Zotonic: the Erlang Content Management System

It's more than just a CMS. Create complicated Web sites quickly with Zotonic.

Described by its authors as a pragmatic and modern CMS, Zotonic is that and much more. When I started using Zotonic, it was because of its efficiency and the fact that I could pack several client CMS sites onto a machine with only humble resources. I soon discovered, however, that Zotonic is not only a CMS, but also a Web framework, which allows me to create very complicated Web sites in a fraction of the time it would have taken me using more traditional languages and frameworks. Zotonic won't fall over if it encounters an error, and it does not need to be poked with a stick and awakened every time a request comes in.

Zotonic is written in Erlang, a functional language that was designed for programming telephone switches. The logic behind using Erlang for Web development is that modern Web sites, with their plethora of connections from users and robots, are starting to look more and more like telephone exchanges. “I have never programmed in a functional language, and Erlang looks like Dutch to me!”, I hear you say. Well, the authors of Zotonic are fluent in Erlang (and Dutch, incidentally), and they have done a good job of creating a piece of software that is useful out of the box, regardless of whether you know Erlang, and Zotonic could be just the killer app you need to dive in and learn Erlang.

Another attractive feature of Zotonic is its PostgreSQL database (see sidebar). As someone who has toyed with learning Erlang for a while, probably one of the big barriers was that on top of learning a completely new programming paradigm, I also would have to learn a new database in the form of mnesia. Zotonic's use of PostgreSQL means one less new thing to learn and at least allows me to feel in familiar territory when I am designing my data.

Dependencies

I am running the latest version of Ubuntu, which has Erlang preinstalled. You can test whether you have Erlang by typing erl at the command line. If you get the Erlang shell, you are good to go. Press Ctrl-c, followed by the letter a and carriage return to exit Erlang. If you don't have Erlang on your system, you can download it from the Erlang Web site or install it with your distribution's package manager.

Another dependency is ImageMagick; to check whether it's installed, run:

convert -version

You, of course, need to have PostgreSQL installed, and you need Mercurial installed to fetch the latest version of Zotonic from the Google code site.

Installing and Configuring Zotonic

Fetch the Zotonic source and build it:

hg clone https://zotonic.googlecode.com/hg/ zotonic
cd zotonic
make

Now, create a database for Zotonic:

CREATE USER zotonic WITH PASSWORD 'yourdbpassword';
CREATE DATABASE zotonic 
    WITH OWNER = zotonic ENCODING = 'UTF8';
GRANT ALL ON DATABASE zotonic TO zotonic;
\c zotonic
CREATE LANGUAGE "plpgsql";

The Default Site

Zotonic comes complete with an example site, which implements a simple blog. You can find the code for this default site in priv/sites/default/, and you can get this default site running by creating a config file and starting Zotonic.

Find the sample config file in priv/sites/default/config.in, and rename it or create a copy with no extension:

cp priv/sites/default/config.in priv/sites/default/config

Open config in your favourite text editor, and modify it to use the database you just created:

% Hostname for virtual host support
{hostname, "127.0.0.1:8000"},
{hostalias, "localhost:8000"},
% PostgreSQL database connection
{dbhost, "127.0.0.1"},
{dbport, 5432},
{dbuser, "zotonic"},
{dbpassword, "yourdbpassword"},
{dbdatabase, "zotonic"},

Now, start Zotonic in debug mode using start.sh:

./start.sh

You should see text fly by on the console that suggests some tables are being created. Point your browser at 127.0.0.1:8000, and you should see your new blog.

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Quitting Out of the Erlang Interpreter

Thomas Legg's picture

Instead of ctrl-C + abort, the faster and cleaner way out of the erlang interpreter command prompt >:
q().
Kind of like typing quit() at a python interpreter command prompt, but shorter and ending with a period/full stop. (Don't all good sentences end with a period? They do in Erlang.)

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