Silas Sewell

The Advanced Message Queuing Protocol (AMQP) is the first open standard for Enterprise Messaging and has been adopted by Cisco, [Microsoft][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 (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 (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

   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
}

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

• Log into GitHub and create a repository named config
• Add your public keys to GitHub (if you haven't done so already)

• Open a terminal and switch to your home directory

  cd ~
  

• Create a configuration directory

  mkdir .config.git
  

• 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
  

• Add your .bash_profile to the configuration repository

  config add .bash_profile
  

• Commit the changes

  config commit -m 'Initial commit'
  

• Change the origin to GitHub

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

• 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