary Marlino, 2004. "Digital Libraries and Educational Practice: A Case for New Models," ACM/IEEE Joint Conference on Digital Libraries (JCDL2004), Tucson, Arizona, June 2004.

(Zong et al., 2005) Wenbo Zong, Dan Wu, Aixin Sun, Ee-Peng Lim, Dion Hoe-Lian Goh, 2005. "On Assigning Place Names to Geography-Related Web Pages," ACM/IEEE Joint Conference on Digital Libraries (JCDL2005), Denver, Colorado, June 2005.


© Copyright 2006 Ee-Peng Lim, Jun Zhang, Yuanyuan Li, Zhe Wang,
Chew-Hung Chang, Kalyani Chatterjea, Dion Hoe-Lian Goh, Yin-Leng Theng

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