Symmetric synchronous collaborative navigation

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Synchronous collaborative navigation is a form of social navigation where users virtually share a web browser. In this paper, we present a symmetric, proxy-based architecture where each user can take the lead and guide others in visiting web sites,
  UNIVERSITYOF TRENTO DEPARTMENT OF INFORMATION AND COMMUNICATION TECHNOLOGY 38050 Povo – Trento (Italy), Via Sommarive 14 SYMMETRIC SYNCHRONOUS COLLABORATIVE NAVIGATIONLuca Gerosa, Alessandra Giordani, Marco Ronchetti, Amy Soller, andRon Stevens May 2004Technical Report # DIT-04-033  .  SYMMETRIC SYNCHRONOUS COLLABORATIVENAVIGATION Luca Gerosa, Alessandra Giordani, Marco Ronchetti  Dipartimento di Informatica e Telecomunicazioni, Università di TrentoVia Sommarive 14, 38050 Povo di Trento, Italy{lgerosa,agiordani,marco.ronchetti}  Amy Soller  Irst-ITC Via Sommarive 18, 38050 Povo di Trento,  Ron Stevens UCLA/IMMEX Lab,560ı W. Slauson Avenue #255, Culver City, CA, ABSTRACT Synchronous collaborative navigation is a form of social navigation where users virtually share a web browser. In thispaper, we present a symmetric, proxy-based architecture where each user can take the lead and guide others in visitingweb sites, without the need for a special browser or other software. We show how we have applied this scheme to aproblem-solving-oriented e-learning system. KEYWORDS Collaborative navigation, social navigation, e-learning 1.   INTRODUCTION Computers can be used to support both individual and collective experiences. Sometimes, even the sametask can be performed individually or cooperatively. For instance, using a word processor to write a letter isindividual task, while using it to write a paper with other authors, and making use of tools like versioning andannotations, is certainly a collaborative action. Even computer games can have individual and networkedversions. For example, Doom can be used as a solitary game, or as a social one when playing over thenetwork with friends, cooperating to defeat the (virtual) enemy. Solitary games can also have a socialcomponent, e.g. when trying to outperform other users. Simply keeping track of the high scores introduces a(indirect) social component in an otherwise individual game. We therefore have a whole spectrum of possibilities, where activities can be classified as individual, indirect social, and social . Moreover, socialactivities can be asynchronous or synchronous . They can also be symmetric or asymmetric : in the first caseall the users play the same role (or at least have equal opportunity to do so), while in the second, a leadercontrols the system. These possibilities are determined by the natural affordances of the technology – thosecharacteristics of the technology that define the ways in which users can carry out activities and interact withother users in a given context, and the ways in which the software mediates these activities (Jermann, et al.,2004). In this introduction, we take a look at a few different examples.Navigating a hypertext or the web appears at first glance to be an individual experience, not unlikereading a book. However, even web navigation can be seen as a social activity (Erickson 1996, Dieberger1997). For instance, indirect social navigation is possible in an on-line grocery store if people visiting the siteare given indications about what other people have bought (Munro et al. 1999). actively uses  this concept for suggesting books to buy according to the behavior of other users having similar interests.Along this idea, recommendation systems have been employed and studied by many authors in the last fewyears. Recommendation can be explicit (like when users are allowed to express their opinion, for instance byvoting on a page or writing a comment) or implicit (when the recommendation is obtained by analyzingindicators of the visitor’s behavior, such as the choices taken by the users, or the time spent on a page and thefollowed links).  Direct social (and interactive) navigation occurs when the navigators can become active authors, like inthe case of Blogs or Wiki’s. In this case the navigator can actively modify portions of a Web site, mirroringthe kind of interaction experienced during the cooperative activity of writing of a paper. A Wiki(WikiWikiWeb, a concept invented by Cunningham in 1995) enables documents to be authored collectivelyin a simple markup language using a web browser (Leuf and Cunningham 2001). Similarly, a weblog, alsoknown as a blog, is a website which contains periodic, reverse chronologically ordered posts on a commonwebpage (see e.g. Stauffer 2002). Individual posts either share a particular theme, or a single or small groupof authors. Because of their ability to support the notion of direct social navigation, Blogs and Wikis aregrowing in popularity. Interactions through blogs and wikis are in most cases asynchronous .A case in which interactions among navigators are synchronous has been proposed and implemented inthe EDUCO system (Nokelainen et al, 2002). EDUCO appears to the users as a visual collection of web sites,where the users can navigate the documents and see when other users are navigating those same documents.Other users can be contacted through a chat by clicking the dots representing users in EDUCO view.Furthermore, users are able to set “alarms” which are triggered when someone (e.g. anyone, or a particularperson) arrives to the systems or to a certain document. (Hoppe and Ploezner 1999). The interactivity here isgiven by the ability to observe, in real time, the population of visitors of the environment, and to contact themexplicitly. The main goal of the system was to let the user break the feeling of “loneliness” when navigating.An even stronger form of  synchronous interaction during navigation is to co-navigate , i.e. to allowmultiple users to share a navigation experience by synchronizing their browsers. Such idea has been exploredin the early days of the web. Yeh et al. suggested in 1996 that a web client (in master mode) could takecontrol of other web clients (in consentient slave mode) to guide them through an internet tour (synchronousnavigation). They argued that such activity could be valuable in an e-learning environment, where a tutormight show domain material or learning artifacts to pupils. In the following years, similar systems have beenproposed (we discuss these later).In this paper, we realize the idea of co-navigation in not only a synchronous , but also symmetric setting.We describe the prototype we implemented, in which users can join a group, and navigate in a collaborative , synchronous and symmetric way. This means that all users of a collaborative learning group view the samescreen on different browser, and the actions taken by any group member has a direct effect on the browsers of all the other users in the group. In our prototype, we also provide tools such as a textual chat, and a system toobtain interface control. The aim of this research was to enhance individuals’ learning experiences in anonline, initially single-user, problem-based learning environment by providing them the opportunity tocollaborate synchronously while navigating together. In our environment, the students typically solveproblems by exchanging ideas while exploring a simulated mini-world through co-navigation. In section 2we describe the environment and our goals in more detail. In section 3 we present the overall architecture. Insection 4 we discuss related work, and then draw our conclusions. 2.   MOTIVATION OF THE WORK Our work was motivated by the desire to extend the IMMEX™ system to support collaboration amongstudents. The IMMEX™ (Interactive Multi-Media EXercises: software, which wasdeveloped at the University of California, Los Angeles, has been used in science classes across middle andhigh schools, universities, and medical schools in the U.S. over the past 12 years, and has logged over140,000 student problem solving performances (Stevens and Palacio-Cayetano, 2003). Through the IMMEXweb-based interface, students learn how to elaborate hypotheses and analyze laboratory tests while solvingreal-world problems. The system presents problem sets as scientific case-studies and realistic multimediadomain-specific simulations. For instance, in one problem set, students perform physical and chemicalchemistry tests to determine, as quickly as possible, whether or not some chemicals that spilled during an  earthquake are dangerous. The system does not allow students to perform an exhaustive exploration of theproblem space, so that they have to be selective and use scientific inquiry to solve the problem. A richportfolio of over 100 problem sets in various disciplines has been developed, and is now available online.Statistics generated by the system has been used to identify the common types of strategies high schoolchemistry students used to solve qualitative chemistry problems (Vendlinski and Stevens, 2002), and we havenow begun to study how collaboration influences students solving strategies. It was therefore necessary toenhance the IMMEX system with collaboration facilities to allow students to cooperatively solve problems.Because IMMEX is a web-based system, students do not need to be co-located to learn together, so it wasnecessary to develop tools to support their synchronous, symmetric cooperation through the web. Importanttools included a chat that allows them to discuss the problem, and their proposed actions, and facilities thatenable students to cooperatively use the IMMEX system as if they were in front of the same computer. Theadvantage of mediating the students’ interaction through the computer is twofold: this enables remotestudents to work together over the network, adding a layer of cooperation to distance learning, and it alsoallows the system to keep track of the actions and discussions. Such logs can be analyzed, for example, toinvestigate how the collaboration influences the student’s learning styles.The concept of synchronous symmetric co-navigation satisfies these goals. We therefore designed andimplemented an architecture based on an HTTP proxy, Java and Javascript to allow the co-navigation on a peer basis . We do not use the concept of a (static) master and slaves. In our implementation, any user cantake control of the navigation, and the effect of each action is visible to all other associated users. Ourarchitecture is scalable, and can be used both in the context of the IMMEX system, and, with minoradaptations, to support other environments where co-navigation can be useful. 3.   THE ARCHITECTURE In order to add extra functions on top of the web paradigm there are three possibilities: to enhance the server,to modify the client, or to interpose an additional actor (typically a proxy).Enhancing the server is, in general, the simplest solution. Several technologies are available to achieve thegoal: CGI programs, scripting languages (like ASP, PHP etc.) and Java Servlets (or their dual: Java ServerPages). Such solution can be applied whenever the desired functionality fully depends on a single Webserver, and when one has full control of the web application that has to be modified.Some degree of customization of the behavior of a client (i.e. of the web browser) is possible by using client-side scripting languages (Javascript being the main player in this field) or by using applets. Such approaches,however, require modification of the srcinal pages coming from the server, so that ultimately, one doeshave to act on the server side. Modifying the server functionality or the content it delivers may not be anacceptable solution in many cases. For instance, one might not have access to the server and its content, orone might rather not touch it.More radical browser behavior modifications can be obtained by building an ad-hoc browser thatincorporates the desired functionalities. The modified client can then talk to the standard “content providers”(i.e. normal web servers) via HTTP, and to a special purpose server providing the needed functionality usingan arbitrary protocol. Such an approach is viable, e.g. in Java some APIs provide the basic building blocks(like the class JEditorPane) to build a rudimentary basic browser with only a few lines of code. The maindrawbacks are, however, that building a full fledged browser is a gigantic task, and moreover having toutilize a special browser in some context, and a standard browser in others, can be very inconvenient for theuser.The last possibility is to encapsulate the desired business logic in an active element interposed between clientand server. The browser must address its requests to the middle layer, that in turn, pushes them to the server,gets the response, and before delivering it to the browser, performs whatever modifications are needed to addthe desired functionalities. The simplest example of such an architecture are the widely employed proxyservers, where the middle layer stores a local copy of any page that is requested so that the successiverequests (of the same or of other users) can be fulfilled quickly without downloading the content again fromthe server. From now on we call “proxies” such middle layers, although they can do much more than justcaching pages. For instance, a proxy can actively modify the served pages. Such modifications may include,for instance, URL rewriting, content filtering, triggering of events, and addition of Javascript code to allow a
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