[IPython-dev] make ipython work over web

[Ondrej Certik]

On Sat, Mar 27, 2010 at 11:42 AM, Brian Granger <ellisonbg at gmail.com> wrote:
> Ondrej,
>
>> Ok. Here is my API (so far I have no sessions there):
>>
>> In [1]: import jsonrpclib
>>
>> In [2]: s = jsonrpclib.SimpleServerProxy("http://2.latest.sympy-gamma.appspot.com/test-service/")
>>
>> In [3]: s.eval_cell("2+3")
>> Out[3]: '5'
>>
>> In [4]: s.eval_cell("""\
>>   ...: from sympy import sin, integrate, var
>>   ...: var("x")
>>   ...: integrate(sin(x), x)
>>   ...: """)
>> Out[4]: '-cos(x)'
>>
>> In [5]: s.eval_cell("""\
>>   ...: from sympy import sin, integrate, var
>>   ...: var("x")
>>   ...: a = integrate(sin(x), x)
>>   ...: """)
>> Out[5]: ''
>>
>> In [6]: s.eval_cell("a.diff(x)")
>> Out[6]: 'sin(x)'
>
> OK, if this is the only API you want, it is possible.  BUT, a few points:
>
> * It is completely blocking and synchronous.  We can create such an
> API using 0MQ, but it obviously has limitations.
> * It handles stdout in a completely synchronous manner.  I think we
> can do this too (again limitations apply).
>
> You are going to have to work *very* hard using json-rpc alone to get
> asynchronous stdout/stderr/displayhook.  Here is the design that you
> want that will entirely do what you want:
>
> client<--jsonrpc-->bridge<--0MQ-->kernel
>
> The bridge would be a fully asynchronous 0MQ client and would receive
> the asynchronous 0MQ stdout/stderr/displayhook and simply put them in
> queues.  The bridge would also be a json-rpc server.  with methods
> like:
>
> eval_cell  # submit but don't block. get back an object that would
> allow you to see if the cell was done evaluating.
> complete # again submit but don't return.  Similar logic.
> get_stdout  # get all the stdout that has been written thus far
> get_stderr  # get all stderr that has been written thus far.
>
> You basically want to put a blocking API on top of the asynchronous 0MQ API.
>
> This type of thing should be be too difficult to write using 0MQ and
> we can help out.  If you are serious about this, let me know and
> Fernando and I can come up with a plan.
> We could probably develop this in the pyzmq tree for now.

My primary concern is the notebook. What is your idea to implement the
asynchronous output update? Let me look at how Sage does it.

As to json-rpc, it is not blocking, that's just how I like to use it
in ipython. But below the hood, it works exactly as you said, e.g. you
get some id back immediately and then your method gets called (in
pyjamas) when the result is back. I don't know how this is done
internally. I think it's just how AJAX works (the browser calls your
javascript method when the result is back).

So I need to do more studying myself now, I know what I want (notebook
working fine, and a nice API), I don't know how to do it.

Ondrej