Monday, July 15, 2019

Ep 5: Better Endings [Memories of Portugal]

This post is part of a series on my life in Lisboa.
5.1: The tale of a time-traveler 

Cloudy beach in the midsummer!
Porto was a city that we enjoyed during those days. After my return to Portugal in 2014, we always wanted to go back to Porto - but we never did somehow. This time, for my Ph.D. defense, I flew from Brussels to Porto airport. Of course, first I had to fly from Atlanta to Brussels. Interestingly, my stay in Porto was on the same days, as in 2013 -  25th - 27th June. That was a coincidence, not at all planned. Since I never had a chance to visit Porto after 2013, coming to Porto was like opening a time capsule, wrapping up a story which I left half-written six years ago. I had to work on rehearsing my Ph.D. defense presentation. Therefore, I did not have much time to enjoy Porto or Portugal until I have defended my thesis on the 1st of July. Porto airport was remarkably similar to that of Lisboa airport, in its size, shops, and decoration.

Beautiful view from the bus
I bought the 72 hours Andante card for 15 Euros, although I knew I would not optimize it as I would not have much time left after spending a few hours presenting my thesis presentation every day. My hotel was in Matosinhos. It was in a walking distance from  Praia de Matosinhos, the beach we enjoyed in 2013. Unfortunately, and weirdly, Portugal was colder than Belgium. Almost in the 20s while Belgium was reaching the 40s! So I could not go into the water. I was not planning to, either. Cannot catch a cold and lose my voice before the defense. The beach was empty except for the surfers, a few tourists who did not want to miss their vacation to the unpredictable cloudy and cold weather, and lots of seagulls! There were also people just starting at the beach in their street clothes. Anyway, it was still lovely to be in Porto 6 years after, and in Portugal after one whole year - the longest I have ever stayed away from Portugal after moving to Lisbon in 2012 August from Sri Lanka. It was like picking the pieces of artwork and stitching them together. Memories scattered everywhere.

The beautiful Douro River
During our last visit to Porto, we missed the opportunity to visit Povoa de Varzim, the town in the far end of the red line of the Porto Metro, unfortunately, due to a metro strike. Not this time. I made sure to make a metro trip to Povoa de Varzim. It was a cute little neighborhood. Every time I went on a train/metro trip, I kept a copy of my presentation slides with me so that I can go through them whenever I wanted to. Although I passed through the Douro riverside a few times, I did not take the river cruise this time. I also walked from the metro station Jardim do Morro to Sao Bento in the night, enjoying the river view in the night lights over the bridge. The river had a romantic atmosphere. Probably, it is just my memories. I cannot say for sure.

Night view from the bridge over Rio Douro
The main streets of Porto, especially, Avenida dos Aliados and the Marques neighborhood, all felt so familiar, even after six years. I did several random walks, without using a map of any sort. Not once I got lost! Eventually, my time in Porto came to an end. I had to take a train to Lisboa. It was precisely six years ago, on the same day, we were leaving Porto to Lisboa full of sadness. That time too, I knew I would be leaving Portugal soon after. This time, I leave Porto with more positive thoughts, somewhat excited and a bit nervous too - as the defense is approaching and I was still fine-tuning my presentation. I also had a feeling I had prepared for this presentation much more than for any of my previous presentations. Overpreparation is not good either, I usually say. But still much better than going to your Ph.D. defense unprepared. Anyway, I got on the train, saying goodbye to Porto. I will be back to Porto on the 4th of July from Lisboa - to return to Brussels. I won't have any time for sightseeing in Porto on that day.

5.2: Just once more - Just once more
A cat made of trashbins
I arrived in Lisboa and reached my hotel in Saldanha neighborhood. The hotel itself was horrible - but close to my university. So I could comfortably reach my defense without a commute by public transport. I had to go to Povoa, a village in the Vila Franca de Xira region to collect our suitcase from a friend. I downloaded an offline Google map of the village to my tablet so that it was easy for me to locate the apartment. I also had a mobile Internet on my mobile phone in any case. I purchased it from Vodafone, as Vodafone had locked my phone when I bought it and did a half-job unlocking it when I requested and paid for that in 2013 January. My phone, therefore, never worked with other carriers for data. We had left 23 kg worth of a suitcase with a friend before we left Lisboa last year. It was nice to recover our old things. Later at the hotel, I eventually moved the contents from that suitcase to my current checked in luggage, and then left the old empty suitcase near the donation box. I had to throw away some old clothes in my current suitcase to give suitcase to the things from the last year. I met my supervisor at earliest on Friday to get his final opinions on my presentation. I had previously received the opinions of my co-supervisor in Belgium before leaving Belgium as well. Over the weekend, I iterated over the presentation based on the feedback I received.

Tagus river and the Vasco da Gama bridge
I had a walk over the Parque das Nacoes riverside, not once - but thrice during this visit. The area was full of memories, from the range of 2013 - 2018. I felt like searching my 6 - 7-year younger-self - and also the younger selves of her and our friends. I almost felt like we are still here after six years. The memories kept me in a state similar to intoxication! I truly missed this place — lots of deja vu. I also realized that my preference for Lisboa, and Portugal in general, comes mostly from the fact that I had great memories there. It was nice to meet a few friends in Lisboa - of course, the majority of my friends had left the city over several years. I was the last to leave among our Erasmus Mundus friends. I had lunch at the Nepal restaurant and Canela e Acucar restaurant. The former is in Rua da Ponta Delgada, the street of my first ever apartment in Lisboa. We used to visit it frequently in 2013, almost daily at a certain point - sometimes twice a day! The latter is close to my lab. My friends and I used to have lunches there in 2012, almost daily. Both restaurants maintained the price. The price did not increase over the years. I could not say the same about the quality. But it was good to relive those memories.

View in Sintra
On the day of defense, 1st of July, I woke up early. The hotel had a balcony, from which the early morning sunshine reached my room abundantly. I left to my lab and met my supervisor again. The defense (30 mins of presentation) and the following question-and-answer session of up to 2 hours went pretty well. I passed with a distinction. Now two free days before leaving Lisboa, to Porto, and then on the same day, to Brussels airport from Porto airport. The first day, I decided to go to Praia das Maçãs, and the second day, a random trip across Lisboa.

Praia das Maçãs is where one of my most favorite songs was shot. Finally, I had a chance to visit there myself. I had to take a train to Portela da Sintra, and then a bus from there. On my return trip, I took a toy train to Portela da Sintra from the Praia das Maçãs village. The beach is a red flag guarded beach. That means not suitable for swimming due to its strong currents. Good for surfing, as I observe the big waves hitting the rocks and the beach as well as the surfers riding the waves.

The large waves of Praia das Maçãs
The second free day, my whole day was in Lisboa. I was doing a random metro ride and bus ride to cover as many places as I can. I was revising my six years in Lisboa (2012 - 2018). I even went to Belem, which I hadn't visited for several years. I went to Restauradores, Rossio - Praca do Comercio, Baixa - Chiado, Bairro Alto, Alfama, Alameda, Arroios, Cais do Sodre, and several other neighborhoods. The day eventually came to an end, and I did not have many things left in Lisboa that I did not cover during this trip. Of course, I did not visit Centro Comercial Colombo and ISCTE-IUL, two of our most frequented places. But it is not necessary to visit all the places again during this short trip, I reminded myself. I had visited the most important ones, where I had the strongest memories. I felt like a time-traveler most of the times. I was checking whether I could run into my old friends or our younger selves from 2012 - 2013.

Good bye, my romantic Lisboa
Finally, it was time for me to leave Portugal again. I felt this was a better ending than what I had in 2018, exactly a year ago. I now have defended my Ph.D. thesis. That leaves me with no real attachment to Portugal or Lisboa. Of course, I have a strong cultural alignment with Portugal after my six years of life there. This trip also completes my seven years of student-life in Portugal. I still have to defend my thesis again in Belgium, since this is a double degree. But that has nothing to do with Portugal or my Portuguese university. I thank Portugal, as I eventually leave Lisboa to Porto in an Alfa Pendular fast train. I came to Portugal for my studies in 2012. I searched and found myself in Portugal over the years to follow. Now, in Porto, I was switching from the past and the present at the same time, as I was waiting for the metro to the airport. My Portugal trip was successful and now is a return trip. I am also leaving Porto once more with a more positive note, compared to 2013, when I left Porto with lots of questions. At present, from Porto airport, I board the flight to Brussels. Goodbye, once again, Portugal. Until I see you again another time!

Wednesday, July 10, 2019

My Ph.D. Defense - Software-Defined Systems for Network-Aware Service Composition and Workflow Placement

I successfully defended my Ph.D. thesis at IST (Tecnico) - ULisboa, Lisbon, Portugal on the 1st of July 2019. I passed with a distinction. My presentation slides and the abstract are given below.

Composing complex workflows efficiently from diverse services on the Internet requires communication and coordination across heterogeneous execution environments, ranging from data centers and clouds to the edge managed by different infrastructure providers. Through complete virtualization of network and its services, network softwarization provides efficient management of network architecture. This dissertation exploits the flexibility and management benefits of the network softwarization to solve the problems of service composition and workflow placement at Internet scale. We present two main contributions: first, a set of extensions to network softwarization to simplify and enhance application development and deployment, and second, a scalable architecture to compose service chains in wide area networks. Finally, we evaluate these contributions in the context of big data applications. We thus intend to mitigate the challenges concerning resource management and interoperability of heterogeneous infrastructures, to efficiently compose and schedule various service workflows at Internet scale, while sharing the network and the computing resources among several users.

Network Softwarization revolutionizes the network landscape in various stages, from building, incrementally deploying, and maintaining the environment. Software-Defined Networking (SDN) and Network Functions Virtualization (NFV) are two core tenets of network softwarization. SDN offers a logically centralized control plane by abstracting away the control of the network devices in the data plane. NFV virtualizes dedicated hardware middleboxes and deploys them on top of servers and data centers as network functions. Despite its growing application, network softwarization has not been fully exploited for effectively composing service workflows of multiple users sharing third-party network infrastructures and services. To this end, we propose our contributions to extend network softwarization for network-aware service composition and workflow placement in heterogeneous infrastructures.

First, we separate network from infrastructure by exploiting network softwarization to move out of data centers toward the edge seamlessly, and from simulations to actual deployments, with little or no additional development effort. We extend SDN in cloud and data center environments to unify various phases of development, by uniformly managing the executions of the network applications from an extended SDN controller, regardless of the execution environment and phase. We thus deploy the workloads seamlessly across the phases, from simulations and emulations to physical deployment environments. We further extend this work to support multiple Service Level Agreements (SLAs) across diverse network flows in data centers, by selectively enforcing redundancy on the network flows. Thus, we aim for Quality of Service (QoS) and efficient resource provisioning, while adhering to user policies. Finally, we design a cloud-assisted overlay network, as a latency-aware virtual connectivity provider. Consequently, we propose cost-efficient data transfers and workflow executions at Internet scale.

Second, we propose a scalable architecture to compose service chains in wide area networks efficiently. We exploit SDN and Message-Oriented Middleware (MOM) for a logically centralized composition and execution of service workflows. We thus propose a Software-Defined Service Composition (SDSC) framework for web service compositions, Network Service Chains (NSCs), and a network-aware execution of data services. We further present Software-Defined Systems (SDS) consisting of virtual network allocation strategies for multi-tenant service executions in large-scale networks comprised of multiple domains.

Finally, we investigate how our proposed SDS can operate efficiently for real-world application scenarios of heterogeneous infrastructures. While traditionally web services are built following standards and best practices such as Web Services Description Language (WSDL), network services and data services offered by different service providers often fall short in providing common Application Programming Interfaces (APIs), thus resulting in vendor lock-in. We look into facilitating interoperability across service implementations and deployments, to enable seamless workflow executions and service migrations. We propose big data applications and smart environments such as Cyber-Physical Systems (CPS) and the Internet of Things (IoT) as our two application scenarios. We thus build CPS and big data applications as composable service chains, offering them an interoperable execution.

Our research contributions highlight that network softwarization can be used to build and deploy network applications with minimal repetitive effort, from initial design and development stages to production. Evaluations on the proposed SDS demonstrate performance and economic benefits to service composition and workflow placement at various scales, from data centers to the Internet. By managing and leveraging redundancy in the network flows and network paths, our SDS prototypes ensure that SLAs are met in the critical network flows of multi-tenant systems. Furthermore, our SDS framework reduces Internet latency by up to 30%, yet in an economic approach. Finally, we elaborate the broader applicability of our proposed SDS by extending it to CPS and big data applications.

Saturday, June 22, 2019

IPSec VPN Configuration on Ubuntu 18.04

This was something I had to do repeatedly on all my Linux laptops. I found that you must follow *both* 2 articles listed below in the same order, to get it working!

The package to install in Ubuntu 18.04 can be found here.

Sunday, May 19, 2019

Thermald and MCE error

I randomly kept getting the below errors in my Centos laptop. I installed thermald. It seems the error is fixed for now. Let's see. :)

Message from syslogd@llovizna-lenovo at Apr 17 14:29:02 ...
 kernel:mce: [Hardware Error]: CPU 0: Machine Check: 0 Bank 5: ee0000000040110a

Message from syslogd@llovizna-lenovo at Apr 17 14:29:02 ...
 kernel:mce: [Hardware Error]: TSC 0 ADDR fef81fc0 MISC 78a0000086

Message from syslogd@llovizna-lenovo at Apr 17 14:29:02 ...
 kernel:mce: [Hardware Error]: PROCESSOR 0:40651 TIME 1555525734 SOCKET 0 APIC 0 microcode 24

Message from syslogd@llovizna-lenovo at Apr 17 14:29:02 ...
 kernel:mce: [Hardware Error]: CPU 0: Machine Check: 0 Bank 6: ee0000000040110a

Message from syslogd@llovizna-lenovo at Apr 17 14:29:02 ...
 kernel:mce: [Hardware Error]: TSC 0 ADDR fef82100 MISC 78a0000086

Message from syslogd@llovizna-lenovo at Apr 17 14:29:02 ...
 kernel:mce: [Hardware Error]: PROCESSOR 0:40651 TIME 1555525734 SOCKET 0 APIC 0 microcode 24

$  dmesg | grep -i 'mce:'
[    0.023131] mce: CPU supports 7 MCE banks
[    1.037974] mce: [Hardware Error]: CPU 0: Machine Check: 0 Bank 6: ae0000000040110a
[    1.038009] mce: [Hardware Error]: TSC 0 ADDR fef87380 MISC 278a0000086
[    1.038033] mce: [Hardware Error]: PROCESSOR 0:40651 TIME 1555486489 SOCKET 0 APIC 0 microcode 24
[  300.672620] mce: [Hardware Error]: Machine check events logged
[24841.300647] mce: [Hardware Error]: Machine check events logged
[24841.300730] mce: [Hardware Error]: CPU 0: Machine Check: 0 Bank 5: ee0000000040110a
[24841.300735] mce: [Hardware Error]: TSC 0 ADDR fef81fc0 MISC 78a0000086
[24841.300739] mce: [Hardware Error]: PROCESSOR 0:40651 TIME 1555525734 SOCKET 0 APIC 0 microcode 24
[24841.300743] mce: [Hardware Error]: CPU 0: Machine Check: 0 Bank 6: ee0000000040110a
[24841.300747] mce: [Hardware Error]: TSC 0 ADDR fef82100 MISC 78a0000086
[24841.300750] mce: [Hardware Error]: PROCESSOR 0:40651 TIME 1555525734 SOCKET 0 APIC 0 microcode 24

Thursday, May 9, 2019

Hosting a RIPE ATLAS Probe in Atlanta

I used RIPE Atlas for my Internet measurements in my IFIP Networking 2018 paper (NetUber: A cloud-assisted overlay network as an alternative connectivity provider) and consequently my thesis. I consumed the RIPE Atlas credits from my co-author for those experiments. Afterward, I requested RIPE to send me a probe, and now I have received it! I have connected it to my home router. My probe is currently connected to the RIPE Atlas network and started receiving traffic. I am happy to contribute back to the Internet measurements community!