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ELearning as a Web Service

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... is a group effort,where content authors,instructional designers,multimedia ... advocate this idea of composing e-learning systems as collections of Web service. ... – PowerPoint PPT presentation

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Title: ELearning as a Web Service


1
E-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

2
Outline
  • Introduction
  • Preliminaries
  • Some Background on E-learning
  • Web Service Basic
  • Towards E-Learning Web Service
  • Provider Side
  • Learner Side
  • Towards the LearnServe Realization
  • Conclusions

3
Introduction
  • 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.

4
Preliminaries-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.

5
Preliminaries-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.

6
Preliminaries-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.

7
Preliminaries-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.

8
Preliminaries-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.

9
Preliminaries-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.

10
Preliminaries-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.

11
Preliminaries-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)

12
SOAP, WSDL,UDDI
  • SOAP?????,??????XML??????????????

13
SOAP,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??

14
SOAP,UDDI,WSDL
15
Preliminaries-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.

16
Preliminaries-Web Service Basic
17
Towards 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.

18
Towards 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.

19
Towards E-Learning Web Service-Provider Side
20
Towards 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.

21
Towards 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

22
Toward 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.

23
Toward 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.

24
Toward the LearnServe Realization
25
Toward 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.

26
Toward 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
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28
conclusion
  • 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.

29
conclusion
  • 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.

30
conclusion
  • 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.

31
Reference
  • ???,.NET Framework??????.NET ?????,????,2003

32
  • The End
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