Title: ELearning as a Web Service
1E-Learning as a Web Service
- Vossen, G. Westerkamp, P.
- Database Engineering and Applications Symposium,
2003. Proceedings. Seventh International , 16-18
July 2003 - Page(s) 242 249
- Speaker???
- Date12/29
2Outline
- Introduction
- Preliminaries
- Some Background on E-learning
- Web Service Basic
- Towards E-Learning Web Service
- Provider Side
- Learner Side
- Towards the LearnServe Realization
- Conclusions
3Introduction
- E-Learning is a group effort,where content
authors,instructional designers,multimedia
technicians,teachers,trainers,database
administrators to serve a community of learner. - Many of activities can be perceived and modeled
as process and consequently be executed as
workflows. - On the other hand,there are many activities which
aim at providing services of any kind on Web.
4Preliminaries-Some Background on E-learning
- Roles and core functionality
- A general agreement seems to exits regarding
roles played by people in a learning environment
as well as regarding the core functionality of
modern e-learning platforms. - The main players in these system are the learners
and the authors.
5Preliminaries-Some Background on E-learning
- Distribution
- Authors create content,which is stored under the
control of a learning management(LMS). - LMS is under control of an administrator,and it
interacts with a run-time environment which is
addressed by learners. - Content can be distributed.
- In order to make such a distribution
feasible,standards such as SCORM try to ensure
plug-and-play compatibility.
6Preliminaries-Some Background on E-learning
- Individualization
- Learners vary significantly in their
prerequisites,their abilities,their goals for
approaching a learning system,their pace of
learning,and the time (and money) they are able
to spend on learning. - Thus,the target group is very heterogeneous.
7Preliminaries-Some Background on E-learning
- Flexibility
- A system is able to provide and present content
for all group. - A learning platform has to meet a number of
requirements,including the integration of a
variety of materials,the potential deviation from
predetermined sequence of actions,personalization
and adaptation,and the verifiability of work and
accomplishments.
8Preliminaries-Some Background on E-learning
- Learning objects(LOs)
- LOs are units of study,exercise,or practice that
can be consumed in a single session and they
represent reusable that can be authored
independently of the delivery medium and be
accessed dynamically. - LOs can be exchanged between different LMS and
plugged together to build classes. - Los need to be context-free that they have to
carry around useful description information on
the type and context in which they may be used.
9Preliminaries-Some Background on E-learning
- Other information relevant to a learning system
- Learner personal data
- Learner profile
- Course map
- LO sequencing or presentation information
- General user data ,etc.
10Preliminaries-Web Service Basic
- A web service is a stand-alone software component
that has a unique URI(the Uniform Resource
Identifier is a unique address),and that operates
over the Internet and especially the Web. - The basic premise is that Web service have a
provider who needs to implement the service,but
also to write a specification and to make this
specification available to potential customers
through publication in a directory.
11Preliminaries-Web Service Basic
- Interoperable
- Web services have to be independent of the OS
they are running on,they should be usable on
every Web service engine regardless of their
programming language. - Standards
- XML-based specifications SOAP(Simple Object
Access Protocol) - UDDI(Universal Description,Discovery Language)
- WSDL(Web Services Description Language)
12SOAP, WSDL,UDDI
- SOAP?????,??????XML??????????????
13SOAP,UDDI,WSDL
- WSDL????XML??,??Web service?????????,?????class???
- DISCO(Discovery of Web Service)????programmer?Web
Service Server??Web Service,??DISCO????web
service?URI,????URI?????WSDL - UDDI???Web service?????,??????Web service??
14SOAP,UDDI,WSDL
15Preliminaries-Web Service Basic-the flow path
- The provider of a Web service register his
service at a UDDI directory,which acts as a
global repository of meta-data for all registered
services and store information about a
service,but it does not store the service itself. - A client request service.The communication rules
for client and Web service are described in a
WSDL file,which is not part of the UDDI
directory.The WSDL file describe the condition
for the input and output data and the protocol
for the communication.
16Preliminaries-Web Service Basic
17Towards E-Learning Web Service
- In an e-learning system,a variety of
aspects,features and component can be perceived
and realized as a Web service,including content
authoring,content configuration into course,LO
management,learner registration,learner profiling
and tracking,testing of acquired
knowledge,tutoring,and etc. - Thus,the entire functionality of a learning
system is decomposed into individual activities
which can provided as services.
18Towards E-Learning Web Service-Provider Side
- Example-content creation
- 1.search service through a UDDI directory
- 2.Upon finishing the creating of the learning
material,the author has to register the new LO to
the central content directory and store it on a
server. - 3.In the end,the author can choose to create
another LO or to perform a different task like
creating classes from existing Los.
19Towards E-Learning Web Service-Provider Side
20Towards E-Learning Web Service-Provider Side
- Special service,also on the provider side,need to
be available for handling trustworthy
actions,like the collection of payment from a
content user and the transfer of royalties to the
respective content author,the certification of
classes for special exams,or the storage of user
profiles.
21Towards E-Learning Web Service-Learner Side
- In a Web-based system the learner ideally just
needs a Web browser to use the system,and he or
she does not have to bother about what part of
the platform is part of the server system and
what part is just an include Web service. - The learner searches a content directory and
orders Los,classes,or courses that match his
needs. - Web service for present the material and for
help,payment,tracking
22Toward the LearnServe Realization
- An e-learning system needs to compose a variety
of Web services. - Complex Web services composed of atomic ones call
each other by using the URI of a follow-up
service the moment that service is needs. - If a Web service is not reachable or available at
the moment of the call,the entire process fails. - We use a dynamic form of service selection where
services are not called directly.
23Toward the LearnServe Realization
- The underlying service platform needs to select
the appropriate services by using the available
UDDI directory.To this end,we are considering the
use of tModels,which can be used in a UDDI
environment both as technical fingerprint of a
service and as a name space identifier.
24Toward the LearnServe Realization
25Toward the LearnServe Realization
- The dynamic selection of services gas several
advantages over a static one. - 1.the availability of composed services no longer
depends on the availability of each single
service in the chain of services. - 2.A dynamic choice enables the system to call the
accessible services and call only
these,independently of crashed services. - 3.The usage of LOs can become dynamic.
26Toward the LearnServe Realization
- Traditional systems have to import learning
objects to their own data pool in order to use
them. - ????????LOs
- ?? ?????authors????
- The content is stored on distributed servers we
have to transfer the dynamic call of web services
to the call of learning objects. - ??1???author????,?????
- ??2?LO???, ????
27(No Transcript)
28conclusion
- In this paper we have tried to advocate this idea
of composing e-learning systems as collections of
Web service. - This even allows for a reuse of services already
offered on the Web,such as payment and cashing
services,chat rooms,or conference.
29conclusion
- Clearly, it is still a long way in order to make
learning Web services a reality. - Various kinds of supporting tools and services
need to be provided,including authoring
tool,testing and examination services,certificatio
n and simulation environment,etc. - Search and selection of learning services
offerings must be made as easy as surfing the Web.
30conclusion
- To ensure the usage of various presentation
styles,the presentation of an LO might need to
execute an application on the client.This might
induce security problems,since the creation of
content is not controlled by some security agency
in order to ensure that an LO dose not comprise
an attack on the client.
31Reference
- ???,.NET Framework??????.NET ?????,????,2003
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