Project Title: Cobra Implementation on Association Service

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Project TitleCobra Implementation on
Association Service
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What is Association Service?

• Association is simply a mapping from a key to a
  value
• Association Service is a service provided by
  the system for this mapping.

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Application of Association Service

• on-line grammar learning service
• telecommunication interfaces for deaf people
• searching engine in internet

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Data Type of Key and Value

• The Key is in a string type.
• The Value is an array of bytes

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The format represented by value

• Simple text(single byte or double byte)
• image
• audio
• video

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Why CORBA ?

• It is more difficult for a programmer to develop
  an application in distributed environment than in
  a single machine.
• CORBA is A middleware designed by OMG to help a
  programmer to develop application in distributed
  system
• CORBA may let server location be transparency to
  the client by its naming service

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How to implement CORBA

• It needs an ORB(Object Request Broker) for CORBA
  implementation

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ORB available?

• Iona's Orbix
• JavaSoft's Java IDL
• Visigenic's VisiBroker for Java

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The Link between Object Implementation and ORB

• By Object Adapters

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What is Object Adapter

• It is a component that an object implementation
  at server side reports its availability for
  request to ORB
• ORB uses it to manage the run-time environment of
  the object implementations

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Currently Developed Object Adapter

• Two interfaces developed by CORBA
• 1) Basic Object Adapter (BOA)
• 2) Portable Object Adapter (POA)

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Programming Steps for CORBA Implementation

• Design on IDL
• Compile IDL file to generate stub code for client
  program and skeleton code for server program
• coding for object implementation
• coding for client program
• compile client and server program and then
  running both server and client program

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Functions of the System

• Construct an association
• Seeking an association
• Delete an association

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Access Control

• Access Control List
• Capability

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Construction of Capability

• Capability Fn(User Name, ID, Access Right,
  Random0)
• Password Capability ID
• (64 bits) (32 bits) (32 bits)

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Different Kinds of Capability generated by the
system

• New Capability
• Restricted Capability

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Structure of the system

• Tuple (id, key, value, size, value type)
• List Link up the tuple
• Hash table index to the 256 lists

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Permanent Storage of Association

• Storing in a series of Unix files
• Storing in database
• Oracle Server
• JDBC

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Recovery of Association

• Permanent table
• Temporary table
• add a flag to indicate the kind of manipulation
• add association
• delete association
• output information to the system when it is waken
  up again
• empty if normal procedure for closing system

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Conclusion

• Association Service is simple but practical
• It makes the programming be much easier in
  distributed environment via CORBA implementation
• It still has more features for the further
  development of this system

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Further Development

• Develop client side of the system as an applet
• Adding more interface for various format of
  "value
• Multi-users supporting
• Directory service as a yellow page

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The End.Thank you!