<?xml version="1.0" encoding="utf-8"?>+ −
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">+ −
<HEAD>+ −
<TITLE>2012/13 MSc Projects</TITLE>+ −
<BASE HREF="http://nms.kcl.ac.uk/christian.urban/">+ −
<script type="text/javascript" src="striper.js"></script>+ −
<link rel="stylesheet" href="nominal.css">+ −
</HEAD>+ −
<BODY TEXT="#000000" + −
BGCOLOR="#4169E1" + −
LINK="#0000EF" + −
VLINK="#51188E" + −
ALINK="#FF0000"+ −
ONLOAD="striper('ul','striped','li','first,second')">+ −
+ −
+ −
+ −
<TABLE WIDTH="100%" + −
BGCOLOR="#4169E1" + −
BORDER="0" + −
FRAME="border" + −
CELLPADDING="10" + −
CELLSPACING="2"+ −
RULES="all">+ −
+ −
<TR>+ −
<TD BGCOLOR="#FFFFFF" + −
WIDTH="75%" + −
VALIGN="TOP">+ −
+ −
<H2>2012/13 MSc Projects</H2>+ −
<H4>Supervisor: Christian Urban</H4> + −
<H4>Email: christian dot urban at kcl dot ac dot uk, Office: Strand Building S1.27</H4>+ −
<H4>If you are interested in a project, please send me an email and we can discuss details. Please include+ −
a short description about your programming skills and Computer Science background in your first email. + −
I will also need your King's username (not student ID) in order to book the project for you. Thanks.</H4> + −
+ −
<H4>Note that besides being a lecturer in the theoretical part of Computer Science, I am also a passionate+ −
<A HREF="http://en.wikipedia.org/wiki/Hacker_(programmer_subculture)">hacker</A> …+ −
defined as “a person who enjoys exploring the details of programmable systems and + −
stretching their capabilities, as opposed to most users, who prefer to learn only the minimum + −
necessary.” I am always happy to supervise like-minded students.</H4> + −
+ −
<ul class="striped">+ −
<li> <H4>[CU1] Regular Expression Matching and Partial Derivatives</H4>+ −
+ −
<p>+ −
<B>Description:</b> + −
<A HREF="http://en.wikipedia.org/wiki/Regular_expression">Regular expressions</A> + −
are extremely useful for many text-processing tasks such as finding patterns in texts,+ −
lexing programs, syntax highlighting and so on. Given that regular expressions were+ −
introduced in 1950 by <A HREF="http://en.wikipedia.org/wiki/Stephen_Cole_Kleene">Stephen Kleene</A>, you might think + −
regular expressions have since been studied and implemented to death. But you would definitely be mistaken: in fact they are still+ −
an active research area. For example+ −
<A HREF="http://www.home.hs-karlsruhe.de/~suma0002/publications/ppdp12-part-deriv-sub-match.pdf">this paper</A> + −
about regular expression matching and partial derivatives was presented this summer at the international + −
PPDP'12 conference. The task in this project is to implement the results from this paper.</p>+ −
+ −
<p>The background for this project is that some regular expressions are + −
“<A HREF="http://en.wikipedia.org/wiki/ReDoS#Examples">evil</A>”+ −
and can “stab you in the back” according to+ −
this <A HREF="http://tech.blog.cueup.com/regular-expressions-will-stab-you-in-the-back">blog post</A>.+ −
For example, if you use in <A HREF="http://www.python.org">Python</A> or + −
in <A HREF="http://www.ruby-lang.org/en/">Ruby</A> (probably also in other mainstream programming languages) the + −
innocently looking regular expression <code>a?{28}a{28}</code> and match it, say, against the string + −
<code>aaaaaaaaaaaaaaaaaaaaaaaaaaaa</code> (that is 28 <code>a</code>s), you will soon notice that your CPU usage goes to 100%. In fact,+ −
Python and Ruby need approximately 30 seconds of hard work for matching this string. You can try it for yourself:+ −
<A HREF="http://www.dcs.kcl.ac.uk/staff/urbanc/cgi-bin/repos.cgi/afl-material/raw-file/tip/re.py">re.py</A> (Python version) and + −
<A HREF="http://www.dcs.kcl.ac.uk/staff/urbanc/cgi-bin/repos.cgi/afl-material/raw-file/tip/re-internal.rb">re.rb</A> + −
(Ruby version). You can imagine an attacker+ −
mounting a nice <A HREF="http://en.wikipedia.org/wiki/Denial-of-service_attack">DoS attack</A> against + −
your program if it contains such an “evil” regular expression. Actually + −
<A HREF="http://www.scala-lang.org/">Scala</A> (and also Java) are almost immune from such+ −
attacks as they can deal with strings of up to 4,300 <code>a</code>s in less than a second. But if you scale+ −
the regular expression and string further to, say, 4,600 <code>a</code>s, then you get a <code>StackOverflowError</code> + −
potentially crashing your program.+ −
</p>+ −
+ −
<p>+ −
On a rainy afternoon, I implemented + −
<A HREF="http://www.dcs.kcl.ac.uk/staff/urbanc/cgi-bin/repos.cgi/afl-material/raw-file/tip/re3.scala">this</A> + −
regular expression matcher in Scala. It is not as fast as the official one in Scala, but+ −
it can match up to 11,000 <code>a</code>s in less than 5 seconds without raising any exception+ −
(remember Python and Ruby both need nearly 30 seconds to process 28(!) <code>a</code>s, and Scala's+ −
official matcher maxes out at 4,600 <code>a</code>s). My matcher is approximately+ −
85 lines of code and based on the concept of + −
<A HREF="http://lambda-the-ultimate.org/node/2293">derivatives of regular expressions</A>.+ −
These derivatives were introduced in 1964 by <A HREF="http://en.wikipedia.org/wiki/Janusz_Brzozowski_(computer_scientist)">+ −
Janusz Brzozowski</A>, but according to this + −
<A HREF="http://www.cl.cam.ac.uk/~so294/documents/jfp09.pdf">paper</A> had been lost in the “sands of time”.+ −
The advantage of derivatives is that they side-step completely the usual + −
<A HREF="http://hackingoff.com/compilers/regular-expression-to-nfa-dfa">translations</A> of regular expressions+ −
into NFAs or DFAs, which can introduce the exponential behaviour exhibited by the regular+ −
expression matchers in Python and Ruby.+ −
</p>+ −
+ −
<p>+ −
Now the guys from the + −
<A HREF="http://www.home.hs-karlsruhe.de/~suma0002/publications/ppdp12-part-deriv-sub-match.pdf">PPDP'12-paper</A> mentioned + −
above claim they are even faster than me and can deal with even more features of regular expressions+ −
(for example subexpression matching, which my rainy-afternoon matcher cannot). I am sure they thought+ −
about the problem much longer than a single afternoon. The task + −
in this project is to find out how good they actually are by implementing the results from their paper. + −
Their approach is based on the concept of partial derivatives introduced in 1994 by+ −
<A HREF="http://reference.kfupm.edu.sa/content/p/a/partial_derivatives_of_regular_expressio_1319383.pdf">Valentin Antimirov</A>.+ −
I used them once myself in a <A HREF="http://nms.kcl.ac.uk/christian.urban/Publications/rexp.pdf">paper</A> + −
in order to prove the <A HREF="http://en.wikipedia.org/wiki/Myhill–Nerode_theorem">Myhill-Nerode theorem</A>.+ −
So I know they are worth their money. Still, it would be interesting to actually compare their results+ −
with my simple rainy-afternoon matcher and potentially “blow away” the regular expression matchers + −
in Python and Ruby (and possibly in Scala too).+ −
</p>+ −
+ −
<p>+ −
<B>Literature:</B> + −
The place to start with this project is obviously this+ −
<A HREF="http://www.home.hs-karlsruhe.de/~suma0002/publications/ppdp12-part-deriv-sub-match.pdf">paper</A>.+ −
Traditional methods for regular expression matching are explained+ −
in the Wikipedia articles + −
<A HREF="http://en.wikipedia.org/wiki/DFA_minimization">here</A> and + −
<A HREF="http://en.wikipedia.org/wiki/Powerset_construction">here</A>.+ −
The authoritative <A HREF="http://infolab.stanford.edu/~ullman/ialc.html">book</A>+ −
on automata and regular expressions is by John Hopcroft and Jeffrey Ullmann (available in the library). + −
There is also an online course about this topic by Ullman at + −
<A HREF="https://www.coursera.org/course/automata">Coursera</A>, though IMHO not + −
done with love. + −
Finally, there are millions of other pointers about regular expression+ −
matching on the Net. Test cases for “<A HREF="http://en.wikipedia.org/wiki/ReDoS#Examples">evil</A>”+ −
regular expressions can be obtained from <A HREF="http://en.wikipedia.org/wiki/ReDoS#Examples">here</A>.+ −
</p>+ −
+ −
<p>+ −
<B>Skills:</B> + −
This is a project for a student with an interest in theory and some+ −
reasonable programming skills. The project can be easily implemented+ −
in languages like+ −
<A HREF="http://www.scala-lang.org/">Scala</A>,+ −
<A HREF="http://en.wikipedia.org/wiki/Standard_ML">ML</A>, + −
<A HREF="http://haskell.org/haskellwiki/Haskell">Haskell</A>, + −
<A HREF="http://www.python.org">Python</A>, etc.+ −
</p>+ −
+ −
+ −
<li> <H4>[CU2] Automata Theory in Your Web-Browser</H4>+ −
+ −
<p>+ −
This project is about web-programming (but not in Java):+ −
There are a number of classic algorithms in automata theory (such as the + −
<A HREF="http://hackingoff.com/compilers/regular-expression-to-nfa-dfa">transformation</A> of regular+ −
expressions into NFAs and DFAs, + −
<A HREF="http://en.wikipedia.org/wiki/DFA_minimization">automata minimisation</A>, + −
<A HREF="http://en.wikipedia.org/wiki/Powerset_construction">subset construction</A>). + −
All these algorithms involve a fair + −
amount of calculations, which cannot be easily done by hand. There are a few web applications, typically+ −
written in <A HREF="http://en.wikipedia.org/wiki/JavaScript">Javascript</A>, that animate these + −
calculations, for example <A HREF="http://hackingoff.com/compilers/regular-expression-to-nfa-dfa">this one<A/>.+ −
But they all have their deficiencies and can be improved with more modern technology.+ −
An instance is the impressive animation of Phython code found + −
<A HREF="http://www.pythontutor.com">here</A>. + −
</p>+ −
+ −
<p>+ −
There now many useful libraries for JavaScript, for example, this + −
<A HREF="http://getspringy.com">one</A> for graphs or this + −
<A HREF="http://demos.bonsaijs.org/demos/star/index.html">one</A> for graphics. + −
+ −
There are also+ −
a number of new programming languages targeting JavaScript, for example+ −
<A HREF="http://www.typescriptlang.org">TypeScript</A>,+ −
<A HREF="http://coffeescript.org">CoffeeScript</A>, + −
<A HREF="http://www.dartlang.org">Dart</A>,+ −
<A HREF="http://scriptsharp.com">Script#</A>,+ −
<A HREF="http://clojure.org">Clojure</A>+ −
and so on.+ −
The task in this project is to use a web-programming+ −
language and suitable library to animate algorithms from automata theory (and also parsing, if wanted).+ −
This project is for someone who+ −
want to get to know these new languages.+ −
</p>+ −
+ −
<B>Literature:</B> + −
The same general literature as in [CU1].+ −
</p> + −
+ −
<p>+ −
<B>Skills:</B> + −
This is a project for a student with very good programming + −
and <A HREF="http://en.wikipedia.org/wiki/Hacker_(programmer_subculture)">hacking</A> skills. + −
Some knowledge in JavaScript, HTML and CSS cannot hurt. The algorithms from automata+ −
theory are fairly standard material.+ −
</p>+ −
+ −
+ −
<!--+ −
<li> <H4>[CU2] Equivalence Checking of Regular Expressions</H4>+ −
+ −
<p>+ −
<B>Description:</b> + −
Solving the problem of deciding the equivalence of regular expressions can be used+ −
to decide a number of problems in automated reasoning. Recently, + −
<A HREF="http://www.cs.unibo.it/~asperti/">Andreas Asperti</A>+ −
proposed a simple method for deciding regular expression equivalence described+ −
<A HREF="http://www.cs.unibo.it/~asperti/PAPERS/compact.pdf">here</A>. + −
The task is to implement this method and test it on examples.+ −
It would be also interesting to see whether Asperti's method applies to+ −
extended regular expressions, described+ −
<A HREF="http://ww2.cs.mu.oz.au/~sulzmann/manuscript/reg-exp-partial-derivatives.pdf">here</A>.+ −
</p>+ −
+ −
<p>+ −
<B>Literature:</B> + −
The central literature is obviously the papers+ −
<A HREF="http://www.cs.unibo.it/~asperti/PAPERS/compact.pdf">here</A> and+ −
<A HREF="http://ww2.cs.mu.oz.au/~sulzmann/manuscript/reg-exp-partial-derivatives.pdf">here</A>.+ −
Asperti has also some slides <A HREF="http://www.cs.unibo.it/~asperti/SLIDES/regular.pdf">here</a>.+ −
More references about regular expressions can be found+ −
<A HREF="http://en.wikipedia.org/wiki/Regular_expression">here</A>. Like in+ −
[CU1], I will give a lot of the background pf this project in+ −
my Automata and Formal Languages course (6CCS3AFL).+ −
</p> + −
+ −
<p>+ −
<B>Skills:</B> + −
This is a project for a student with a passion for theory and some+ −
reasonable programming skills. The project can be easily implemented+ −
in languages like Scala+ −
<A HREF="http://www.scala-lang.org/">Scala</A>,+ −
<A HREF="http://en.wikipedia.org/wiki/Standard_ML">ML</A>, + −
<A HREF="http://haskell.org/haskellwiki/Haskell">Haskell</A>, + −
<A HREF="http://www.python.org">Python</A>, etc.+ −
Being able to read <A HREF="http://haskell.org/haskellwiki/Haskell">Haskell</A>+ −
code is beneficial for the part involving extended regular expressions.+ −
</p>+ −
-->+ −
+ −
<li> <H4>[CU3] Machine Code Generation for a Simple Compiler</H4>+ −
+ −
<p>+ −
<b>Description:</b> + −
Compilers translate high-level programs that humans can read into+ −
efficient machine code that can be run on a CPU or virtual machine.+ −
I recently implemented a very simple compiler for a very simple functional+ −
programming language following this + −
<A HREF="http://www.cs.princeton.edu/~dpw/papers/tal-toplas.pdf">paper</A> + −
(also described <A HREF="http://www.cs.princeton.edu/~dpw/papers/tal-tr.pdf">here</A>).+ −
My code, written in <A HREF="http://www.scala-lang.org/">Scala</A>, of this compiler is + −
<A HREF="http://www.dcs.kcl.ac.uk/staff/urbanc/compiler.scala">here</A>.+ −
The compiler can deal with simple programs involving natural numbers, such+ −
as Fibonacci + −
or factorial (but it can be easily extended - that is not the point).+ −
</p>+ −
+ −
<p>+ −
While the hard work has been done (understanding the two papers above),+ −
my compiler only produces some idealised machine code. For example I+ −
assume there are infinitely many registers. The goal of this+ −
project is to generate machine code that is more realistic and can+ −
run on a CPU, like x86, or run on a virtual machine, say the JVM. + −
This gives probably a speedup of thousand times in comparison to+ −
my naive machine code and virtual machine. The project+ −
requires to dig into the literature about real CPUs and generating + −
real machine code. + −
</p>+ −
+ −
<p>+ −
<B>Literature:</B>+ −
There is a lot of literature about compilers + −
(for example <A HREF="http://www.cs.princeton.edu/~appel/papers/cwc.html">this book</A> -+ −
I can lend you my copy for the duration of the project). A very good overview article+ −
about implementing compilers by + −
<A HREF="http://tratt.net/laurie/">Laurie Tratt</A> is + −
<A HREF="http://tratt.net/laurie/tech_articles/articles/how_difficult_is_it_to_write_a_compiler">here</A>.+ −
An introduction into x86 machine code is <A HREF="http://ianseyler.github.com/easy_x86-64/">here</A>.+ −
Intel's official manual for the x86 instruction is + −
<A HREF="http://download.intel.com/design/intarch/manuals/24319101.pdf">here</A>. + −
A simple assembler for the JVM is described <A HREF="http://jasmin.sourceforge.net">here</A>.+ −
An interesting twist of this project is to not generate code for a CPU, but+ −
for the intermediate language of the <A HREF="http://llvm.org">LLVM</A> compiler+ −
(also described <A HREF="https://wiki.aalto.fi/display/t1065450/LLVM+IR">here</A> and+ −
<A HREF="http://llvm.org/docs/LangRef.html">here</A>). If you want to see+ −
what machine code looks like you can compile your C-program using gcc -S.+ −
</p>+ −
+ −
<p>+ −
<B>Skills:</B> + −
This is a project for a student with a deep interest in programming languages and+ −
compilers. Since my compiler is implemented in <A HREF="http://www.scala-lang.org/">Scala</A>,+ −
it would make sense to continue this project in this language. I can be+ −
of help with questions and books about <A HREF="http://www.scala-lang.org/">Scala</A>.+ −
But if Scala is a problem, my code can also be translated quickly into any other+ −
language. + −
</p>+ −
+ −
<li> <H4>[CU4] Implementation of Register Spilling Algorithms</H4>+ −
+ −
<p>+ −
<b>Description:</b> + −
This project is similar to [CU3]. The emphasis here, however, is on the+ −
implementation and comparison of register spilling algorithms, also often called register allocation + −
algorithms. They are part of any respectable compiler. As said+ −
in [CU3] my simple compiler lacks them and assumes an infinite amount of registers instead.+ −
Real CPUs however only provide a fixed amount of registers (for example+ −
x86-64 has 16 general purpose registers). Whenever a program needs+ −
to hold more values than registers, the values need to be “spilled”+ −
into the main memory. Register spilling algorithms try to minimise+ −
this spilling, since fetching values from main memory is a costly + −
operation. + −
</p>+ −
+ −
<p>+ −
The classic algorithm for register spilling uses a+ −
<A HREF="http://en.wikipedia.org/wiki/Register_allocation">graph-colouring method</A>.+ −
However, for some time the <A HREF="http://llvm.org">LLVM</A> compiler+ −
used a supposedly more efficient method, called the linear scan allocation method+ −
(described + −
<A HREF="http://www.cs.ucla.edu/~palsberg/course/cs132/linearscan.pdf">here</A>).+ −
However, it was later decided to abandon this method in favour of + −
a <A HREF="http://blog.llvm.org/2011/09/greedy-register-allocation-in-llvm-30.html">+ −
greedy register allocation</A> method. It would be nice if this project can find out+ −
what the issues are with these methods and implement at least one of them for the + −
simple compiler referenced in [CU3].+ −
</p>+ −
+ −
<p>+ −
<B>Literature:</B> + −
The graph colouring method is described in Andrew Appel's + −
<A HREF="http://www.cs.princeton.edu/~appel/modern/java/">book</A> on compilers+ −
(I can give you my copy of this book, if it is not available in the library).+ −
There is also a survey + −
<A HREF="http://compilers.cs.ucla.edu/fernando/publications/drafts/survey.pdf">article</A> + −
about register allocation algorithms with further pointers.+ −
</p>+ −
+ −
<p>+ −
<B>Skills:</B> + −
Same skills as [CU3].+ −
</p>+ −
+ −
<li> <H4>[CU5] A Student Polling System</H4>+ −
+ −
<p>+ −
<B>Description:</B>+ −
One of the more annoying aspects of giving a lecture is to ask a question+ −
to the students and no matter how easy the questions is to not + −
receive an answer. Recently, the online course system + −
<A HREF="http://www.udacity.com">Udacity</A> made an art out of+ −
asking questions during lectures (see for example the+ −
<A HREF="http://www.udacity.com/overview/Course/cs253/CourseRev/apr2012">Web Application Engineering</A> + −
course CS253).+ −
The lecturer there gives multiple-choice questions as part of the lecture and the students need to + −
click on the appropriate answer. This works very well in the online world. + −
For “real-world” lectures, the department has some + −
<A HREF="http://en.wikipedia.org/wiki/Audience_response">clickers</A>+ −
(these are little devices part of an audience response systems). However, + −
they are a logistic nightmare for the lecturer: they need to be distributed + −
during the lecture and collected at the end. Nowadays, where students+ −
come with their own laptop or smartphone to lectures, this can+ −
be improved.+ −
</p>+ −
+ −
<p>+ −
The task of this project is to implement an online student+ −
polling system. The lecturer should be able to prepare + −
questions beforehand (encoded as some web-form) and be able to + −
show them during the lecture. The students+ −
can give their answers by clicking on the corresponding webpage.+ −
The lecturer can then collect the responses online and evaluate them + −
immediately. Such a system is sometimes called+ −
<A HREF="http://en.wikipedia.org/wiki/Audience_response#Smartphone_.2F_HTTP_voting">HTML voting</A>. + −
There are a number of commercial+ −
solutions for this problem, but they are not easy to use (in addition+ −
to being ridiculously expensive). A good student can easily improve upon+ −
what they provide. + −
</p>+ −
+ −
<p>+ −
The problem of student polling is not as hard as + −
<A HREF="http://en.wikipedia.org/wiki/Electronic_voting">electronic voting</A>, + −
which essentially is still an unsolved problem in Computer Science. The+ −
students only need to be prevented from answering question more than once thus skewing+ −
any statistics. Unlike electronic voting, no audit trail needs to be kept+ −
for student polling. Restricting the number of answers can probably be solved + −
by setting appropriate cookies on the students'+ −
computers or smart phones.+ −
</p>+ −
+ −
<p>+ −
However, there is one restriction that makes this project harder than it seems+ −
at first sight: The department does not allow large server applications and databases+ −
to be run on calcium, which is the central server in the department. So the problem + −
should be solved with as few resources as possible + −
on the “back-end” collecting the votes. + −
</p>+ −
+ −
<p>+ −
<B>Literature:</B> + −
The project requires fluency in a web-programming language (for example + −
<A HREF="http://en.wikipedia.org/wiki/JavaScript">JavaScript</A>,+ −
<A HREF="http://en.wikipedia.org/wiki/PHP">PHP</A>, + −
Java, <A HREF="http://www.python.org">Python</A>, + −
<A HREF="http://en.wikipedia.org/wiki/Go_(programming_language)">Go</A>, + −
<A HREF="http://www.scala-lang.org/">Scala</A>,+ −
<A HREF="http://en.wikipedia.org/wiki/Ruby_(programming_language)">Ruby</A>). + −
For web-programming the + −
<A HREF="http://www.udacity.com/overview/Course/cs253/CourseRev/apr2012">Web Application Engineering</A>+ −
course at <A HREF="http://www.udacity.com">Udacity</A> is a good starting point + −
to be aware of the issues involved. This course uses <A HREF="http://www.python.org">Python</A>.+ −
To evaluate the answers from the student, Google's + −
<A HREF="https://developers.google.com/chart/image/docs/making_charts">Chart Tools</A>+ −
might be useful, which are also described in this + −
<A HREF="http://www.youtube.com/watch?v=NZtgT4jgnE8">youtube</A> video.+ −
</p>+ −
+ −
<p>+ −
<B>Skills:</B> + −
This project needs very good web-programming skills. A + −
<A HREF="http://en.wikipedia.org/wiki/Hacker_(programmer_subculture)">hacker mentality</A>+ −
(see above) is probably very beneficial: web-programming is an area that only emerged recently and+ −
many tools still lack maturity. You probably have to experiment a lot with several different+ −
languages and tools.+ −
</p>+ −
+ −
<li> <H4>[CU6] Implementation of a Distributed Clock-Synchronisation Algorithm developed at NASA</H4>+ −
+ −
<p>+ −
<B>Description:</B>+ −
There are many algorithms for synchronising clocks. This+ −
<A HREF="http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20120000054_2011025573.pdf">paper</A> + −
describes a new algorithm developed by NASA for clocks that communicate by exchanging+ −
messages and thereby reach a state in which (within some bound) all clocks are synchronised.+ −
A slightly longer and more detailed paper about the algorithm is + −
<A HREF="http://hdl.handle.net/2060/20110020812">here</A>.+ −
The point of this project is to implement this algorithm and simulate a networks of clocks.+ −
</p>+ −
+ −
<p>+ −
<B>Literature:</B> + −
There is a wide range of literature on clock synchronisation algorithms. + −
Some pointers are given in this+ −
<A HREF="http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20120000054_2011025573.pdf">paper</A>,+ −
which describes the algorithm to be implemented in this project. Pointers+ −
are given also <A HREF="http://en.wikipedia.org/wiki/Clock_synchronization">here</A>.+ −
</p>+ −
+ −
<p>+ −
<B>Skills:</B> + −
In order to implement a simulation of a network of clocks, you need to tackle+ −
concurrency. You can do this for example in the programming language+ −
<A HREF="http://www.scala-lang.org/">Scala</A> with the help of the + −
<A HREF="http://akka.io">Akka</a> library. This library enables you to send messages+ −
between different <I>actors</I>. <A HREF="http://www.scala-lang.org/node/242">Here</A> + −
are some examples that explain how to implement exchanging messages between actors. + −
</p>+ −
+ −
<li> <H4>[CU7] An Infrastructure for Dispalying and Animating Code in a Web-Browser</H4>+ −
+ −
<p>+ −
<B>Description:</B>+ −
The project aim is to implement an infrastructure for displaying and+ −
animating code in a web-browser. The infrastructure should be agnostic+ −
with respect to the programming language, but should be configurable.+ −
Something smaller than projects such as <A HREF="http://www.pythontutor.com">here</A>,+ −
<A HREF="http://ideone.com">here</A>,+ −
<A HREF="http://codepad.org">here</A>,+ −
<A HREF="http://www.w3schools.com/html/tryit.asp?filename=tryhtml_intro">here</A>+ −
+ −
</p>+ −
+ −
</ul>+ −
</TD>+ −
</TR>+ −
</TABLE>+ −
+ −
<P>+ −
<!-- Created: Tue Mar 4 00:23:25 GMT 1997 -->+ −
<!-- hhmts start -->+ −
Last modified: Wed Sep 12 16:30:03 GMT 2012+ −
<!-- hhmts end -->+ −
<a href="http://validator.w3.org/check/referer">[Validate this page.]</a>+ −
</BODY>+ −
</HTML>+ −