Supporting the Authoring and Operationalization of Educational
Modelling Languages
Iván Martínez-Ortiz
(Dept. of Software Engineering and Artificial Intelligence Complutense
University of Madrid, Spain
imartinez@fdi.ucm.es)
Pablo Moreno-Ger
(Dept. of Software Engineering and Artificial Intelligence
Complutense University of Madrid, Spain
pablom@fdi.ucm.es)
José Luis Sierra-Rodríguez
(Dept. of Software Engineering and Artificial Intelligence
Complutense University of Madrid, Spain
jlsierra@fdi.ucm.es)
Baltasar Fernández-Manjón
(Dept. of Software Engineering and Artificial Intelligence
Complutense University of Madrid, Spain
balta@fdi.ucm.es)
Abstract: The modelling of educational processes and their operational
support is a key aspect in the construction of more effective e-learning
applications. Instructional models are usually described by means of an
educational modelling language (EML). The EML used can be one of the available
standards (e.g. IMS Learning Design), the customization of a standard to
meet a specific application profile, or even a domain-specific EML specifically
designed to better fit the very particular needs of a learning scenario.
In this paper we present <e-LD>, a general authoring and operationalization
architecture capable of dealing with all these possibilities in a highly
modular and flexible way. We also outline a specific implementation of
<e-LD> based on standard XML technologies and workflow management
systems, and we describe how this implementation can be used to support
IMS Learning Design.
Keywords: IMS LD, learning design, graphical notation, units
of learning, authoring
Categories: K.3.1,
K.3.2
1 Introduction
In the last years, the representation of learning content in the form
of potentially reusable learning objects that can be adapted and assembled
in many different e-learning scenarios [Downes 2001,
Polsani 2003] has received a lot of attention. However this is only a piece
of the whole puzzle. To obtain a full learning experience, the learning
process usually involves other activities like solving some problems, making
some experiments in a lab, discussing with the teacher about a specific
topic, etc.
Thus, an optimal e-learning application should coherently integrate
resources and participants such as students or instructors across a well-defined
set of learning activities that are structured carefully and delivered
in a learning flow to promote more effective learning. In other words,
e-learning applications must be based on a well-founded activity-based
educational process.
To achieve this objective, these learning processes must be modelled
with the level of detail required in the development of computer applications
able to execute them. For this purpose, a suitable educational modelling
language (EML) can be used [Koper 2001]. An EML is
a domain-specific language specially suited for describing instructional
processes, which allows for the creation of a formalized version of the
learning process that is usually called a unit of learning (UoL). A good
example of EML is IMS Learning Design (IMS LD) [IMS 2003,
Koper and Olivier 2004]. For a comparative study of
different EMLs see also [Martánez-Ortiz et al. 2007].
There are several factors that must be addressed regarding the applicability
of the EMLs:
- On one hand, the instructional models should be provided by educators.
Although EMLs are domain-specific, and therefore they integrate concepts
close to the domain of expertise of these educational experts, the additional
objective of making these languages directly executable by computers hinders
their usability. For instance, to have educators who directly represent
their educational designs in the XML encoding of IMS LD is not a realistic
assumption, even with the help of XML editing tools (e.g. XML Spy). For
this purpose, authoring tools must be provided.
- On the other hand EMLs are equipped with operational semantics, and
therefore they can be interpreted by execution platforms in order to automatically
produce e-learning applications. Moreover, there is no universal EML that
can be applied to all learning scenarios. In fact, there are different
types of EMLs that can be catalogued in terms of their complexity and objectives.
In addition, while the use of a standard EML (e.g. IMS LD) makes it possible
to reuse educational designs (i.e. UoLs) and tools (e.g. execution platforms
and players), the EML itself can evolve into a new version, or its operational
semantics, and even the language itself, can be specialized to meet the
needs of particular application profiles. Finally, some learning domains
can require more specialized EMLs (if there is a single lesson learned
in Computer Science, it is that there is no such thing as a universal solution).
Thus the authoring and the execution environments must be able to rapidly
react to these changes.
In this paper we propose <e-LD>, an authoring and execution architecture
equipped with the flexibility required by the effective use of EMLs in
realistic learning scenarios. It is a revised and extended version of the
previous work described in [Martínez-Ortiz et al.
2006].
The rest of the paper is organized as follows. In section
2 we describe our <e-LD> architecture from a conceptual point
of view. In section 3 we propose a concrete implementation
of <e-LD> based on standard XML technologies and BPEL4WS, a workflow
management and web service orchestration language. In section
4 we outline how this architecture is used to support a specific EML
(i.e. IMS LD). Section 5 outlines the related work.
Finally, in section 6 we give the conclusions and the
lines of future work.
2 The <e-LD> Conceptual Architecture
The conceptual architecture for <e-LD> is outlined in [Figure
1]. This architecture, which is conceived to accommodate the different
sources of variability identified in the introduction, distinguishes the
following components:
Figure 1: The <e-LD> conceptual architecture
- Units of learning. The main goal of the architecture is to produce
e-learning applications based on units of leaning. A unit of learning is
formed by a learning design that is a formal description of a particular
educational process, and a set of learning resources, which are other information
items required for the model to work (e.g. contents, services, etc.). Notice
that, although the terminology used is to some extent borrowed from IMS
LD, here we are using it in a conceptual and a representation-agnostic
sense.
- Authoring tools. These tools are used by instructional designers
to formalize the learning designs that are integrated in the units of learning.
Besides the educational concepts, EMLs usually include technical concepts
or concepts related to reusability and standardization efforts (e.g. LOM
Metadata, IMS Content Packaging). However, these elements mostly distract
the attention of the designer from her main task: producing good learning
designs. Hence, one of the objectives of authoring tools must be to isolate
learning designers from those aspects that are not directly relevant for
their needs. A good example of an authoring tool is RELOAD Editor for IMS
LD (web site: www.reload.ac.uk).
- Execution Platform. This component is intended to help during
the execution of the learning process, coordinating the people involved
in this process and also providing tools and learning contents. This component
plays a role analogous to engines for IMS LD such as Coppercore (web site:
www.coppercore.org). As recognized
by some researchers [Vantroys and Peter 2003, Paquette,
Marino et al. 2005] and in the IMS LD specification itself, learning
designs can be viewed as particular cases of workflows, as defined in the
context of business process integration [Dumas, Aalst
et al. 2005]. Therefore, <e-LD> adopts a workflow management
system as the basic execution environment for the learning designs. The
system provides a suitable workflow language, which is used to describe
workflows that will be interpreted by a workflow engine. The chosen workflow
language will be to <e-LD> as an assembling language is to a compiler
of a high-level programming language. Moreover this component includes
different support services (e.g. a dossier service to manage user model
properties) that are internal to the execution platform, usually used for
management purposes. In addition, this component includes definitions of
the different tools that will be used during the running of the unit of
learning. The implementation of these services can be packaged inside the
execution platform or can be implemented outside (e.g. adapting an existing
application to the tool service contract).
- Players. These components are the graphical user interfaces
that are used by students and teachers to interact with a unit of learning
during its execution. Therefore they have a similar role to IMS LD players
such as IMS LD Reload player or SLeD (a player for Coppercore; web site:
sled.open.ac.uk). Players also interact with tools and other services used,
providing a unique user interface for all of these tools.
- Design mappings. These components are used to translate a learning
design from a source representation to a target one. Design mappings are
used to connect the other components together. This way, authoring tools
can be designed in an EML-neutral way and later on translated to a suitable
specific EML. In addition, those mappings are used to translate a UoL into
a specific EML, or into a general-purpose execution-oriented format (e.g.
a workflow-oriented language script). It is interesting to notice that
a design mapping architecture does not require these mappings to be entirely
automatic. Instead, they can comprise intervention by the user (e.g. in
order to translate complex parts). This possibility also promotes a rational
separation of roles in the development process (e.g. collaboration between
instructors and EML experts during authoring, and collaboration between
learning designers and developers during operationalization).
3 Implementing the <e-LD> Architecture
We are implementing the <e-LD> architecture in the context of
our experimental XML-based <e-Aula> Learning Management System [Sierra,
Martínez-Ortiz et al. 2005, Sierra, Moreno-Ger
et al. 2007].
To facilitate the authoring of units of learning, a graphical notation
for the concepts typically found in an activity-oriented EML is proposed.
This graphical notation is intended to be used not only during the authoring
process but also to facilitate the reuse of already available units of
learning. In particular, the UML-like notation [OMG 2005,
OMG 2006] has been selected.
Regarding the operationalization of EMLs, we have chosen BPEL4WS [Andrews,
Curbera et al. 2003] as the workflow language. The resulting implementation
is outlined in [Figure 2]. BPEL4WS plays the role of
conductor, coordinating learning activities and tools that will be used
during the learning process.
In this implementation, learning designs must be represented using suitable
XML-based domain-specific languages. Notice that this is not a severe constraint,
since XML is currently being adopted as a standard interchange format between
tools, and existing non XML-compliant authoring tools can be wrapped to
produce an XML-based representation. Besides, it is also common practice
for the existing EMLs to provide an XML binding, and it also facilitates
the provision of EMLs tailored to specialized domains following a document-oriented
approach, such as those described in [Sierra, Fernández-Valmayor
et al. 2004, Sierra, Fernández-Manjón
et al. 2005, Sierra, Fernández-Valmayor et
al. 2006]. Finally, BPEL4WS itself also has an XML-based language.
Figure 2: <e-LD> BPEL4WS-based implementation
As a consequence of the use of XML, the design mappings are transformations
between XML-based markup languages. Notice that the design mappings can
be provided using standard XML processing technologies and many of these
mappings can be given using transformation languages such as XSLT. For
more complex mappings, it may be possible to use standard XML processing
frameworks (e.g. DOM or SAX), and even more sophisticated solutions for
the incremental operationalization of XML-based domain-specific languages
[Sierra, Navarro et. al. 2005]. Finally, since basic
activities in BPEL4WS are represented as web services, the implementation
of the basic activities in the architecture must be provided by a web service
programmatic interface. Thus, the resulting applications will exhibit a
service-oriented architecture.
4 Supporting IMS LD in <e-LD>
IMS LD has been readily integrated in <e-LD>. This section describes
this integration, which has been implemented by reusing existing tools
and technologies in order to decrease the overall cost as further explained
in [Martínez-Ortiz, Moreno-Ger et al. 2005].
Figure 3: UML Activity Diagram representing a simple educational
scenario
The authoring of IMS LD descriptions is mostly done using UML activity
diagrams ([Figure 3]), establishing a parallelism between
IMS LD activities and UML activities. Sequencing is expressed using transitions,
synchronization bars and diamond shapes. Activity structures are represented
using simple sequencing of the corresponding UML activities, when the activities
in the structure must be executed in a sequential way (e.g. Grade Exam
and Evaluate in [Figure 3]), or by using a number of
transitions when they must be chosen in random order (e.g. Prepare Test
and Prepare Questionary in [Figure 3]).
Finally, assignments of roles to activities are represented using swimlanes
in the activity diagrams (as Teacher and Student in [Figure
3]). In addition to these dynamic aspects, in our integration of IMS
LD the static aspects (e.g. environments, conditions, and the definition
of the prerequisites/objectives and learning contents to be presented in
the atomic activities) are edited using the RELOAD editor.
Regarding operationalization, the dynamic parts of IMS LD (method, activity
structures) have a correspondence with the flow control structures of BPEL4WS
and the static parts of the learning design are used as configuration parameters
for the web services to be orchestrated by the BPEL4WS process. Some of
these web services will be reusable across many different learning scenarios,
while others will be specific to a concrete application. In addition, many
of these web services will be fed with the appropriate learning resources
during the initialization stages.
Figure 4: Integration of IMS LD in <e-LD>
The architectural details of the integration are depicted in [Figure
4]:
- The authoring of the activity diagrams can be performed with any tool
supporting XMI (an XML-based specification which allows interchange of
UML models between tools as XML documents) as interchanging format. Besides,
the representation conventions described below allow for the provision
of a design mapping for generating IMS LD-aware representations from XMI
documents containing activity diagrams, as well as another mapping for
performing the inverse step (i.e. for representing any IMS LD-aware learning
design as an XMI document that can be edited with the UML editing tool).
These two mappings are largely based on XSLT stylesheets, although tackling
a few issues requires more conventional programming (e.g. dealing with
the IMS Package Interchange Format used in packaging units of learning
in this implementation).
- Operationalization is carried out using a design mapping for translating
IMS LD onto BPEL4WS. This mapping, which follows the operationalization
conventions described above, is again implemented using an adequate set
of XSLT stylesheets with conventional programming support.
5 Related Work
The application of business process management techniques as operational
support for e-learning solutions and the application of workflow management
systems is not new. They have been applied in the creation of LMSs [Gibson
2003], also using BPEL4WS as the workflow language [Anane,
Bordbar et al. 2005], or generalized workflows to support SCORM language
[Kim, Yoo et al. 2005]. Another interesting work was
the ASSIS project (web site: www.hull.ac.uk/esig/assis.html)
in which BPEL4WS was used to orchestrate and integrate an IMS QTI engine
and an IMS Simple Sequencing Engine. The main contribution of the present
work with respect to these approaches is the promotion of a general architecture
where educational modelling languages are conceived as the main artefacts
for the production and operationalization of e-learning applications. Since
these languages can be conceived as particular cases of workflow modelling
languages, it is natural to adopt a workflow management system as a common
execution platform.
The <e-LD> implementation is service oriented. Service Oriented
Computing and Web Services are becoming standard technologies for the development
of software applications. LMSs and other learning tools have been influenced
by this emerging technology. Projects like the ELF Framework (web site:
www.elframework.org) propose a set of the services that make up an e-learning
platform. Another initiative based on web services is the OKI project (web
site: www.okiproject.org) which defines an e-learning architecture by providing
a set of specifications of common services and collections of programming
bindings for such services. In addition to these abstract efforts, there
are also commercial and open source projects that are based on service
oriented computing such as the SAKAI project (web site: www.sakaiproject.org).
Finally a more related work to IMS LD and services is the SLeD project,
which tries to improve the functionalities of the Coppercore engine through
the integration with services using service-oriented computing. In <eLD>,
however, the use of web services is a natural consequence of the choice
of BPEL4WS as workflow representation language. The result is an architecture
that can be tailored to each specific situation by introducing the appropriate
set of supporting services.
6 Conclusions and Future Work
We think that the modelling of educational processes and their operational
support is a key aspect in the construction of more effective e-learning
applications. We conceive EMLs as domain-specific languages that can be
used directly by educational experts in the modelling of educational processes.
In <e-LD> these languages acquire an operational flavour, allowing
educational experts to lead the development of this kind of applications.
The architecture allows the integration of authoring tools with a workflow-oriented
execution platform.
The connection between these components is carried out using suitable
design mappings. Therefore, the architecture can support a wide variety
of EMLs and authoring styles. In addition, since the execution platform
can be enriched with an appropriate set of basic activities, the execution
capabilities can be tailored to each specific domain. The main drawback
is the effort required to set up the production environment. However, this
initial investment should pay off during the production and maintenance
stages and it will allow the reuse of workflow tools previously developed
for the business domain.
Currently we are finishing the integration of IMS LD in <e-LD>
following the approach described in this paper. The next step in the project
is to carry out an evaluation of the results involving educators in several
domains. We are also working on the development of more integrated authoring
support for IMS LD. As future work we are planning to test other workflow
management systems as execution support, as well as to integrate other,
more specialized, EMLs.
Acknowledgements
The Spanish Committee of Science and Technology (projects TIN2004-08367-C02-02
and TIN2005-08788-C04-01) has partially supported this work, as well as
the Regional Government of Madrid (grant 4155/2005) and the Complutense
University of Madrid (research group 910494).
References
[Anane, Bordbar et al. 2005] Anane, R., Bordbar,
B., Deng F., Hendley, R. J.: "A Web services approach to learning
path composition"; Proc. ICALT 2005, IEEE Computer Society, Kaohsiung,
Taiwan (2005), 98-102.
[Andrews, Curbera et al. 2003] Andrews, T., Curbera,
F., Dholakia, H., Goland, Y., Klein, J., Leymann, F., Liu, K., Roller,
D., Smith, D., Thatte, S., Trickovic, I., Weerawarana, S.: "Business
Process Execution Language for Web Services Version 1.1"; IBM, BEA
Systems, Microsoft, SAP AG, Siebel Systems Specification (2003).
[Downes 2001] Downes, S.: " Learning Objects:
Resources for Distance Education Worldwide"; The International Review
of Research in Open and Distance Learning, 2, 1, (2001).
[Dumas, Aalst et al. 2005] Dumas, M., Aalst, W.
M. P. v. d., Hofstede, A. H. M. t.: "Process-Aware Information Systems:
Bridging People and Software through Process Technology"; Wiley-Interscience,
(2005).
[Gibson 2003] Gibson, F. P.: "Supporting Learning
in Evolving Dynamic Environments"; Computational & Mathematical
Organization Theory, 9, 4 (2003), 305-326.
[IMS 2003] IMS: "IMS Learning Design Information
Model Version 1.0 Final Specification"; IMS Global Learning Consortium
Specification, (2003).
[Kim, Yoo et al. 2005] Kim, K.-H., Yoo, H.-J., Kim,
H.-S.: "A process-driven e-learning content organization model";
Proc. ICIS 2005, IEEE Computer Society, Jeju, Island (2005), 328-333.
[Koper 2001] Koper, R.: "Modeling units of
study from a pedagogical perspective: the pedagogical meta-model behind
EML"; Educational Technology Expertise Centre (OTEC) Working Paper,
Open University of the Netherlands, http://hdl.handle.net/1820/36, (2001).
[Koper and Olivier 2004] Koper, R., Olivier, B.:
"Representing the Learning Design of Units of Learning"; Educational
Technology & Society, 7, 3 (2004), 97-111.
[Martínez-Ortiz et al. 2006] Martínez-Ortiz,
I., Moreno-Ger, P., Sierra, J.L., Fernández-Manjón, B.: "A
General Architecture for the Authoring and the Operationalization of e-Learning
Applications with Educational Modelling Languages"; Proc SIIE06, León,
Spain (2006), 280-288.
[Martínez-Ortiz et al. 2007] Martínez-Ortiz,
I., Moreno-Ger, P., Sierra, J.L., Fernández-Manjón, B.: "Educational
Modeling Languages: A Conceptual Introduction and a High-Level Classification";
In Fernández-Manjón, B, Sánchez, J.M et. al (eds.)
Computers and Education: E-learning ? from theory to practice. Springer
(2007), 27-40.
[OMG 2005] OMG: "Unified Modelling Language
version 2.0: Superstructure"; Object Management Group Specification,
(2005).
[OMG 2006] OMG: "Unified Modelling Language
version 2.0: Infraestructure"; Object Management Group Specification,
(2005).
[Paquette, Marino et al. 2005] Paquette, G., Marino,
O., De la Teja, I., Lundgren-Cayrol, K., Léonard, M., Contamines,
J.: "Implementation and Deployment of the IMS Learning Design Specification";
Canadian Journal of Learning and Technology 31, 2 (2005).
[Polsani 2003] Polsani, P.: "Use and Abuse
of Reusable Learning Objects"; Journal of Digital Information 3, 4:
Article No. 164, (2003).
[Sierra, Fernández-Majón et al. 2005]
Sierra, J. L., Fernández-Manjón, B., Fernández-Valmayor,
A., Navarro, A.: "Document-Oriented Construction of Content-Intensive
Applications"; International Journal of Software Engineering and Knowledge
Engineering, 15, 6 (2005), 975-993.
[Sierra, Fernández-Valmayor et al. 2004]
Sierra, J.L., Fernández-Valmayor, A., Fernández-Manjó,n,
B., Navarro, A.: "ADDS: A Document-Oriented Approach for Application
Development"; Journal of Universal Computer Science, 10, 9 (2004),
1302-1324.
[Sierra, Moreno-Ger et al. 2007] Sierra, J.L.,
Moreno-Ger, P., Martínez-Ortiz, I., Fernández-Manjón,
B.: "A Highly Modular and Extensible Architecture for an Integrated
IMS based Authoring System: The <e-Aula> Experience"; Software-Practice
& Experience 37, 4 (2007), 441-461.
[Sierra, Fernández-Valmayor et al. 2006]
Sierra-Rodriguez, J. L., Fernández-Valmayor, A., Fernández-Manjón,
B.: "A Document Oriented Paradigm for the Construction of Content-Intensive
Applications"; The Computer Journal, 49, 5 (2006), 562-584.
[Sierra, Martínez-Ortiz et al. 2005]
Sierra-Rodriguez, J. L., Martínez-Ortiz, I., Moreno-Ger, P., Lopez-Moratalla,
J., Fernández-Manjón, B.: "Building Learning Management
Systems Using IMS Standards: Architecture of a Manifest Driven Approach";
Lecture Notes in Computer Science 3583 (2005), 144-156.
[Sierra, Navarro et. al. 2005] Sierra-Rodriguez,
J. L., Navarro, A., Fernández-Valmayor, A., Fernández-Manjón,
B.: "Incremental Definition and Operationalization of Domain-Specific
Markup Languages in ADDS"; ACM SIGPLAN Notices 40, 12 (2005), 28-37.
[Vantroys and Peter 2003] Vantroys, T., Peter, Y.:
"COW, a Flexible Platform for Enactment of Learning Scenarios";
Proc. CRIWG 2003, Springer Verlag, Autrans, France (2003), 168-182.
|