Yes, it is. We've built in a way to gain access to the rendering context. There, you can access data on the current document (called the NodeLibrary internally).

So you could create a node with one part called "context" of (custom) type "context". This will take in a NodeContext. Then you can write something like this (in Python):

def cook(context):
    library = context.nodeLibrary
    width = float(library.getProperty("canvasWidth"))
    height = float(library.getProperty("canvasWidth")) 
    # Do whatever you want with width / height

Hope this helps,

F