Assessing the Benefits of AJAX in Mobile Learning Systems Design

34 Pages·2014·1.52 MB·English

Innovative Mobile
Learning:
Techniques and Technologies
Hokyoung Ryu
Massey University, New Zealand
David Parsons
Massey University, New Zealand
INFORMATION SCIENCE REFERENCE
Hershey • New York
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Library of Congress Cataloging-in-Publication Data
Innovative mobile learning : techniques and technologies / Hokyoung Ryu and David Parsons, editor.
p. cm.
Includes bibliographical references and index.
Summary: "This book includes the challenges and practical experience of the design of M-Learning environments, covering current
developments in M-learning experiences in both academia and industry"--Provided by publisher.
ISBN 978-1-60566-062-2 (hardcover) -- ISBN 978-1-60566-063-9 (ebook)
1. Mobile communication systems in education. I. Ryu, Hokyoung. II. Parsons, David, 1959 Oct. 13-
LB1044.84.I56 2009
658.3'1240402854678--dc22
2008010308
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324
Chapter XVI
Assessing the Benefits of
AJAX in Mobile Learning
Systems Design
Feng Xie
Massey University, New Zealand
David Parsons
Massey University, New Zealand
ABSTRACT
Mobile technologies are rapidly changing our lives with increasing numbers of services supported by
mobile devices, including Web-based learning applications, providing opportunities for people to study
anytime and anywhere. However, using Web-based mobile applications to present learning resources
is a challenge for developers because the performance of the mobile Internet over GPRS networks is
often unacceptably slow. A new Web development model, Ajax, may help to address this problem. Ajax
(asynchronous JavaScript and XML), is an approach to Web application development that uses client-side
scripting to reduce traffic between client and server and provide a seamless user application experi-
ence. In this chapter, we address the question of whether mobile Ajax provides measurable performance
advantages over non-Ajax mobile learning applications. An empirical study was undertaken to measure
mobile learning application performance over a GPRS network, comparing an Ajax application and an
active server pages (ASP) application with identical functionality. Our results suggest that mobile Ajax
can reduce the bandwidth requirement by around 70 percent, and cut the server’s response time in half.
In addition, these performance improvements were noticed by users in our small group usability test.
Copyright © 2009, IGI Global, distributing in print or electronic forms without written permission of IGI Global is prohibited.
Assessing the Benefits of AJAX in Mobile Learning Systems Design
INTRODUCTION technological fragmentation in the wireless
communications market, this has not happened
We live in an information society where learning in practice and there are several competing 3G
becomes ever more important, and not all of this technologies. Cost is also an important factor,
learning can take place in a static environment. with a large number of low cost GSM/GPRS
The mobile revolution is changing our lives and devices on the market, and in many territories
can also facilitate new learning processes, but the GSM/GPRS service fee is cheaper than 3G.
learners need educational services with a fast Therefore, despite their limitations, we will need
response speed and good user interaction if mobile to continue to work with GPRS systems for some
learning systems are to be readily adopted. time to come.
An increasing number of people have been
using mobile Internet access through wireless Mobile Learning Technical
networks (Church, Smyth, Cotter, & Bradley, Challenges
2007), but due to the limitations of the mobile
communications infrastructure and hardware The combination of wireless telecommunications
this can still be very problematic. There are a and mobile computing is resulting in a transfor-
number of reasons, for example: small device mation of the educational landscape (Alexander,
screens, high network latency, low bandwidth 2004). The growth and rapid evolution of wireless
and interaction complexity (Chakravorty & Pratt, technology have created new opportunities for
2002). Such weaknesses can impede the mobile the ‘anytime and anywhere’ learning paradigm
learning process. (Seong, 2006) that is mobile learning.
The poor performance of commonly used Various researchers have defined mobile learn-
wireless networks such as GSM (global system for ing (m-learning) in different ways. Pinkert et al.
mobile communications) and its associated digi- (2003) define it as e-learning that uses mobile
tal packet switched data service, GPRS (general devices and wireless transmission. Polsani (2003)
packet radio service) is a major problem for mobile defines it as a form of education whose site of
learning systems. There are various reasons for production, circulation, and consumption is the
this poor performance, for example high and vari- network. Traxler (2005) defines m-learning as any
able latency, fluctuating bandwidth, occasional educational provision where the sole or dominant
link ‘blackouts’ (Chakravorty, Cartwright & Pratt, technologies are handheld or palmtop devices.
2002), packet loss, and link outages. Sometimes, Sharples (2005) defines it as a process of coming
even simple requests can lead to long delays to know, by which learners in cooperation with
(Stuckmann, Ehlers & Wouters, 2002). However, their peers and teachers, construct transiently
despite these problems we should recognise that stable interpretations of their world.
one distinct feature of mobile learning over other Regardless, mobile learning is different from
learning activities is mobility (Leung & Chan, our traditional learning experience; it has its own
2003). The GPRS mobile phone network is the problems and limitations. Mobile learners may feel
most commonly used network in the world, with uncomfortable because they cannot have face-to-
the widest coverage, considerably larger globally face interaction with teachers or other students
than 3G (third generation) wireless networks. Us- (Stodel, Thompson, & MacDonald, 2006). There
ing this network for mobile learning can provide are also limitations on what it can deliver. Berri,
services anytime almost anywhere around the Benlamri & Atif (2006) describe it as mainly a
world, with extensive international roaming. In time-constrained exercise with lightweight con-
addition, although 3G was intended to resolve tent-oriented instruction.
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Assessing the Benefits of AJAX in Mobile Learning Systems Design
Traxler (2007) categorizes previous mobile These examples all use Web-based technologies
learning studies into 6 aspects: plus a mobile Web browser or mobile application
as the mobile learning client.
• Technology-driven These Web-based mobile learning systems use
• Miniature but portable e-Learning a traditional synchronous client-server applica-
• Connected classroom learning tion architecture, typically using the GSM/GPRS
• Informal, personalized, situated mobile network, but in most cases Web application perfor-
learning mance over a high latency GPRS network is poor
• Mobile training / performance support (Chakravorty et al., 2002; Chakravorty & Pratt,
• Remote / rural / development mobile learn- 2002; Stuckmann et al., 2002). One issue is that
ing the TCP/IP Internet protocol needs to initialize
before it starts to transfer actual data; this process
From a design process point of view, these takes over 7 seconds to enable the connection
aspects fall into three major categories: peda- when the initial request is made (Chakravorty,
gogical learning models, adapting to mobile Clark, & Pratt, 2003). In addition all wireless
environments, and technical challenges (Berri et networks have high latency; GPRS link latency
al., 2006). Currently, most mobile learning studies is 600ms-3,000ms for the downlink and 400ms-
focus on pedagogical learning models, or mobile 1,300ms on the uplink. Round-trip latencies are
environments. In contrast, this study focuses on therefore are least 1,000ms (Chakravorty et al.,
technical challenges. 2002). In a lab environment, download times for
Despite extensive research into mobile learn- CNN’s Web site over GPRS was between 125
ing systems, technical support for Web-based and 170 seconds (Chakravorty & Pratt, 2002).
mobile learning has been explored in a relatively This latency does not improve with increased
small number of studies. On example is a mobile bandwidth, and deploying a 3G mobile phone
learning system using Instant Messaging and network is not necessarily helpful (Hunaiti, Garaj,
wireless networks (GSM/GPRS and 802.11 Wi- Balachandran & Cecelja, 2005), for example the
Fi), developed by Kadirie (2007). This system is TCP initialization time on GPRS is 5-7 seconds,
Web-based, and the kernel of the instant mes- but the TCP initialization time on 3GSM is up to
saging server is written in Java. Learners use 12-15 seconds (Nortel, 2007).
a mobile Web browser to login to this learning This poor network performance is compound-
system to chat with other learners or view their ed by the synchronous request/response model of
messages. Nakahara, Hisamatsu, Yaegashi, and traditional Web applications. Therefore to improve
Yamauchi (2005) describe a Web-based collab- mobile learning system performance we might
orative learning site with a bulletin board system use a higher performance network, where one is
(BBS) that allows learners to interact, exchange available, or perhaps apply some new approach to
information, engage in discussion, and collaborate the architecture of the Web-based mobile learning
on projects. Another technical paper is by Seong system itself.
(2006). He developed a mobile learning course
manager portal to demonstrate and exemplify the Ajax Web Applications
usability guidelines proposed. Kukka and Ojala
(2006) developed a Java and XML based learning To address performance issues in Web-based mo-
system for both desktop and mobile devices. Other bile learning applications, we may look to recent
technical examples include Cao, Tin, McGreal, et developments in desktop browser technologies
al. (2006), Lee and Lu (2003) and Theng (2007). that might be implemented in the mobile environ-
326
Assessing the Benefits of AJAX in Mobile Learning Systems Design
Figure 1. The pioneers of the Ajax approach (Google Suggest & Google Maps)
ment. In 2005, Garrett introduced the concept of The traditional Web application allows users
Ajax (Asynchronous JavaScript and XML) (Gar- to submit a request, which the server will process
rett, 2005). Since then, an increasing number of and respond to. Then the client browser will refresh
Web applications have used the Ajax approach the whole Web page, even if only a small part of
(including learning systems—see chapter VIII of the content is changed. In most cases, however,
this book). Although Garrett’s article was the first the new Web page will be very similar to the old
to use the term ‘Ajax,’ the technique he described one, which means that during these transmissions
was already being used by many Web applica- some duplicate content is transferred. This can
tions. The pioneer developers of this technique waste both network resources and users’ time.
were Google, with Google Suggest and Google Ajax uses a browser hosted ‘Ajax engine’ to
Maps being two early examples of this approach handle both data transmission and partial updates
(Figure 1), though some of the key technologies to the Web page. The Ajax engine only requests
(such as the XMLHttpRequest object) were first new content from the server, reducing unnecessary
developed by Microsoft. data transmission. It can also partially update the
Ajax was originally introduced as a desktop current Web page when the response is received.
Web programming model, not a mobile environ- Because the Ajax engine runs locally in the client
ment solution, but because of its key characteris- browser, the Web application's response speed is
tics (small transmission volumes, asynchronous faster and the user’s experience is improved. In
communication and partial Web page updates), addition, client server communication in Ajax
it can actually be very useful in the mobile en- can be carried out asynchronously, enabling the
vironment, especially in high latency networks user to continue interacting with the system even
where Ajax can reduce the frequency and volume while the browser is waiting for data from the
of data transfer. server. Compared with the traditional Web ap-
plication model, Ajax can significantly increase
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Assessing the Benefits of AJAX in Mobile Learning Systems Design
a Web application’s performance in the desktop to assess the perceived benefits of Ajax over a
browser environment (Smullen & Smullen, 2006, non-Ajax system.
2007; White, 2005). To perform our experiments we needed to
implement a representative mobile learning
Applying Ajax to a Mobile Learning system that was structured enough to enable ef-
Application fective performance measurement. To meet these
requirements we chose to implement a mobile
Previous studies have shown that Ajax reduces the quiz as the learning content of the applications.
data transmission volumes between the server and Quizzes are popular components of learning sys-
client device, and improves the user experience tems, which can help the learner to improve their
on the desktop. These are particularly relevant personal knowledge and problem solving ability
issues for Web based mobile learning systems, (Yokomoto, 2000). They force the learner to think
which tend to be content rich and require extensive about every question, answer them all carefully,
client server interaction. Such systems can surely and review all answers at the end. A good quiz-
benefit from a strategy to reduce transmission based learning system needs a responsive user
volumes in the context of expensive and low speed interface to give rapid feedback. This requirement
connections, and provide a better user experience can be easily met in a desktop environment, but
in browsers with limited screen real estate and it is not so easy in a mobile Web-based system.
navigation tools. With the increasing sophistica- Nevertheless there have been some examples of
tion of mobile browsers, there are many mobile using quizzes in mobile learning systems (Black
devices that can easily support Ajax applications. & Hawkes 2006; Bar et al., 2007; Seong, 2006).
Therefore, we might ask the question, if we ap- Therefore we concluded that a mobile quiz was
ply Ajax to a mobile learning environment, what both an appropriate and effective example to use
might be the result? Does an Ajax mobile learning for our experiments.
application provide measurable advantages over
a non-Ajax mobile learning application?
In this chapter, we describe the development WEB APPLICATIONS, AJAX AND
and analysis of a mobile learning system built MOBILITY
using Ajax and tested in a GPRS mobile environ-
ment. We evaluate the system in terms of both Since the first Web page built by Tim Berners-
measured performance against a non-Ajax system Lee in 1991 (Lee, 1992; Watson, Rainer & Koh,
and usability testing, and assess what benefits we 1991), a synchronous request and response cycle
might gain from this approach. has been used for Web access, with a ‘click, wait
We developed two mobile learning systems and refresh’ action approach (Figure 2) where
with identical functionality, one using Ajax and the user needs to click to send a request and
the other using a more traditional active server wait until the browser refreshes with a new page
pages (ASP) architecture. These two Web ap- (Wei, 2005).
plications have the same user interface and can In this Web interaction model the user must
both be accessed by commonly available mobile wait for a request to be converted into a data
browsers. We measured the performance of these stream, sent by HTTP over the Internet, processed
two applications over a GPRS network based on on the server, and have its response returned by
the data collected from the Web server’s log files. HTTP to be displayed in the browser (Crane,
We also carried out a small group usability test Pascarello & James, 2005). The user’s waiting
328
Assessing the Benefits of AJAX in Mobile Learning Systems Design
Figure 2. Classic Web application model: Full page refresh and synchronous communication (adapted
from Wei, 2005)

Figure 3. The synchronous request and response model
time includes network transition time, server re- the user to act like a machine; input, wait for the
sponse time and the browser’s display time. The process to finish, and finally get the output.
problem is that users cannot do anything when The traditional Web application communica-
they are waiting, and this waiting time can be up tion model is based on synchronous requests and
to minutes depending on the network status. The responses. The client initiates a request and the
‘click, wait and refresh’ approach makes a lot of server responds to it. The communication is always
technical sense, because it makes it easy for Web initiated one way, from the client to the server.
developers to build applications, but it is not ef- During communication, users cannot do anything;
ficient or good for the user’s experience. It forces they have to wait until the server responds to the
329
Assessing the Benefits of AJAX in Mobile Learning Systems Design
request. This approach is like a car running on Asynchronous JavaScript and XML
a freeway connected between the client and the (Ajax)
server. The freeway allows two lines of traffic to
travel at the same time, but due to the approach Ajax is a Web development technique for creat-
we are using, at any point in time only one car ing interactive Web applications. It is not a single
is actually running on the freeway (Figure 3). new technology but combines a set of powerful,
The traditional Web application cannot therefore widely-used, well-known and mature technolo-
provide a seamless user experience. gies, mostly hosted by the client browser and
According to Watson et al. (1991), most users largely independent of the server. The intent of
will run out of patience after six seconds, so we Ajax is to make Web pages feel more responsive
need some way of avoiding such delays. Under the by exchanging small amounts of data with the
limitations of network bandwidth and latency, the server behind the scenes, so that the entire Web
only way to improve Web application performance page does not have to be reloaded each time the
is to break down the synchronous model, and user makes small changes. This increases the Web
jump off the ‘click, wait and refresh’ cycle. One page’s interactivity, speed, and usability.
approach to this problem is Ajax (asynchronous Garrett (2005) first defined Ajax as a combi-
JavaScript and XML). nation of:
Figure 4. Asynchronous communication and partial user interface updates (adapted from Wei, 2005)

330
Assessing the Benefits of AJAX in Mobile Learning Systems Design
• Standards-based presentation using exten- users can keep using other functions of the Web
sible hypertext markup language (XHTML) application. When the new information arrives,
and cascading style sheets (CSS); the Ajax engine will partially update the user
• Dynamic display and interaction using the interface (Figure 4).
document object model (DOM); With this interaction model, the user can enjoy
• Data interchange and manipulation using a seamless browsing experience. Compared to the
the XML and extensible stylesheet language analogy of freeway with a single vehicle, it is like
transformations (XSLT); a busy and efficient freeway with multiple vehicles
• Asynchronous data retrieval using the travelling in both directions (Figure 5).
XMLHttpRequest object; The weaknesses of the traditional Web interac-
• JavaScript binding everything together. tion paradigm and communication model are the
strengths of the Ajax model. The Ajax approach for
By controlling the submission and properties the first time introduces some common features of
of XMLHttpRequest objects using JavaScript, desktop applications to Web-based applications.
partial screen updates replace the click, wait, The partial update and asynchronous features
and refresh user interaction model, and the syn- provide a number of advantages.
chronous request/response model is replaced
by asynchronous communication (Wei, 2005). • Instead of submitting form data a page at a
Asynchronous communication allows users time when explicitly requested by the user,
to continue to interact with Web applications Ajax does submissions automatically, when
without waiting for server responses. The Ajax the user triggers some event.
engine will automatically request information • Requests can be sent asynchronously, with
from the server in the background. Meanwhile, the browser receiving results continually.
Figure 5. The asynchronous request and response model
331