Don't let it crash

22 Jan

We have a specific mindset when writing Erlang programs. We focus on the normal execution of the program and don’t handle most of the errors that may occur. We sometimes call this normal execution the happy path. The general pattern behind writing only for the happy path, letting the VM catch errors (writing them to a log for future consumption) and then having a supervisor restart the processes that failed from a clean state, has a name.

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Cowboy 2.0 pre-release 4

03 Jan

Cowboy 2.0.0-pre.4 has been released! This is the new recommended version of Cowboy. While I would not recommend putting it in production just yet, I do recommend you start writing new applications with this Cowboy version. The most significant changes in the pre-release are: A new architecture: there now is one process per connection and one process per request. This was done because HTTP/2 allows running requests concurrently.

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Ranch 1.3

28 Nov

Ranch 1.3.0 has been released! This release fixes a number of long standing issues and adds a small number of features: The ssl application has been added to the list of dependencies. If you don’t need it, you can remove it automatically when fetching Ranch or when building the release. If you do need it, you will no longer have issues shutting down a node because of Ranch.

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Mailing list archived

29 Aug

The old mailing list archives have been added to the site, mainly for referencing purposes. The mailing list has been shut down and all personal information has been deleted. If you need help with a project, consider either opening a ticket on that project’s issues tracker or going through the community channels (erlang-questions, #ninenines or #erlang on Freenode). Prefer tickets; often when people have issues it highlights an underlying problem in the project or its documentation.

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Website update

02 Apr

Last week-end I updated the Nine Nines website. I switched to Hugo. The site is now built from Asciidoc documents. You probably saw me switch to Asciidoc for documentation this past year. This is the natural conclusion to that story. The great thing is that with a little bit of Makefile magic I can just copy the documentation files into Hugo and poof, they appear on the website. I am very happy with that new setup.

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The Erlanger Playbook September 2015 Update

02 Sep

An update to The Erlanger Playbook is now available! The Erlanger Playbook is a book about software development using Erlang. It currently covers all areas from the conception, design, the writing of code, documentation and tests. The book is still a work in progress. Future topics will include refactoring, debugging and tracing, benchmarking, releases, community management (for open source projects). This update fixes a number of things and adds two chapters: IOlists and Erlang building blocks.

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The Erlanger Playbook

18 Jun

I am proud to announce the pre-release of The Erlanger Playbook. The Erlanger Playbook is a book about software development using Erlang. It currently covers all areas from the conception, design, the writing of code, documentation and tests. The book is still a work in progress. Future topics will include refactoring, debugging and tracing, benchmarking, releases, community management (for open source projects). The following sections are currently available:

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Validating UTF-8 binaries with Erlang

06 Mar

Yesterday I pushed Websocket permessage-deflate to Cowboy master. I also pushed a change in the way the code validates UTF-8 data (required for text and close frames as per the spec). When looking into why the permessage-deflate tests in autobahntestsuite were taking such a long time, I found that autobahn is using an adaptation of the algorithm named Flexible and Economical UTF-8 Decoder. This is the C99 implementation: // Copyright (c) 2008-2009 Bjoern Hoehrmann <[email protected]

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On open source

05 Sep

Last week I read a great article on contributing to open source by Alvaro Videla. He makes many great points and I am in agreement with most of it. This made me want to properly explain my point of view with regard to open source and contributions. Unlike most open source evangelism articles I will not talk about ideals or any of that crap, but rather my personal feelings and experience.

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The story so far

23 Aug

As I am away from home with little to do (some call this a vacation) I wanted to reflect a little on the story so far, or how I arrived to Erlang and got to where I am now. The raw personal experience. It’ll be an article that’s more about social aspect, communities and marketing a project than technical considerations. As a period piece, it will also allow me to reflect on the evolution of Erlang in recent years.

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Cowboy 2.0 and query strings

20 Aug

Now that Cowboy 1.0 is out, I can spend some of my time thinking about Cowboy 2.0 that will be released soon after Erlang/OTP 18.0. This entry discusses the proposed changes to query string handling in Cowboy. Cowboy 2.0 will respond to user wishes by simplifying the interface of the cowboy_req module. Users want two things: less juggling with the Req variable, and more maps. Maps is the only dynamic key/value data structure in Erlang that we can match directly to extract values, allowing users to greatly simplify their code as they don’t need to call functions to do everything anymore.

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January 2014 status

07 Jan

I will now be regularly writing posts about project status, plans and hopes for the future. Before that though, there’s one important news to share. Until a year ago all development was financed through consulting and development services. This worked alright but too much time was spent doing things that didn’t benefit the open source projects. And that didn’t make me happy at all. Because I like being happy I stopped that for the most part and spent the year figuring things out, experimenting and discussing with people about it.

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Farwest got funded!

27 Jun

This was a triumph! I’m making a note here: HUGE SUCCESS!! It’s hard to overstate my satisfaction. Thanks to everyone who made this possible. If you have backed this fundraiser, and haven’t provided your personal details yet, please do so quickly so that your rewards can be sent! I am hoping that we will be able to make good use of all that money. The details of the expenses will be published regularly on the 2013 Fundraiser wiki page, giving you full disclosure as to how your money is used.

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Build Erlang releases with and Relx

28 May

Building OTP releases has always been a difficult task. Tools like Reltool or Rebar have made this simpler, but it’s no panacea. This article will show you an alternative and hopefully much simpler solution. There is two steps to building a release. First you need to build the various OTP applications you want to include in the release. Once done, you need to create the release itself, by including the Erlang runtime system alongside the applications, a boot script to start the node and all its applications, and some configuration files.

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Xerl: intermediate module

25 Mar

Today we will start the work on the intermediate module that will be used to run the code for the expressions found in our file’s body, replacing our interpreter. This is what we want to have when all the work is done: xerl -> tokens -> AST -> intermediate -> cerl Today we will perform this work only on the atomic integer expression however, so we will not build any module at the end.

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Xerl: expression separator

01 Mar

As promised we are adding an expression separator this time. This will be short and easy. In the tokenizer we only need to add a line recognizing the comma as a valid token. , : {token, {',', TokenLine}}. Then we need to change the following lines in the parser: exprs -> expr : ['$1']. exprs -> expr exprs : ['$1' | '$2']. And add a comma between the expressions on the second line:

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Erlang Scalability

18 Feb

I would like to share some experience and theories on Erlang scalability. This will be in the form of a series of hints, which may or may not be accompanied with explanations as to why things are this way, or how they improve or reduce the scalability of a system. I will try to do my best to avoid giving falsehoods, even if that means a few things won’t be explained.

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Xerl: atomic expressions

18 Feb

We will be adding atomic integer expressions to our language. These look as follow in Erlang: 42. And the result of this expression is of course 42. We will be running this expression at compile time, since we don’t have the means to run code at runtime yet. This will of course result in no module being compiled, but that’s OK, it will allow us to discuss a few important things we’ll have to plan for later on.

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Xerl: two modules

03 Feb

Everything is an expression. This sentence carries profound meaning. We will invoke it many times over the course of these articles. If everything is an expression, then the language shouldn’t have any problem with me defining two modules in the same source file. mod first_module begin end mod second_module begin end Likewise, it shouldn’t have any problem with me defining a module inside another module. mod out_module begin mod in_module begin end end Of course, in the context of the Erlang VM, these two snippets are equivalent; there is nothing preventing you from calling the in_module module from any other module.

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Xerl: empty modules

30 Jan

Let’s build a programming language. I call it Xerl: eXtended ERLang. It’ll be an occasion for us to learn a few things, especially me. Unlike in Erlang, in this language, everything is an expression. This means that modules and functions are expression, and indeed that you can have more than one module per file. We are just starting, so let’s no go ahead of ourselves here. We’ll begin with writing the code allowing us to compile an empty module.

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