To clarify, Futures is required for bokeh server as an extra dependency on Python 2.7 since it's not a battery included like for Python > 3.2.. if you conda install Bokeh it should be installed already for you. You can find more info about the bokeh server features here: http://bokeh.pydata.org/en/latest/docs/user_guide/server.htm... and here: http://bokeh.pydata.org/en/latest/docs/user_guide/cli.html#m...
Flexx, on other hand, is not required by bokeh server itself but instead to define python functions to handle interactivity that runs on the browser (no need of bokeh server). Flexx is used to convert python to JS. You can find more info here: http://bokeh.pydata.org/en/latest/docs/user_guide/interactio...