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My first web app (Python): use CGI, or a framework like Django?

I don’t want to burden you all with the details, but basically I’m a 2nd year compsci student with no Web dev experience.
Basically I want to create a small “web app” that takes in input from a html form, have a python script perform some calculations, and re-display those results in your browser.
As of right now, I have the form and script built. However, when I try to test the form, instead of running the script, my browser tries to download it. To my understanding, this is a cgi script problem, and that I must create a web server in order to test this script.
And heres were I’m stuck. I know little to nothing about web servers and how to set them up. On top of that I’ve heard that GCI scripting is a thing of the past, and requires major overhead in order to run properly.
This leads to my questions. How do I go about completing my app and testing my cgi script? Do I install apache and mess around with it or should I be looking into something like google app engine? Are there other ways to complete this task without cgi scripts? Where do frameworks like Django fit into this?

Django, while being nice, all-encompassing and well-supported, is sometimes too much for a small web application. Django wants you to play by its rules from the beginning, you'll have to avoid things like the database and admin panels if you don't need them. It's also easier, with Django, to follow its project layout, even when it's too complex for a simple app.
The so-called micro frameworks might suit you better for your small app. They are built upon the opposite principle: use the bare minimum of features now, add more as you need them.
Flask is based on Werkzeug WSGI library and Jinja2 templating (the latter is switchable), is extensively documented (with notes concerning virtualenv and stuff) and well-suited for small and larger apps alike. It comes bundled with an auto-reloading dev server (no need for Apache on your dev machine) and Werkzeug-powered interactive debugger. There are extensions for things like HTML forms and database ORM.
Bottle is as small as a microframework can get, consisting of 1 (one) file, dev server included. Drop it into your project folder and start hacking. The built-in SimpleTemplate templating engine is switchable, but the dev server is flakier in comparison to Flask's. The documentation is less complete, and, in my opinion, the whole thing is less polished and convenient as Flask.
In both cases, you use dev server locally, and then deploy using WSGI, the server interface for Python web apps which both frameworks support. There are many ways to deploy a WSGI app, Apache mod_wsgi being one of the popular ones.
I'd totally go with Flask unless one dependency (Bottle) is better than three (Flask, Jinja2 and Werkzeug).
(There are many other frameworks as well, so wait for their users to come and tell about them. I'd suggest to avoid web.py: it works, but is full of magic, and is inelegant compared to Flask or Bottle.)

One way of getting to working webapp quickly is by first understanding, and then modifying, something like the App Engine "guestbook" example. This has the benefit that much of the otherwise necessary tedium of running a web server and setting up a database server (assuming you need persistence) is done for you. App Engine also provides a fairly flexible development environment. It's certainly not the only way to go, and I'll admit to bias in recommending it, but it's fairly low friction.
GCI scripting is hardly a thing of the past, though it's not what the cool kids are doing. CGI has the benefit, and the curse, of exposing more of the raw plumbing. It forces you to understand a lot about primitive (in the low-level sense) web architecture, but it's also a bit of a large bite to chew on if you have an immediate problem to solve that can solved by simpler means.

It appears most python web development seems to be done by frameworks these days. There are a couple reasons for this:
a plethora of mature tools. Django has built in user auth, built in database management, built in sessions, built in just about everything ORM which lets you seamlessly supports a couple databases.
Built in webservers. The larger python frameworks like django and pylons have built in webservers. Django has a very simple webserver python manage.py startserver (that simple) That makes it extremely easy to create and debug applications. It is single threaded so dropping a debugger into it is painless
Huge communities. If you have a django question it will be answered very quickly the so community is huge.
The django tutorial will introduce you to all the major aspects of development. It is only 4 pages and you will be able to get your app going a lot simpler than having to read, learn and fiddle with an apache setup.
https://docs.djangoproject.com/en/dev/intro/tutorial01/
Although django for right now might be overkill if your app is just going to be 1 form and a script to process it. Because of its seamless testing framework it is quite easy to grow any project. I have never used flask or bottle or the other microframeworks, but I would keep in mind where your project will be in the future.
As for where django fits into this, it is a full stack framework encompassing presentation (templates), data management (server orm), authentication, middleware, forms ... everything necessary to create a completely inclusive web application. Django and almost all other python frameworks implement the wsgi standard. It is an interface that allows for interoperation between webservers. http://en.wikipedia.org/wiki/Web_Server_Gateway_Interface it is pretty dry and you will never have to interface it directly. That is what these frameworks do under the hood.

Why setup and maintain your own webserver if you can use app engine. It has an excellent SDK for testing your code. Here is an example https://developers.google.com/appengine/docs/python/gettingstarted/handlingforms
And Django you will find here : https://developers.google.com/appengine/docs/python/gettingstarted/templates
I prefer to use Jinja for templating.

Django comes with its own server, but in your case i would recommend apache and mod_python since it seems to be a rather simple site you're building.
Setting up Apache is a breeze and a simple search on the web should give you all you need.
You can find more information on mod_python here read up a little bit on it and then google after a tutorial that fits your needs.

How to develop a simple web application with server-side Python

I am wondering how to go about implementing a web application with Python.
For example, the html pages would link to python code that would give it increased functionality and allow it to write to a database.
Kind of like how Reddit does it.

If you're looking for server side programming with databases and html templates etc, I think Django is great, along with Pyramid. However, I use Flask ( http://flask.pocoo.org/ ) for this since it is easy to use, learn and deploy even though it may not have as much support as the before mentioned 2 framework since it's just a microframework, using the Jinja2 templating engine, including a development test server with it's own debugger.
On the other hand, if you're going for client-side programming (i.e. in browser implementation ) You can look up .NET Ironpython or even Brython which uses python like javascript.

You might want to check out mod_wsgi or mod_python.
What Is mod_wsgi?
The aim of mod_wsgi is to implement a simple to use
Apache module which can host any Python application which supports the
Python WSGI interface. The module would be suitable for use in hosting
high performance production web sites, as well as your average self
managed personal sites running on web hosting services.
-
Current State of Mod_Python
Currently mod_python is not under active development. This does not
mean that it is "dead" as some people have claimed. It smiply means
that the code and the project are mature enough when very little is
required to maintain it.

This is a good article from the Python website:
http://docs.python.org/howto/webservers.html

Plain CGI is a good starting point to learn about server side scripting, but it is an outdated technology and gets difficult to maintain after certain level of complexity. I would think it is no longer used in industrial-grade web server anymore. Plus you have to setup a web server and then install some module to interpret python script (like Apache with mod_python) just to get started.
I had some experience with Django (https://www.djangoproject.com/) and found it fairly easy to get started with since they come with development test server. All you need to have is a Python interpreter + Django and you can get up-and-running quickly and worry about the deployment setup later. They have pretty good documentation for beginner as well.

We have never used Python for a web site without a framework. In our case that is Django. In other words, we do not use Python for our web sites the way Perl can be used, just having Apache run a Perl script.
The recommendations you have received about Django are sound. If you go the Django route, Graham Dumpleton and the modwsgi Google group were very helpful to me. I could
not have gotten mod_wsgi deployed on Red Hat Enterprise 5 64-bit without Graham's help.
Whether you choose Django or "straight" Python, you will need to become familiar with mod_wsgi.
Good luck in quantum time, which means by now, I hope this all worked out for you.

Suggest a standalone python web framework?

I have a python program that I would like to present as a simple web application. The program currently uses sqlite for storage. I also need to distribute the whole thing to colleagues so having something standalone and easy to start would be ideal ( no install if possible). This web app is meant to be used locally , not by multiple users over a network.
Is there a suitable python framework that might fit my needs? I looked at Django so far but it seems a bit heavy handed for what I need.
Thanks for any suggestions.

I have never tried it myself, but you could try Bottle:
Bottle is a fast, simple and lightweight WSGI micro web-framework for
Python. It is distributed as a single file module and has no
dependencies other than the Python Standard Library.

try http://docs.python.org/library/simplehttpserver.html

As web frameworks are not part of the standard lib, you will have to install something in every case. I would propse to look at http://flask.pocoo.org/. It has a build in WSGI server.

Lots of choices for Python web frameworks! Another is web2py which is designed to work out of the box and allows, but doesn't require, through-the-web development. It is mature and has a strong community and is well-documented.

Tornado as a framework may be a lot more than what you're looking for. However it will meet the requirement of being a completely python based web server. http://tornadoweb.org
I generally just download the source, drop it in /tornado/ of my project and do includes there from the app.

I don't think that any web framework is specifically oriented for the use case you're talking about; They all assume they are running on a server and there's a browser on a remote machine that is accessing them.
A better approach is to think about the HTTP server you'll be using. It's probably preferable to use a server that's as easy to pack and ship as the rest of the python code you'll be using. Now most frameworks provide a 'development' server that's easy to invoke from the command line, but most of them are intended to be "easy for the developer" which often means they are restricted to a single thread. This is bad for deployment because single threaded servers will always feel a bit sluggish.
CherryPy stands out in contrast, by providing a full featured, embedded server that's easy to configure for many use cases, and is available by default with the rest of the framework. There are probably others, but I haven't used 'em.

Using python to develop web application

I have been doing some work in python, but that was all for stand alone applications. I'm curious to know whether any offshoot of python supports web development?
Would some one also suggest a good tutorial or a website from where I can pick up some of the basics of web development using python?

Now that everyone has said Django, I can add my two cents: I would argue that you might learn more by looking at the different components first, before using Django. For web development with Python, you often want 3 components:
Something that takes care
of the HTTP stuff (e.g.
CherryPy)
A templating language
to create your web pages.
Mako
is very pythonic and works with Cherrpy.
If you get your data from a
database, an ORM comes in handy.
SQLAlchemy
would be an example.
All the links above have good tutorials. For many real-world use-cases, Django will be a better solution than such a stack as it seamlessly integrates this functionality (and more). And if you need a CMS, Django is your best bet short of Zope. Nevertheless, to get a good grasp of what's going on, a stack of loosely coupled programs might be better. Django hides a lot of the details.

Edited 3 years later: Don't use mod_python, use mod_wsgi. Flask and Werkzeug are good frameworks too. Needing to know what's going on is useful, but it isn't a requirement. That would be stupid.
Don't lookup Django until you have a good grasp of what Django is doing on your behalf. for you. Write some basic apps using mod_python and it's request object. I just started learning Python for web-development using mod_python and it has been great.
mod_python also uses a dispatcher in site-packages/mod_python/publisher.py. Have a ganders through this to see how requests can be handled in a simple-ish way.
You may need to add a bit of config to your Apache config file to get mod_python up and running but the mod_python site explains it well.
<Directory /path/to/python/files>
AddHandler mod_python .py
PythonHandler mod_python.publisher
PythonDebug On
</Directory>
And you are away!
use (as a stupidly basic example):
def foo(req):
req.write("Hello World")
in /path/to/python/files/bar.py assuming /path/to is your site root.
And then you can do
http://www.mysite.com/python/files/bar/foo
to see "Hello World". Also, something that tripped me up is the dispatcher uses a lame method to work out the content-type, so to force HTML use:
req.content_type = 'text/html'
Good Luck
After you have a good idea of how Python interacts with mod_python and Apache, then use a framework that does all the boring stuff for you. Up to you though, just my recommendation

If you really don't want to delve into the frameworks - and you should, I heartily recommend Django or Pylons - there's still need to go down the road of CGI. This is a totally out-of-date technology, not to mention slow and inefficient.
There is a standard way of building Python web applications, and it's called WSGI. If you want to roll your own web app from scratch, this is absolutely the way to go.
That said, if you're just starting out, really you should go with one of the frameworks.

Python Wiki: Web Frameworks for Python
If you decide to use Django, the official tutorial is an excellent place to start. The Django Book is also free.

There are a couple of choices for web development. From my experience, your choice will again be dependent on your application. I used django and web.py in production and I am about to deploy an app based on pylons.
Django hides a lot of choices (comes with its ORM and templating). The documentation is extensive and well-written. There are many reusable app available for django, but you will likely to invest a little time in integrating them seamlessly. One thing mentioned on djangocon 08 was the fact, that there is cool stuff in django, which can't be easily
accessed in non-django projects.
web.py impressed me by its raw simplicity. Before I knew it, I wrote a small app (78 lines quasi-wiki) in it.
pylons feels like in the middle of both. I can use sqlalchemy and jinja, all in all a pleasant experience for the start.

Lookup Django.

Python can be used for web development, but there isn't a special language extension or anything in the language that will handle all the HTML generation or that works like PHP.
It's pretty much run through some sort of interpreter on a web server (CGI, mod_python, etc.).
I would recommend looking into Python Web Application Frameworks or how to write Python CGI scripts.

There are quite a few web frameworks for python out there, but the only one I've used is Django, and I really like it.
If you've got a few hours, do the tutorial, I promise you, you'll enjoy it :)

As others have mentioned, one of the more prominent python "offshoots" as you call them would be Django. It is a rather powerful framework that allows you to quickly and securely build web applications. The first place to look would be their overview which gives some insight as to what Django does as a framework.
Going through their tutorial taught me alot about the prominent Model-View-Controler design pattern and how it may be used in a web-development context. I found it a great way to start writing an application that worked and learn by improving it.

Django -vs- Grails -vs-?

I'm wondering if there's such a thing as Django-like ease of web app development combined with good deployment, debugging and other tools?
Django is a very productive framework for building content-heavy sites; the best I've tried and a breath of fresh air compared to some of the Java monstrosities out there. However it's written in Python which means there's little real support in the way of deployment/packaging, debugging, profilers and other tools that make building and maintaining applications much easier.
Ruby has similar issues and although I do like Ruby much better than I like Python, I get the impression that Rails is roughly in the same boat at Django when it comes to managing/supporting the app.
Has anyone here tried both Django and Grails (or other web frameworks) for non-trivial projects? How did they compare?

You asked for someone who used both Grails and Django. I've done work on both for big projects. Here's my Thoughts:
IDE's:
Django works really well in Eclipse, Grails works really well in IntelliJ Idea.
Debugging:
Practically the same (assuming you use IntelliJ for Grails, and Eclipse for Python). Step debugging, inspecting variables, etc... never need a print statement for either. Sometimes django error messages can be useless but Grails error messages are usually pretty lengthy and hard to parse through.
Time to run a unit test:
django: 2 seconds.
Grails: 20 seconds (the tests themselves both run in a fraction of a second, it's the part about loading the framework to run them that takes the rest... as you can see, Grails is frustratingly slow to load).
Deployment:
Django: copy & paste one file into an apache config, and to redeploy, just change the code and reload apache.
Grails: create a .war file, deploy it on tomcat, rinse and repeat to redeploy.
Programming languages:
Groovy is TOTALLY awesome. I love it, more so than Python. But I certainly have no complaints.
Plugins:
Grails: lots of broken plugins (and can use every java lib ever).
Django: a few stable plugins, but enough to do most of what you need.
Database:
Django: schema migrations using South, and generally intuitive relations.
Grails: no schema migrations, and by default it deletes the database on startup... WTF
Usage:
Django: startups (especially in the Gov 2.0 space), independent web dev shops.
Grails: enterprise
Hope that helps!

However it's written in Python which
means there's little real support in
the way of deployment/packaging,
debugging, profilers and other tools
that make building and maintaining
applications much easier.
Python has:
a great interactive debugger, which makes very good use of Python REPL.
easy_install anv virtualenv for dependency management, packaging and deployment.
profiling features comparable to other languages
So IMHO you shouldn't worry about this things, use Python and Django and live happily :-)
Lucky for you, newest version of Django runs on Jython, so you don't need to leave your whole Java ecosystem behind.
Speaking of frameworks, I evaluated this year:
Pylons (Python)
webpy (Python)
Symfony (PHP)
CakePHP (PHP)
None of this frameworks comes close to the power of Django or Ruby on Rails. Based on my collegue opinion I could recommend you kohana framework. The downside is, it's written in PHP and, as far as I know, PHP doesn't have superb tools for debugging, profiling and packaging of apps.
Edit: Here is a very good article about packaging and deployment of Python apps (specifically Django apps). It's a hot topic in Django community now.

The statement that grails deletes the database on start-up is completely wrong. It's behavior on start-up is completely configurable and easy to configure. I generally use create-drop when running an app in dev mode. I use update when I run in test and production.
I also love the bootstrap processing that lets me pre-configure test users, data, etc by environment in Grails.
I'd love to see someone who has really built and deployed some commercial projects comment on the pros / cons. Be a really interesting read.

Grails.
Grails just looks like Rails (Ruby),but it uses groovy which is simpler than java. It uses java technology and you can use any java lib without any trouble.
I also choose Grails over simplicity and there are lots of java lib (such as jasper report, jawr etc) and I am glad that now they join with SpringSource which makes their base solid.

I have two friends who originally started writing an application using Ruby on Rails, but ran into a number of issues and limitations. After about 8 weeks of working on it, they decided to investigate other alternatives.
They settled on the Catalyst Framework, and Perl. That was about 4 months ago now, and they've repeatedly talked about how much better the application is going, and how much more flexibility they have.
With Perl, you have all of CPAN available to you, along with the large quantity of tools included. I'd suggest taking a look at it, at least.

The "good deployment" issue -- for Python -- doesn't have the Deep Significance that it has for Java.
Python deployment for Django is basically "move the files". You can run straight out of the subversion trunk directory if you want to.
You can, without breaking much of a sweat, using the Python distutils and build yourself a distribution kit that puts your Django apps into Python's site-packages. I'm not a big fan of it, but it's really easy to do.
Since my stuff runs in Linux, I have simple "install.py" scripts that move stuff out of the Subversion directories into /opt/this and /opt/that directories. I use an explicit path settings in my Apache configuration to name those directories where the applications live.
Patching can be done by editing the files in place. (A bad policy.) I prefer to edit in the SVN location and rerun my little install to be sure I actually have all the files under control.

cakephp.org
Cakephp is really good, really close to ruby on rails (1.2). It is in php, works very well on shared hosts and is easy to implement.
The only downside is that the documentation is somewhat lacking, but you quickly get it and quickly start doing cool stuff.
I totally recommend cakephp.

Personally I made some rather big projects with Django, but I can compare only with said "montrosities" (Spring, EJB) and really low-level stuff like Twisted.
Web frameworks using interpreted languages are mostly in its infancy and all of them (actively maintained, that is) are getting better with every day.

By "good deployment" are you comparing it with Java's EAR files, which allow you to deploy web applications by uploading a single file to a J2EE server? (And, to a lesser extent, WAR files; EAR files can have WAR files for dependent projects)
I don't think Django or Rails have gotten quite to that point yet, but I could be wrong... zuber pointed out an article with more details on the Python side.
Capistrano may help out on the Ruby side.
Unfortunately, I haven't really worked with either Python or Ruby that much, so I can't help out on profilers or debuggers.