CONTENT PACKAGE ADAPTATION: A WEB SERVICES

APPROACH

Ricardo Fraser, Permanand Mohan

Department of Mathematics and Computer Science

The University of The West Indies

St. Augustine, Trinidad and Tobago

Keywords: e-Learning, Web Services, Adaptive Hypermedia, Content Package, Learning Services, Learning Object,

Personalisation, Accessibility

Abstract: The IMS Content Packaging Specification is a format that facilitates the deployment of discrete units of

learning resources based on an XML structure called a manifest. The contents and structure of a content

package are determined at design time when it is created. Since the package has been authored for use in a

particular instructional setting, re-purposing the content package to meet the demands of a different

instructional setting is difficult. Although there have been attempts to improve the flexibility of the package

such as using IMS Simple Sequencing, the adaptation provided is still inadequate. In this paper we argue

that Web Services can be used to facilitate the dynamic adaptation of a content package so that it can be

reused in diverse instructional scenarios and accessed by additional learners who otherwise would not be

able to utilize it. We present a framework for adaptation based on web services and identify a representative

set of web services that could be used for content package adaptation. We then discuss in detail the Media

Integration and Translation Services for Accessibility (MITSA), a category of web services designed to

promote media accessibility of a content package. Finally, we conclude by highlighting the benefits of the

web services approach for content package adaptation.

1 INTRODUCTION

An IMS content package (CP) (IMS Content

Packaging Information Model, 2003) is a format that

can be used for storing learning objects. A learning

object is commonly understood to be an independent

and self-standing unit of learning content that is

predisposed to reuse in multiple instructional

contexts (Polsani, 2003). A content package contains

a set of digital learning resources as well as a

manifest that describes how the learning resources

should be organized to form a unit of instruction. If

learning objects are stored in the form of an IMS

content package, the content package essentially

combines learning content into a discrete unit of

learning that could potentially be reused in different

instructional platforms and scenarios.

One approach for reusing learning objects stored

as co

ntent packages is to disaggregate and assemble

the learning resources contained in the package to

form new units of instruction. However a more

recent approach by Fraser and Mohan (2004)

suggests that a content package can be imbued with

knowledge about web services that can facilitate

dynamic adaptation when used in different

instructional scenarios. In this paper, we argue that a

web services approach can be used to provide a

more sophisticated form of content package

adaptation. This in turn promotes a deeper kind of

reusability of learning resources than what is

possible using the ‘pure’ learning objects approach.

We present a viable framework for content package

adaptation and identify a representative set of web

services that could be used to facilitate content

package adaptation. Additionally, we briefly review

and discuss other service-oriented frameworks for

adaptation in learning systems. We also present the

Media Integration and Translation Services for

Accessibility (MITSA), a category of web services

designed to promote media accessibility of content

packages.

238

Fraser R. and Mohan P. (2005).

CONTENT PACKAGE ADAPTATION: A WEB SERVICES APPROACH.

In Proceedings of the Seventh International Conference on Enterprise Information Systems, pages 238-243

DOI: 10.5220/0002529302380243

 SciTePress

2 CONTENT PACKAGING

The IMS content packaging specification was

designed to address interoperability issues with

regard to the import and export of aggregate and

disaggregate packages of content between learning

management systems (LMS). It is a standardised

format for specifying the assembly of learning

resources into an interoperable unit at different

levels of granularity. A content package consists of a

single top-level

manifest file together with the

physical files it specifies. It is shipped via a single

digital resource called a package interchange file

(PIF), which could be in some appropriate archive

format such as zip, cab or jar. The basic structure of

a content package is shown in Figure 1. The function

of the manifest is to specify the structure of the

content in the package by means of an organizations

section (currently, only hierarchical structures are

permitted). The resources section of the package

identifies the physical files that comprise the content

package. It may also identify URLs, which are links

to external resources. Items in the content structure

are linked to the resources that are required for

rendering the content on a learner’s web browser.

The manifest is serialized in XML and optionally

describes a set of simple sequencing rules and a

learning design. Additionally, the content package

may contain metadata that describes its

characteristics. The IEEE Learning Object Metadata

(LOM) standard can be used for this purpose (IEEE

LTSC). Metadata instances can be used to describe

the entire content package (i.e., learning object) or

individual resources and items within the package. A

resource may also refer to a sub-manifest. Thus, a

manifest may consist of other sub-manifests, each of

which is a content package in its own right. This

enables the aggregation of learning resources into

coarser-grained structures of learning.

In its present form, the IEEE metadata standard

does not contain enough information to allow re-

purposing of a content package in a new

instructional scenario (Farance, 2003). When a

content package is assembled, it is intended for use

in a particular context and instructional scenario. A

unit of instruction refers to a content package with

an appropriate instructional design. Thus, a learning

object is really a unit of instruction at different levels

of granularity. When learning objects are dis-

aggregated and assembled into new content

packages, the instructional design that applied to the

original content package is no longer applicable. It is

important to note that some researchers (Koper,

2001) do not consider a learning object that does not

have an associated relevant learning design to be a

unit of instruction. The specification does not

address this limitation.

Another limitation is that the content package

specification does not facilitate the dynamic

adaptation that responds to the changing needs of

learners. Since the delivery structure has been

designed and shipped with the package (i.e., the

items of content and the physical media associated

with those items have already been determined), it is

not possible for the LMS to adapt the content

package to new learner requirements. This is also

true when an item of content references an external

resource since the same resource is shipped to every

learner whether or not a server has prepared it

dynamically. This is the classic, traditional client-

sever paradigm of server-side applications. The

problem is that the resource is independent and

largely irrelevant of the new instructional scenario

since the request for the resource on a web server

has been hard-coded in the CP and cannot change.

Thus, the assumption that a CP is a reusable

resource is misleading since it cannot be re-purposed

in a timely manner. The main goal of the paper is to

address the latter limitation and show how more

sophisticated forms of reusability are permitted

using a web services approach.

PACKAGE

MANIFEST

(an XML file

that consists of

metadata and a

catalog of

component

resources)

PHYSICAL

FILES

(The actual

digital contents

and other files

of the package)

3 ADAPTIVE LEARNING

SYSTEMS

An adaptive learning system (ALS) is one that

facilitates a learning environment that meets the

goals and objectives of the learner by presenting

pedagogically sound learning material as the needs

of the learner change. Since the learning materials

on the WWW commonly take different media forms,

ALS are sometimes called Adaptive Hypermedia

Systems (AHS). ALS is based on a move away

from the “one size fits all” thinking as regards the

distribution of learning material (Brusilovsky, 1996).

The navigational freedom in conventional

hypermedia applications leads to comprehension and

Figure 1: IMS content package – basic structure

CONTENT PACKAGE ADAPTATION: A WEB SERVICES APPROACH

239

orientation problems (Brusilovsky, 1996). Adaptive

hypermedia attempts to overcome these problems by

adapting the presentation of information and the

navigation structure, based on a user model

(Brusilovsky, 1996). This guidance and direction

essentially channels and fosters the cognitive links

that learners seek to create in order to truly

understand the concepts the media aims to teach.

The most popular techniques used in ALS can be

classified into two main types (De Bra, Brusilovsky

and Houben, 1999). These are:

• Adaptive presentation - system determines

what the user currently experiences

• Adaptive navigation support – system

decides where the user goes next

The user model, which importantly measures the

student’s grasp or knowledge state of a concept,

drives the adaptation.

For adaptive navigation support, the user model

is applied to classify learning items into several

groups according to the user's current knowledge

state and interests or goals. The ALS manipulates

the link structure to guide users towards interesting,

relevant information (Brusilovsky, 1996). A classic

example of this strategy is in a recently proposed

architecture that identifies and groups learning

elements that share common concepts into candidate

groups. The user model then motivates the system to

guide the user to learning items in a particular

candidate group (Dagger, Conlan and Wade, 2003).

Other techniques under this category include link

hiding, link annotation, link disabling, and link

removal (Brusilovsky, 1996).

Adaptive presentation adapts the presentation of

the current page according to the user model

particularly the knowledge state. It is typically used

to provide “scaffolding” for the learner. Scaffolding

is a term used to provide additional support to

learning beyond the mainstream delivery. This may

include providing prerequisite, additional, or

comparative explanations for “hard to understand”

concepts (Brusilovsky and Maybury, 2002).

Techniques used to provide adaptive presentation

include:

STUDENT

Pedagogic

Agents

(Decisions

for CP

adaptation)

Web

Services

(Execution of

CP)

ADAPTIVITY

SERVERS

LMS

ADA

(ADAPTED)

RENDERED CP

• Conditional inclusion of learning fragments

based upon the user’s knowledge state (De

Bra, Aerts, Berden and de Lange, 2003)

• Stretch text: system initiated stretching or

shrinking of learning fragments and

subsequently controlled by user (De Bra,

Brusilovsky and Houben, 1999)

• Providing alternative explanations

(Vassileva and Deters, 1998)

• Reordering of presented items on a page

(De Bra, Brusilovsky and Houben, 1999)

Figure 2: Content package adaptation via web services

4 WEB SERVICES ADAPTATION

4.1 Overview of Web Services

A web service is a service provided on the Web by a

server computer that may be invoked by several

clients in a distributed framework. In order to

communicate with a web server that provides a

service, a client uses SOAP (W3C, 2004) - a

packaged, XML-formatted method call to a service

on a particular server. The web server provides a

catalogue of available methods from which the client

may choose to access a particular service. This

catalogue is in XML format and conforms to a

platform independent Web Services Description

Language (WSDL) (W3C, 2003), which is an API

for the service invocation. It indicates a parameter

list and return type of each method belonging to a

particular web service. After executing the client’s

request encoded in a SOAP envelope, the web

service replies to the client using a SOAP message

of its own. The client then unravels the SOAP

package to retrieve the response. In this way, web

services provide a run time environment for

executing methods over an HTTP or HTTPS wire

(i.e., over the Web).

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4.2 Architecture

We propose that web services can act as a runtime

environment for the execution of services identified

in a CP. CP services are standardised XML

formatted tags that identify the resource to be

adapted, a description of the specific adaptation to

be carried out and the actual endpoint address of the

web service that carries out the adaptation. These

service tags are invisible to the LMS so that they do

not intrude on the traditional model of interaction

that exists between the LMS and the CP. In the

classic model of interaction, the LMS receives a

content package from a digital repository and simply

renders it to the learner. See Figure 2.

Software agents use the information recorded in

a CP to actually invoke the web services specified

by the endpoint address. These agents are aware of

the services specified in the CP and continually

monitor the user model (student profile) for

noteworthy changes. There are also agents that

create, manage and update the user model based on

the learner’s interaction with the system.

Information in the user model may include the user’s

learner preferences and style, competencies,

objectives, learning history and browser and client

capabilities. Agents that determine user model

changes that warrant adaptation invoke the web

service endpoint address in the CP - called a CP web

service (CPWS). When the web service has carried

out the adaptation of the CP (or part of it), the result

is returned to the adaptation agent. This agent then

forwards the adapted CP to the LMS so that it can

render the newly adapted learning resource. Since

the user model drives the adaptation, the new change

improves the user’s learning experience and leads to

better learning. Thus CP services, via specified web

services, dynamically re-purposes reusable online

learning resources by adapting the CP to learner

needs (Fraser and Mohan, 2004). The capability of

the web client to correctly display any adapted

content also affects the agent’s decision-making

process for adaptation. In the main, this web services

approach provides dynamic (on the fly) adaptation.

Particularly, it provides a powerful mechanism for

adaptive presentation. It is thus an effective service-

oriented approach to adaptive e-learning.

It may be necessary to procure learning resources

based on the type of adaptation they are capable of

undergoing. Thus, adaptive capability forms part of

metadata search criteria and digital repositories can

be queried for specific service types. We will now

suggest some candidate web services for e-learning

and look closer at the MITSA services.

5 WEB SERVICES AND

IMPLEMENTATION

5.1 Candidate Web Services

To support our argument that the web services

approach is a viable means of providing dynamic

and meaningful content package adaptation, we

present a non-exhaustive list of representative

classes of basic web services for e-learning. These

are listed in Table 1.

5.2 Overview of MITSA

There is a need to provide quality educational

content to the differently able. However in most

cases, the educational material is not aimed at

persons who possess hearing and visual impairment

or some other form of impairment. Both the W3C

Accessibility Initiative Policies and Web Content

Accessibility Guidelines (W3C WAI, 2004) strongly

encourages that content providers on the WWW take

this target audience into account in the design of

Table 1: A representative set of web services for content package adaptation

Candidate Set of Web Services

Service class Functional Description Benefits

Language Translation

Services (LTS)

Translate the language of the resources

and any associated metadata

Extend the reach of learning resource

to speakers of diverse languages

thereby increasing reusability

Media Integration and

Translation Services for

Accessibility (MITSA)

Transform media type of learning

resource from one to the next

Makes content accessible to a new

learner type and increases the didactic

effectiveness of resource

Dynamic Metadata

Adaptation and Generation

for Interoperability (DMAGI)

Translate one metadata profile to

another, adapt metadata profiles to a

change in resource, generate new

profile from resource

Improve interoperability between

learning systems, promote better

resource discovery and reusability

CONTENT PACKAGE ADAPTATION: A WEB SERVICES APPROACH

241

their sites and products. The policy also generally

defines requirements for educational content

providers.

MITSA aims to fulfil the need to reach a broader

range of individuals including those who could not

otherwise access quality educational content because

of the alienation imposed upon them by traditional

forms of text and other multimedia. It facilitates

translation from one multimedia format to another

and also reintegrates disparate pieces of processed

multimedia so that the resulting product is

meaningful and pedagogically viable. MITSA is

intended to widen the reach of reusable learning

content by distributing educational content equitably

thereby bridging the accessibility barriers.

Consider the following use case of MITSA. This

use case is for ‘normal’ learners who wish to get a

text to voice translation of a learning resource. First,

the learner clicks on an item from the content

package (usually generated as a hierarchical frame

display by the LMS). The monitoring agent senses

the request and on checking the user-modelling

agent, determines that the learner has new

preferences for both textual and voice formats of a

learning resource or certain competency levels

demand both. An agent then retrieves the

appropriate learning resource from the LMS. The

adaptation agent then examines the content package

and finds the web service identified for translation.

This web service is invoked with the learning

resource as a parameter. The web service returns its

results in the form of an audio file, which is passed

to the LMS for delivery. The LMS then streams the

audio file to the learner’s browser and

simultaneously displays the textual content.

5.3 MITSA Implementation

The MITSA implementation is based on the

architecture presented in Section 4. The

implementation involves the inclusion of a services

element in the general element of the metadata

section of a CP, its individual items or resources.

MITSA and other candidate services implement the

CP services alluded to by the architecture in a way

that extends the CP specification. Examples of

services that reside under the umbrella of MITSA

include text to voice services such as that described

in the use case and text to Morse code services.

Consider the sample excerpt of content package

metadata that elaborates one MITSA service element

below.

<cpws:services>

<id>resource1</id>

<mime-type>text/plain</mime-type>

<encoding>ASCII</encoding>

</parameter>

</parameters>

<loc>http://sage.uwi.tt/cpbehave/audio</loc>

<method>toAudio</method>

<description>text to audio</description>

<mime-type>wav</mime-type>

</return>

</service>

</cpws:services>

The agent gathers the necessary information for

adaptation by parsing the cpws:services element. In

the above example, the agent recognises the service

as belonging to the MITSA class. The web service

will take one parameter, which is resource1 and is

plain text. The name of the web service that will

execute the action in the description element is

toAudio. It will return a wav file but it will be in

base64 format. This information is necessary to

inform the agent how to store and deploy the media

to the LMS. Many service elements are possible

each belonging to its own class. This is a simple yet

very powerful example of adaptive presentation

using web services. We will now discuss and

compare other service-oriented approaches to

adaptive e-learning.

6 DISCUSSION

Other researchers are increasingly recognising the

value of learning services in adaptive e-learning. For

example, a system (Dolog, Henze, Nejdl and

Sinteky, 2004) provides a framework for

personalized e-learning using web services and

describes an architecture for personalised learning

support in a P2P, distributed e-learning environment.

They identify two sets of services. These are

personalization services and supporting services.

Web services are used as a means of carrying out

personalization functionalities for personalized

learning support. However they are not used to

directly adapt a learner resource. That is, their

approach does not use services in a way that extends

the reach of the CP (learning resource) for

accessibility by increasing its plasticity for different

learning types.

A major benefit of the web services approach is

the quality of adaptation that may be performed by

the most powerful and sophisticated software that

underlie the web services. For example, for the

MITSA, Java Web Services are used and the text to

voice conversions are done by software that uses the

Java Speech API (JSAPI). There are several third

party software firms who specialise in the creation

ICEIS 2005 - SOFTWARE AGENTS AND INTERNET COMPUTING

242

and execution of particular services. This

specialisation of labour leads to greater productivity

as is well known in the field of economics. As the

learning services industry becomes lucrative other

firms will be attracted to participate. As more

participate, competition and market forces will cause

service provision and execution costs to learning

systems to become cheaper. The quality of services

increases further as firms attempt to remain

competitive in their service provision and execution

portfolios for education. In sum, the web services

approach promises affordable, personalised and

adaptive quality learning.

7 CONCLUSION

The web services approach has been presented in

this paper as a viable means of extending the reach

of a rigidly and statically designed content package.

Much effort has been spent in specifying standards

for packaging learning objects and describing them

using metadata. Our approach integrates well with

these existing standards. It simply extends the

content package with information related to services

that can lead to dynamic adaptation in diverse

instructional scenarios. In doing so, it takes

reusability and adaptability to a new level, allowing

service providers on the Web to augment the

potential of learning objects in many different ways,

media translation and formatting being one of them.

We feel that providing services that can enrich

content in a more controlled environment is

potentially a more viable means of reusability than

the pure learning objects approach that has been

promoted over the past few years. Of course, the

development of tools to annotate these services in

the learning object will encourage adoption of the

approach.

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