A Computer Aided Despatch System

on CORBA/Java Platform

Chau Chi Wing

Introduction

• Computer Aided Despatch (CAD) systems are used in the service industry to provide prompt service to their clients.

• In this project, a prototype CAD system will be implemented on CORBA/Java platform.

CORBA

• CORBA was designed to allow intelligent components to discover each other and interoperate on an object bus.

• CORBA is much more sophisticated than alternative forms of client/server middleware, including RPC, MOM, database store procedures.

Distributed Systems on CORBA

• City of Pittsburgh – Crime Information System

• Allied Signal – Vacation Time Tracking System

• Standard Chartered Bank – Customer Service Terminal

• Harvard University – Educational Records System

The Java Platform

• The Java platform is a fundamentally new way of computing, based on the power of networks and the objective to run the same software on different kinds of computers.

• CORBA provides the link between the Java portable application environments.

Computer Aided Despatch (CAD) System

• Two main entities: incident and resource.

• Track incidents and resources, and the interactions between them.

• Inteface with other systems, e.g., PABX, GIS, GPS, mobile radio system, systems in immigration and transportation departments.

Computer AidedDespatch System

Telephone callfrom publicnetwork

Private AutomaticBranch Exchange(PABX)

ManagementInformationSystem (MIS)

Historic incident &historic resource

Addressinformation

GeographicInformationSystem (GIS) /GlobalPositioningSystem (GPS)

Radio callinformation

Mobile RadioSystems

External systems,e.g. those inimmigration andtransportationdepartments.

RCCC, H K Police

System Requirements

• Functions: functions to manipulate incidents and resources, multiple communication patterns, e.g. client-server, server-client.

• Performance: response time in seconds, intuitive user interface.

• System Management: complex distributed application - needs easy update.

Design Considerations

• 3-tier Architecture– Thin client– Business logic in middle tier– RDBMS for persistence

• CORBA– Cross platform– Cross language– Support all communication patterns

Design Considerations (2)

• Front End– Java - write-once-run-anywhere– Applet - no installation needed, browser plugins

can be used.– Swing - consistent look-and-feel, sophisticated

GUI.– Java 2 - drag-and-drop, plugin caching.– CORBA - multiple communication patterns

Design Considerations (3)

• Middle Tier– Java - write-once-run-anywhere, no vendor

lock-in, high-end production platform but low-end development platform

– JDBC - database connectivity– CORBA - multiple communication patterns,

native languages can be used for performance or reuse of existing code.

Design Considerations (4)

• Back End– RDBMS - mature, robust, high performance.– Features - parallel processing, fault-tolerance,

extended SQL functionality.– Connection - computationally expensive,

should be made on server object startup.

Outline Software Design Specification

• Platform– Java Platform -Sun Microsystems Java

Development Kit 1.3– CORBA ORB - Inprise VisiBroker for Java 3.4– RDBMS - Oracle8i

OSDS (2)

• User interface– Command line– Context-sensitive popup menu– Drag-and-drop operations

OSDS (3) - Architecture

Server JVMWeb browser JVM

ORB ORB RDBMS

ResList

DynaWinHandler

Resource

Incident

IncQueue

IIOP JDBC

Calls

Callbacks

CadApplet

AccessControl

CadApplet ResList IncQueue AccessControl Resource IncidentDynaWinHandlerlogin

registerResList

registerIncQueue

fillIncQueue

fillResList

CadApplet ResList IncQueue AccessControl Resource IncidentDynaWinHandlerlogout

unregisterResList

unregisterIncQueue

OSDS (4) - Object interactions

CadApplet ResList IncQueue AccessControl Resource IncidentDynaWinHandlerresource operations

addRes/updateRes/deleteRes

addInc/updateInc/deleteInc

addRes/updateRes/deleteRes

addInc/updateInc/deleteInc

CadApplet ResList IncQueue AccessControl Resource IncidentDynaWinHandler

incident operations

addRes/updateRes/deleteRes

addRes/updateRes/deleteRes

addInc/updateInc/deleteInc

addInc/updateInc/deleteInc

OSDS (5)

Future Directions

• The CAD system lacks attributes of a mission-critical system – manageability, scalability and high reliability.

• Answered by Enterprise Java Bean (EJB) technology, the Java server-side component architecture.

Conclusion

• CORBA provides a solid and versatile distributed object foundation. It enables the invocation of methods on objects, with network transparency. CORBA callbacks can be used to control client from the server side.

Conclusion (2)

• Swing of the Java 2 standard enables the construction of sophisticated GUI, with user-friendly features like drag-and-drop mechanism and popup menu, that has consistent look-and-feel across platforms.

• With the help of Java Just-In-Time (JIT) compiler, the performance of applet and server objects are excellent.

Conclusion (3)

• Both Java and CORBA are open standards – vendor lock-in is eliminated and so hardware and software can be chosen based solely on performance, features and services.

END

• Thanks for coming.