Python threads synchronization: Locks, RLocks, Semaphores, Conditions and Queues

This article describes the Python threading synchronization mechanisms in details. We are going to study the following types: Lock, RLock, Semaphore, Condition and Queue. Also, we are going to look at the Python internals behind those mechanisms. The source code of the programs below can be found at under threads/. First, let’s look at... » read more

OpenStack Nova internals of instance launching

This article describes the internals of launching an instance in OpenStack Nova. Overview Launching a new instance involves multiple components inside OpenStack Nova: API server: handles requests from the user and relays them to the cloud controller. Cloud controller: handles the communication between the compute nodes, the networking controllers, the API server and the scheduler.... » read more

Cars monitoring client/server application using Python Twisted

This article describes how to use Twisted to build a client/server cars monitoring system. We are going to focus on the client/server communication. The client and server source code can be retrieved using Git: Overview Some researchers invented a system capable of monitoring cars and detecting the brand and color of a car. We are... » read more

OpenStack Nova script explained

Update 11/24/2011: Updated article based on the latest script. This article describes the internals of the script used to get the OpenStack Nova source code, install it and run it. Nova is a cloud computing fabric controller, the main part of an IaaS system. The script can be retrieved using Git: Arguments The... » read more

Distributed messaging using RabbitMQ and Python

This tutorial shows how to distribute messages to multiple servers for processing. We will be using RabbitMQ which is based on AMQP. The way messaging works is that you have producers producing messages and consumers consuming them. We are going to have 1 producer generating random integers and 2 consumers: 1 consuming the odd integers... » read more

Add REST resources to a database using Python and SQLAchemy

This tutorial shows how to download REST resources to your database using Python and SQLAchemy. We are going to download manufacturers and cars resources to our database. We will also show how easy it is to query them once they are stored. Requirements We need to install SQLAchemy and simplejson Python libraries: You can use... » read more

C++ Twilio REST and TwiML Helper Library

The C++ Twilio help library simplifies the process of making requests to the Twilio REST API, generating TwiML and validating HTTP request signatures using C++. Checkout the library: git clone Source files: Rest.cpp: Twilio REST helper TwiML.cpp: TwiML generation helper Utils.cpp: Utils to validate a HTTP request signature: X-Twilio-Signature Examples.cpp: Examples of usage UnitTests.h:... » read more

Amazon S3 upload and download using Python/Django

This article describes how you can upload files to Amazon S3 using Python/Django and how you can download files from S3 to your local machine using Python. We assume that we have a file in /var/www/data/ which we received from the user (POST from a form for example). You need to create a bucket on... » read more