Wathsala's blog

ACM Author-Izer Service

2011-10-18T20:46:00.000-07:00

ACM Author-Izer service allows authors to share full text of their ACM publications and Bibliometrics through their blogs and websites. A cool feature indeed! I hope IEEE too will follow. I have linked one of my publications below.

Bassa: a time shifted web caching system for developing regions

Wathsala W. Vithanage, Ajantha S. Atukorale
NSDR '11 Proceedings of the 5th ACM workshop on Networked systems for developing regions, 2011

<p>&amp;amp;amp;lt;p&amp;amp;amp;gt;&amp;amp;amp;amp;amp;amp;amp;lt;p&amp;amp;amp;amp;amp;amp;amp;gt;&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;frames are not supported&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;/p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;&amp;amp;amp;amp;amp;amp;amp;lt;/p&amp;amp;amp;amp;amp;amp;amp;gt;&amp;amp;amp;lt;/p&amp;amp;amp;gt;</p>

Bro: An IDS that Can be Used for Collecting Network Traffic Traces

2011-10-08T12:21:00.000-07:00

I recently started a project to archive network traffic traces with some fellow researchers from whom I learned about Bro. Bro is an amazing intrusion detection system that has been developed at UC Berkeley based on many years of research done by Prof. Vern Paxson and his team. The interesting thing about Bro is that it could be used for archiving network traffic traces with a high granularity. That is unlike utilities like tcpdump Bro is intelligent enough to uniquely identify connections between hosts (TCP/UDP) and application level protocols being used in those connections. As a result Bro logs network level connections, HTTP, SMTP, FTP, SSH, SSL, etc with their protocol data instead of logging raw packet headers without much detail.

Another cool feature of Bro is the new extensible logging framework which will be available in up coming version 2.0. A well written document on the extensible logging framework can be found here. I extended the logging framework to anonymize traces captured by Bro on the fly. Even though Bro was capable of on the fly anonymization of traces in version 1.5 it is broken and will be removed from the next version (version 2.0). According to Bro devs we will have to wait for sometime to see this very useful feature back. Until they come up with the code for it based on Pang R, et al. "A High-level Programming Environment for Packet Trace Anonymization and Transformation" I came up with a workaround that works but far less elegant (More on this in my next blog post). Anyways since logs are anonymized sufficiently we can now carry out our research. Except issues on trace anonymization which is very much needed when data is shared between institutions Bro does a fantastic job. Its fast, clean and extensible!

A Time Shifted Web Caching System for Developing Regions

2011-08-02T23:01:00.000-07:00

I presented the paper titled as "A Time Shifted Web Caching System for Developing regions" at NSDR 2011 held in Washington D.C. on 28th of June 2011.

Bassa presentation

View more presentations from Wathsala Vithanage

A Long Awaited Report on Dalesa

2011-05-09T10:29:00.000-07:00

I received a report on Dalesa P2P web cache from Nikhita Dulluri and Shruti Pathak on 8th May 2011. This is one of the long awaited reports on Dalesa. They have performed a performance analysis on Dalesa covering some of the key areas such as latency, number of HTTP/HTTPS packets sent/received, bandwidth saving and memory consumption. Overall it is a very positive review. I thank both Shruti and Nikhita for their valuable contribution.

Got Two Papers Accepted for IEEE - ISCC and ACM NSDR

2011-05-08T12:36:00.000-07:00

Two of my most recent papers titled as "A Novel Classifier for Engineering Web Traffic" and "Bassa: A Time Shifted Web Caching System for Developing Regions" were accepted to 16th IEEE Symposium on Computer and Communication (ISCC) in Greece and 5th ACM workshop on Networked Systems for Developing Regions (NSDR) in Washington D.C respectively. NSDR is an ACM Mobisys 2011 workshop. However publishing at these conferences will depend on travel grants.

ISCC

NSDR

Dalesa Reached an Important Milestone

2010-11-03T13:03:00.000-07:00

2nd, November, 2010 was one of the most memorable days for the Dalesa project. On this day for the first time Dalesa was released for Windows family of operating systems after a long overdue. Win32 porting and C# based user interface development began on this highly anticipated release soon after release 1.1.0 was made. Version 1.2.0 of Dalesa runs equally well on Linux, Windows XP, Windows Vista and Windows Seven. You can download binaries for windows and Ubuntu versions from here.

Version 1.2.0 of Dalesa has the same set of features you will find in it's predecessor the version 1.1.0. Only difference is from this release on Dalesa will listen on two network interfaces in parallel. The loopback interface is used for all local browser interactions and wired or wireless interface is used for all peer interactions. The advantage is that users now do not have to change their proxy settings each time they change the listen interface or when DHCP server gives them a different IP address as the loopback IP address (127.0.0.1) is being used. Therefore setting up the browser proxy is a one time task with version 1.2.0.

I believe that first generation of Dalesa software has delivered what it has promised nearly two years ago. The second generation or the 2.x.x releases will use both multicasting and distributed hash tables in peer - to - peer object lookup algorithms. Therefore I hope that version 2.0.0 will be more ambitious and an exciting project for both users and developers of Dalesa.

Finally a big thank goes to all the members of team Dalesa at LSF who were behind Dalesa in various ways since it's inception in 2009.

Virtual Learning Model for Metaverses was Published at ICTer 2010

2010-10-02T22:11:00.001-07:00

My second publication at ICTer 2010 was Virtual Learning Model for Metaverses. This paper tries to generalize learning in virtual worlds. You can get the paper from here.

Virtual learning model for metaverses

View more presentations from Wathsala Vithanage.

Real-Time Mobile P2P Video Streaming Overlay was Published at ICTer 2010

2010-10-02T21:58:00.001-07:00

This is the presentation of Real-Time Mobile P2P Video Streaming Overlay concept paper which I published at ICTer 2010 conference. I did this presentation on the first day of the conference at Cinnamon Lakeside Colombo. Get paper from here.

P2P Mobile Streaming

View more presentations from Wathsala Vithanage.

Two Papers were Published at ICTer 2010

2010-10-02T14:34:00.000-07:00

ICTer 2010 conference was held from 29th October to 1st September at Cinnamon Lakeside, Colombo. I published two papers in this conference titled as Real-time Mobile Peer – to – Peer Video Streaming Overlay and Virtual Learning Model for Metaverses.

I will post the two presentations in two separate blog posts.

Dalesa - 1.1.1 Released

2010-08-22T12:05:00.000-07:00

Dalesa 1.1.1 has been released. This is the first micro release after 1.1 series began last week. Latest in the line 1.1.1 has fixed the issue with the disabled language selection list box experienced by ReiserFS users. In parallel to 1.1.1 release a new KDE interface was also released as a separate package. All the packages can be downloaded from the website (dalesa.lk) as binaries for Ubuntu 9.10 and 10.04 with source tarballs as usual.

Dalesa - 1.1

2010-08-13T03:52:00.000-07:00

We were able to release version 1.1 of Dalesa roughly after eight months from the first release of Dalesa (version 1.0.0-rc1). Version 1.1 is now available for download at dalesa.lk. From 1.0 to 1.1 Dalesa greatly improved it's usability. The major change visible to the user in 1.1 is new standalone user interface provided for GNOME and KDE interfaces coupled with the Dlaesa cache (Dcache) with D-Bus. By using the interface users can now setup Dalesa with few clicks and skim through networked caching statistics effortlessly using temporal graphs displayed on the main window.

New Dalesa UI displaying networked caching statistics.

Major changes in version 1.1 includes

Shifting from MySQL to embedded - MySQL database environment.
Providing an API for external applications to communicate with the configuration component/statistics reporting component of Dalesa cache through D-Bus.
Implementation of a dynamic URL elimination list that avoids useless cache lookups initiated by recurrent AJAX calls (ie:- GMail web chat application periodically makes HTTP requests to the origin server which produce responses which are not cache-able, Dalesa can now dynamically identify such URLs and avoid execution of P2P lookup algorithm on those).
Removal of web based UI (version 1.0).

Previously Dalesa was released as a source package only (1.0). From this release (1.1) on Dalesa will be released in binary packages as well. Version 1.1 can be downloaded as Debian packages for Ubuntu 9.10 and 10.04. KDE user interface which is dubbed as KDalesa will be released as a separate binary package in few days for KDE users.

Dalesa Web Cache (Dcache) Howto

2010-02-05T01:23:00.000-08:00

Why do I need Dalesa Web Cache?

Dalesa web cache is a cooperative web caching platform based on peer – to – peer computing. Dalesa web cache exposes your local cache to a peer – to – peer network of such caches. Ones your cache joins the network you will be downloading fresh content from your peers rather than from the origin server if they have already visited the same site and the content cached in them is fresh enough. By exposing your web cache to the network Dalesa lets you to experience a faster web.

How Dalesa find web content stored in peers?

Dalesa web caceh uses a peer – to – peer document lookup protocol which multicasts UDP datagrams. On top of these datagrams the cache sends lookup messages in XML format posing a question similar to “who has URL X which is fresh enough for consuming”? Receiving nodes of this message will check their local cache index and multicast a message indicating the availability of the requested URL if it is already in it's cache. If the requester receives the response within a preset time slot then the content will be accessed through the peer node by making the peer node a parent cache, otherwise it will fetch the file from the origin server. (Implementation actually uses SHA1 hash of X instead of real URL to ensure constant message lengths and privacy)

How to install Dalesa Web Cache?

As of this writing Dalesa works well on Linux (we have tested on Debian and Fedora based systems). It also works on windows but very unstable at the moment. On Linux you can first get the the source of Dalesa from SVN at https://dalesa.svn.sourceforge.net/svnroot/dalesa. Use following command to get it svn co https://dalesa.svn.sourceforge.net/svnroot/dalesa dalesa. This will create a directory named dalesa. You can start by building the code in the trunk.

Prior to compiling dalesa it is wise to install lighttpd, MySQL, PHP, and PHP PDO drivers for both MySQL and Sqlite. However it is perfectly ok to go without installing these stuff as missing components are being revealed by the cofigure script.

Once you have done this move to trunk directory and start compiling. If cofigure script complains you about missing libraries and software then install those dependencies and rerun the script.

./autogen.sh
./configure --prefix=/usr
make
sudo make install

Now it is time to run and configure Dalesa. Configuring Dalesa is very easy since it uses a web based user interface to interact with user. Dalesa doesn't need changing any configuration file to do this.

Start Dalesa

sudo dcache

Now use your web browser and go to following URL http://127.0.0.1:8085/

Now create a user account and login to the system with it.

In the above interface click on edit to change settings. Set listen interface and the port appropriately so that Dalesa will use that configuration. If you are not already behind a proxy then set next node field to false. In the MySQL configuration section insert a valid MySQL user account which has permissions to create databases. Once you are done with the interface then click Save data, unfortunately at the moment the UI is incapable of restarting the server with new parameters. Therefore you have to manually restart Dalesa by using the command given below.

sudo killall dcache
sudo dcache

Now Dalesa is ready to work, but you have to configure your browser before using Dalesa. Open your browser's proxy settings dialogue (depends on the browser you use) and set proxy address and port to IP address of the interface you have selected and the port you have entered in the configuration web interface. From now onwards you will be accessing the web through Dalesa P2P web cache.

When you click on caching status button you will see many different options to visualize your caching statistics.

Dalesa Web Cache (Dcache) with New Looks

2010-01-02T23:44:00.000-08:00

Dalesa Web Cache (Dcache) got some new looks for 2010 thank to Nishshanka Sirisena's work and feedback from others. It now has a Web2 interface and some useful graphs to visualise caching activity. I have attached some screenshots below with a description.

This is the main page. In the main page you will find a host cloud which visualises the most visited hosts. Size of the fonts used to display the hosts increase as the number of hits to the host increases. In other words higher the hits to a displayed host larger it will appear.

This is one of the most crucial interfaces. The control panel; which can be used to configure Dalesa Web Cache. Here you can click on edit to add or override settings of the web cache. Once you are done just click on save button. (Both edit and save buttons are located in the bottom of the page which is not seen in this screenshot.

This page gives a snapshot of caching activities which took place in the last 60 minutes. Pink line shows the number of items cached directly from origin servers and the blue line shows the number of files cached from peers within a minute.

This page provides some pie charts that can be used to get an idea of the peer to origin ratio of the downloaded content either by number of objects or size.

You can search for content in your web cache.The image shows search results for word blogger. At the moment search only works on URLs. However in the future we will provide more search options like search by content type.

In few days you will be able to find dalesa-1.0.0-rc1 release which comes with this interface. I hope that 2010 will be a great year for Dalesa and the team as we make the web faster.

Dcache presented at eAsia 2009

2009-12-17T02:42:00.000-08:00

I did a presentation at eAsia 2009 on Dcache.

Dcache

View more presentations from University of Colombo School of Computing.

I Can Feel the Happiness of a Farmer

2009-12-08T12:11:00.000-08:00

To me November happened to be the harvesting season. I have harvested what I have cultivated few months back with many sleepless nights and long stressful days at work. In the month of November I became a proud farmer in the field of computing.

Last month we won an award for Dcache at e-Swabhimani - 2009 and my paper on Dcache (which was a work in progress) was accepted to be presented at eAsia - 2009 which I see as the harvest of my hard work at Lanka Software Foundation. In few days we will be releasing dcache-1.0.0-rc1 release candidate (getting ready to sell the harvest). At the same time I'm excited about the revival of my pet project Bassa (which I did for Google Summer of Code in 2007 as one of my own ideas). As of this writing I'm helping a group of 3rd year students at UCSC to complete the front-end of WS enabled Bassa server. I hope in few weeks it will be ready and running again at UCSC network taking care of everyone's large file download utilising the bandwidth effectively. I'm now thinking about releasing bassa-2.0.0-rc1 in January.

I have few ideas in distributed/parallel computing brewing in my mind for the next year. 2010 will be a time for expanding my field with 3 or 4 projects running parallel (including my MS project and a very very personal project which may lead to a social event). I will be blogging about these new projects and status of bassa/dcache and a possible integration of bassa and dcache in the coming days.

Dalesa - Cache (Dcache) a Distributed Web Cache Based on Libdalesa

2009-06-11T13:36:00.000-07:00

At LSF we have developed a P2P web cache which has the potential to replace any centralized web cache like Squid. This is the project which I have lead, designed and coded so far with two other guys named Nuwan and Nishshanka. At the moment code which is still being developed is available here. You can get it's full functionality at the moment though it is not ready for a release yet due to some missing pieces like admin web UI component and win32 port. The software comes in two components. The core of the system is libdalesa, it is the core library we have developed as a group communication framework. The other component is dcache which is the web cache that uses libdalesa for remote cache object lookups. libdalesa is a generic framework for group communication which currently supports IP multicasting. However in the future we will make it an abstract layer which will encapsulate numerous group communication protocols like Pastry/Scribe. Once it is completed there will be more innovations based on libdalesa group communication framework apart from dcache. The architectural diagram is illustrated in Figure 1.

The dcache has to be installed in all nodes that are willing to take the advantage of the content mesh. Once installed, the browser or any user agent should start using it's local dcache as a proxy. dcache can then find nodes with cached URLs with appropriate freshness and promote them from peer proxy status to parent proxy state on the fly and on a per request basis. The Figure 2 illustrates how dcache operates in a networked environment. dcache supports following HTTP features as well.

Persistent connections

HTTP pipe-lining

HTTP tunneling

Caching based on Expire, ETag, Last-Modified-Date, Cache-Control headers

We have tested this system on IEEE 802.11a/b/g networks in both infrastructure and ad-hoc mode and also in IEEE 802.11s mesh networks. Performance in those networks were fine and up to the expectations. Right now we are busy porting the system to Windows platform, in next couple of weeks we will hopefully complete the Windows port and the Admin UI driving the project towards it's first release.

Got LSF Fellowship

2009-01-23T19:56:00.000-08:00

After two years from graduation I joined Lanka Software Foundation on January 05th 2009. At LSF I will be a senior software engineer and a team lead. This year LSF is planning to develop some P2P applications and a framework for P2P communication based on Multicasting/DHT etc. Initially we will work on a simple P2P substrate and a P2P web cache on top of it. We are also focused on deploying this application on XO laptops developed by OLPC project, and we believe it's mesh technology (IEEE 802.11s) will get utilized fully as mesh networks seems to be ideal for P2P.

Packaman Fixed to Work with Proxy Servers

2008-09-24T23:31:00.000-07:00

After installing Minix3, I tried to install software as mentioned in the manuals. However as mentioned in those manuals I was unable to get software from the Internet even though I have set the environment variable http_proxy and ftp_proxy. After checking the /usr/bin/packman I figured out that it was shell script using a tool called urlget to download software from the Internet. By looking at the urlget code which was in /usr/src/commands/urlget (which is written in C) I figured out it is written without any consideration to proxies.

The C code for urlget was well written. Therefore I was able to modify it in few hours to work with ftp_proxy and http_proxy environment variables. I have posted the patch to gforge.cs.vu.nl Minix3 tracker. You can patch the /usr/src/commands/urlget with the patch given above. Once you have done do make and make install. Then run the packman with http_proxy and ftp_proxy environment variables set, it will go through the proxy without any problem.

Howto Run Minix3 on Linux with KVM and TAP Network

2008-09-22T21:49:00.000-07:00

Yesterday I spent hours trying to get Minix3 working on kvm with CPU VT (Virtualization). However I manged to setup Minix3 running on kvm with CPU VT and TUN/TAP network. After getting Minix3 running as I wished, I thought that putting every little detail in to a small HOWTO would be a definite help for newbies (developers/students) trying out Minix3.

Before starting the work you should check your system for CPU VT support. You can do this by using the following command.


grep 'vmx' /proc/cpuinfo

After running this command, if you see some output on your console then that means your CPU has VT. But this does not mean kvm will work fine, in most cases hardware vendors disable VT support from system BIOS. In such cases you will have to go back to BIOS setup of your computer to enable the feature (In some computers new setting will be effective only after power on off cycle ie:- HP nx6320 note books). Before using the command given below you need to install kvm in your Linux box (if it is not installed already).

For Debian/Ubuntu


sudo apt-get install kvm

For Fedora


sudo yum install kvm

Now you can verify whether VT is enabled by BIOS by using the following command.
For Intel CPUs


sudo modprobe kvm_intel

For AMD CPUs


sudo modprobe kvm_amd

If modprobe exits silently it means that CPU VT is enabled and available for virtualization tasks.

Now it is time for you to download Minix3 iso image. This image is available at www.minix.org. Once you have downloaded the Minix3 iso, you can create an image for Minix3 hard drive.


qemu-img create minix.img 2G

This will create 2 GB file that will work as a hard disk for Minix.

After the file has been created you can start Minix3 installation as given below.


sudo kvm -no-kvm -localtime -net user -net nic -m 128 -cdrom IDE-3.1.2a.iso -hda minix.img -boot d

With above command the Minix should boot from the iso image. After booting is done you will get a login prompt. On the login prompt login as root, no password is required. After login in you can start the installation by issuing the command setup.


setup

When setup goes on it will ask the Ethernet device used in your computer, here you will have to select Realtek rtl8139 as this is one of the Ethernet devices that are emulated by kvm. After selecting this option setup will take you to several other prompts which are quite self explanatory. Once setup is completed give following command to shutdown Minix installation.


shutdown

At this stage Minix3 will run on kvm but with limitations (without network and CPU VT). These problems can be easily solved.

The network problem can be solved by creating a TAP device in your Linux box which comes with UML (User Mode Linux) utilities. You can install UML utilities as given below in Debian/Ubuntu and Fedora system respectively.


sudo apt-get install uml-utilities
sudo yum install uml-utilities

TAP device can be easily created by using the tunctl command as given below.


tunctl -b -u root -t tap0

The above command will create the tap0 device. Now you have to create an Ethernet bridge device in your Linux box which tap0 will be connecting to. To create a bridge Ethernet named br0 use the command given below.


brctl addbr br0

Now put an IP for this bridge device.


ifconfig br0 192.168.1.254 netmask 255.255.255.0 up

You can connect the tap0 to br0 and start the tap0 network interface by using the commands,


brctl addif br0 qtap0
ifconfig qtap0 up 0.0.0.0 promisc

Now it is time to boot Minix3 with network support, as given below.


sudo kvm minix.img -no-kvm -cdrom IDE-3.1.2a.iso -net nic,macaddr=55:43:0F:32:25:12 -net tap,ifname=qtap0,script=no -m 256 -localtime

Remember to put what ever (valid) bogus mac address to macaddr value in -net option. Otherwise your network wont function. At the boot prompt give following commands.


qemu_pci=1
save
boot

Now login as root (no password required) and reboot Minix3.


reboot

After rebooting the Minix system you can configure its' network interface with an IP as shown below.


ifconfig -I /dev/ip -h 192.168.1.1 -n 255.255.255.0
add_route -g 192.168.1.254

Now you should be able to ping 192.168.1.254 which is the IP address of the bridge device. And also you should be able to ping what ever IP address given to your Ethernet interface in your Linux box. But if you try to ping a different computer in your LAN it will fail, to do this go back to your Linux box and configure iptables as given below.


echo "1" > /proc/sys/net/ipv4/ip_forward
iptables -t nat -F POSTROUTING
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

Now pinging to a computer in your LAN from Minix should work without any problem. You can also setup your nameserver by adding nameserver x.x.x.x int to the file /etc/resolv.conf. You can use elvis editor to edit this file. Further details on setting up Minix network with a permanent IP address, etc can be found at Deep's blog

Once you have setup your network correctly you can recompile Minix kernel with a small modification to it's boot code. Even with the CPU VT support sometimes kvm will crash when booting the guest OS. This happens due to incompatibilities in the sub set of 16bit real mode instructions used by the guest OS and kvm. Unfortunately this happens with standard Minix kernel. Fortunately the problem can be resolved by editing boothead.s located in /usr/src/boot. Before editing this file I recommend you to install vim or emacs (using packman). Once you have opened the file /usr/src/boot/boothead.s go to line 643 and change hlt to !hlt, then go to line 744 and change hlt to !hlt. After saving the changes made to the file go to the directory /usr/src/boot and give following commands.


make
make install

Now shutdown Minix and quit kvm.


shutdown

Now try the command given below, it will start kvm with CPU VT.


sudo kvm minix.img -cdrom IDE-3.1.2a.iso -net nic,macaddr=55:43:0F:32:25:12 -net tap,ifname=qtap0 script=no -m 256 -localtime

After completing all these steps you will have Minix3 running on kvm (with CPU VT) with networking.

I have put all these commands in to a single shell script. All you have to do is running this shell script when you need Minix3 inside your Linux box. (Change file paths to suite your settings)


#!/bin/bash

#load tun module
modprobe tun
#create a bridge and attach eth0
brctl addbr br0
ifconfig br0 192.168.1.254 netmask 255.255.255.0 up
#create tap device and attach it to bridge br0
tunctl -b -u root -t qtap0
brctl addif br0 qtap0
ifconfig qtap0 up 0.0.0.0 promisc
#enable IP forwarding and natting 
echo "1" > /proc/sys/net/ipv4/ip_forward
iptables -t nat -F POSTROUTING
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

#invoke kvm and load minix
kvm minix.img \
    -cdrom IDE-3.1.2a.iso \
    -net nic,macaddr=55:43:0F:32:25:12 \
    -net tap,ifname=qtap0,script=no \
    -m 256 \
    -localtime
#clean tap and bridge devices
ifconfig qtap0 down
brctl delif br0 qtap0
tunctl -d qtap0
ifconfig br0 down
brctl delbr br0
#delete iptable entries
iptables -t nat -D POSTROUTING -o eth0 -j MASQUERADE

Some of My Weird Ideas

2008-05-29T05:39:00.000-07:00

I have documented some of the weird ideas brewing in my mind. The first one is called emotional smart spaces, the second one is called Internet Parenting.

My First Publication

2008-02-24T04:22:00.000-08:00

I finally managed to publish a my first research paper at the 10th International Conference on Advanced Communication Technology held on Feb 17-20, 2008 in Phoenix Park, Korea. In few days it will be indexed by IEEE Xplore and you folks can read the paper titled as "Next Generation Proxy Servers" on 10th ICACT conference proceedings (published by IEEE Communication Society) which was authored by myself and co-authored by Buddhika Siddhisena and Dr. Ajantha Atukorale.You can get the paper from here.

2007 Google Summer of Code T-Shirt & Cirtificate Arrived

2007-11-27T02:13:00.000-08:00

We received 2007 Google summer of code T-Shirt. And again a big thanks to Google. The T-shirt was bit criticized by students this time, due to the white flowers on the black T-Shirt. I don't find this T-shirt particularly unappealing, but I found it too tight. What a shame I did not click on the size option on Google's web app correctly. At the end of GSoC I'm an unhappy dude without the cool T-shirt worn by all other GSoC participants and mentors.

Good Bye Sony T100, I'm switching to Canon 400D DSLR

2007-11-27T01:23:00.000-08:00

Few months ago I bought my first digital point and shoot camera,a Sony T100. Sony T series has a good reputation for it's ultra slim body. Apart from being slim T100 was an awesome camera with 5x optical zooming and 8.1MPs. It usually gave very sharp pictures and it was pretty easy to operate even in the so called Program Auto Mode. How ever I soon found photography very interesting and felt the limitations of point and shoot cameras. I was worrying about its small image sensor which did not give any depth of field. And I worried about the speed of the camera also. So finally I decided to sell my T100 and switch to a Canon 400D DSLR which is an entry level DSLR.

Canon and Nikon are the best DSLR makers. I prefer Canon due to low price compared to Nikon D80. And it has new anti dust technology. I'll update when I receive the Canon 400D. By the way you can see the photos which I have taken from my Sony T100.

Google Summer of Code is over.

2007-10-08T22:56:00.000-07:00

I was able to complete Google Summer of Code successfully with my mentoring organization Lanka Software Foundation. The code of Bassa changed a lot during last summer. And you can get it now from our Sourceforge SVN (svn co https://bassa.svn.sourceforge.net/svnroot/bassa bassa). After all it has been the best summer for me. Also during last summer I created the official product blog for Bassa, which can be found at http://bassa-blog.blogspot.com. And finally I have to say "THANK YOU GOOGLE for organizing this event".

Nokia N800

2007-07-09T20:44:00.000-07:00

Nokia N800 is a great gadget. Unlike other products from Nokia this is an Internet tablet. You will not find a phone integrated with this device. And it is quite noteworthy that this device is powered by Linux. Obviously this is an upgrade for the Nokia N770 which could be considered as the predecessor of N800. I was first informed about the device by Bud, then I decided to order one of these beasts with the initial payment of Google Summer of Code program.

What attracts me to this device is its UPnP support, High-resolution touch screen (800 x 480 pixels) with up to 65,536 colors, Wi-Fi, Web cam. You can get more details by referring to the spec. How ever Nokia claims that this device is powered by Internet tablet OS 2007, even though this is Desktop Linux. So don't get fooled by such claims. The other interesting thing is that you can write your own applications using maemo framework. If you are not interested in developing your own application like me, then there are lot of ready to install apps at garage.maemo.org. And Ruby fanatics now you can even install Ruby on Rails.

The only drawback I found in this device is lack of phone. Apart from that rest of the features really satisfies me.

Many changes after long silence

2006-11-15T06:40:00.000-08:00

I finally completed my final year project and exams, now I'm awaiting for my results. This is a big relief for me. After project demonstration I got a new job at University Of Colombo School Of Computing. This opertunity was given to me by Dr Ajantha Athukorala (director of NOC). Now my final year project is on sourceforge and, very soon there will be a release. Keep in touch for future development.

Abstract network layer

2006-01-13T20:50:00.000-08:00

By now I have almost designed two of the major components in my project. The latest of the 2 is abstract network layer, I call this VNET [Virtual Network]. The server core [httpd core] only knows about the HTTP and send(), recv() like functionality. These functionalities are provided by the VNET interface. Underneath the VNET there exists various drivers for many different protocols [IPV4, IPV6, TIN_CAN and etc]. This insulation has given the httpd to expand and grow with newer technologies without having change to itself. [Code will be available after mid july at sourceforge.net]

Sun's javax.comm driver has problems

2006-01-08T09:13:00.000-08:00

I suspect that Sun's javax.comm driver has other problems in bit stuffing (or related). I found out this by sending an array of bytes including 0xd in it, to another computer over a serial link (NULL modem cable), and the perticular byte (0xd) was recieved as 0xa while all other bytes being transmitted properly just as in the form they were originated at the source. I think this is a bit stuffing problem in the driver provided with Sun's javax.comm.

It is quite noteworthy to mention that this perticular problem can be solved by using rxtxComm, as an alternative to Sun's javax.comm. This is an open source comm API for java, all you have to do is changing the "import javax.comm.*" in to "import gnu.io.*" in your source codes and set CLASSPATH and LD_LIBRARY_PATH accordingly on Unix platforms.

Sun's javax.comm is a real pain on win32

2005-12-30T00:25:00.000-08:00

Sun's javax.comm driver for win32 platform does not implement enableReceiveThreshold(). At the end of the day I felt like a loser when I started porting a software to win32. Linux implementation looks OK.

Wathsala submits his final year project proposal

2005-12-29T11:53:00.000-08:00

Today at about 1.30 PM I submitted my proposal for final year project to UCSC. Project has a separate site at sourceforge (http://dike.sourceforge.net). The project's goal is to develop a light weight http daemon for embedded systems.