CODEWITHSUNDEEP
jupyter-notebookjupyter
ejang
ejang

Reputation: 4062

Send json data to Jupyter Notebook Frontend via Comm

I want to send some arbitrary data to the Jupyter Notebook frontend.

According to http://jupyter-client.readthedocs.org/en/latest/messaging.html#opening-a-comm, the Comm protocol is a way to send custom message types without resorting to hacks like using execute_request msg_type.

On the Python side, I have

from ipykernel.comm import Comm 
c=Comm()
#c.open()
#c.send(data={'foo':'bar'})

However, on the JavaScript side I get an error on initializing Comm():

Error: Class comm not found in registry at http://localhost:8888/static/notebook/js/main.min.js?v=40e10638fcf65fc1c057bff31d165e9d:12751:28 at Object.load_class (http://localhost:8888/static/notebook/js/main.min.js?v=40e10638fcf65fc1c057bff31d165e9d:12736:16) at CommManager.comm_open (http://localhost:8888/static/notebook/js/main.min.js?v=40e10638fcf65fc1c057bff31d165e9d:21802:37) at x.isFunction.i (http://localhost:8888/static/notebook/js/main.min.js?v=40e10638fcf65fc1c057bff31d165e9d:89:5488) at Kernel._handle_iopub_message (http://localhost:8888/static/notebook/js/main.min.js?v=40e10638fcf65fc1c057bff31d165e9d:23101:20) at Kernel._finish_ws_message (http://localhost:8888/static/notebook/js/main.min.js?v=40e10638fcf65fc1c057bff31d165e9d:22936:29) at http://localhost:8888/static/notebook/js/main.min.js?v=40e10638fcf65fc1c057bff31d165e9d:22926:44

What does this error mean?

Upvotes: 4

Views: 1987

Answers (1)

ejang
ejang

Reputation: 4062

Figured it out - IPyWidgets notebook extension provides nice examples of how to do this: https://github.com/ipython/ipywidgets

On the JS side:

var comm_manager=Jupyter.notebook.kernel.comm_manager
var handle_msg=function(msg){
    console.log('got msg'); 
    console.log(msg)
}

comm_manager.register_target('myTarget', function(comm,msg){
    console.log('opened comm');
    console.log(msg);
    // register callback
    comm.on_msg(handle_msg)
})

Then in Python,

from ipykernel.comm import Comm 
c=Comm(target_name='myTarget',data={})
c.send('hello')

The response in the browser console:

opened comm
VM4511:3 Object {parent_header: Object, msg_type: "comm_open", msg_id: "331ba915-0b45-4421-b869-7d9794d72113", content: Object, header: Object…}
VM4464:2 got msg
VM4464:2 Object {parent_header: Object, msg_type: "comm_msg", msg_id: "9fdc83c8-49c5-4629-aa43-7ddf92cb4f5e", content: Object, header: Object…}

Upvotes: 10

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