Rich Atkinson

Simply Delicious is a simple, rock-solid extension for Google Chrome which provides a neat bookmarking button.

Install it here…
Simply Delicious for Google Chrome

Background

I decided to write this extension after I tried the alternatives and realised that they mostly sucked. The objective here is to provide a neat “bookmark in delicious” button; that’s it.

I eventually plan to include a feature to enable local searching of delicious bookmarks, possibly by downloading them into the browsers bookmark store. Rest assured that this will only be done if it can be done sans-bloat.

Note for Windows users

Windows users currently need the Beta version of Chrome to fully use extensions; available here.

Note for OSX users

Mac users have two options for using Chrome Extensions right now:

1. Developer edition of Chrome (mac)
It’s kind of like a pre-beta. But you want to be on the bleeding edge right? Available here.

2. Chromium (open source)
You can also use Chrome extensions on OSX right now with Chromium. Chromium is basically the open source foundation of Chrome, it’s almost identical but slightly ahead in features.

It’s not as scary as it sounds, just use this Automator app to get and install the latest build for you. If it doesn’t work out it’s easy to reinstall the release version.

Please let me know what you think!

(Updated: 2nd November for Cassandra 0.4.1)

I couldn’t find much in the way of an OS X install guide for Cassandra and (particularly) Thrift, so here’s a brief summary of the steps I took to get Cassandra up and running on Snow Leopard.

Requirements: xcode (provides java, ant and g++, autotools etc for compiling thrift) & svn.

I used macports to get “boost, “pkgconfig” and “libevent”, all used by for Thrift.

Part 1: JAVA_HOME

OSX does not set JAVA_HOME for you, instead it must be done manually.

A simple way is to add the following line to ~/.bashrc

export JAVA_HOME=$(/usr/libexec/java_home)

After setting JAVA_HOME, you will need to exit and reopen terminal before the change will take effect.

Part 2: Installing Cassandra

# I installed Cassandra into /opt and run it as me.
mkdir -p /opt/cassandra
chown -R {you} /opt/cassandra

# Need to create the log directory
mkdir -p /var/log/cassandra
chown -R {you} /var/log/cassandra

# Also Cassandra created a directory instead of a file for system.log, so...
touch /var/log/cassandra/system.log

# By default Cassandra 0.4.1 uses /var/lib for data, so...
mkdir -p /var/lib/cassandra
chown -R {you} /var/lib/cassandra

# now lets get the source
svn co https://svn.apache.org/repos/asf/incubator/cassandra/tags/cassandra-0.4.1 /opt/cassandra/cassandra-0.4.1

# If all is well you should be able to build.
cd /opt/cassandra/cassandra-0.4.1
ant

# If that works, you should be able to run cassandra
bin/cassandra -f

All going well, you should be able to, in a new terminal tab, run through the CLI tests here.

Part 3: Installing Thrift

First you’ll need boost, pkgconfig and libevent. So (using macports):

sudo port install boost
sudo port install libevent
sudo port install pkgconfig

Now, with a lack of tags and branches in SVN, I just grabbed trunk (please could someone let me know if this unwise).

svn co http://svn.apache.org/repos/asf/incubator/thrift/trunk/ /opt/cassandra/thrift

SVN revision at time of writing was 817923

Next, we build it…

(Note the /opt/local references, that’s where macports puts it’s stuff by default)

cd /opt/cassandra/thrift
./bootstrap.sh
./configure --with-boost=/opt/local --with-libevent=/opt/local --prefix=/opt/local

# If you get the error:
# ./configure: line 16440: syntax error near unexpected token `MONO,'
# ./configure: line 16440: ` PKG_CHECK_MODULES(MONO, mono >= 2.0.0, net_3_5=yes, net_3_5=no)'

# It's documented, to fix it: (assuming you installed pkgtools from macports)
ln -s /opt/local/share/aclocal/pkg.m4 /opt/cassandra/thrift/aclocal/pkg.m4

# once again:
./bootstrap.sh
./configure --with-boost=/opt/local --with-libevent=/opt/local --prefix=/opt/local
sudo make install


Language bindings

The make install should have installed libraries for ruby, perl, python etc.

EDIT: Python bindings were installed into /usr/lib/python2.6/site-packages. I had to move them to my (default apple provided python 2.6) site-packages.

If you want to install them into a virtualenv you will find the setup.py in /opt/cassandra/thrift/lib/py

Part 4: Generate “cassandra” from thrift.

Navigate to /opt/cassandra/cassandra-0.4.1/interface

and then…
thrift --gen py:new_style cassandra.thrift

This generates the cassandra python package which you can copy to your project.

If you have any suggestions for improvement here, please let me know.

Cassandra is a highly scalable, eventually consistent, distributed, structured key-value store. (apache.org)

Originally developed by facebook, it is now an Apache project and at present has incubator status.

From my point of view, Cassandra stands out from the crowd of non-relational databases for three reasons:

1. Reference Sites: Apart from facebook, Cassandra recently replaced MySQL for parts of Dig. Also Rackspace are doing something secret with it; although I don’t know what it is, my guess would be something along the lines of Amazon’s SimpleDB.

2. True peer clustering: Cassandra does not require a central master. A key feature of Cassandra is you can write to any node in the cluster, at any time. Writes are never blocked. The trade off for this is you get consistency eventually. So transactions aren’t strictly ACIDic, but depending on what you are doing, that might not matter at all.

3. Column Querying: BigTable really popularised (and proved) the concept of the column database for large scale applications. Cassandra really is similar to BigTable from this perspective, but introduces the SuperColumn.

In addition to those things, a couple of other nice features of Cassandra are:

1. It’s JVM based, which makes it nicely portable. It really was a 1 minute job to get it up and running on Snow Leopard.

2. Cross platform API, via a remote Thrift interface.

My intention is to use Cassandra in our current project, where I need a horizontally scalable data store with geographically separate cluster nodes. Fortunately eventual consistency suits this project very well indeed.

Addendum: Here is the best getting started guide I have found so far.

Addendum 2: Eric Flo also sums up Cassandra nicely, although in a slightly different context.