Mobile agents based implementation of a distance

evaluation system

Vikram Jamwal Sridhar Iyer

School of Information Technology

IIT Bombay

SAINT’2003

Mobile agentsPrograms that can autonomously migrate amongst

nodes of a network and perform computations on behalf of a user

Client Server

Request

Response

Client/server communication

Client Server

Request

Response

Mobile agent communication

Mobile agent

DataBase

Desktop

Server

SystemResources

Laptop

User Application Legacy Software

Execution EnvironmentMobile Agent

Service AgentApplication

Agent MigrationLocal Communication

Global Communication

Typical mobile agent frameworkTypical mobile agent framework

Student Examination SystemExisting approaches• Computer Based Testing (CBT)

• Dynamic: different questions to diferent examinees• Adaptive: different weights to different questions• Entire database has to be present at the exam site

• Internet Based Testing Schemes• Front End: HTML forms/Applets based• Back End: CGI scripts/Servlets based• Vulnerable to network latencies

Difficult to push information to participantDifficult to handle dynamic contents

Examination process

• Exam setting– examiners set the question papers

• Distribution and testing– question papers are presented to the students

• Evaluation and result compilation– answers are collected and results compiled

Desirable features in DE application

• Ability to cater to all three stages of DE

• Delivery of dynamic content

• Support synchronous, off-line examination

• Support for push communication

• Ability to incorporate subjective questions

Extending client-server based implementations would be cumbersome and ineffective

Exam setting: CS design• Requirements

– Paper Setters (PS) may want to work offline or over a long period

– PS may need to be sent notifications by the Paper Assembler (PA)

– Question Paper (QP) may need to be collected, even if incomplete

• Typical CS Design– Each PS submits a QP using a HTML form provided the PA server– PA server stores the QPs and later builds a comprehensive paper

• Drawbacks– PS may not submit QP within deadline

• PA has to use other means to send notifications to the PS

• PA cannot force-fetch the partial QP

– PS may work over an extended period of time• Client and server may get disconnected

• Partial data on the form may be lost

PS-2

PS = Paper Setter

PS-3

PS-5PS-4

PS-1

Paper Assembler

Comprehensive Paper

= Mobile Agents

To Distribution Server

Examination setting: overviewExamination setting: overview

NS

N-1

N-2

NS

NS

Cloning

Install Agent

GUI

Fetch Agent

Launcher

Controller GUINS = Name ServerN = Paper Setter Node

Examination setting: detailsExamination setting: details

Dynamic Upgrade

Distribution and testing: CS design• Requirements

– Question paper (QP) should be distributed to the centers just-in-time– QPs may contain dynamic content– Students should be offline for the duration of the examination

• Typical CS-Design– Variations of CBT or Internet based testing schemes

• Drawbacks– Server may need to maintain state information for each student

• the number of sections that have been offered

• the time elapsed

– Difficult to manage dynamic content

– Difficult to force-fetch an answer paper

DistributionServer

Exam Center Distribution

Server

Single copy of paper

c9611060

Separate Copy per user

List of Students enrolled…

…

Each Candidate get a Copy

1

4

3

2

Answered and Returned

5

Each copy returned

Distribution and TestingDistribution and Testing

Evaluation and result compilation: CS design

• Requirements– Different sections of an answer paper may be evaluated by different

examiners– Examiners may want to work offline or over a long period of time– Evaluation Server (ES) may need send notifications to the examiners

• Typical CS design– ES partitions each answer paper according to the different sections– ES provides forms for examiners to access the appropriate sections

and submit their evaluation– ES compiles the results and publishes them

• Drawbacks:– ES has to maintain state information for each student

• Status of evaluation of the different sections

– ES has to depend upon the examiners to pull the sections

c9611060

Examiner B

Examiner A

Examiner D

Examiner C

Distributor

Results

……

Agents collaborate to produce the final result

Objective Questions Evaluator

Evaluation Server

Evaluation and Result CompilationEvaluation and Result Compilation

Evaluation Server

Examiner –1

Objective Question Evaluator

Distribution Server –1

Paper Assembler

Question Paper Courier Agent

Student- 1a Student- 1b Student- 2a Student- 2b

Distribution Server –2

Result PublishingServer

Answer Paper Agent

Examiner –2

Student examination system: summaryStudent examination system: summary

PS-1

PS-2

PS-3

Install Agent

Fetch Agent

050

100150

200250

300350

400450

500

1 2 3 4 5 6 7 8 9 10 11

Request Number

Res

po

se i

n m

illi

seco

nd

Mobile Agent

Client-Server

Student Paper Interface Client

MA Interactions

Client –Server Interactions

Response time of CS v/s MA

Observations• Mobile agents enable

– Local interactions to reduce response times– Handling dynamic contents– Application level multicasting– Dynamic up-gradation of application components– Centralized control and management of logistics

• Mobile agents provide effective and flexible mechanisms for structuring distributed applications like student examination systems