Project Title: Cobra Implementation on Association Service

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.

Application of Association Service on-line grammar learning service telecommunication interfaces for deaf people searching engine in internet

Data Type of “Key” and “Value” The “Key” is in a string type. The “Value” is an array of bytes

The format represented by “value” Simple text(single byte or double byte) image audio video

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

How to implement CORBA It needs an ORB(Object Request Broker) for CORBA implementation

ORB available? Iona's Orbix JavaSoft's Java IDL Visigenic's VisiBroker for Java

The Link between Object Implementation and ORB By Object Adapters

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

Currently Developed Object Adapter Two interfaces developed by CORBA: 1) Basic Object Adapter (BOA) 2) Portable Object Adapter (POA)

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

Functions of the System Construct an association Seeking an association Delete an association

Access Control Access Control List Capability

Construction of Capability Capability = Fn(User Name, ID, Access Right, Random0) Password = Capability + ID (64 bits) (32 bits) (32 bits)

Different Kinds of Capability generated by the system: New Capability Restricted Capability

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

Permanent Storage of Association Storing in a series of Unix files Storing in database –Oracle Server –JDBC

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

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

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

The End. Thank you!