Mobile agents based implementation of a distance evaluation system Vikram Jamwal Sridhar Iyer School of Information Technology IIT Bombay SAINT’2003

Mobile agents Programs 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

Data Base Desktop Server System Resources Laptop User Application Legacy Software Execution Environment Mobile Agent Service Agent Application Agent Migration Local Communication Global Communication Typical mobile agent framework

Student Examination System Existing 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 participant Difficult 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-5 PS-4 PS-1 Paper Assembler Comprehensive Paper = Mobile Agents To Distribution Server Examination setting: overview

NS N- 1 N- 2 NS Cloning Install Agent GUI Fetch Agent Launcher Controller GUI NS = Name Server N = Paper Setter Node Examination 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

Distribution Server Exam Center Distribution Server Single copy of paper c Separate Copy per user List of Students enrolled … Each Candidate get a Copy Answered and Returned 5 Each copy returned Distribution 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

c 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 Compilation

Evaluation Server Examiner –1 Objective Question Evaluator Distribution Server –1 Paper Assembler Question Paper Courier Agent Student- 1aStudent- 1bStudent- 2aStudent- 2b Distribution Server –2 Result Publishing Server Answer Paper Agent Examiner –2 Student examination system: summary PS-1 PS-2 PS-3 Install Agent Fetch Agent

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