Saturday, October 3, 2015

2015 and the Flowers of Autumn

Flowers once more.
Each year is different, specially in Europe. This year, it started to get colder in August. But summer returned in September. It is getting a bit colder, yet sunny in Lisbon in October. The small plants in my apartment are having colourful flowers, just like in summer, once again in 2015.
God Ganesh with flowers

This summer was pleasant. Spring was equally comfortable. Autumn has just started. So I will refrain from complimenting it yet. I kinda miss the early days of 2015. :) It went smooth and I had a good time.

Frankfurt river view.

The trip to Frankfurt was the first this summer. It is just a small city. Till early September, I was travelling a lot this year. Even after that, I still have 3 papers accepted to 3 different conferences - that means, in 3 different countries. Due to the clash in my time schedule, visa delay, or other reasons, I could not attend. Hence, I missed the opportunity to travel Sydney - Australia, Rhodes - Greece, and Vancouver - Canada this year. However, that does not demotivate me, as I am enjoying the sunny Lisbon, working on my EMJD-DC projects. :)

Also I just completed my first year of PhD, and entered the second year a few days ago. Have a long way to go. This year felt long, but at the same time, it also felt that the time passed pretty quick. It is contradictory, I know. Winter is not so cool in Lisbon. Specially when it just rains - wet and cold. There is no proper central heating system either. No snow and so there is no fun associated with snow, unless I decide to travel to some other countries. More or less, I have been living in Portugal for 3 years. However, with the mandatory mobility and internships, I am foreseeing my next migration next year. I am starting to feel the fear how can I pack all my things for the migration. :P Probably I will have to throw a considerable amount of things before moving. I also contribute to the Humana Portugal regularly. That is really a great initiative, reducing wastage specially when we leave the country.

Thursday, September 24, 2015

Configuring Mininet with Floodlight Controller

Configuring Mininet with Floodlight controller is pretty straight-forward.

First, download and build Floodlight.

$ git clone git://
$ cd floodlight
$ git checkout stable
$ ant
$ sudo mkdir /var/lib/floodlight
$ sudo chmod 777 /var/lib/floodlight

Once built, you can execute Floodlight by,
$ java -jar target/floodlight.jar

Execute Mininet and connect to the controller.
sudo mn --arp --topo tree,3,2 --mac --switch ovsk --controller remote,ip=

Now if you connect to the Floodlight UI in browser, you may view the nodes emulated by Mininet.

Floodlight Dashboard

Network Topology

$ java -jar target/floodlight.jar
$ git clone git:// $ cd floodlight $ git checkout stable $ ant; $ sudo mkdir /var/lib/floodlight $ sudo chmod 777 /var/lib/floodlight - See more at:
$ git clone git:// $ cd floodlight $ git checkout stable $ ant; $ sudo mkdir /var/lib/floodlight $ sudo chmod 777 /var/lib/floodlight - See more at:
$ git clone git:// $ cd floodlight $ git checkout stable $ ant; $ sudo mkdir /var/lib/floodlight $ sudo chmod 777 /var/lib/floodlight - See more at:
$ git clone git:// $ cd floodlight $ git checkout stable $ ant; $ sudo mkdir /var/lib/floodlight $ sudo chmod 777 /var/lib/floodlight - See more at:

Thursday, September 3, 2015


View from the apartment in Rijeka
I often find it hard to fix my mind on whether to visit a new place, or a place that I have visited and enjoyed a lot once more. I visited Stockholm for the 3rd time recently for the EMDC Summer Event 2015. That was the last EMDC event as 2014 was the last intake of EMDC. I stayed in Stockholm for just 4.5 months. Still it left very nice memories, and going back early this summer in May and now again in August gave life to strong memories of 2013.

So far I have lived in Colombo, Lisbon, and Stockholm. Since I am still in Lisbon, I do not miss it right now. I also have lived in Rijeka, Croatia for 22 days. Though that was a very short period, I had a routine life with cooking, working, and going to the nearest super market. I also had some time to travel during the weekends, to the nearest cities. It was a short-stay. But Rijeka is clearly recorded in my mind. In the future, if I ever go back to Rijeka, I will get the memories back. I do not think I will ever go back to Rijeka, as I do not foresee the reason. But I cannot say for sure. In 2013, I never would have guessed that I would go back to Fejan in 2015 for another summer event.

During my second trip to Stockholm, I did not pay a visit to KTH main campus. This time, I did. However, I did not visit Kista even this time. Kista is where I lived during my stay of 4.5 months in Stockholm. I stayed in the student apartments in the upper floors above a shopping mall.

In 2013, I came back to Lisbon two times for short trips, from Stockholm. In 2015, it is from Lisbon to Stockholm, two times. I admire the random patterns that appear in my life.

ShareLatex and local compilation of Latex

ShareLatex is good at swallowing the compilation errors and still producing the correct PDF. However, when locally compiling, the local errors often prevent the compilation. For example, TexStudio often fails for similar or same errors. Typing "Enter" upon encountering such errors will make the compilation proceed, regardless of such error reports.

! Missing $ inserted.
> Check empty or blank lines between the \begin{equation} and \end{equation} tags.

! You can't use `\eqno' in horizontal mode.
> Check the closing braces in the equations.

! Missing $ inserted.

l.112 $\forall$ n $\in$ $\mathbb{Z}$^{+}: $C_
                                             {Nn}$ represents the coordinato...

> Changing
$\forall$ n $\in$ $\mathbb{Z}$^{+}: $C_ 

$\forall$ n $\in$ $\mathbb{Z} ^{+}$: $C_
fixed this.

Wednesday, September 2, 2015

A lunch can never get unhealthier

The lunch at Trst, Italy
I am a big fan of summer. Most probably because I live in a country where the summer is sunny and pleasant, where winter and autumn are cold and wet. Spring is just the anticipation to summer. We never really have well-defined seasons in Sri Lanka, unlike Europe. It is easier to remember the events with the right month that happened thanks to the seasons.

This summer was considerably hot in this part of Europe. I came to Europe for my masters program EMDC, when the summer was almost finishing, in 2012. I was in Sri Lanka during most part of the 2013 summer. I was in Europe for 2014 summer completely, completing my EMDC and beginning my PhD, EMJD-DC. So in fact, 2015 was just my second complete summer in Europe.

My short trip to Trst, Italy was remarkable. It was terribly hot in Trst. I never thought that I would experience a weather hotter than Colombo, in Europe. I was proven wrong. I am not a fan of Italian food. I however was eating all unhealthy food and ice cream during my short trip. :)