Connection issues with own metakernel

[freifrauvonbleifrei]

Hi,

I have recently ported my own Python-based Jupyter kernel to derive from metakernel instead of ipykernel.
Since then, I had the following issues:

• I get "forbidden" errors such as

[W 14:42:21.580 NotebookApp] Forbidden
[W 14:42:21.580 NotebookApp] 403 GET /api/config/common?_=1520862141398 (127.0.0.1) 1.43ms referer=http://localhost:8889/notebooks/ ...

which is possibly resolved by using the --NotebookApp.token='' flag

• The %connect_info magic gives this info:

{
  "stdin_port": UNKNOWN,
  "shell_port": UNKNOWN,
  "iopub_port": UNKNOWN,
  "hb_port": UNKNOWN,
  "ip": "UNKNOWN",
  "key": "UNKNOWN",
  "signature_scheme": "UNKNOWN",
  "transport": "UNKNOWN"
}

which should be more sensible, comparing to the metakernel echo example.

• when playing around with matplotlib, I got errors saying that there are no comm and interactive shell instances - but then I am not sure if there should be.

Any ideas on what is happening here?
I think that I have adapted the necessary lines from the examples to my kernel.
Do you have recommendations on how to debug these errors?

[dsblank]

Looking into this...