ELearning as a Web Service

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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

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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

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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)

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SOAP, WSDL,UDDI

• SOAP?????,??????XML??????????????

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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??

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SOAP,UDDI,WSDL
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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.

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Preliminaries-Web Service Basic
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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.

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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.

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Towards E-Learning Web Service-Provider Side
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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.

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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

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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.

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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.

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Toward the LearnServe Realization
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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.

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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???, ????

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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.

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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.

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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.

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Reference

• ???,.NET Framework??????.NET ?????,????,2003

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• The End