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Talking about Erlang, Riak and Vector Clocks with Christopher Meiklejohn (@cmeik)

February 16, 2014 1 comment

Hello! Today you may read here my interview to Christopher Meiklejohn, one of the speakers at the upcoming Erlang Factory in San Francisco. Christopher is working on Riak at Basho Technologies.

Erlang, Vector Clocks and Riak!

 

Paolo – Hello Chris! It’s great to have another Basho Erlanger here! Can you introduce yourself please?

Christopher – It’s great to be here! My name is Christopher Meiklejohn, and I’m currently a software engineer at Basho Technologies, Inc., where I work on our distributed datastore, Riak. In addition to that, I’m also a graduate student at Brown University, in Providence, RI, where I study distributed computing.

Paolo – Before joining Basho you were working in a different company (i.e., Swipely) where you dealt with Ruby code. Did you already know Erlang when you started at Basho? How would you describe the switch between these two languages?

Christopher – During the time I was at Swipely they had Riak deployed in production, which was what initially got me interested in Basho, Riak, in particular, Erlang. When I joined Basho, I knew very little Erlang and spent my first few weeks at the company learning it.

That said, I love Erlang as a language and as platform to build application on. I wouldn’t necessarily say that the change from Ruby to Erlang was anything that was unexpected, specifically because I already had functional programming experience using languages like Scheme and Haskell.

Paolo – Rubyists tend to be addicted to TDD. Were you able to maintain such a good practice also when coding Erlang?

Christopher – Well, I’ll start with a disclaimer. I was primarily responsible for the introduction of behavior driven development at Swipely for feature development, in addition to promoting pair programming within the development team.

That said, testing and verification of software is a very interesting topic to me.

While I believe that all software should be properly tested, I’ve never been particularly dogmatic about when in the cycle of development testing is performed: whether it’s done during development to guide the design of the software or whether it’s done afterwards to validate the authored components. I do, however, have one major exception to this rule: when attempting to reproduce a customer issue and validate a fix for the issue.

This is purely a pragmatic decision that’s come from working on large scale distributed systems: testing and verification of distributed systems is extremely hard given the number of cooperating components involved in completing a task.

At Basho, we take two major approaches to testing Riak: integration testing using a open source test harness we’ve developed that allow us to validate high level operations of the system, and QuickCheck for randomized testing of smaller pieces of functionality.

Paolo – At the upcoming Erlang Factory in San Francisco you will give the following talk: “Verified Vector Clocks: An Experience Report”. Can you introduce in a few words the arguments you will treat during the talk?

Christopher – My talk is going to look at an alternative way of asserting correct operation of software components, commonly known as formal verification.

The talk will specifically focus on modeling vector clocks for use in the Riak datastore using an interactive theorem prover called Coq. This allows us to assert certain mathematical properties about our implementation, and perform extraction of the component into Erlang codewhich we can directly use in our system.

Paolo – Who should be interested in following your talk and why?

Christopher – Given the topics involved, I’m planning on keeping the talk pretty high level and will touch a variety of topics: the theorem prover Coq, which implements a dependently-typed functional programming language, the basics of using Core Erlang, a de-sugared subset of the Erlang programming language, and how we put all of the pieces together.

Paolo – Lamport’s vector clocks are well known by people working in fields connected to distributed systems. Can you explain briefly what they are and in what fields they can be used?

Christopher – Vector clocks provide a model for reasoning about events in a distributed system. It’s a bit involved for this interview to get into the specifics about how they work and when they should be used, so I’ll refer to you two excellent articles written by Bryan Fink and Justin Sheehy of Basho.

“Why Vector Clocks Are Easy”
http://basho.com/why-vector-clocks-are-easy/

“Why Vector Clocks Are Hard”
http://basho.com/why-vector-clocks-are-hard/

Paolo – About the application vvclocks, are you planning to keep the development on? If so how can people contribute?

Christopher – At this point, the project mainly serves as a playground for exploring how we might begin to approach building verifiable software components in Erlang. What has been done so far is available on GitHub, it’s actively being worked on by myself as my time allows, and if you’re interested in helping to explore this further, feel free to reach out to me via e-mail or on Twitter.

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Talking about Erlang with Fernando Benavides

February 3, 2014 Leave a comment

Hello! Probably most of you already know the Erlang Factory Light will be held in San Francisco between 3 and 15 March . Among the 50 talks there will be the one held by Ferndando Benavides. Fernando is an Erlang developer from Argentina, currently working at Inaka as director of engineering. Let’s talk with him about Erlang, Inaka and his talk!

Let’s get started!

Paolo – Hello Fernando, thanks for making yourself available for the interview. Would you like to introduce yourself?

Fernando – Hi! Well… I’m an software developer from Argentina. I started programming when I was 10 using QBasic and “improving” gorillas.bas :P. From that point on I studied computing and programming my whole life until I graduated as a computer scientist in the Universidad de Buenos Aires, a couple of years ago. I started working when I was 18, coding in Visual Basic, then moved to .Net after several years. But thanks to my career path in the university I discovered functional programming (Haskell) and fell in love with it, so when I had a chance to actually work doing functional programming (this time in Erlang) I had no doubt I wanted to do so. That was 5 or 6 years ago. And I’ve been doing Erlang development ever since. About an year ago, I’ve been assigned as the Director of Engineering at Inaka. That basically means I’m now in charge of the architecture and design of all Inaka’s systems, whether they’re written in Erlang or not.

Paolo – You are currently working as Director of Engineering at Inaka: would you like to give some insight about Inaka?

Fernando – Well… you should check out our website: inaka.net 🙂
Inaka was found on September 2008 by Chad DePue, and I’m glad to say I was there. We were just 5 people working in a small apartment in Buenos Aires and we had just one project. Now we are a much much bigger team, with people working from different countries, in a big number of projects. But the idea behind our work was always the same: Our clients have beautiful startup ideas… and we do our best to turn them into real systems or applications that they can quickly launch and grow. Most of our products are iOS/Android applications with Erlang and/or Ruby servers on their backend. And most of the products we build have some important large-scale and/or high-concurrency requirements.

Paolo – How does Erlang fit in Inaka’s ecosystem? Why did you start using it?

Fernando – Erlang is our #1 language choice (at least since I’m Director of Engineering :P) for server developing.
We started using it since our very first system. That was a second screen system that provided additional content to display on iOS devices when a particular show was on air on TV. It also let users interact, by writing comments and “kinda” chatting. When designing the system, Chad detected the high concurrency and real-time demands that it had: during the hour the show was on air, lots of users would be connected and interacting and they devices had to be showing the right content in the right moment, not later. Erlang was the right choice for a language to write the servers with. BTW, making that system scale was not an easy task, even when written in Erlang, and that was what my last talk in an Erlang Factory was about 😉

Paolo – At Inaka you have been using Erlang for many years. How would answer to this question? Do you confirm what Bob Ippolito wrote in his answer?

Fernando –  Being a Haskell fan myself, I can tell you I nodded in approval on almost every paragraph he wrote, including the last one ;). So, yes… I confirm what he wrote.
As him, I’m also not aware of another platform that has the right combination of features, performance and maturity to make it possible to build the kind of systems that we build at Inaka. Maybe instead of binary matching syntax, I would mention that one of the main parts of most of our servers is a RESTful API that usually has a SSE component that keeps clients up to date with server pushes. How easy, clean and nice it is to write the code to implement that and make it scale in Erlang is hardly comparable to any other language that I know.

Paolo – In your talk at Erlang Factory Lite you will talk about: “Lucene Server: From Erlang to Java and Back Again”. Do you mind giving us some information about the talk?

Fernando – It will be a similar talk as the one I gave on the last ErlangDC. I’ll talk about a system that I’ve built and it’s now open-source, thanks to TigerText: Lucene Server. It’s an Erlang application that lets its users index, delete and query documents (i.e. proplists, in Erlang terms) using Lucene (which is written in Java). The key point here is that no Java knowledge is required for lucene_server users. All Java compilation, running, handling, stopping, etc. is managed internally by the lucene_server application. I’ll tell you how it’s works and how it’s implemented, and I’ll show you some lessons I learned along the way 😉

Paolo – Who should attend your talk and why?

Fernando – My talk is mostly aimed at Erlang developers that once faced JInterface, got scared and then decided to implement their solution in a different way… I was there, too 😉
Also, those devs that need a great indexing solution like Lucene as part of their systems. They will learn about an open-source application that may be exactly what they need.

Paolo – About Erlang and Java, I really liked your blog post on Inaka’s blog. Can you talk briefly about it?

Fernando – I wrote that post before lucene_server was open sourced and, in the same way that I couldn’t talk about the second screen system I described before but nevertheless I wrote a blog post about its story, I wrote this post (or rather this still unfinished series of posts) about lucene_server’s history.

You worked both with JVM and Erlang VM which are widely acknowledged among developers. Talking about performances and tuning, can you give some pros and cons for both?

I never feel comfortable talking about performances and tuning of VMs. I’m not sure I know enough about Erlang VM to talk about that and I’m positive I know nothing about JVM in this respect. Also, comparing the performance of two virtual machines for two completely different languages is tricky to say the least. It’s not like you can run the same code in both of them and see which one behaves better 😉

Paolo – Last question: lately I have seen a lot of tweets complaining about the Erlang syntax. What do you think about this?

Fernando – I’m not much of twitter user myself, but the same topic raises up every now and again at Inaka’s office. Personally, I have worked/coded in a big number of languages including Basic for Commodore (where you had to write the line-number before each line yourself), Javascript, Haskell, Prolog, etc. and I never had any problem with any language syntax. Ok, I know, I’m not talking about brainfuck or shakespeare or any other esoteric language. But, besides those funny examples, I always saw syntax as just something to learn and get used to. I would never quit learning or using a language just because I don’t like the way it’s code is written. That said, I love Smalltalk syntax and how easy it is to read and write Smalltalk code. And I also like Haskell syntax even when it’s so hard to just read a Haskell program when there are monads around. About Erlang syntax, well it’s not that I love it specially, but I never had an issue with it… ¯\_(ツ)_/¯

Paolo – BTW, I am really puzzled about your name: is it Brujo or Fernando?

Fernando – Well… According to my passport, I’m Fernando Benavides Rodriguez. According to anyone else, I’m just “Brujo” :). In other words, “Brujo” is my nickname, it means something close to “sorcerer” or “shaman” in spanish. The nickname was taken from my favorite character in a series of books I love (La Saga de Los Confines, by Liliana Bodoc) and it stuck with me forever. So, just call me Brujo 🙂

Talking about Elixir and the Erlang VM with José Valim

November 30, 2013 Leave a comment

Hello! CodeMesh 2013 is coming and if you are planning to attend this wonderful event you may have the chance of learning more about Elixir from his creator: José Valim. For those of you who will not be able to be in London the 4th, 5th  December I prepared this interview to José. In the interview we talked about Elixir, its roots in the Erlang VM and the future of this newborn language. Enjoy! 😀

Elixir of life

Paolo – Hello José! It is a great thing to have you here in my blog for an interview. Would you like to introduce yourself in few words?
 
José – Hello Paolo! In few words, I am co-founder of Plataformatec, a consultancy based in Brazil and the creator of the Elixir programming language!
 
Paolo – José, you were previously known for you work in the Ruby on Rails Core Team. What was you experience with Erlang before writing Elixir? Why did you decide to write a new language and for what reason did
you choose the Erlang VM?
 
José – Before writing Elixir, I already had a good knowledge of the Erlang language and the Erlang VM. At the time, I was unhappy with the tools available to solve the concurrency issues in the Ruby ecosystem and the fantastic Seven Languages in Seven Weeks book helped me lay out the options out there. After reading the book, it solidified my opinion that the Erlang VM is one of the best environments to build and deploy robust concurrent software (my goals at the time).
 
After digging deeper into the Erlang language, I missed some of the flexibility and constructs that I find important in my toolbox, like meta-programming and polymorphism, as well as a better unicode support and other things, which led me to write Elixir.
 
Paolo – Elixir is based on the Erlang VM but has a syntax close to Ruby: for what reasons an Erlang developer should learn Elixir? What about Ruby developers?
 
José – Erlang developers know quite well syntax is often one of the first things that come up when discussing a new language. So while the syntax is similar to Ruby, the semantics are mostly from the Erlang VM. So leaving syntax out, an Erlang developer would find appeal in Elixir if he/she misses the same tools I missed when I started it. For example, we provide a macro system which gives developers the ability to meta-program, i.e. to write code that generates code. Another example is polymorphism, where Elixir provides something called protocols, heavily inspired by Clojure’s protocols, which allows developers to provide well-defined extension points in their libraries.
 
It is hard to explain such features in broad terms, so let me try to give some examples. Erlang developers are familiar with typespecs. In Elixir, we also have typespecs, except they were all implemented in Elixir itself using macros. There is no language extension because macros give users the ability to access and modify existing code. Another good example of macros is how we embed the unicode database into Elixir, at compilation time, which allows us to speed up many Elixir string operations by avoiding work at runtime.
 
Elixir also aims to provide a tidier standard library. For example, we provide an Enum module that is able to enumerate (i.e. map, fold, take, etc) all the collections in the language and such module is powered by protocols: Elixir knows how to enumerate your collection as long as you implement a protocol. After all, it is preferable to have a small set of functions that work well with a handful of collections than a completely different set of APIs for each data structure.
 
For any other developer, be a Ruby, Java, Python or Javascript programmer, learning Elixir means learning the semantics in the Erlang VM and all the amazing tooling existent for building robust, concurrent, fault-tolerant applications and that is more than enough reason for giving it a go.
 
Paolo – I have read the enthusiastic blog post “A week with Elixir” by Joe Armstrong. I also know that you are giving several talks around the world about Elixir. What kind of feedback do you receive from the Erlang community?
 
José – In general the feedback is quite good as the community agrees that the power lies on the Erlang VM and, while Elixir offers a slightly different perspective on it, the more developers using the Erlang VM translates into more knowledge, tools and enthusiasm in the ecosystem altogether.
 
Paolo – Some of our readers maybe want to contribute to some open source project based on Elixir. Do you want to suggest some projects in particular?
 
José – The community is still very young so the best suggestion right now is to try to solve a problem and see if there are any tools available and, if not, wright your own! We see some efforts converging though, we already have an “official” monad library, another for talking to postgresql, other to work with data and time, and so on.
 
Also I want to point out that Elixir is mostly written in Elixir, with the exception of a dozen of macros that we call “special forms”. This makes it very easy to contribute to Elixir itself, once you start learning the language!
 
Paolo – The 4th and 5th December you will give a talk at Code Mesh 2013. The talk title is: “Ecto: A language integrated query for Elixir”. Can you give to our readers some insights on you talk?
 
José – Besides the keynote about programming and Elixir, which I will give with Dave Thomas, I will also talk about Ecto.
 
In a nutshell, Ecto is a language integrated query to talk to relational databases in Elixir, heavily inspired by LINQ (from .NET). The goal of the talk is to introduce Ecto but, more importantly, also show how features provided by Elixir made the implementation of Ecto in the first place!
 
Paolo – Looking at the future: what should we expect from the new Elixir releases? In which part of the language will you focus the most?
 
José – In the short-term, we want to integrate with maps (when Erlang R17 comes out) while we work on a solid logging system to be shipped with the language, that builds on Erlang’s logger. Once that is done, we will release Elixir v1.0.
 
After Elixir v1.0 is out, we have many options to explore and the interesting thing is that we can explore those outside of the language, because macros give us all support we need. Some plans include providing better comprehensions, improving how we work with nested data structures, support to discriminated unions and more!