vdeli Video Deliver Network (c) 2011 INFTEC

vdeli is a CDN (content delivery network) specialized in video delivery. The project is composed of several components that work together to allow a publisher to send a file, distribute this file in a controlled manner in a distributed network, and then allow end users to access and watch movies.

SERVERS

The main elements of the architecture are:

1) The Management Server, which is a central node for the system. It hosts the cdnmanager and the ftpserver parts of the project.

2) The CDN Servers, which hosts the files that the end user will access to watch videos. There may be from one to a large number (over 4000) servers.

CDN Servers are grouped in clusters, which are servers located in the same subnet, directly connected via LAN. CDN Servers also can be grouped in regions, which allow to setup different distribution policies (by region).

COMPONENTS OF THE CDN MANAGEMENT SERVER

The main components of the architecture, on the software side, are:

1) ftpserver

This is a simple FTP server based on pyftpdlib, which is a great library that supports almost everything you need for a working FTP. It checks the user authorization in a user library stored in a database, that is managed by the cdnmanager component (see it below).

Publishers use this service to put new files into the network. These files will be copied to the servers under control of the cdnmanager application.

2) cdnmanager

It's a Django application which integrates with a message queue done using RabbitMQ. It can be used to create and manage users, servers, and video files. It's also the frontend for statistics of the entire system.

3) RabbitMQ

The RabbitMQ server is a central component of the project. All the messages between the servers pass through it. When a user uploads a new file, the ftpserver component sends a message that is removed by the cdnmanager, telling it that a new file just arrived and that it needs to be distributed. The cdnmanager checks the distribution policy associated with the file, and creates jobs for the cdnservers to do.

4) ftpput

A simple testing tool, just to send files for the ftpserver automatically.

COMPONENTS OF THE CDN SERVER

1) cdnserver

This is the component in the server that talks to the message queue to receive commands for file syncronization. It also collects statistics of the nginx server and sends to the central node.