In this blog, I will cover a policy based forwarding application that I wrote in Python.

Use case:

There are many scenarios where regular routing decisions do not suffice and customers want more fine grained control over paths their traffic takes. This could be because of security reasons, better link utilization, vpn concerns etc. Following scenarios are covered in the application.

• Traffic type(Either cos based or L4 based)
• Time of the day
• Bandwidth based

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In this blog, I will cover Python REST library that I wrote to simplify writing Python ODL applications.

In an earlier blog, I had indicated that the primary programming language choice for ODL applications is either Java or Python.

Following is my experience in Python programming with Opendaylight.

• Python programming model for ODL is using REST api to talk to Controller, so control is limited to what REST api provides. There are few things that are not possible(or atleast I have not figured out) like sending/receiving packets from the Controller, getting asynchronous event based callback to Python.
• REST api returns data either in xml or json format. Python has in-built json parser that makes it very easy to manipulate data coming back from the controller.
• Python has a lot of standard libraries so there is a lot of code reuse.
• There is plenty of documentation and tutorials in the web for Python, so learning Python is straightforward. For folks familiar with C, Perl or any scripting language, learning Python should be straightforward. Python supports object-oriented programming though I have not used it.

Continue reading Python REST Library for Opendaylight →