Online Shell for SymPy (sympy-live) is a simple web application based on Google App Engine, which allows to evaluate Python code with SymPy in web browsers.

This is accomplished by providing a HTML/JavaScript GUI for entering source code and visualization of output, and a server part which evaluates the requested source code. Note that this shell is not scalable and it uses only one instance on GAE, thus all evaluation requests are queued and it make take quite a lot of time, before our code can be evaluated (depending on the current load of the instance).

Google App Engine has intrinsic 30 second request handling limit, so each evaluation request is a subject to this limit. There are also other limits related to memory consumption, output size, etc. (see Google App Engine documentation for details).

Download and unpack most recent Google App Engine SDK for Python from http://code.google.com/appengine/downloads.html, e.g.:

$ wget http://googleappengine.googlecode.com/files/google_appengine_1.5.1.zip
$ unzip google_appengine_1.5.1.zip

On the Mac, it is a disk image with an application, which you should drag to your Applications folder. Open the program and install the symlinks (it should ask you the first time you open the application, but if it doesn't, choose "Make Symlinks..." from the GoogleAppEngineLauncher menu).

Then clone sympy-live repository:

$ git clone git://github.com/sympy/sympy-live.git
$ cd sympy-live

We use submodules to include external libraries in sympy-live:

$ git submodule init
$ git submodule update

This is sufficient to clone appropriate repositories in correct versions into sympy-live (see git documentation on submodules for information).

Now you are ready to run development web server:

$ ../google_appengine/dev_appserver.py .

On the Mac, just run:

$ dev_appserver .

(make sure you installed the symlinks as described above).

I couldn't figure out how to make it work in the GUI (it won't find the sympy git submodule). If you figure out how to do it, please update this file and send a patch describing how to do it.

This is a local server that runs on port 8080 (use --port option to change this). Open a web browser and go to http://localhost:8080. You should see GUI of SymPy Online Shell.

Assuming that sympy-live works properly (also across different mainstream web browsers), you can upload your changes to Google App Engine:

$ ../appcfg.py update .

This requires admin privileges to http://sympy-live.appspot.com. If you don't have access to this App Engine application, you can make your own. To achieve this, create an account on Google App Engine, start a new application and make appropriate changes to app.yaml (replace in the first line sympy-live with the name of your application). Then you can use appcfg.py as above, to upload to GAE.

Make sure SymPy Online Shell works in major mainstream web browsers. This includes Chrome, Firefox, Safari and Internet Explorer. Be extra cautious about trailing commas in JavaScript object and arrays. IE doesn't allow them, so you have to remove them, if any were introduced.

GAE development server allows to use any Python interpreter, but Google App Engine uses Python 2.5, so if the default Python isn't 2.5, then make sure to test your changes to the server part, if it runs properly on 2.5. Also don't use any modules that aren't supported by GAE.

In projects that don't use submodules, pulling changes boils down to:

$ git pull origin master

in the simplest case. SymPy Live, however, requires additional effort:

$ git submodule update

The above command assures that if there were any changes to submodules of the super-project, then those submodules will get updated to new versions. This is related to the following section.

Make sure that you followed instructions above and SymPy's submodule is properly initialized. Assuming that you are in the directory where SymPy Live was cloned, issue:

$ cd sympy/
$ git fetch origin
$ git checkout sympy-0.7.0
$ cd ..
$ git add .
$ git ci -m "Updated SymPy to version 0.7.0"

Now if you issue:

$ git show -v

you should get:

commit 5138e824dc9fd46c243eea2d7c9581a9e58feb08
Author: Mateusz Paprocki <mattpap@gmail.com>
Date:   Wed Jul 6 07:45:19 2011 +0200

    Updated SymPy to version 0.7.0

    diff --git a/sympy b/sympy
    index df7a135..c9470ac 160000
    --- a/sympy
    +++ b/sympy
    @@ -1 +1 @@
    -Subproject commit df7a135a4ff7eca361ebbb07ccbeabf8654a8d80
    +Subproject commit c9470ac4f44e7dacfb026cf74529db3ec0822145

This was done for SymPy's version 0.7.0, so in future updates of SymPy replace 0.7.0 with appropriate newer version (e.g. 0.7.1) and you are done (of course particular SHA signatures will be different in your case). If unsure, refer to git help submodule or git book: http://book.git-scm.com/5_submodules.html.

An interactive, stateful AJAX shell that runs Python code on the server.

Part of http://code.google.com/p/google-app-engine-samples/.

May be run as a standalone app or in an existing app as an admin-only handler. Can be used for system administration tasks, as an interactive way to try out APIs, or as a debugging aid during development.

The logging, os, sys, db, and users modules are imported automatically.

Interpreter state is stored in the datastore so that variables, function definitions, and other values in the global and local namespaces can be used across commands.

To use the shell in your app, copy shell.py, static/, and templates/ into your app's source directory. Then, copy the URL handlers from app.yaml into your app.yaml.