Creating new compositing nodes in python

I created a new node, but I do not know how to realise actions to it
Which function is called when used the node?

self_node.blend (520 KB)

(open scene and run script to add new node to compositor)

Any ideas?

I don’t think Blender supports custom node sockets of the image type yet. Making a purely python based compositor node can not be done using the 2.71 API. You can, of course, make a node that relays a string or number to another node.

What is your node supposed to accomplish?

custom glsl fragment shaders for fast images processing

You can’t write node for the compositor/cycles and similar using python and pynodes, you have write it in c/c++. You can only make the interface parts of nodes, and for limited cases like the one atom suggests above you can do, but that is not what you want.