Online Assessment System with Offline Capabilities*

Transcription

1 Computer Technology and Application 3 (2012) D DAVID PUBLISHING Online Assessment System with Offline Capabilities* Supriya Lohgaonkar and Sharad Sharma Department of Computer Science, Bowie State University, Bowie, MD 20715, USA Received: October 06, 2011 / Accepted: November 02, 2011 / Published: January 25, Abstract: There has been increasing research in developing offline web applications. This paper concentrates on developing a new methodology for the online assessment web applications that could be used while offline. It is important to retrieve the critical data collected during an examination without a provision of a backup mechanism. There is a need for an assessment system that can adapt to work uninterruptedly and without loss of critical data while there is intermittent internet discontinuity. This paper describes architecture and implementation of online assessment system with offline capabilities. Online assessment system with offline capabilities will not interrupt examinee s experience while appearing for an assessment test if internet connection is not available. A development methodology is designed and a compliant framework is implemented to enhance online assessment system with offline capabilities. Key words: Offline web application, assessment system, critical data. 1. Introduction An assessment system can be described as a system that evaluates examinee s performance and attainment. The online assessment system is a rapidly expanding system. Although there are many online assessment systems available, most of them only work online, i.e., as long as there is internet connectivity. These assessment systems need continuous communication with the server. Users of typical online web applications are only able to use the applications while they have a connection to the internet. When they go offline, they cannot access any of the information on the web page. With offline access, web applications can be viewed from the desktop using local storage and data access when disconnected from the internet. Internet connection is not always available and it leads to loss of data when the internet connection gets disconnected. The internet connection can also get disconnected when the user goes beyond the range * Extended paper from Proceedings of the 2010 World Congress in Computer Science, Computer Engineering, and Applied Computing, pp , July 12-15, Corresponding author: Sharad Sharma, assistant professor, Ph.D., research fields: multi-agent systems, modeling and simulation of emergency scenarios, evacuation, virtual reality. ssharma@bowiestate.edu. during wireless connection. Offline access creates an additional layer of reliability, extends the reach of web applications, and improves application performance by moving important data closer to its users. Nowadays, online assessment systems have become a cost-effective and popular means of assessing student/examinee knowledge. Students can access the online resources through distance learning. Besides, it enables the instructors to conduct online examination anywhere in the world. The system has expanded rapidly recently, because it is an effective solution for mass education evaluation. The main idea of an online assessment system is to enable instructor to create and store a bank of examination questions. The system will then randomly assemble the questions to become an online examination paper. Examinee can then access the online system and take part in the assessment. Although the online assessment system is an effective solution for mass education evaluation, there are some difficulties in this kind of evaluation. The main difficulty is the use of appropriate assessment techniques to support student learning and to record their critical evaluation data. Most of the present systems are designed to work assuming there is

2 Online Assessment System with Offline Capabilities 33 continuous and uninterrupted network connectivity. There is a need to use a different assessment system in order to prevent assessment data loss in case of intermittently interrupted network connectivity. Let us take a scenario where an examinee is appearing for an online assessment test (it could be an examination or an assignment). Examinee works on the online assessment test for a while and then tries to submit the test. As soon as examinee submits the test, the browser displays unavailability of internet connection message. The examinee has worked hard to complete the assessment test/assignment, but realizes that all the work has been trashed out because of unavailability of internet connection. Hence, there is a need to have an online assessment system which will be intelligent enough to work online as well as offline without disturbing an examinee who is undertaking assessment examination in an intermittent network connectivity environment. The paper is organized as follows: Section 2 discusses related work; section 3 introduces the architecture of online assessment system with offline capabilities; section 4 is implementation; section 5 gives conclusions. 2. Related Work Zhenming [1] has developed a web based examination distributed collaborative system which is based on DCOM (Distributed Component Object Model) technology. It is a multi-layer system which is composed of the web server, database server, WOES (Web based Online Examination System) middleware server, WOES client module and browser [1]. The WOES client module is a Microsoft DCOM component which can instance and bind objects over different network. These components work well only with Microsoft platforms. Firewalls presented serious challenges for DCOM components. Also client and server need to maintain same set of DCOM libraries installed. Jin [2] has proposed an intelligent examination system that checks the examinee s ability of E-business application operation. The system adopts the common client-server pattern with two major parts, student site and teacher site. The student site provides examinee a GUI (Graphics User Interface) embedded in web browser for answering the paper. The teacher site includes paper management subsystem for managing paper database, a building paper subsystem for building a new paper, and a scoring paper subsystem for scoring the paper of the examinees. Their system could work well in LAN (Local Area Network) where computer are connected to the server with intranet. However, these examples do not consider scenarios of working offline or during network outage. Davidrajuh [3] has proposed a design and implementation of a dynamic online assessment system. Their system is Java-XML (Extensible Markup Language) based solution for developing a distributed information system. In pre-examination phase, the faculty uses a web browser to design, edit, store, and retrieve text-based exam questions in a database remotely. Examination phase is an internet-based chat system used to enable geographically distributed individuals). Bottcher et al. [4-5] have discussed the problem of lost connection and data exchanged over a small bandwidth. They suggest optimistic approach to synchronization. There work suggests using XPath (XML Path Language) expressions instead of XML fragments wherever possible. Mobile computers operate in constantly changing network environments. According to Kavasseri [6], it is possible for a mobile computer to become temporarily disconnected from a network when it changes base stations or goes out of range from a base station. There work focuses on disconnected web browsing from a mobile host. Tamara et al. [7] discuss a framework for enabling web application to work offline. They argue for offline technologies like Google gears, web2os [8]. While the user is online, the framework creates a background simulation of all possible user actions and stores the output in the local drive and utilizes it when the user is offline [9-10]. While offline [9-10], the system pulls out the resources from its local drive and stores all user

3 34 Online Assessment System with Offline Capabilities input requiring server side scripts in its local database When connection is reestablished, a synchronization framework facilitates the update of its server database and ensures that recent resources are being used by the web application. Similar methodology would be helpful in an online assessment system. Online assessment systems aid in education evaluation. Most of these systems are designed to work when internet connection is available. Today, more and more organizations prefer web applications to perform their business processes, because these allow collaborative work between several users. However, many tasks must be done while being offline [10]. This goes against today s web architecture, where a remote server must be contacted for each performed operation [11]. Google gear enable user to read and search s when they are offline. However, when a person boards an airplane or train journey without Wi-Fi connectivity, some of the goggle gear compatible web applications continue to work as before. Ananthanarayanan [12] argues about offline web browsing framework, where RSS feeds are published by web server gives accurate information about new updated contents. 3. Architecture of Online Assessment System with Offline Capabilities (OAS) Applications are either thick or thin clients. A thick client stores all applications on the client computer and has a user interface. A thin client, on contrary has all its applications stored on the server. A thin client only retrieves and displays data. A major concern for thin clients is that data is transferred over many round trips to the server, slowing performance. A major concern of thick clients is that distribution is challenging and causes porting issues. The online assessment system with offline capabilities is a solution that combines the best features of both approaches. A remote client may loose its connection to the server during the execution of a transaction, but nevertheless the server should support completion of such a transaction after re-establishing the lost connection. Microsoft.NET technologies and XML standard make a great combination for implementing distributed information systems. XML enables disparate software systems to exchange messages. C# enables implementation of distributed information systems in a methodical way. As C# together with XML provides several technologies for integration, designers face the challenge of combining the technologies in the most effective and flexible manner possible to create an integration architecture that is opt for future extensions and changes. XML fragments are transferred from server to client, where they are read or modified, and modifications of client transactions are transferred back to the server. The clients use XPath expressions to access XML fragments, i.e., all XML fragments read or written by clients. This reduces the data exchange in synchronization. We furthermore suggest exchanging XPath expressions instead of larger XML fragments wherever possible. This allows us not only to treat lost connections more flexible but also to operate efficiently on clients with small bandwidth connections to a server. The assessment exams are displayed on client side with the help of XML, XSLT (Extensible Stylesheet Language Transformations) HTML (HyperText Markup Language) and JavaScript. XSL transformation is declarative XML based language. XSLT transforms XML documents into other XML document without changing original contents. OAS uses XSLT to convert XML data in the form of questions and possible answers from local data storage into HTML documents to display as a web page. Examinee s test responses in local data storage are stored in encrypted format. Every response saved in local data storage will be first encrypted and then saved at respective node structure in the XML document with the help of XQuery/XPath. File handling in JavaScript is done using FileSystemObject object, and its properties and methods. A mechanism to encrypt data at client is implemented with JavaScript.

4 Online Assessment System with Offline Capabilities 35 Fig. 1 Architecture of online assessment system with offline capabilities. There is a separate mechanism implemented at the web server to interpret data received from client and save it in the database. XQuery can be used to query XML data. OAS will use XQuery functions to extract data from XML documents. XPath will help to navigate through elements in an XML document. XMLHttpRequest is an API that can be used inside a web browser. XMLHttpRequest will invoke self initiated call to file transfer web service. This web service will pick the updated response XML file after particular time interval. Thus file transfer web service transfers student s responses from client to server. 3.1 Assessment Database Server Assessment database server contains several databases like question database, student database. The question database stores assessment test question bank. Student database contains student s progress. It also stores backup of examinee s responses during and at the end of the examination. It maintains information about the questions student has attempted and assessment measure for each question. Also the database server stores login credentials of users of an online assessment system. 3.2 XML Encoder/Decoder XML document is human readable and easier for user to examine and manipulate. XML encoder is used to encode XML documents at client. XML decoder is a mechanism to decode XML data received from clients. It uses a data encryption algorithm to decrypt data. Later data are stored in the OAS database. This is used to keep students responses secure and avoid it from getting tampered. 3.3 Client Application UI The assessment test is displayed in web browser. This component is responsible for lossless data capture on examinee s machine. Web browser communicates with the OAS web server to download the assessment test. Web browsers utilize HTTP (Hypertext Transfer Protocol) protocol for data transfer between client and the server. It stores examinee s responses in XML file in encrypted format.

5 36 Online Assessment System with Offline Capabilities Fig. 2 Flowchart of online assessment system with offline capabilities. 3.4 Client XML Data Storage As examinee starts taking test, examinee s responses get stored in XML file in encrypted format without knowledge of examinee. The updated examinee s responses will be retrieved with the help of XPATH and XQuery (XML Query) for particular timestamp. These responses are further picked by the File transfer web service at OAS server. XmlHttpRequest is initiated from client to call to the file transfer web service. The file transfer web service synchronizes this XML data with assessment database server on predefined periodic basis. 4. Implementation Fig. 2 depicts the flowchart of online assessment system with offline capabilities. It gives general overview of the system. Examinee logs into the OAS (Online Assessment System) website by authenticating himself/herself with the valid credentials. If login is successful, the test will be downloaded on examinee s computer. We will refer it as a client. If there is problem downloading the exam due to internet connection, the examinee (will have to try again until internet connection is re-established) can try it again. Once the exam is downloaded, the examinee clicks on the start button to start the assessment test. Examination time starts at this moment and the examinee starts taking the exam. Examinee s answers are stored in a local XML file. After a predefined time period (which is a configurable time period) only new and updated answer data from local data storage (Examinee s answer data) will be sent back to main server and synchronized with the data in the database server. If the internet connection is not available at the time of periodic synchronization, the answers will be stored on local machine in an encrypted format until the internet connection is re-established. As soon as client reconnects to the OAS server, all stored answers will be sent back to the OAS server and synchronized with database server. The examinee will

6 Online Assessment System with Offline Capabilities 37 either hit the submit button if he/she is done before the allowed time or the test will close automatically after the prescribed exam duration. It will inform examinee about the submission of the test if internet connection is available at that moment. If internet connection is not available and examinee submits the test, examinee will be informed to check the availability of internet connection. In this state, examinee will not be able to see answers as examination is already timed out and all the answers are saved in encrypted format on local hard drive. It is the examinee s responsibility to make internet connection available, so that the saved answers data can be transmitted to the remote OAS server. Once internet is back up, the examinee can click the sync button in the browser to submit the test. The answers will be synchronized with OAS database server. An online assessment system with offline capabilities shows modeless characteristic. In a modal application, when the application is online it communicates with the server. When it s offline, it uses the local storage. Data must be synchronized when the application switches between modes. Switching between online and offline modes is done automatically in the background while examinee is appearing for an assessment test. An online assessment system with offline capabilities uses the local storage as much as possible and does continuous, small data synchronization in the background when the server is available. The advantages of modeless applications are: (1) A better user experience; (2) The user does not have to be aware of network connectivity or switching states; (3) The application work smoothly even with intermittent network connections. Since the local data store is kept up-to-date, it can be used to optimize the server connection. 5. Conclusions This paper presents online assessment system with offline capabilities, which will work online when internet connection is available and offline when internet connection is not available. This paper describes the architecture and implementation of proposed online assessment system. We are currently testing the proposed system. Our future work will involve evaluating and validating the online assessment web application. References [1] Z.M. Yuan, L. Zhang, G.H. Zhan, Novel Web-based online examination system, Frontiers in Education, 2003, pp. S3F_7-S3F_10. [2] X. Jin, Research on e-business intelligent examination system, World Scientific and Engineering Academy and Society 6 (2009) [3] R. Davidrajuh, K. Tharmalingam, Dynamic online assessment system, International Association for Computer Information System 6 (2005) [4] S. Bottcher, A. Turling, Transaction synchronization for xml data in client-server web applications, GI Jahrestagung 1 (2001) [5] S. Bottcher, A. Turling, Transaction validation for XML documents based on XPath, informatik, GI 19 (2002) [6] R. Kavasseri, T. Keating, M. Wittman, A. Joshi, S. Weerwarana, Web Intelligent query disconnected web browsing using cooperative techniques, in: IFCIS International Conference on Cooperative Information Systems, [7] R.C.T. Mercado, J.G. Song, A framework for enabling offline web applications over a collaborative environment, Hannam University, Korea, [8] A. Russell, G. Wilkins, D. Davis, Bayeux A JSON Protocol for Publish/Subscribe Event Delivery Protocol 0.1draft3, available online at: [9] Y. Yang, Supporting online web-based teamwork in offline mobile mode too, in: Proceedings of the First International Conference on Web Information Systems Engineering, 2000, pp [10] J. Song, G. Yu, D. Wang, T. Nie, Offline web client: approach, design and implementation based on web system, Web Information Systems WISE 2006, Springer Berlin, [11] E. Goncalves, A.M. Leitao, Offline execution in workflow-enabled web applications, in: Quality of Information and Communication IEEE International Conference, [12] G. Ananthanarayanan, S. Blagsveldt, K. Toyama, OWeB: a framework for offline web browsing, in: Web Congress (LA-Web 06), 2006.