The Real Experiment eXecution
approach to Networking courseware

M. Chirico, F. Giudici, A. Sappia and A. M. Scapolla

1. Introduction

2. The Real Experiment approach (REX)

2.1 Basic concepts

2.2 System architecture

3. A REX based networking courseware

4. Conclusions and future work




Courseware development and delivering represent one of the main topics of present research activities in the field of computer assisted learning (CAL). New education technologies have been driven by the improvement in computer networks capabilities addressing client-server dynamics, access mechanism and network services. Furthermore multimedia authoring tools, WorldWide Web and the programming paradigm of Java are leading to the creation of new and effective didactic environments.In this scenario, particular attention must be paid to the learning design process, since students can learn better when they are stimulated by the high level of interactivity and they can follow a personal way to learn. In this paper a new approach to Web based courseware development is presented: the Real Experiment eXecution (REX) approach. The proposed approach is well suited to the development of courseware in the field of computer science. Following the REX approach it is possible to integrate into the courseware a high degree of interaction since no simulation activity is performed, but real experiments are carried out through the execution of operations. The Java programming paradigm allows the execution, control and monitoring of these operations. We present a courseware prototype featuring network services and protocols, where the students are introduced to the use of the FTP service. They start a file transfer session and execute typical commands. The system traces the generated network traffic and let the students analyse and understand the results of the ongoing software experiments.

1. Introduction

The growth of communication resources like Internet and the availability of authoring and distribution tools for computer-based learning products have changed the traditional way to support learning and training activities and to produce and distribute learning materials and publications. The research activities in Computer Based Training (CBT) delivering have taken advantage of computer networks capabilities addressing client-server dynamics, access mechanism and available network services.

The impact of information technology on teaching methods has been driven mainly by:

MM technology, based on the integration of hypertext with images, video, sounds, animations and simulations is very suited to the contemporary educational needs for its intrinsic aspects such as modularity and multisensorial non-linearity [1].

The MM approach requires that teachers make a great effort in preparing, organising and structuring the courseware. This work supported by progressive validation phases can produce good learning material.

In order to exploit the advantage of MM based teaching methods, it is very important to choose the most effective medium to capture and increase the learner's interest and to combine different media correctly to address the complexity of the real world. Particular attention must be paid to the learning design process, in order to maximise the effectiveness of the new technology and to obtain the most suitable presentation and distribution model [2].

Students can learn better and more quickly when they are stimulated by the high level of interactivity and they can follow a personal way to learn [3] . In particular they can customise their participation to the courseware, establishing the amount of time to be spent on each topic and individuating their self-paced learning.

The WWW represents a powerful medium for its intrinsic deliverability and its larger and larger diffusion through Internet [4] ; therefore it can play as an effective educational environment and researchers are working to incorporate their pedagogical tools into it. Main advantages of WWW based courseware are:

  • location and time independent delivery of course material with a large number of possible concurrent attendees;
  • simple and familiar interface (browser-centric approach);
  • reduced time spent for the pedagogical material creation or upgrading;
  • different strategies of learning addressed to differentiate students curricula by means of customisable guided tours through the course material.

Moreover, the add-on of tools for collaborative learning and co-operative work can significantly improve the quality of education [5] [6].

The increasing complexity of such educational environment based on the WWW has led to dedicated frameworks addressed to their assisted development. Nowadays useful environments are available to help the courseware author to build and manage an instructor site with full multimedia data synchronisation capabilities and communication facilities between teachers and students [7] .

Java has been defined by its designers as "a simple, object-oriented, network-savvy, interpreted, robust, secure, architecture neutral, portable, high-performance, multithreaded, dynamic language" [8]. Originally it was mainly introduced to develop distributed and network-centric applications and, in particular, now it exhibits a very high coupling with the WWW technology. More in detail, Java allows the creation of small applications ("applets") that can be easily embedded in the WWW pages, enhancing them with active capabilities.

A number of Java features are highly valuable for the development of WWW based courseware:

  • Native networking support. Java was explicitly written for networking deployment.
  • Programming facilities. One of the primary goals in Java design is to relieve programmers of low-level tasks. On this purpose, it creates an intermediate layer between the application and the operating system, for instance taking care of operations such as memory garbage collection.
  • Portability and Performance. Java programs are compiled into a "virtual machine" code (bytecode) that is interpreted. In this way Java programs are architecture-neutral and their portability is not an issue.
  • Flexibility and Power. Java programs are naturally dynamic and can be easily extended with external modules.
  • Robustness. Java intrinsic robustness allows the creation of programs that are reliable in a variety of ways.

These features are valuable for a wide range of applications and they also offer relevant benefits in the development of educational material, for both courseware designers and users:

  • Benefits for courseware designers. The typical expertise of courseware designers is teaching, not programming: it is essential for them to concentrate on the data and the presentation model, thus avoiding to waste time in low-level programming activities. Java programming facilities satisfy this need and their high performance allow the production of complex courseware.
  • Benefits for courseware users. While robustness is intrinsically a plus for any kind of application programs, it is even more important for didactic software: an application that abruptly fails can induce disorientation in students, jeopardising its pedagogical goals. It is also worth noting that the small footprint of Java executables reduces download times: a valuable benefit for courseware users connected through a modem.

2. The Real Experiment approach (REX)

2.1 Basic concepts

A courseware must be well structured and guided to capture and maintain the interest of the student: for this reason, the interactive components in a courseware are acquiring more and more importance. The interaction can be carried on in several ways according to the specific educational goal:

  • Animations on canned drills. The use of animations can lead to attractive presentations and vivid explanations of the solution of an exercise. Selecting among different sets of input parameters, the student finds the solution written into a static table. The most relevant pitfall of this approach is given by the finite number and the repetitive nature of drills: when the student has tried all the possibilities, these are not useful any longer. Moreover, the implementation of animations for every single drill is cumbersome and relatively expensive.
  • Simulations. A high level of interaction is reached when the educational activity involves simulation of lab experiments both in the case of software based experiments and even in the case of experiments concerning virtual instrumentation [9]. Besides the relevant costs for developing simulators, this approach can lead to the oversimplification of real experiments. As a typical consequence of this fact, students may run into difficulties facing the complexity of the real world.

We propose a model that deals with real experiments (REX). In this case, no simulation activity is performed, but real experiments are carried on through the execution of sequences of real operations. The model implements software interfaces capable of both acting on the real world and collecting results from it (see Figure 1).

Figure 1

Figure 1 - Traditional Model vs REX Model

According to the traditional model the learner deals with the courseware and with the real world in two separate moments, and the courseware can just present a picture of the real world. On the opposite, according to the REX model the learner deals directly with the real world, the courseware acting as a tutor. The main goals of the courseware become to guide the execution of the experiment, to give online instructions and information about the involved subjects and to stimulate the partecipation of the student. It is worth noting that all the possible experimental responses cannot be anticipated and covered, but nevertheless the students certainly increase their skill.

A courseware taking advantage from the WWW and MM technologies and the REX approach acts as a "virtual teacher", offering a high level of assistance by means of:

  • effective lectures based on MM documents;
  • a set of practice activities;
  • tools for evaluation;
  • tools for co-operative learning.

This approach is very convenient in those educational domains where the simulation is a heavy and not exhaustive activity, such as in computer science dealing with operating systems, programming languages and networking topics.

The execution of real experiments requires the creation of interfaces which, in the case of computer science applications, consist of a layer software for the communication between the learners' commands and the target system (operating system, network application, programming language environment). For instance, in the case of a course addressed to the operating system teaching, the layer software must run the command chosen by the student, capture and return the results. The results are then presented in an attractive form together with related virtual teacher's explanations and comments, but it is worth noting that the command is really executed on a real system: this fact leaves the student free to test all the possible choices associated with the command even running into error prone situations like those in the real world. The courseware progress is driven by the captured results.

The development of the interface requires efforts related to the problem analysis and the software implementation. However these costs are comparable to the costs related to the development of simulators or to the inclusion of rich collections of exercises and examples into the courseware.

In general, the REX approach is likely to succeed in improving courseware effectiveness since it leads to practice activities diffusion driven by the virtual teacher and lets the students access real instruments remotely. It represents a way to share a resource, concurrently and wherever it is located.

2.2 System architecture

The REX general architecture is depicted in Figure 2. It is based on a traditional WWW courseware model, with the addition of the REX interface. More in detail, this component is made of two parts:

  1. the interface towards the student that is written in form of Java applets, hosted on the WWW browser and distributed over the network;
  2. the interface towards the real world that is generally a collection of Java and native code programs running on the WWW server.

Both sides of the REX interface communicate by means of the Java RMI API.

Thanks to the Java technology, the client computers only need to execute a WWW browser. For this reason a client can be a PC, a workstation or even a machine based on the emerging Network Computer architecture [10]. In particular, this last solution seems appealing to the use in the educational domain thanks to its low costs and administration costs.

Figure 2

Figure 2 - The REX Architecture

3. A REX based networking courseware

At present we are developing a networking courseware prototype which intends to teach network services (FTP, Telnet. ...) and protocols (TCP/IP, SNMP, ARP) using a practical method.

The networking courseware presented is planned to be used in the curricula of electronic engineering in our department. During the "Industrial Electronics" course, the students of the diploma and laurea degree in Electronic Engineering attend lectures on networking themes; we plan so that they can practise with the most widespread network services and protocols in the laboratory.

The courseware will consist of hypertexts and exercises with a high degree of interaction obtained through a guided execution of laboratory experiments.

During exercises and interactive sessions of the courseware students can actually use some network services; the network traffic produced by these activities is then acquired using a dedicated software (Sniffer) and explained to the students. In this way the student can learn the network operational behaviour and the low-level protocols by observing what is actually transmitted on the network.

A pre-release of the courseware is available: it describes a sketch of the lesson where the FTP service is explained showing all the protocols involved during the session. Also a demo version is available. This demo version illustrates the network service using a data file which was previously acquired using the complete version of the courseware. This simplification is made necessary in order to avoid the installation of all the modules which make up the courseware.

4. Conclusions and future work

In this paper a new approach for courseware development has been presented; it is addressed mainly to the computer science educational domain; it is based on real experiment execution and, according to the emerging trends in computer based training, it retains the students' interest by means of a high level of interactivity. Given the distributed nature of the courseware and the requirement to interface WWW documents with complex applications, the Java paradigm appears to be the best solution for its implementation.

Future work will concern the add-on of other applications to complete the existing courseware. The REX approach is well suited not only for the explanation of network concepts, but also to monitor network traffic. It can be addressed to the development of tools for network problem analysis and resolution. Future work will be devoted to this direction.


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