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I took a crack at installing Merb today, just to see how it works out. It’s a very minimal Ruby framework which in my (admittedly not very scientific) testing appears to be a lot faster than Rails, especially under conditions of high concurrency.

To get it running, I followed the instructions at the Merb book which is currently a work in progress at http://4ninjas.org. A quick tip: due to a dependency on extlib 0.9.3, the sake edgy technique didn’t work for me at first. I got it all running happily by doing the following.

First, install the Git source-code management tool and the Debian build tools if you don’t already have them:

sudo apt-get install build-essential git-core

sudo gem install rack mongrel json erubis mime-types rspec hpricot mocha rubigen haml markaby mailfactory  english addressable templater

Update: in the last few weeks gem dependencies have changed and you need to ensure you’ve got some specific versions available:

sudo gem install ruby2ruby --version=1.1.8

sudo gem install ParseTree --version=2.1.1

You’ll also need to ensure that you’ve got the MySql headers available in order to build the datamapper MySql libraries.

sudo apt-get install libmysqlclient15off libmysqlclient15-dev

git clone git://github.com/sam/extlib.git  
git clone git://github.com/sam/do.git

cd extlib
rake install ; cd ..
cd do
cd data_objects
rake install ; cd ..
cd do_mysql  # || do_postgres || do_sqlite3
rake install

For whatever reason, DataMapper 0.9.4 has a dependency on Merb-core 0.9.3, so you’ll need to install it and then proceed to build the newest DataMapper:

sudo gem install merb-core

git clone git://github.com/sam/dm-core.git
git clone git://github.com/sam/dm-more.git

cd dm-core ; rake install ; cd ..
cd dm-more
rake install; cd ..

After that stuff, the

sudo gem install sake
sake -i 'http://edgy.4ninjas.org/edgy.sake'
sake edgy:install packages="merb-stack"

commands worked just fine for me.

Bonus: install CouchDb, the wicked distributed database system which is currently an Apache incubator project.

sudo apt-get install build-essential erlang libicu38 libicu-dev libmozjs-dev
wget http://www.apache.org/dist/incubator/couchdb/0.8.0-incubating/apache-couchdb-0.8.0-incubating.tar.gz
tar -xvzf apache-couchdb-0.8.0-incubating.tar.gz 
cd apache-couchdb-0.8.0-incubating/
./configure
make && sudo make install

You can set up the CouchDb datastore as a service, with its own user, like this (thanks to these instructions, slightly modified to avoid the creation of a “couchdb” home directory):

sudo useradd couchdb
sudo mkdir -p /usr/local/var/lib/couchdb
sudo chown -R couchdb /usr/local/var/lib/couchdb
sudo mkdir -p /usr/local/var/log/couchdb
sudo chown -R couchdb /usr/local/var/log/couchdb
sudo mkdir -p /usr/local/var/run
sudo chown -R couchdb /usr/local/var/run

sudo cp /usr/local/etc/init.d/couchdb /etc/init.d/
sudo update-rc.d couchdb defaults
sudo /etc/init.d/couchdb start

After that, go to http://localhost:5984/_utils/index.html and you can administer your new distributed datastore. Of course, you could just ignore CouchDb and use Merb with a more “normal” database server like Mysql or Postgres.

If any of the version dependencies change again please leave a comment and I’ll update these instructions until Merb 0.9.4 is a little easier to get.

Second in our “friendly web programming” series, this installment starts with a pop-quiz for new programmers. If you’re trying to learn programming for the first time, you’ve got a whole lot of unfamiliar stuff to think about, and most of the time you don’t understand at least half of what’s going on. In such a situation, which of the following two options would you like to be presented with when you are trying to learn web programming?

It’s not tough to set up a video-encoding facility in Rails. Here’s a quick run-through with some code examples.

Video encoding is a long-running process and you don’t want to have to wait for the video encode to finish before the web-request can complete. One strategy to avoid having extremely long web-requests is to have Rails hand off the encoding job to BackgroundRb, a job-scheduling server which does long-running work in a separate thread. The same thing could be accomplished in most other web-languages by spawning a new thread and doing the work, but BackgroundRb gives us a bit of extra love: if multiple users upload a whole bunch of videos at the same time, BackgroundRb will queue them up and work on them in sequence so the CPU doesn’t go through the roof.

Here are some installation instructions for installing a Ruby development environment on a Debian or Ubuntu computer. It’s targeted at people who have never tried programming before or installed a computer language, but who are ok with firing up a terminal and installing stuff. While there are lots of programming tutorials on the web, there aren’t very many available for people who don’t know what the hell they’re doing but want to try web programming.