TechTALK: A Web Based System for Mathematical Collaboration 1
Contents
1. e The client applet receives information from the TechTalkServer in pack ages with information about what to do with it such as which window to display it in and displays it accordingly The client applet does not refor mat textual output from Maple Matlab in the present implementation e A user with permission to do so can login as an administrator An admin istrator performs such functions as maintaining a list of all bona fide users and their passwords creating terminating users fixing the numbers and locations of various servers etc If a user logs in as an administrator the client applet displays a special button in addition to the various windows called the Administrator Button Pressing this button causes the client to show an editor interface for changing any of the above information At any time only one user can login as administrator to ensure integrity of administrative information Password files and information about server locations and socket numbers are maintained on the same file system as the one used by the host running the TechTalkServer Any request from an administrator to update this information is handled by the TechTalk Server e A user can choose to record an entire TechTalk session or a part of it in a log or peruse the log of an earlier session The StartLog EndLog and ShowLog buttons enable the user to perform these tasks The log facility is particularly useful and we will describe it in more detail la2. The user can only choose to view a session that he was part of The user can choose to view the entire session or just the Maple queries and responses including graphical output or just the Matlab queries and responses or just the chat part or some combination of these The chosen part of the log is displayed in a separate window The displayed messages are numbered and can be referred to by those numbers The log window has basic scroll features and the user can display messages numbered next increment previous decrement or a range of messages The user can reissue a command or a range of commands from the 11 log window by either referring to them by their numbers or cutting and pasting the commands to TechTalk s Maple Matlab window The results are displayed in the Maple Matlab window as appropriate Simple editing features enable the user to make changes to a command from the log file prior to reissuing it Piisi Log Log 1 1 amp commands 1 Server all ibcosdoast Gat Oot S 16 57 00 PET 1997 qelosbey has started logging this TechTalk session es al Bae fot S H 57 00 BST 1997 al matlab bronpit brunas a 1 The log files are stored as HTML files with some additional tags and can be viewed independently if desired Allowing TechTalk users to save logs intro duces the problem of maintaining files and the risk of someone accidentally or maliciously filling up TechTalk s host s disk space We adopt a simp
3. the applet came from and passes the information collected from the user to the TechTalkServer in a convenient form e Once a user is authenticated by the TechTalkServer the TechTalkClient applet opens up a window that can be used to communicate with Maple Matlab or with other users in the session A user can direct a message to any of the above destinations by hitting buttons labelled as to Maple to Mat lab Alternately a user can request three separate windows a Maple window a Matlab window and a conversation window for communicat ing with the servers and other users The windows have several buttons for sending commands to the servers and getting various kinds of infor mation For instance in the conversation window there is a list users button that causes the client to obtain a list of all users currently logged on to the TechTalk session and display it In the Maple and Matlab win dows the client applet tries to present interfaces close to the standard Maple Matlab interfaces respectively The current implementation sup ports two dimensional textual output from Maple and Matlab The user can type text into any window The client applet packages chunks of text from a window with additional information such as the name of the win dow the text was typed into whether the user requested the results to be broadcast returned only to him and the length of the text It then sends the package to the TechTalkServer
4. title Network Enabled Optimiza tion System howpublished http www mcs anl gov home otc Server Miscnetlib author Netlib Support title Netlib A repository for mathematical software data documents address lists and other useful things howpublished http cm bell labs com netlib Booknierstrasz author Oscar Nierstrasz and Dennis Tsichritzis title Object oriented software composition publisher Prentice Hall year 1995 Miscopenmath author The OpenMath Consortium title The Open Math Specification Version 1 1 howpublished http www openmath org year 1997 Bookorfali96 author Robert Orfali and Dan harkey and Jeri Edwards title The Essential Distributed Objects Survival Guide publisher Wiley year 1996 Articleperline91 author Ron Perline and Joel Langer title Poisson geometry of the filament equation journal Journal of Nonlinear Science year 1 volume 1 pages 71 93 Articleperline94 author Ron Perline and Joel Langer title Local geometric invariants of integrable evolution equations journal Journal of Mathematical Physics year 1994 volume 35 number 4 pages 1732 37 manualpolymathBeans organization PolyMath Group title Descrip tion of Java OpenMath Demonstration Beans Version 0 3 Preview Release note Available on the World Wide Web at http pdg cecm sfu ca openmath lib bean html year 1997 Articlepsedefn author E Gallopoulos and
5. E N Houstis and J R Rice title Computer as Thinker Doer Problem solving environments for Com putational Science journal IEEE Computational Science and Engineering volume 1 number 1 year 1994 month Summer pages 11 23 Miscpurduepde author E N Houstis and J R Rice and S Weerawarana and A C Catlin and P Papachiou and K Y Wang and M Gaitatzes title Par allel ELLPACK A problem solving environment for pde based applica tions on multicomputer platforms howpublished ELLPACK Research Report http www cs purdue edu research cse pellpack pellpack paper 1 htm1l InProceedingssui90 author Y Doleh and P S Wang title SUI A system independent user interface for an integrated scientific computing en vironment booktitle Proceedings of the 1994 International Symposium on Symbolic and Algebraic Computation year 1990 pages 88 95 Bookszyperski author Clemens Szyperski title Component Software Beyond Object oriented programming publisher Addison Wesley year 1997 18 Miscteachtalk author J R Johnson and Y N Lakshman and P Morgovsky and T T Hewett and T Souder and S Donegan and T Fitzgerald title Virtual office hours in mathematics instruction howpublished manuscript submitted for publication year 1998 Miscttdesc author Y N Lakshman and Michael R Miller and Santiago Lombeyda title TechTalk A web based system for mathematical collabora tion howpublished manuscript
6. The user can cut and paste information from the log window to any of the other windows Each type of interaction described here is implemented through a general set of protocols that can also be used in other settings The TechTalkServer clearly handles a lot of traffic and can be a bottle neck In our trials with up to a couple of dozens of users we have not experienced any significant delay other than web traffic delays which is location and time dependent 3 3 The TechMathServer The TechMathServer module is essentially a Java wrapper for stand alone ap plications such as Maple and Matlab It communicates with the TechTalkServer on one side and an application Maple or Matlab in this case on the other The TechMathServer controls the standard input output error streams of the application it is running It receives requests from the TechTalkServer which is one of the packages described earlier extracts the commands to be sent to the application sends the commands to the application and waits Re quests that arrive while the TechMathServer is waiting are queued on a first come first served basis The TechMathServer has special ways of handling input errors unexpected command termination etc and these depend largely on the application at this time since there are no standard ways yet for applications such as Maple to inter act with other programs in a client server mode TechMathServer also performs some buffering since the size of
7. file which it uses to authenticate the user id password pair sent to it by TechTalkClient ap plets The TechTalkServer recognizes two kinds of users administrators and regular users The type of a user is part of the information main tained in the password files Password information is transmitted after encryption by the TechTalkClient The TechTalkServer maintains a list of active users for each TechTalk room that it supports After a user is authenticated the TechTalkServer adds the user name and the location of the user to the list of active users for the particular TechTalk room that the user has chosen pimini a f n e Conversation Handling Users in a TechTalk room converse by typ ing text into his conversation window and pressing a send button The user s TechTalkClient applet packages the text along with information about the user s identity the room to which the user belongs and the type of information conversational text in this case and sends it to a specific port on the host running the TechTalkServer on which the TechTalkServer is listening A listener thread constantly monitors the port Upon receiv ing such a package the listener thread hands it off to another thread for dealing with it and goes back to its monitoring duty The other thread extracts the text and sends it to every user on the current list of active users who are in the same TechTalk room as the sender Other requests from the conversa
8. release of the system had quite different ways of doing I O All this of course points to a need for acceptable server interfaces In light of the problems 13 mentioned with replicating interfaces we feel that the nice interfaces that some of these systems provide may be in the way when it comes to their functioning as servers Maple provides a version called MathEdge that comes without the worksheet interface but all the other parts of Maple intact Such a stripped down version capable of communicating through a standard mark up language with the rest of the world would be a desirable thing In addition the server version ought to be able to respond to simple remote system queries commands such as are you ready for the next job are you busy please stop whatever you are doing The need for platform independence cannot be over emphasized Based on our experiences with building these servers we are currently devel oping a generic server for mathematics to work with existing computational programs inlcuding typical interactive mathematics systems IMS The design of our generic server is guided by our desire to e provide simple mechanisms to encapsulate commercial or non commercial mathematics engines such as Maple Matlab Mathematica Singular Gb or other Gr bner software etc as well as suitably wrapped up code libraries for doing symbolic numerical and graphic processing into servers capable of providing th
9. submitted for publication year 1997 Miscttmanual author Y N Lakshman and Santiago Lombeyda title TechTalk 1 0 User and Installation guide howpublished available from http penguin mcs drexel edu techtalk year 1997 InProceedingswang97 author Paul S Wang title Tools for Paral lel Distributed Mathematical Computation booktitle Proceedings of the Sec ond International Symposium on Parallel Symbolic Computation PASCO 97 editor Markus Hitz and Erich Kaltofen year 1997 publisher ACM Press pages 188 195 Unpublishedweber98 author Andreas Weber and Wolfgang Kiichlin and Bernhard Eggers and Volker Simonis title A parallel Gr bner solver as a web component note To be presented in ACM 1998 workshop on Java on high performance network computing February 28 March 1 1998 Miscxml author Tim Bray and Jean Paoli and C M Sperberg McQueen title Extensible Markup Language XML Proposed W3C Recommendation PR xml 971208 Dec 1997 howpublished http www w3 org TR PR xm1 year 1997 19
10. the output in many cases in unpredictable and can be quite large The TechMathServer is fairly general in its conception and implementation in the sense that it can be used as a wrapper for other applications besides Maple Matlab Still it is the most application and platform dependent part of the TechTalk system The Java language makes the platform dependence less of a problem than in other languages We are currently investigating the use of common standards such as MathLink and OpenMath for exchanging mathe matical information to decrease application specific actions in TechMathServer 10 3 4 System Start Up and Shut Down Starting up a system like TechTalk with multiple servers on different hosts can be quite a task Recognizing this we have made up a command to start up TechTalk and a command to shut down TechTalk These commands make use of some initialization files and the password file The password file contains basic user information the privileges that each user has guest regular admin istrator and encrypted passwords The initialization files contain such information as the hostnames of the hosts running the various servers along with relevant port numbers fully qualified path names of directories to be used for temporarily storing GIF files and log files and access permissions for various user levels These files have to be created before starting TechTalk A stand alone initialization program called InitTT prompts the ad
11. used to different interfaces on different machines Such a situation in an introductory class using two different interfaces for Maple for example can create tremendous confusion This is a problem we have had to face in building TechTalk The user interfaces provided by systems such as Mathematica and Maple are getting more sophisticated with each new release the parts of the system that handle the interface are proprietary and built into the system meaning one can not find a free floating module that can recreate the Mathematica interface The effort involved in replicating the interfaces of all the systems that we might want to connect in a TechTalk session is tremendous Again it would be useful to have these systems put out things for display in a standard mark up language There are efforts underway to evolve such standards notably the MathML working group under the WWW consortium is attempting to come up with specifications for a mark up language for mathematical notation Another difficulty encountered in building TechTalk was the process of coax ing Maple and Matlab to pretend to be servers Considerable effort had to be put in to understand how these systems handle low level I O The task was made harder by the fact that these details are not spelt out and are very hard to get out of the makers of the systems An even more vexing problem was that having found out some of the intricacies of a particular system we found that a new
12. Karsten Homann and Jacques Calmet title Theorems and Algorithms an interface between Isabelle and Maple booktitle Proceedings of the 1995 International Sympo sium on Symbolic and Algebraic Computation editor A H M Levelt year 1995 publisher ACM Press pages 150 157 Bookjava97 author David Flanagan title Java in a nutshell publisher O Reilly year 1997 edition Second InProceedingsKajler92 author Norbert Kajler title Building a Com puter Algebra Environment by Composition of Collaborative Tools booktitle Design and Implementation of Symbolic Computational Systems Proceedings of DISCO 792 editor John Fitch year 1992 publisher Springer Verlag pages 85 94 note Lecture Notes in Computer Science 721 InProceedingsKajler93 author Robet Fournier and Norbert Kajler and Bernard Mourrain title IZIC a portable language driven tool for mathemat ical surfaces visualization booktitle International Symposium on the design and implementaiton of symbolic computation systems DISCO 93 editor Al fonso Miola year 1993 publisher Springer Verlag pages 341 353 Bookjacobson92 author Ivar Jacobson title Object oriented Software engineering publisher ACM Press Addison Wesley year 1992 MiscjavaStudio key Java Studio title Java Studio howpublished http www sun com studio index html year 1997 Articlejscspec author L Lambe Ed title Special Issue on Appli
13. Talk room or just by the sender of the command The results of a computation can be textual graphic e Under certain situations the results of a Maple computation can be sent directly to the Matlab server and the results of the Matlab computation observed by all the users for instance a user might use Maple to generate Matlab code for solving an ordinary differential equation and send the code directly to the Matlab server and have its output a color plot perhaps displayed to all the users e The users can have a multi way conversation in a separate talk window on each user s screen A logging facility enables one to save a session and replay either the entire session or selected portions of it the flexible replay facility allows different uses of a log including broadcasting of class lessons notes in an electronic tutorial setting e TechTalk is implemented in the Java programming language This has several obvious advantages for the designer and the users of the system TechTalk takes advantage of the communication infrastructure offered by the world wide web Java makes it easier to use this infrastructure The implementation is largely platform independent Users of TechTalk only require a Java enabled web browser users of TechTalk do not need to have accounts on the server s running TechTalk In our set up the Maple and Matlab servers run on Unix systems and the users of TechTalk connect from Unix Windows Macintosh systems After
14. TechTALK A Web Based System for Mathematical Collaboration Lakshman Y N Department of Mathematics and Computer Science Drexel University Philadelphia PA 19104 USA Michael R Miller Siemens Corporate Research Princeton NJ 08536 USA Santiago Lombeyda t Department of Mathematics and Computer Science Drexel University Philadelphia PA 19104 USA April 22 1999 1 Introduction Imagine two mathematicians working at a blackboard discussing their work as it develops imagine three students sitting around a workstation working on a homework assignment with the help of a mathematics system such as Maple or Matlab What if one of the mathematicians is in Philadelphia and the other is in Bombay What if two of the students are in their dorm rooms while the third is at her parents home TechTalk is a mathematical collaboration system for the World Wide Web It enables a group of people in different locations to perform calculations generate graphical output and discuss their results It allows them to interact as though they were in the same room even if they are located in different parts of the world TechTalk attempts to simulate one or more rooms with several people with access to Maple and Matlab in each room Supported in part by NSF Grants CCR 9527130 and CCR 9712219 Current Address Computing Sciences Research Bell Laboratories 600 Mountain Avenue Murray Hill NJ 07974 t Current Address Center for Advanced Computin
15. a simple guided initial set up TechTalk requires very little additional adminis tration such things as adding new users or changing the host servers can be done remotely over the web by an authorized administrator TechTalk has been successfully used to conduct remote tutorial sessions in an elementary numerical analysis course It has also been used to conduct mathematical conversations involving computations among small groups of people in different geographic locations In the rest of this paper we describe TechTalk system and its archi tecture in detail and mention some of the experiments that we have conducted with it More details of the use of TechTalk as a web based tutorial for teaching of mathematics can be found in 3 TechTalk Behind the Scenes In this section we give a short description of the architecture of TechTalk There are three main components to TechTalk the TechTalkClient the TechTalk Server and the TechMathServers e The TechTalkClient handles client side affairs such as maintaining dis plays packaging client requests and interpreting server responses e The TechTalkServer holds together a TechTalk session by maintaining connections to and relevant information about the users in a session It also maintains connections to any number of mathematical engines such as Maple Matlab in principle TechTalk can wrap any interactive pro gram as a server we use Maple and Matlab as they were suitable for our purpo
16. ands and the source of the command the user s identity and location whether the results are to be broad cast or not and sends it to the appropriate Maple Matlab server Each TechTalk room has a separate Maple and Matlab server at this point All users in a TechTalk room interact with them Certain shell escapes from Maple Matlab are disabled a user cannot issue them from the ap plet for security reasons The responses from Maple Matlab are sent in packages created by TechMathServer They contain the actual response from the Maple Matlab session to a command sequence and some header information indicating the source of the response Maple Matlab and the intended recipient user name TechTalk room number broadcast single user response The TechTalkServer handles the package based on the header information e Graphical Output Graphical output from Maple Matlab is handled differently Maple Matlab is made to save the graphical output in GIF for mat and send the location of the file containing the output The TechTalk Server conveys this location to the TechTalkClient applets that are sup posed to see the output which then load the image on to the users screens This mechanism requires the GIF files to be saved on the same host as the TechTalkServer since the TechTalkClient applets can only connect to that one host In our present implementation we run the Maple Matlab servers on different hosts that share the same file system as
17. ca tions of Symbolic Computation to Research and Education journal Journal of Symbolic Computation volume 23 number 5 and 6 year 1997 month May June Articlelsoda author Linda Petzold title Automatic Selection of Meth ods for Solving Stiff and Nonstiff Systems of Ordinary Differential Equations journal SIAM Journal of Scientific and Statistical Computing year 1983 volume 4 number 1 month March TechReportmathlink author Wolfram Research Inc title MathLink Reference Guide Mathematica Technical Report institution WRI Inc year 1993 Miscmathml author The MathML Working Group title Mathemati cal Markup Language W3C Working Draft howpublished http www w3 org TR WD math year 1998 InProceedingsmp94 author Simon Gray and Norbert Kajler and Paul Wang title MP a protocol for efficient exchange of mathematical expressions booktitle Proceedings of the 1994 International Symposium on Symbolic and Algebraic Computation year 1994 pages 330 335 InProceedingsmp96 author Simon Gray and Norbert Kajler and Paul Wang title Pluggability issues in the Multi Protocol booktitle Interna tional Symposium on the design and implementaiton of symbolic computation systems DISCO 96 editor Jacques Calmet and Carla Limongelli year 17 1996 publisher Springer Verlag pages 343 355 note Lecture Notes in Computer Science 1128 Miscneos author Neos Server Group
18. eir services to client requests on the Internet e provide means for incorporating these mathematical servers as components of distributed applications including a simple and powerful communication infrastructure e support existing and upcoming protocols for exchanging mathematical graphical information e use existing commercial and public domain software as much as possible to realize the above goals More details of the generic server can be found in In using TechTalk locally we found hardly any delays in communication While using it long distance coast to coast occasionally we found serious network delays One of the users would not see anything for a long time and a bunch of things all at once The delays are not uniform and appear to be location and time dependent In any case this is not acceptable for a collaboration tool Currently the amount of data sent between the various servers and clients is not large a few kilobyte chunks and we are trying to understand the reasons for the delays and what can be done to lessen them Currently we are working on a new version of TechTalk Our plans include the use of OpenMath with some enhancements to set up communication pro tocols among symbolic and numeric engines We also plan to provide a visual interface for specifying and setting up distributed computations and the ability to access code repositories on the web The Java bytecode for the current im plementation of TechTa
19. g Research California Institute of Tech nology 1200 East California Boulevard Pasadena CA 91125 imagine all the people in a room looking at the same screen but each with a separate keyboard Since people sitting in a room tend to talk to each other TechTalk includes support for conversation A user needs only a Java enabled web browser to participate in a TechTalk session 2 Computing and Collaborating on the Internet In the past several years we have seen a maturing of general purpose computer algebra systems such as Maple and Mathematica and the evolution of several next generation systems Magma Macaulay II and Kant to name a few Besides having extensive libraries of mathematical functions these systems come with the capability to write generic programs There are also numerous special purpose packages that are meant to perform huge computations in particular domains for instance PARI and Kant for number theory Singular and GB for commutative algebra Often there is a need to use the capabilities of more than one of these systems packages to solve a problem For example in order to solve a certain system of polynomial equations one might perform some initial simplification of the equations using Maple then compute a Gr bner basis for the ideal generated by the system on GB use Maple again to generate matrices of multiplication for certain endomorphisms on the residue class ring modulo the ideal generated by the i
20. language or interface At present there is no adequate candidate for this job In the context of computer algebra open standards are under development for exchanging mathematical information The OpenMath standard proposed by the OpenMath consor tium focusses on semantic markup and the MathML standard proposed by the World Wide Wed Consortium s task group for mathematics concentrates on presentation mark up They provide a common notation for sharing informa tion involving the basic entities that one plays with in computer algebra systems polynomials rational functions general arithmetic expressions and the ability to extend this notation to other composite types While these may be adequate in a situation involving the interaction of one or more pure symbolic systems we need the ability to represent a much richer domain of entities as we are interested in setting up interactions among engines that perform quite different types of computation for instance a symbolic a numeric and a visualization engine In our current set up we pass Matlab code or just numerical matrices from Maple to Matlab If we were to use say the NAG Explorer for visualization then we would need to provide a lattice for the visualizer It is essential to bring together the efforts of the symbolic numeric and visualization communities to evolve acceptable standards for communicating mathematical information As users of software systems we have to get
21. le policy of allowing each user a certain maximum amount of disk space to which the user has access only through the TechTalkServer and log files have a fixed lifetime after which they are deleted A log file can only be viewed by the creator of the log file or in his company The log facility turns out to be particularly helpful when TechTalk is used in a classroom tutorial setting For example an instructor can prepare a Maple lesson test it out in a TechTalk session save it as a log and replay it to the class later or a student can study the lesson on his own at a later time Students can save their work and show it to a tutor who can see exactly what the students did TechTalk was used in a small class on introductory numerical analysis with out the log facility We plan to use it with the log facility in a large introduc tory calculus class in the near future Our experiences with using TechTalk in the introductory linear algebra class are reported in 4 Lessons Learnt and Future Plans In implementing TechTalk we ran into two kinds of problems the first was that the mathematical packages that we used were not built to be used as servers 12 the second kind had to do with the communication support provided by the in ternet One of the key features of a TechTalk like system is that mathematical information can be passed from one engine to the other To do this in a reason able way the various engines should share a common
22. lk along with instructions for installation and use can be downloaded from http penguin mcs drexel edu see 14 Acknowledgements The implementation of TechTalk s administrative module was performed by Hoi Man Chang and Todd Zino We thank our PSE group colleagues at Drexel Bruce Char Tom Hewett Jeremy Johnson and Raji Venkatesan for many help ful discussions and Joseph Kiniry of CalTech for detailed comments on installing TechTalk Our thanks to Randy Bramley of the University of Indiana at Bloom inton for editorial comments that greatly improved this presentation InProceedingsavitzur95 author Ron Avitzur and Olaf Bachmann and Norbert Kajler title From Honest to Intelligent Plotting booktitle Pro ceedings of the 1995 International Symposium on Symbolic and Algebraic Com putation editor A H M Levelt year 1995 publisher ACM Press pages 32 41 InProceedingsbayram92 author M Bayram and J P Bennett title A simple general purpose technique for interfacing between Computer Algebra and numerical analysis systems booktitle International Symposium on the design and implementation of symbolic computation systems DISCO 90 editor John Fitch year 1992 publisher Springer Verlag pages 145 151 note Lecture Notes in Computer Science 721 annote Implements Fortran Reduce interprocess communication InProceedingscentralControl author St phane Dalmas and Marc Ga tano title Making syste
23. ministra tor for all the information needed to start TechTalk and creates the password and initialization files The StartTT command starts a TechTalkServer and sev eral TechMathServer s running Maple Matlab their number and resident host information is found in the initialization files The ShutTT command needs a handle to a TechTalk session and systematically shuts down all the servers that are part of the TechTalk session with the given handle It also removes several temporary files GIF files created by the TechTalk session The ClearTT command can be invoked periodically to delete dated log files and GIF files to free up space on the host running the TechTalkServer The current implemen tation of these commands assumes that all the TechTalk servers are running on a network of computers with a shared file system The StartTT ShutTT and ClearTT commands are written in Perl A short online manual provides all the information needed to set up and use TechTalk 3 5 The Log Facility As mentioned before users can log part or all of a session and replay it later The TechTalkServer views a log file as a sequence of messages where each message is one unit of information that passed through the TechTalkServer at some point The messages are tagged with information about the source recipient s and other information A user can replay a session by hitting the ShowLog button The user is shown a list of viewable session logs and asked to choose one
24. ms communicate and cooperate the central control ap proach booktitle International Symposium on the design and implementa tion of symbolic computation systems DISCO 96 editor Jacques Calmet and Carla Limongelli year 1996 publisher Springer Verlag pages 308 319 InProceedingschar89 author Bruce W Char title Automatic Reason ing About Numerical Stability of Rational Expressions booktitle Proceedings of the 1989 International Symposium on Symbolic and Algebraic Computation editor Gaston Gonnet year 1989 publisher ACM Press pages 234 241 Articledabdub95 author Donald Dabdub and J H Seinfeld title Ex trapolation techniques used in the solution of stiff ODEs associated with chem ical kinetics of air quality models journal Atmospheric Environment year 1995 volume 29 pages 403 410 Articledabdub97 author A Sandu and J G Verwer and M van Loon and others title Benchmarking stiff ODE solvers for atmospheric chemistry problems I implicit versus explicit journal Atmospheric Environment year 1975 pages 3149 3164 Articledabdub98 author D Dabdub and R Manohar title Perfor mance and portability of an air quality model journal Parallel Computing year 1998 note To appear MiscdabdubPersonal author Donald Dabdub title Personal Commu nication year 1998 month January InProceedingsdsc91 author A Diaz and E Kaltofen and K Schmitz and T Valente ti
25. nfospheres Infrastructure Documentation APIs and User s Guide author K Mani Chandy and Joe Kiniry and Adam Rifkin and Dan Zimmerman organization Infospheres Group address De partment of Computer Science California Institute of Technology year 1997 month August note Available from http www infospheres caltech edu papers index html Articleinfo98 author K Mani Chandy and Joe Kiniry and Adam Rifkin and Dan Zimmerman title A Framework for Structured Distributed Ob ject Computing journal Parallel Computing year 1998 note To appear Available from http www infospheres caltech edu papers index html Miscinfo98a key info98a title The Caltech Infospheres Project how published OMG DARPA MCC Workshop on Compositional Software Ar chitecture year 1998 month January note Available at http www infospheres caltech edu infospheres html ManualirisExplorerReference title IRIS Explorer version 3 5 Reference pages Module and programmer s interface information Unix edition orga nization Numerical Algorithms Group Ltd note Available at http www nag co uk visual IE iecbb DOC REF Index html ManualirisExplorerUsers title IRIS Explorer version 3 0 User s Guide Unix version organization Numerical Algorithms Group Ltd OPTnote Available at http www nag co uk visual IE iecbb DOC UG CONTENTS html 16 InProceedingsisabelle95 author Clemens Ballarin and
26. nput polynomials and then use a numerical package to compute the eigenvalues of these matrices from which one can infer the solutions to the input polynomial system We would like to be able to perform such computations involving several computational engines possibly running on very different hardware configurations located in different geographical locations in a seamless manner With the wide spread use of the World Wide Web we find code repositories and servers accessible from the web that provide mathematical services for example the Netlib facility offers a huge repository of routines for solving a host of numerical problems the NEOS server at the Argonne National Laboratories offers numerical optimization services and the partial differential equations server at Purdue University offers the capability of solving partial differential equations We would like to be able to configure such servers in a smooth manner to carry out computations that might need multiple services In recent years computer algebra systems have made deep inroads into the mathematical curricula at the high school and college levels There has been much discussion on harnessing the power of computers for effective teaching of mathematics There appears to be general agreement that too much time may be spent in learning the intricacies of one or more computer algebra systems and timely answers to specific questions concerning the use of these systems ma
27. ses and easily available to us The TechTalkServer collects client requests interprets and routes them to the appropriate mathematical en gines It also directs the responses from the mathematical engines to the appropriate clients waiting for those responses e The TechMathServers are essentially wrapper programs that make servers out of interactive programs such as Maple and Matlab One TechMath Server is needed for each mathematical server It maintains a connection with a TechTalkServer interprets computational requests which are com mands that the mathematical engine can understand wrapped in different protocols passes them to the mathematical engine and sends responses from the engine to the TechTalkServer after appropriate packaging TECHTALECLIENT TECHTALESENTER TECHTALEMATHSERNTER We now describe the capabilities of each of these components in detail 3 1 The TechTalkClient The TechTalkClient is responsible for handling client side affairs such as manag ing the displays and relaying user inputs responses to the servers This compo nent is implemented as a Java applet When a user hits a TechTalk session from a web browser the applet comes over to his machine and starts communicating with a TechTalkServer The TechTalkClient performs the following functions e Requests user id and password for authentication by the TechTalkServer It opens up a communication link with the TechTalkServer running on the same host that it
28. t or Matlab part or the chat part or all of the session recorded Messages coming from a client who is in the record session mode are specially tagged and depending on what parts of the session the user wants saved the TechTalkServer saves the relevant messages passing through it into a named file after putting some tags on them Allowing clients to save sessions on the host server introduces some administrative problems such as space management and there is also the potential for some user to inadvertently maliciously fill up the host s disk To prevent this the TechTalk administrator can set limits on the amount of space available to a single user for logging purposes It also helps to clear up logs older than a certain length of time Pressing the end log button ends the recording the session continues e Replaying a log A user can view the log of an earlier session by pressing the ShowLog button He will be prompted for the session name name of the file in which the log is stored After checking access rights the TechTalkServer will ask the user whether he wants to view the entire log or only portions of it such as just the Maple queries and responses in the log The log file is shown in a separate window with basic scrolling and the capability to jump to the next previous next a number previous a number chunk of information A chunk of information is one entire query or the response to a query or a single chat message
29. ter 3 2 The TechTalkServer The TechTalkServer is the hub of the activities performed by TechTalk The TechTalkServer is a stand alone Java application that must be running on the same host as the web server that houses the TechTalk homepage and hands out the TechTalkClient applet The TechTalkServer maintains connections to the TechTalkClient applets for every user in each TechTalk room as well as various servers offering Maple Matlab services and directs the flow of infor mation among these As part of the system set up one has to start up the TechTalkServer and several Maple Matlab servers All this is achieved by a single command that uses information about the number type and locations of the servers this information is to be maintained by the person responsible for running TechTalk During the start up process the TechTalkServer estab lishes connections to the Maple Matlab servers and maintains those connections through the life of the TechTalk session When a TechTalk user downloads the TechTalkClient applet from the web site offering TechTalk the applet con nects to the TechTalkServer running on the same host as the one on which the TechTalk web page resides A single TechTalkServer is capable of support ing several TechTalk rooms sessions Some of the specific functions that the TechTalkServer performs are e Password Authentication TechTalkServer is responsible for authen ticating TechTalk users It has access to a password
30. the one run ning the TechTalkServer The GIF files are saved in a directory known to all the servers and no special protocols are needed for this task Maple to Matlab This mode lets a user type commands in to a Maple window and have the results sent directly to a Matlab server and the results of the Matlab computation displayed to the TechTalk room At this time it is assumed that the output of the Maple command s will be understood by Matlab We have used this mode to generate Matlab code for solving ODEs and PDEs in Maple and send the code directly to Matlab and then display the Matlab output usually graphical to a TechTalk room For the TechTalkServer this is a two step process the first one involving an interaction with a Maple server followed by an interaction with a Mat lab server Messages in this mode are tagged differently from others and trigger different protocols e Recording a TechTalk session A user can choose to record a TechTalk session by pressing the StartLog button Upon receiving a request to record a session the TechTalkServer issues a message to all the users currently in the same room as the requesting user to the effect that the current session is being recorded Since the typical TechTalk session has a small number of cooperating participants we assume that such requests are agreed upon by all the participants in the room It prompts the user for an identifying session name whether the user wants only the Maple par
31. tion window such as for listing all the users in a TechTalk room are handled similarly this request results in a response only to the client that requested it Maple Matlab Requests A user can type any Maple Matlab com mands into the appropriate window and press the send button The com mands can be multi line single line The results of a command can be either broadcast to all the users in a room or sent back just to the per son issuing the command we have found the second mode to be helpful in somewhat embarrassing situations such as when we have forgotten the first three decimal digits of some universal constants The user can spec ify the mode by ticking off a toggle on the appropriate window As before the user s TechTalkClient applet packages the command along with in formation about the user s identity the room to which the user belongs and the type of information Maple Matlab commands in this case and the response mode broadcast single user response sends it to the lis tening port of the TechTalkServer The client does not perform any syn tax check this is done by the actual mathematical system itself and if there are syntactic errors the user receives error messages warnings from the particular system just as when the user types commands directly into Maple Matlab On receiving a package containing user commands the listener thread hands it off to another thread This thread creates a new package containing the comm
32. tle DSC A system for distributed symbolic computation 15 booktitle Proceedings of the 1991 International Symposium on Symbolic and Algebraic Computation editor Stephen M Watt year 1991 publisher ACM Press pages 323 332 Miscgenericserver author Y N Lakshman and Bruce Char and Jeremy Johnson title Software components using symbolic computation for problem solving environments howpublished manuscript submitted for publication year 1998 Miscgenserver author Y N Lakshman and Bruce Char title Im plementing mathematical servers using a generic Java server A user manual howpublished manuscript under preparation year 1997 InProceedingsinfo96 author K Mani Chandy and Adam Rifkin and Paolo A G Sivilotti and Jacob Mandelson and Matthew Richardson and Wes ley Tanaka and Luke Weisman title A World Wide Distributed System Using Java and the Internet booktitle IEEE International Symposium on High Performance Distributed Computing HPDC 5 year 1996 month August note Available from http www infospheres caltech edu papers index html Articleinfo97 author K Mani Chandy and Joe Kiniry and Adam Rifkin and Dan Zimmerman title Webs of Archived Distributed Computations for Asynchronous Collaboration journal Journal of Supercomputing year 1997 volume 11 number 3 note Available from http www infospheres caltech edu papers index html Manualinfo97guide title I
33. y be of great help to students We believe that a web based tutorial environment can be quite helpful in this regard On a certain level such an en vironment would require infrastructure similar to the distributed mathematical computations described earlier TechTalk was designed as a prototype to gain an understanding of the issues involved in the above situations and to perform some experiments in collabo rative computing and web based tutorials for elementary mathematics There have been servers offering mathematical services including Maple and Mathe matica servers on the web Most of these offer a single user the ability to in teract with a server TechTalk offers a much richer environment where multiple users can share multiple mathematical servers chain computations on differ ent servers talk to each other record and replay sessions etc A user enters a TechTalk session or TechTalk room by hitting a web site that is set up for running TechTalk A password mechanism ensures that only authorized users can enter the room Upon entering a TechTalk room a user can interact with Maple Matlab and other users in the room TechTalk offers the following fea tures e TechTalk makes it possible for multiple users in different locations to share Maple and Matlab sessions running on remote servers Each user can send Maple Matlab commands programs to the remote servers The results of the computations can be viewed by all the users in a Tech
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