How to run d3js at server-side in a Python web application (Heroku)?

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votes

In my web application, the user is able to draw some objects. The drawing functionality is implemented (at client-side) using d3js (SVG). The attributes of the objects (shape, coordinates, colours) are saved at server-side in a structured database.

Now, I need to render the drawings at server-side as well. I would like to reuse (at server-side) the rendering logic implemented at client-side. That is, to obtain a SVG (then convert it to PNG / PDF), given the object attributes saved in the database.

I see (at least) the following options:

  • install NodeJS on Heroku as well, and execute node from my Python web application. This would require JSDOM if I understood well - see this;
  • use ghost.py to open a local HTML file that does the actual rendering (using d3js);
  • send the rendered SVG from client-side to the back-end - this is a poor choice, though.

What is your recommendation?

Later edit

Ghost.py is not an option, since it requires PyQt or PySide, neither of which can be installed on Heroku. See this.

PhantomJS seems a great choice.

Some references

Migrate from jsdom to phantomJS ? (basic DOM creation)

Server-side rendering of visualisations using NodeJS

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pythonnode.jsd3.jsherokusvg

1 Answers

1
votes

I wouldn't recommend the third option because going back and forth from client to server can cause issues, and best to avoid it.

The first option would work, but then you have a whole framework for one specific problem.

I like the second option, using ghost.py, because it's conceptually easy to understand, and very lightly couples with other parts of the codebase, which is always a goal in well written projects.

You can also use phantomJS to run this (or something like it), which is the same kind of approach as ghost.py, but straight to the javascript.