Architectural Considerations for WebBased Learning Systems

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Architectural Considerations for Web-Based
Learning Systems

• Ho Ngoc Duc
• September 2002

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Introduction

• WWW great opportunity for offering and accessing
  learning resources
• How should an e-Learning system be designed and
  realized?
• Common architecture client-server, thin client,
  fat server(s)
• Problem complex user interaction

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Contents

• Two Web-based e-Learning systems
• Scalable, open architecture for e-Learning
  systems
• How to structure the overall application
  architecture?
• The proper division of behavior between client
  and server?

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The ONGDO project

• From 1997. Teaching / leaning Vietnamese language
  over the Internet
• Over 2 millions overseas Vietnamese
• (Multimedia) dictionaries, language lessions,
  simple exercises and text units
• Hyperlinks, automatically created
• Profile-based (e.g., 1st language)

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Media archive and virtual slide magazine

• Centralized management of digital media objects.
  Teaching at Lübeck University
• Metadata stored in DBMS (relational or native
  XML)
• Virtual Slide Magazine Java client program
• User-friendly GUI to media objects
• Creating, previewing, arranging thumbnails

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Lessons learned

• The thin-client architecture server generates
  HTML. Browser client
• Fast, easy, but no complex user interaction
• The fat-client architecture domain and display
  logic on client side
• Big, slow, inefficient. Many tasks should be
  server job (e.g., thumbnail creation)

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Our solutions

• Start with fat client. Move functionalities to
  server step by step
• Client View, Application Model
• Server Domain Model, Infrastructure
• Four Layer Architecture. Further development of
  MVC. New issues addressed, e.g., connection of
  domain to outside world

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Discussion

• Simple architecture, easy to communicate
• Minimizes amount of processing on client
• Client and server can be in different languages
  if object-object communication provided, e.g.,
  via XML