Lecture Notes in Computer Science- P93 pps

An E-Learning System Engineering Ontology Model on the Semantic Web 449
2) Services registration Module: The module stores the information of the specific
services agent systems including their credit evaluation records. When the system
adds some new services, the information of those services should be published to the
registration information database through credit evaluation / service module.
3) Order Module: The module addresses the implementation of orders and transmits
the results to the heterogeneous systems in a unified RDF form to the Web servers.
2.3 Agent System Layer
Agent systems layer provides a variety of logistics services. There are a lot of differ-
ences in the data forms due to the difference of the size and type of the E-learning
system, collection and requirements of data. These data has still significant difference
whether in the description or in storage, therefore, information center and converter
should be constructed for various services agency. E-learning system converter can
convert the services submitted by the services parser into a variety of operations for
different services, and hand them for the order actuator to implement their services by
accessing the data dictionary in the information center. Similarly, when a new agency
joins the E-learning system, its service information should be transformed and stored
in the information center. At the same time, its integrity and the basic conditions will
be stored in the registration information database to be accessed by users online.
3 Ontology and E-Learning System
3.1 Ontology
Ontology is the study of existence of all kinds of entities (abstract and concrete) that
make up the world. Ontology defines the kinds of things that exist in the application
domain. Without ontology, the terms and symbols of a domain will be ill-defined and
confusing [10], [11]. Ontology, therefore, is a content theory about the sorts of ob-
jects, properties of objects, and relations between objects in a specified domain [12].
It is a representation vocabulary specializing in a domain and includes terms that
capture the conceptualizations of the domain elements. A conceptualization is an
abstract, simplified view of the world that we wish to represent for some purpose
[13]. The subject of ontology is the study of the categories of things that exist or may
exist in some domain.

On the Web, the use of Ontology needs the support of language Web in order to
promote interoperability and make full use of existing tools. In order to enable Web
Ontology data can be widely understood and accepted, a clear set of terms must be
defined on the Web in the name space so as to provided consistent understanding of
the semantics for the data described by the ontology.
Ontology describes resources, but also describes services [13]. For example, Web
services based on OWL ontology can be used to support Web services, through sign
language to provide a core constructed set to describe the functions and attributes of
Web services in a computer understandable form. OWL-S's goal is to promote the
automation of Web services, including automated Web services such as synthesis and
interoperability.
450 W. Tan et al.
3.2 Semantic Ontology Mapping Model
Semantic Ontology mapping is used to describe the semantic relationships between
the concepts. The semantic exchange and reservations of information between the two
E-learning applications need to build a logic mapping mechanism for the similar con-
cept in each application [14]. Therefore, semantic integration is equivalent to building
a correct mapping relationship between the two E-learning systems, which provide a
means of communication in the mapping implementation. Semantic Mapping is a
very effective visualization technology in the E-learning process description [15]. In
the paper, we designed a semantic mapping model based on goals, task, and property
to describe the mapping of process and organization, the process model and the coor-
dination, and the learning activities and related resources. The education service
model is mapped to the application system model based on the concept of peer-
related, partial-overall, and includes-ownership shown in Figure 2.


S
i
mp

l
e
Methods
A
ddi
t
i
ona
l

Actions
Met
h
o
d

Combination
A
ll
S
i
nge
Methods
Ontologies
Final Mappings
Similarity
Multiple rounds

Fig. 2. Ontology mapping model
This process deals with the mapping of different data descriptions in the ware-

house. For example, data source formats are usually mapped to the attributes of the
staging tables.
4 Communication Module Based on SOAP and ONTOLOGY
In this module, we design a common client terminal, which can automatically gen-
erate one or more the corresponding client agent objects to access the services in the
server through the URL of the ontology documents inputted by user (obtained
through the above modules), or the address of the local disk location, or analytical
ontology text of the ontology string directly inputted by user. The function of the
module is that whatever services is provide by the server, as long as service user
give out ontology documents, the model should be able to automatically generate
the corresponding request to access the different services that provided by different
subsystems crossed the heterogeneous systems. Meanwhile, we had done an expan-
sion that an encryption and decryption model is embedded for the information of
the server and client communication in the application layer of the model, in order

An E-Learning System Engineering Ontology Model on the Semantic Web 451
Learning
ClassInstruction
Instructor
Use
Communication
UserInfoMassage
use
Learner
LearningPlanning
Mas sager

Fig. 3. A segment of use case
to ensure information security. The learners of the system own mainly operations
that are learning, user information management, communication with each other

and learning planning. The use case figure is shown in Fig. 3.
Meanwhile, the instructors of every course take charge of the consultations of the
learners, and answer their question online. The consultations have got together to the

: Learner
Learning
Task1
Learning
Task2
Learning
Task3
Learning
Task4
1: inputTask'sInfo
2: click"AddTask"button
3: AddTask(taskInfo)
4: New(TaskInfo)
5: add a item into Listbox
9: re-back
7: re-back
6: New(TaskInfo)
8: re-back

Fig. 4. Sequence diagram of learning activation
452 W. Tan et al.
class instruction model to the course instructor. The duty of the manager is update the
learning source, manage the communication personal information of learners.
In the Fig. 3, the work flow model is showed of the learning activation. After the
login, the learner inputs the information of the learning task to do the first learning
task, then, clicks the Add Task button to start the second learning task. If the second

task is unready, the work flow re-backs to the first task.
The module is designed to dynamically generate client agents to communicate with
the corresponding services in the server based on analytic ontology documents, which
is the key idea of the module [16, 17]. Meanwhile, there is another one that an encryp-
tion and decryption expansion model is implemented by SOAP in application layer.
Namely, sensitive information Packaged in the SOAP body is achieved encryption
through the SOAP extension technology. The encrypted information is transmitted in
the network. And then the decryption or other treatments are implemented respec-
tively in the client terminal and server. The general process of the communication in
the client and server is as follows.
5 A Case Study
Based on the communication model designed in above paragraphs, we implemented a
program of the core issues, which includes a services discovery module, a registration
module, and a communication module based on SOAP and ontology. Meanwhile, the
three modules were tested and evaluated in our laboratory. The implementation of the
communication model is achieved on the .NET development platform and in the C#
language both provided by Microsoft. Following the design of the section 4, the paper
gives out the timing plan diagram that is shown in Fig. 5.
: Learner
LearningTask1 LearningTask2 LearningTask3 LearningTask4
inputTask'sInfo
click"AddTask"button
AddTask(taskInfo)
New(TaskInfo)
add a item into Listbox
New(TaskInfo)
re-back
re-back
re-back

Fig. 5. Timing plan diagram of learning activation
An E-Learning System Engineering Ontology Model on the Semantic Web 453
5.1 UDDI-Based Service Discovery Module
As a complete communications model, first of all, needs for the existing Web service
discovery and positioning[17], finds the corresponding ontology files, thus further
analyses ontology documents, to the structure corresponding SOAP message to
achieve communications. Therefore, we firstly designed the discovery service model.
Require Services
Release Services
Communication
Using SOAP
UDDI Registration
Centre
Provided by
Microsoft or IBM

User
Terminal
Server

Fig. 6. Principle of service discovery model

Fig. 7. Class relation of learning activation