Silas Sewell

The Advanced Message Queuing Protocol (AMQP) is the first open standard for Enterprise Messaging and has been adopted by Cisco, Microsoft, Novel, Red Hat and others.

One implementation of AMQP currently packaged by Red Hat and Fedora is Qpid. Qpid is a collection of brokers (C++, Java) and clients (C++, Java, Python, Ruby) which aims to be 100% AMQP Compliant.

Below is a step-by-step tutorial on getting started with Qpid and the Python client in Fedora.

1. Install the Qpid broker and Python client

   yum install qpidd python-qpid

2. Start the broker

   service qpidd start

3. Create a message producer

   vim producer.py

   from qpid.connection import Connection
   from qpid.datatypes import Message, uuid4
   from qpid.util import connect
    
   # Create connection and session
   socket = connect('localhost', 5672)
   connection = Connection(sock=socket, username='guest', password='guest')
   connection.start()
   session = connection.session(str(uuid4()))
    
   # Setup queue
   session.queue_declare(queue='message_queue')
   session.exchange_bind(exchange='amq.direct', queue='message_queue', binding_key='routing_key')
    
   # Setup routing properties
   properties = session.delivery_properties(routing_key='routing_key')
    
   # Send messages
   session.message_transfer(destination='amq.direct', message=Message(properties, 'Message one'))
   session.message_transfer(destination='amq.direct', message=Message(properties, 'Message two'))
   session.message_transfer(destination='amq.direct', message=Message(properties, 'Done'))
    
   # Close session
   session.close(timeout=10)

4. Create a message consumer

   vim consumer.py

   from qpid.connection import Connection
   from qpid.datatypes import RangedSet, uuid4
   from qpid.util import connect
    
   # Create connection and session
   socket = connect('localhost', 5672)
   connection = Connection(sock=socket, username='guest', password='guest')
   connection.start()
   session = connection.session(str(uuid4()))
    
   # Define local queue
   local_queue_name = 'my_local_queue'
    
   # Create local queue
   queue = session.incoming(local_queue_name)
    
   # Route messages from message_queue to my_local_queue
   session.message_subscribe(queue='message_queue', destination=local_queue_name)
   queue.start()
    
   content = ''
    
   while content != 'Done':
     # Get message from the local queue
     message = queue.get(timeout=10)
     # Get body of the message
     content = message.body
     # Accept message (removes it from the queue)
     session.message_accept(RangedSet(message.id))
     # Print message content
     print content
    
   # Close session
   session.close(timeout=10)

5. First run the producer and then the consumer

   python producer.py && python consumer.py

   Message one
   Message two
   Done

Source: Qpid direct example

A simple function to slice strings in Bash similar to Python’s string slicing functionality.

Examples

[silas@pluto ~]$ string_slice "12345" 0 1
1
[silas@pluto ~]$ string_slice "12345" 0 3
123
[silas@pluto ~]$ string_slice "12345" 2 3
3
[silas@pluto ~]$ string_slice "12345" 2 -2
3
[silas@pluto ~]$ string_slice "12345" -3
345

Implementation

function string_slice {
  STRING="$1"
  declare -i LENGTH="${#STRING}"
  declare -i START="$2"
  declare -i END="$3"
  if [ $START -lt 0 ]; then
    START=$[ $LENGTH + $START ]
  fi
  if [ $END -le 0 ]; then
    END=$[ $LENGTH + $END ]
  fi
  START=$[ $START + 1 ]
  (echo "$STRING" | cut -c $START-$END) 2> /dev/null
}

I’ve packaged pytyrant–a pure python client implementation of the Tokyo Tyrant protocol–as an RPM.

I’ve packaged pyrc–Python bindings for Tokyo Cabinet–as an RPM.

The following describes a simple way to manage you profile configuration files using GitHub.

Features

• Centralized configuration management
• Files live in their native locations (no symbolic linking)
• Home directory is not a Git repository
• All the power of git with a simple alias

Setup Repository

1. Log into GitHub and create a repository named config
2. Add your public keys to GitHub (if you haven’t done so already)
3. Open a terminal and switch to your home directory

   cd ~

4. Create a configuration directory

   mkdir .config.git

5. Add the following alias to your current session and your .bash_profile

   alias config='git --git-dir=$HOME/.config.git/ --work-tree=$HOME'
   echo "alias config='git --git-dir=$HOME/.config.git/ --work-tree=$HOME'" >> .bash_profile

6. Add your .bash_profile to the configuration repository

   config add .bash_profile

7. Commit the changes

   config commit -m 'Initial commit'

8. Change the origin to GitHub

   config remote add origin git@github.com:GITHUB_USERNAME/config.git

9. Push the changes

   config push origin master

If you get an error when running config pull to the effect of You asked me to pull without... run the follow:

echo -e '[branch "master"]\n  remote = origin\n  merge = refs/heads/master' >> ~/.config.git/config

Setup Configuration Management on a Different System

1. Add your public keys to GitHub (if you haven’t done so already)
2. Switch to your home directory

   cd ~

3. Backup your local configuration files, example:

   mv .bash_profile .bash_profile.bk

4. Clone your configuration repository

   git clone git@github.com:GITHUB_USERNAME/config.git config.git

5. Move the git metadata to ~/.config.git

   mv config.git/.git .config.git

6. Enable dotglob

   shopt -s dotglob

7. Move your configuration files to your home directory

   mv -i config.git/* .

8. Delete the config.git directory

   rmdir config.git

9. Logout and log back in

Basic Usage

• config pull – get latest configuration changes
• config add FILENAME – add a configuration file
• config commit -a – save all configuration changes
• config push – push configuration changes to GitHub
• and any other config GIT_OPTION

You can see my configuration repository at http://github.com/silas/config.

Source: Manage your $HOME with git by Robert Escriva