So I've done some reading about Python web frameworks (or servers?), mostly Tornado and Bottle but also FAPWS3, and there are still some grey areas.
First, these three web frameworks are all said to be fast, yet they all include a web server written in Python (except FAPWS3) which should be put behind nginx/Apache. Isn't this reducing the performance? I mean, we know that Python is much slower than C, why not only use nginx, or at worst, only the included Python web server?
First of, Tornado and FAPWS3 are web servers, while Bottle is a web framework. Those belong to completely different categories.
Web frameworks are usually run as a WSGI server behind a HTTP ("web") proxy. The HTTP server included in most frameworks is only there for fast development and deployment and easy deployment on sites where high efficiency doesn't matter.
The idea is basically that the HTTP Server (Apache/Lighttpd/Nginx/Tornado/FAPWS3 etc) is very good at understanding HTTP and serving static files from the disk. The dynamic content on the other hand is generated by a Python server using a web framework like Bottle/Flask/web.py/Pylons/etc. The document produced by the web framework is then sent back to the HTTP server over WSGI, put in a HTTP Response and sent to the client.
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I am a .net developer coming over to python. I have recently started using Flask and have some quick questions about serving files.
I noticed a lot of tutorials focused on nginix and flask. However, I am able to run flask without nginx. I'm just curious as to why this is used together (nginx and flask). Is nginx only for static files?
Nginx is a proxy server, imagine your apps have multiples microservices on differents languagues.
For more info NGINX REVERSE PROXY
On a development machine flask can be run without a webserver (nginx, apache etc) or an application container (eg uwsgi, gunicorn etc).
Things are different when you want to handle the load on a production server. For starters python is relatively very slow when it comes to serving static content where as apache / nginx do that very well.
When the application becomes big enough to be broken into multiple separate services or has to be horizontally scaled, the proxy server capabilities of nginx come in very handy.
In the architectures I build, nginx serves as the entry point where ssl is terminates and the rest of the application is behind a VPN and firewall.
Does this help?
From http://flask.pocoo.org/docs/1.0/deploying/ :
"While lightweight and easy to use, Flask’s built-in server is not suitable for production as it doesn’t scale well. Some of the options available for properly running Flask in production are documented here."
I need to create a REST server of a python module/API of a BCI, so that the application can be accessed on my Drupal website. Will I need to create and host the REST server on a python-based website or CMS, so that it can be accessed by my Drupal website, or is the api and rest server uploaded and hosted directly on my web hosting server? If so, what is the simplest python CMS that for creating a REST server for a python module/API already available?
The beauty of REST is precisely that it doesn't matter where your API is, as long as its accessible from your Drupal server, or from the client if you have a javascript API client.
If it's a simple application and you have admin access to your Drupal server, there's nothing preventing you from hosting the Python webservice side-by-side. They may even share the same HTTP Server, like Apache or Nginx, although depending on your demands on each one it might be better to keep them separate.
If you're new to Python, the Flask framework is a decent option to write a simple REST-like API interfacing with a Python module.
I been using python to create an web app and it has been doing well so far. Now I would like to encrypt the transmission of the data between client and server using https. The communication is generally just post form and web pages, no money transactions are involve. Is there anything I need to change to the python code except setting the server up with certificate and configurate it to use https? I see a lot of information regarding ssl for python and I not sure if I need those modules and python setup to make https work.
Thanks
Typically, the ssl part for Python web app is managed by some frontend web server like nginx, apache or so.
This does not require any modification of your code (assuming, you are not expecting user to authenticate by ssl certificate on client side, what is quite exotic, but possible scenario).
If you want to run pure Python solution, I would recommend using cherrypy, which is able providing rather reliable and performant web server part (it will be very likely slower then served behind nginx or apache).
What type of server Django uses when "runserver" command is ran? Documentation says more or less that it's "lightweight development Web server". Is it for example Apache? Thanks in advance.
It's exactly what it says on the tin - a simple, lightweight web server implemented in Python that ships with Django and is intended for development purposes only. It's not a free-standing web server in its own right and is intended purely for developing applications with Django - you should never use it in production because it simply doesn't offer all the functionality you need in a production web server.
A web server can be implemented in virtually any programming language, and so it makes sense to ship one implemented in Python with Django in order that you can get working with it immediately without having to install something like Apache as well. Most web servers that might be used in production, such as Apache and Nginx, are written in C so it wouldn't really be practical to ship them with Django.
Also, shipping your own development server cuts down on complexity. Apache and Nginx are both complex pieces of software that require a fair amount of configuration, and while there are ways to automate that during development, it's not something you really want to have to deal with when you'd rather be writing code. All you need to get you started is something that will serve static and dynamic content - you don't need a lot of the other functionality required. It's notable that even PHP now ships with a development server.
When you go live with a Django project, you should use of course use a proper web server. It's generally recommended that with Django, in production you should use two web servers, one to serve static content, the other to serve dynamic content, because involving Django in serving static content will slow it down. This sounds odd at first, but it actually makes a lot of sense, because what you do is set one web server to serve all the static content, then have it reverse proxy to the other server, which is running on a non-standard port, and serves all the dynamic content. The setup I have for my current project is Nginx for the static content, with Gunicorn for the dynamic content.
I have been working with Django for some time now and have written several apps on a setup that uses Apache 2 mod_wsgi and a PostgreSQL database on ubuntu.
I have aa app that uses xsendfile to serve files from Apache via a Django view, and also allow users to upload files via a form as well. All this working great, but I now want to ramp up the features (and the complexity I am sure) by allowing users to chat and to see when new files have been uploaded without refreshing their browser.
As I want this to be scale-able, I don't want to poll continually with AJAX as this is going to get very heavy with large numbers of users.
I have read more posts, sites and blogs then I can count on integrating comet functionality into a Django app but there are so many different opinions out there on how to do this that I am now completely confused.
Should I be using orbited, gevent, iosocket?
Where does Tornado fit into this debate?
I want the messages also be stored on the database, so do I need any special configuration
to prevent my application blocking when writing to the database?
Will running a chat server with Django have any impact on my ability to serve files from Apache?
I'd recommend using WebSockets for bidirectional realtime communication. Keep running Django as is and run a WebSocket server on another port. As far as your database blocking, yes, you'll need to keep that in mind as you write your WebSocket server and either use a non-blocking database driver, or address that in some way.
Client-side you'll want to use Socket.IO or web-socket-js to support flash fallback for older browsers which don't support flash.
For the server, I would lean towards gevent or tornado, personally. For gevent there is gevent-websocket and gevent-socketio, for tornado you get built-in WebSocket support and can use tornadio if you want to use Socket.IO. Eventlet and twisted both support WebSockets as well. There is also a pretty cool new project called autobahn which is built on twisted, and meinheld has WebSocket middleware you can use.
WebSockets are pretty exciting, and as such there are tons of great posts out there on the subject. I found these posts useful:
http://gehrcke.de/2011/06/the-best-and-simplest-tools-to-create-a-basic-websocket-application-with-flash-fallback-and-python-on-the-server-side/
http://codysoyland.com/2011/feb/6/evented-django-part-one-socketio-and-gevent/
http://toastdriven.com/blog/2011/jul/31/gevent-long-polling-you/
http://blog.jupo.org/post/8858247674/real-time-web-apps-with-django-and-websockets/
Instead of Apache + X-Sendfile you could use Nginx + X-Accel-Redirect. That way you can run a gevent/wsgi/django server behind Nginx with views that provide long-polling. No need for a separate websockets server.
I've used both Apache + X-Sendfile and Nginx + X-Accel-Redirect to serve (access-protected) content on Webfaction without any problems.