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Modifying the EXPLORER system for ESL/EFL

Steven D. Tripp
University of Aizu, Japan
There is now great interest in the Internet system called the World Wide Web (WWW). The EXPLORER client/server system is a WWW system for educators. It facilitates the storage and retrieval of curriculum materials electronically. The purpose of this research is to convert the EXPLORER WWW client/server system into a WWW database server for English as a Second Language/English as a Foreign Language (ESL/EFL) curriculum resources.

The EXPLORER system is an original WWW client/server system which serves as an archive for curriculum materials. It is unique in that it combines a dbml (database markup language) with an html (hypertext markup language) interface to make Boolean searches of the database possible with either the EXPLORER client or other html browsers such as Mosaic or Netscape. Curriculum materials are stored in a curriculum hierarchy based upon standard curriculum classification schemes. Additionally, searchable information is stored on all of the following categories: resource type, physical media, educational level, process skills engaged, and geographical locus, as well as normal information about title, author, publisher, and availability.

At the current time the EXPLORER system is structured to accept only science and mathematics curriculum resources for North America. This project is extending the system both conceptually and geographically. First it will create a curriculum hierarchy for English as a Second Language (ESL) and it will expand the geographic locus to the entire world. The resulting product will be of benefit to English teachers, not only in Japan, but across the globe.


The development of user friendly World Wide Web (WWW) browsing interfaces like Mosaic and Netscape have led to an explosion in the amount of readily available information. Unfortunately, too much information presents as many as or perhaps more problems than a lack of information. If the information you need is not readily accessible, it may as well not exist. The WWW is growing at a rate that makes it hard to locate information of interest. The Lycos system indexes over 860,000 Web documents from 34,000 sites and is adding 5,000 documents a day (December, 1995). This quick growth is due to its easy to use, point and click interface, simple standards (HTML, MIME) which allow the exchange of multimedia documents, and a simple unified interface to a range of useful tools (ftp, gopher, news, etc.).

The EXPLORER system was an early WWW application which attempted to provide information to educators. The intent was to develop a system contributing to K-9 mathematics and science education by allowing educators and students to remotely contribute and access multimedia educational resources. This paper gives a short sketch of the WWW and the design of servers and clients. Then it describes our approach to these issues, focusing on search capability, and how EXPLORER will be modified to support EFL/ESL applications.

The World Wide Web

The WWW, begun by Tim Berners-Lee at CERN in 1989 as the HyperText Project, was officially described as a wide area hypermedia information retrieval initiative. Its purpose is to allow universal access to a large universe of documents (Hughes, 1994). Its initial goal was to provide a common protocol for requesting, through networks, remotely stored, human readable information using hypertext as the interface and networks as the access. Hypertext, like regular text, can be stored, read, searched, or edited. The only difference is that hypertext contains links to other documents. The power of the WWW is that these links can lead anywhere in cyberspace; to a file in the same directory, another directory on the same computer, or another computer anywhere in the world.

The WWW uses a distributed client/server architecture. The client supports the user by transparently fetching a desired document when the user clicks on a link. On the other hand, the server receives requests generated by clicking a link and returns to the client the required file. Early clients were line mode browsers which performed in the client hardware and software environment. In September, 1993, the National Center for Supercomputing Applications (NCSA) released the Mosaic browser in three versions: X-windows, PC/Windows, and Macintosh. Since Mosaic handled both text and images as well as new media formats such as video and sound, it quickly gained popularity and became the most popular interface to the WWW.

The growth of the WWW is extraordinary. In the year 1993, the traffic attributed to WWW use across the National Science Foundation's North American network increased by 187 times. Between December 1992 and December 1993, the WWW went from 128th to 11th of all network services in terms of traffic. Matthew Gray's WWW Wanderer, a robot which searches for WWW sites and documents, found roughly 100 sites and over two hundred thousand documents in June 1993. By March 1994 this robot had found 1,200 sites. A similar program at the University of Washington, called the WebCrawler, found over 3,800 unique WWW sites in mid-May 1994 (Hughes, 1994), and found 12,000 WWW servers in mid-March of 1995.

This rapid pace of growth is likely to continue. A major problem posed by the WWW is clearly one of making information available in an organised and useful way. The remainder of this section gives a description of WWW servers and clients, giving some idea of the kinds of services they can potentially provide.

WWW servers

A WWW server is a computer program running on a host computer. When a user, by means of client software, makes a request for a document, that file is supplied by the server. The client and server need to speak the same language, or use the same set of protocols, to communicate.


The WWW uses the Hypertext Transfer Protocol (HTTP). HTTP is an application level protocol with the brevity and speed necessary for distributed hypermedia information systems. It is a generic, stateless, object oriented protocol which can be used for several kinds of tasks (Berners-Lee, Fielding, and Hughes, 1995). It is stateless because the server keeps no information about current transactions. It is object oriented because it applies methods to objects (files or programs). HTTP uses addresses provided by the Universal Resource Identifier (URI), as a location (URL) or name (URN), for identifying the resource upon which a method should be applied. Messages are passed much like Internet mail and use the Multipurpose Internet Mail Extensions (MIME) (Berners-Lee, Fielding, Nielson & Hughes, 1995).

HTTP uses a request/response dialogue between the client and server. The client connects with a server and submits a request consisting of a request method, a URI, and a protocol version, followed by a MIME like section containing request modifiers, client information, and an optional body. Unlike some protocols, HTTP does not keep the connection open longer than necessary. Normally, the connection is closed by the server after each response. The closing of the connection by either or both parties always terminates the current request, regardless of its status (Berners-Lee, Fielding, Nielson & Hughes, 1995).

A client request includes the method which should be applied to the resource requested, the resource identifier, and the HTTP version. There are seven methods in HTTP: GET, HEAD, PUT, POST, DELETE, LINK, UNLINK (Berners-Lee, Fielding, Nielson & Hughes, 1995). Of these, it is the GET method which is primarily of interest here. The GET method retrieves information identified by the Request-URI. If the Request-URI refers to a data producing process, it is the produced data which is returned as the entity in the response and not the source text of the process (Berners-Lee, Fielding, Nielson & Hughes, 1995). The HEAD method is identical to GET except that the server does not return any entity body in the response. The meta-information contained in the HTTP headers in response to a HEAD request is identical to the information sent in response to a GET request (Berners-Lee, Fielding, et al, 1995).

The POST, PUT, DELETE, LINK, and UNLINK methods can all be used to make modification to files stored on the server (Berners-Lee, Fielding, Nielson & Hughes, 1995).

Server features

One feature, directory indexing, allows the viewing contents of directories on the server with a WWW client. Depending on how the server is configured, the listing can display distinct icons for different file formats. A header and trailer file can be added in the listing to give more information on the contents. Another feature, CGI (common gateway interface) scripts, a powerful feature of HTTP servers, are used to run programs on the server. These scripts are primarily used as gateways between WWW servers and other applications like database software. Another popular use of CGI scripts is in image maps, which associate HTTP links with different areas of an image. The images are segmented so a click a part of the image takes the user to an associated URL.

The features mentioned above are only a subset of those available by full powered WWW servers.

WWW clients

WWW clients, often called browsers, render documents retrieved from WWW servers on the user's computer. They also send requests to a server when the user selects a hypertext link. Currently,. the most familiar browsers are Netscape and Mosaic, both of which run on multiple platforms (PC, Mac, UNIX based stations).


The HyperText Markup Language (HTML) is a subset of SGML (Standard Generalised Markup Language). It is a simple markup language used to create hypertext documents that are portable across platforms. HTML markup can display a variety of content types including hypertext news, mail, documentation, hypermedia; menus of options; database query results; simple structured documents with in-lined graphics; and hypertext views of existing bodies of information (Berners-Lee & Connolly, 1995). Figure 1 shows a short HTML document.
<TITLE>Example HTML Document</TITLE>
<H1>My HTML Document</H1>
This is a <A HREF="http://www.u-aizu.ac.jp/~tripp/">link</A> to my home page.
<P> This is an <B>inlined</B> image of my boat:<BR>
<IMG SRC="/graf/tp2.jpeg">
Figure 1: HTML example

HTML is an evolving language, causing different browsers to render the same HTML documents differently. Currently there are four versions of HTML, the most common being HTML 2.0. HTML 2.0 introduced forms which support more complex interaction between users and servers by enabling them to supply information beyond simple item selection. For example, forms are commonly used by the user to specify character strings for searching, and to provide user specific data when interacting with a business's WWW page. HTML 3.0 recently become available, which adds the features of tables, mathematical equations, and other graphic layout effects.

Netscape and Mosaic, the most widely used Web browsers, provide similar feature sets. They both have a consistent GUI, and support point and click actions to navigate in hyperspace. They both display hypertext and hypermedia documents in a variety of character sets (including non-Roman sets like Japanese), fonts and styles. They also support layout elements such as paragraphs, lists, numbered and bulleted lists, and quoted paragraphs (Hughes, 1994). All of these are defined by the HTML tags within the WWW document being rendered.

The browsers use external applications to support additional operations. For example, they can show movies, play audio files, or display graphical images. With forms support, they support interaction with users. Forms allow such objects as fields, check boxes and radio buttons. In addition they can access information beyond the WWW. They provide links to the following network services: FTP, telnet, gopher, NNTP, and WAIS. Moreover, they can: (1) store and retrieve addresses of documents for future use; (2) keep a record of links traversed; and (3) allow remote applications to control the local display.

WWW clients may differ in many ways but because they all use HTML they will be able to exchange information with other clients.


The EXPLORER project developed a WWW server and client which provide access to a multimedia educational database. The target audience included teachers in 52 schools in the northeastern United States that are part of the Great Lakes Telecommunications Collaborative. The teachers generally have minimal computer skills, therefore, the design team's objectives included: 1) designing a user friendly interface; 2) organising educational resources in ways consistent with existing school practices; 3) facilitating distributed contributing and reviewing of resources; and 4) providing both browsing and search strategies that are familiar to users of educational resources. EXPLORER provided an archive and a search mechanism for educational resource materials. BY implementing a graphical user interface, we created a system which was accessible to novice users. Finally, by involving the users themselves in the design of the database they were encouraged to contribute original resources. However, resources are not added to the system uncritically. A series of editors approve and improve the contributed materials, providing quality control. The current database consists of material useful to K-12 mathematics and natural science teachers. Database resources contributed by users are entered into the database after a two stage review process. The database can be accessed via the hierarchically structured curriculum taxonomy or the graphical search window can be used to specify Boolean queries.

The server

The EXPLORER server is HTTP based so it can be used as a regular Web server. In other words it can be accessed by any WWW client not just the EXPLORER client. It supports the GET, DELETE, POST, PUT, and SEARCH methods. It runs CGI scripts and supports directory access. On the other hand, the EXPLORER server does not support a number of other services which were not required for this project.

The SEARCH method is a unique EXPLORER server feature created to allow it to respond directly to queries from the client rather than relying on CGI scripts. The SEARCH method defines a search syntax. To support access from other WWW clients, which do not have a SEARCH method, a generic forms interface was built.

This interface allows the user to select the database and fields of the database to search on. Unfortunately, the forms interface uses several separate HTML pages to present the interface. This requires the preservation of information across request boundaries, which contradicts the stateless design of HTTP. As a solution, the server generates invisible HTML documents which preserve the required information. This information is then sent back to the server with each exchange providing the necessary information. This effectively makes the stateless HTTP protocol into a stateful design.

The EXPLORER search engine is CSO, originally written for a simple computer resident phone book, but requiring only slight modification to fit EXPLORER's needs. It can keep small amounts of information about a large number of objects, and provide access to that information over the Internet [5]. CSO also allows for vague queries in the form of wild card expansion. The main problem with CSO is that it is inappropriate for large text items and it does not have Boolean search capabilities.

Another search engine that is being integrated into the server is WAIS (Wide Area Information Server), a free text search engine which supports natural language queries and inexact searches while returning a ranked list of matches. This allows the selection of best match resources without having to review the whole list.

User characteristics

Rapidly evolving information technologies are significantly altering social institutions. Schools, once dominated by top down systems, are responding by encouraging more opportunities for teachers. To address these needs, systems for distributing educational resources must provide: 1) mechanisms that allow teachers and students to contribute their ideas, 2) a review process to control quality and 3) structures for easily locating valuable resources. Earlier research in designing network information services for educators suggested that teachers found hierarchical browsing structures to be an easy way to locate information (Aust, 1994). As the teachers used the browsing mechanism they became familiar with available resources including lesson plans, field trip descriptions, lab activities, videos, and student created materials. However they also expressed a desire for a more focused search devices. These kinds of questions require more advanced document indexing and query mechanisms than the parent-child hierarchy needed for a curricular browsing structure.

Client: User interface

The initial design for the client user interface is based on a prototype developed during pilot projects (Aust, 1994). This design used a layers to represent curriculum hierarchy structures as directories are represented in typical GUIs. Novices understand how to navigate this structure and are successful in locating resources. They also comprehend icons used to represent various resource types. The pilot users also provided several suggestions for a more serviceable browsing view of the curriculum's hierarchy, and the ability to locate items using multiple criteria.

Recent user interface development has centred on incorporating recent additions to HTML for constructing Boolean queries using standard WWW clients. We have also implemented features in the EXPLORER client to easily identify selections in extensive hierarchical lists.


In EXPLORER, the available resources are organised in databases. In each database the structure, format, and treatment of the database records is described in a configuration file. A database configuration language is used to specify record structure, and defines four basic objects: TABLE, ENUMERATION, RECORD, and DATABASE OBJECT. TABLEs keep information about icons used by the client. ENUMERATIONs list the possible instantiations for a descriptive category. RECORDs keep information about the filename and size. DATABASE OBJECTs keep information about classification categories among other things. This language provides a centralised user readable and modifiable specification of the data stored and its treatment by the system. Figure 2 illustrates a simple example of a database configuration file.
TABLE "PhysMedia_Table" {
     "CD" "CD_icon.GIF";
     "LP" "LP_icon.GIF";
     "VHS" "VHS_icon.GIF";
     "DEFAULT_ENTRY" "Default_icon.GIF";
     "CD" "LP" "VHS"
     "Natural Science" {
     "General Natural Science"
     "Physical Science" {
     "General Physical Science"
     "Properties of Matter" {
     "General Properties of Matter" }
     "Electricity-Magnetism" }
     "Common Themes" }
RECORD "FileDescT" {
     "integer" "One" "NoSearch" "FileSize";
     "string" "One" "Keyword" "FileName";
     "string" "One" "Keyword" "Title";
     "uid" "One" "NoSearch" "IDNumber";
     "FileDescT" "One" "NoSearch" "FileDesc";
     "CurricT" "One" "Keyword" "Curriculum";
     "PhysMediaT" "One" "Keyword" "PhysMedia";
Figure 2: Data base configuration language example

In the example of Figure 2, the language specifies (from bottom to top) the physical medium of the resource, the area of the curriculum it represents, the name and size of the file, and other bookkeeping information. The physical media are represented by three choices, whereas the curriculum area is a hierarchical structure.

Constructing searches

Many searches are formed by selecting one of a set of controlled vocabulary items (authority lists). CURRICULUM is one of the controlled vocabularies used in indexing the educational resources. Other controlled vocabularies include: RESOURCE TYPES, PHYSICAL MEDIA, GRADES and PROCESS SKILLS. These controlled vocabulary fields may be coupled with the remaining text entry fields to form complex queries for specifying resources.


The success of a distributed database depend on the participation of users to generate source material. For this, we implemented a method called the Contribution Process, supported by software called the Contributor. The Contributor asks which database the user wishes to contribute to. Then the Contributor prompts the user to enter information for each field of the database. The Contributor then sends the newly defined record to a local reviewer. The local reviewer's duties are to make sure the record relates to the application area to which it is being contributed, that it is properly formatted, and is well formed. The local reviewer then passes the record along to a master reviewer whose duties are to check the local reviewer's work and approve or reject the record for inclusion in the database. From there, the record is sent to the EXPLORER server for integration in the database.

Once the record is transferred to the server, a series of steps are taken to add the record to the proper section of the database. The first step is to generate an HTML document following the format of the database record definition. Then a database record is created and added to the database. Following that, the layered and outline views are rebuilt. This Contribution Process is run nightly and therefore the turn around time for a newly defined record is usually 24 hours.

Conversion for ESL/EFL curriculum resources

The current database structure is optimised for science and mathematics, based upon North American curriculum standards. The intention is to implement a server at the University of Aizu in Japan, where a world wide archive of ESL/EFL resources will be collected. In order to modify this system for worldwide EFL/ESL resources, the following modifications to the database structure are considered.
TABLE "ResourceType_Table" {
     "Lab Activity"
     "Instructional Aid"
     "Instructional Module"
     "Field Trip"
     "Student Created Material"
     "Parent Material"
     "Practical Article"
     "Research Article"
Figure 3: Database table of resource categories and icons

The database resource categories are listed in Figure 3. Reference materials are especially useful to language teachers. A new category to encompass dictionaries, grammar handbooks, and similar materials will need to be added. Authentic materials, such as signs, menus, and other real world language examples will also be a category.

TABLE "PhysicalMedia_Table" {
     "Audio CD"
     "Downloadable File"
     "Floppy Disk 3.5"
     "Overhead Transparencies"
     "Paper Based Media"
     "VHS Video Tape"
Figure 4: Database table of physical media and icons

Language teachers make great use of audio cassettes which are not listed in Figure 4. These and other audio resources will he added. New media are appearing constantly and may be added if they find a place in the ESL/EFL community.

TABLE "FileFormat_Table" {
Figure 5: Database table of file formats and icons

File formats differ from country to country. Especially in Japan where computers systems differ from the North American standards which are listed in Figure 5, some new formats may need to be entered. It is not clear how non- Roman fonts, such as Japanese, will be handled. There is now a WWW server located in California which allows you to display Japanese HTML documents on your computer, even if you don't have the proper fonts installed. At any rate, there are at least three encoding systems for Japanese characters, so some system for recording this information in the database will need to be developed.

TABLE "Fields_Table" {
     "ID Number";
     "Resource Type";
     "Process Skills";
     "Physical Media";
     "File Size in KBytes";
     "File Format";
     "File Name";
     "File Description";
Figure 6: Database table of descriptive fields

No modification of the fields in Figure 6 are envisioned.

     "Pre-K" "K"
     "1" "2" "3" "4" "5" "6"
     "7" "8" "9" "10" "11" "12"
     "Undergraduate" "Graduate" "Adult"
Figure 7: Database table of applicable educational levels

Not all school systems are of the K-12 + university variety. Some way of accommodating differing systems will need to be devised. This is largely a matter of adding new categories.

     "Hawaii" "Idaho" "Illinois" "Iowa" "Kansas" "Kentucky" 
     "Washington" "West Virginia" "Wyoming" "Alberta"
     "British Columbia" "Manitoba" "Newfoundland"
Figure 8: Database table of geographic areas

The current system encompasses only a few American states and four Canadian provinces as listed in Figure 8. This can easily be expanded by adding countries, but note that the above is not based on countries but states and provinces. The logical expansion is to use Japanese prefectures and Thai provinces, but this runs into the problem that most people are not familiar the subdivisions of other countries, so this enumeration will probably need to be hierarchical, with countries at the top and political subdivisions below, and perhaps cities below that. The problem here is that the EXPLORER database allows educational excursions as a curriculum category. This is useful only within a local area, so the search engine needs this information in order to limit its search.

ENUMERATION "CurriculumT" {
     "Mathematics" {
     "General Mathematics"
     "Problem Solving and Reasoning" {
     "General Problem Solving and Reasoning"
     "Logical Reasoning"
     "Mathematical Tools" {
     "General Mathematical Tools"
     "Calculators" {
     "General Calculators"
     "Mathematical Instruments"
     "Whole Numbers and Numeration"
     "Natural Science" {
     "General Natural Science"
     "Life Science"
     "General Life Science"
     "Cells" {
     "General Cells"
     "Cell Growth"
     "Cell Reproduction"
     "Living Things"
     "Physical Science"
     "Earth Science"
     "Common Themes"
Figure 9: Database table of hierarchical curriculum structure

Obviously, the mathematics and science curriculum categories listed in Figure 9 do not apply to EFL/ESL. The problem here is that the above categories are based on accepted standards of academic societies. EFL/ESL, being a world wide phenomenon, does not have accepted curriculum categories. Some such approximation will be necessary.

ENUMERATION "ProcessSkillsT" {
     "Mathematics Process" {
     "Calculators and Computers"
     "Mental Arithmetic"
     "Problem Solving"
     "Natural Science Process" {
     "Gather Data"
     "Analysis Synthesis Evaluation"
     "Communicate Ideas"
     "Values and Attitudes"
Figure 10: Database table of process skills for science and mathematics

The category "Process Skills" may be unnecessary for language learning. However some who emphasise the communicative aspects of language acquisition may prefer to list some communication skills here. This is an area for further research


The EXPLORER client-server system has many features which make it attractive as a database browsing/query system for ESL/EFL purposes. The HTML structure of its output make it accessible by a wide variety of platforms in many countries. The power of its SEARCH method is needed for large information systems. As was mentioned at the beginning, the WWW and its information archives are growing at a staggering pace. ESL/EFL teachers need a well structured source of information if that information is to be useful. At present the database structure is not adapted to ESL/EFL, but the actual database categories can be extended to include new categories with little recoding. The real problem is determining which categories will be useful to users in the EFL/ESL community.


Aust, R. (1994). Designing network information services for educators. Machine-Mediated Learning, 4, 251-267.

Berners-Lee, T., & Connolly, D. (March 29,1995). HyperText Markup Language - 2.0. INTERNET DRAFT ftp://ietf.cnri.reston.va.us/internet-drafts/draft-ietf-html-spec-01.txt

Berners-Lee, T., Fielding, R. T., Frystyk Nielson, H., and Hughes, K. (March 8, 1995). Hypertext Transfer Protocol - HTTP/1.0. INTERNET-DRAFT. ftp://ietf.cnri.reston.va.us/internet-drafts/draft-ietf-http-v10-spec-00.txt

December, J. (1994). New Spiders Roam the Web. Computer Mediated Communication Magazine, 1(5).

Hughes, K. (1994). Entering the World-Wide-Web: A Guide to Cyberspace. Enterprise Integration Technologies.

Please cite as: Tripp, S. D. (1996). Modifying the EXPLORER system for ESL/EFL. In C. McBeath and R. Atkinson (Eds), Proceedings of the Third International Interactive Multimedia Symposium, 405-411. Perth, Western Australia, 21-25 January. Promaco Conventions. http://www.aset.org.au/confs/iims/1996/ry/tripp.html

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