How to correctly use kernel.execute method of Jupyter notebook in Javascript (timing issues)?

* I would expect the shell callback to be called after the iopub callback but it seems to be the other way around. Is this the expected behavior? Also see following SO question for details:

https://stackoverflow.com/questions/55828900/how-to-correctly-use-kernel-execute-method-of-jupyter-notebook-in-javascript-ti

* I would like to pass some SQL query from JavaScript to Python and use Python to execute the query. That works in principle. However, the data that I can pass back from Python to JavaScript seems to be limited to about 60 lines. For large dataFrames only some sort of preview is returned.

Also see
https://stackoverflow.com/questions/32974051/ipython-notebook-using-javascript-to-run-python-code

* I could not find out how to retrieve the html output that corresponds to some executed python code. Please allow to do so and improve documentation about the execute method and its callback object.

Also see
https://stackoverflow.com/questions/55849165/how-to-retrieve-html-output-from-jupyter-notebook-kernel-execute-method

Start with the Jupyter kernel.execute API and its shell and iopub callbacks. Investigate the callback object and how large data-frame results and HTML output are returned; done would mean documented callback ordering, reliable result retrieval, and clear guidance for these use cases.

Written by the indexing model from the issue text.