Closed. This question needs to be more focused. It is not currently accepting answers.
Want to improve this question? Update the question so it focuses on one problem only by editing this post.
Closed 9 years ago.
Improve this question
I am new to Python and i am not able to understand the server concepts in Python.
First of all what is WSGI and what are Wsgiref and Werkzeug and how are they different from CherryPy WSGI Server, Gunicorn, Tornado (HTTP Server via wsgi.WSGIContainer), Twisted Web, uWSGI, Waitress WSGI Server.
If i need to develop a web application from scratch, i mean starting from the beginning, where should i start, my company needs a custom framework and the application is based on critical performance overheads.
Please help and explain how they are different.
P.S I am not a beginner to programming.
WSGI is just a set a rules to help unify and standardize how Python applications communicate with web servers. It defines both how applications should send responses and how servers should communicate with applications and pass along the environment and other details about the request. Any application that needs to communicate with any web server implements WSGI, because its the de-facto standard and recommended method for Python. WSGI came about to unify the other implementations (CGI, mod_python, FastCGI).
wsgiref is a reference implementation of the WSGI interface. Its like a blueprint to help developers understand how to implement WSGI in their own applications.
The other things you mentioned are all different applications that implement the WSGI standard; with some exceptions:
Twisted is a library to create applications that can communicate over a network. Any kind of network, and any kind of applications. Its not limited to the web.
Tornado is similar to Twisted in that it is also a library for network communication; however it is designed for non blocking applications. Things that require a long open connection to the server (like say, an application that displays realtime feeds).
CherryPy is a very minimal Python framework for creating web applications. It implements WSGI.
Werkzeug is a library that implements WSGI. So if you are developing an application that needs to speak WSGI, you would import werkzeug because it provides all various parts of WSGI that you would need.
uWSGI is a project that allows easily hosting of multiple web applications. The fact that it as WSGI in the name is because WSGI was the first plugin that was released with the application. It is perhaps the odd duck in this list because it is not a development framework, but more of a way to manage multiple web applications.
Web servers that implement WSGI can talk to any application that also implements WSGI. modwsgi is a popular implementation of WSGI for webservers; it is available for both Apache and Nginx and for IIS there is the isapi wsgi module.
Related
I want to build an web application using python as a backend so, as I did not learned any of the web frameworks that are available for python I want to know is there any way to create backend for an app without frameworks.
While there is a discussion in the comments about the utility of frameworks, I am trying to answer the question at its face value.
WSGI
Python frameworks like Flask and Django both at the end are WSGI applications. WSGI (Web Service Gateway Interface) is a PEP specification which defines how the server and client must communicate. If I were to start from scratch, I would probably start with learning about WSGI and even try implementing a little ping-pong server with it. The read the docs page here https://wsgi.readthedocs.io/en/latest/learn.html lists a number of pages to learn about it.
Werkzeug
Once the WSGI specs are understood then one can attempt building a simple library that will wrap the core concepts into reusable functions and modules for easily writing an application. Here Werkzeug can be a good guide to make one understand the different aspects. https://www.palletsprojects.com/p/werkzeug/
Your own application
Based on the understanding of the WSGI spec and the Werkzueg library you can go on to write your applications either from scratch, or write a library like werkzueg yourself and then use it to write an application.
Finally reimplement the same app in Flask or Django to see what frameworks offer.
If it's something small for internal use you can use
https://docs.python.org/3/library/http.server.html
I created a RESTful application in Python. I'm now trying to know what kind of server I should use to deploy the application. Currently I'm looking at Gunicorn, which is a WSGI server. But I often hear about this popular web-server Apache as well.
So my questions are:
What is the difference between the WSGI and web-server?
If I don't need a public domain (i.e. my application only needs to
run within the private network), should I use WSGI or a web-server?
WSGI is the standard interface for running Python web server applications. Python frameworks already implement this standard so you don't need to worry about this. There is no point in using apache if your application is written in Python.
I'm looking at the WSGI specification and I'm trying to figure out how servers like uWSGI fit into the picture. I understand the point of the WSGI spec is to separate web servers like nginx from web applications like something you'd write using Flask. What I don't understand is what uWSGI is for. Why can't nginx directly call my Flask application? Can't flask speak WSGI directly to it? Why does uWSGI need to get in between them?
There are two sides in the WSGI spec: the server and the web app. Which side is uWSGI on?
Okay, I think I get this now.
Why can't nginx directly call my Flask application?
Because nginx doesn't support the WSGI spec. Technically nginx could implement the WSGI spec if they wanted, they just haven't.
That being the case, we need a web server that does implement the spec, which is what the uWSGI server is for.
Note that uWSGI is a full fledged http server that can and does work well on its own. I've used it in this capacity several times and it works great. If you need super high throughput for static content, then you have the option of sticking nginx in front of your uWSGI server. When you do, they will communicate over a low level protocol known as uwsgi.
"What the what?! Another thing called uwsgi?!" you ask. Yeah, it's confusing. When you reference uWSGI you are talking about an http server. When you talk about uwsgi (all lowercase) you are talking about a binary protocol that the uWSGI server uses to talk to other servers like nginx. They picked a bad name on this one.
For anyone who is interested, I wrote a blog article about it with more specifics, a bit of history, and some examples.
NGINX in this case only works as a reverse proxy and render static files not the dynamic files, it receives the requests and proxies them to the application server, that would be UWSGI.
The UWSGI server is responsible for loading your Flask application using the WSGI interface. You can actually make UWSGI listen directly to requests from the internet and remove NGINX if you like, although it's mostly used behind a reverse proxy.
From the docs:
uWSGI supports several methods of integrating with web servers. It is also capable of serving HTTP requests by itself.
WSGI is just an interface specification, in simple terms, it tells you what methods should be implemented for passing requests and responses between the server and the application. When using frameworks such as Flask or Django, this is handled by the framework itself.
In other words, WSGI is basically a contract between python applications (Flask, Django, etc) and web servers (UWSGI, Gunicorn, etc). The benefit is that you can change web servers with little effort because you know they comply with the WSGI specification, which is actually one of the goals, as stated in PEP-333.
Python currently boasts a wide variety of web application frameworks, such as Zope, Quixote, Webware, SkunkWeb, PSO, and Twisted Web -- to name just a few 1. This wide variety of choices can be a problem for new Python users, because generally speaking, their choice of web framework will limit their choice of usable web servers, and vice versa.
A traditional web server does not understand or have any way to run Python applications. That's why WSGI server come in. On the other hand Nginx supports reverse proxy to handle requests and pass back responses for Python WSGI servers.
This link might help you: https://www.fullstackpython.com/wsgi-servers.html
There is an important aspect which we are missing . Flask and Django are web frameworks and we build web applications out of them . uWSGI or Gunicorn process the framework files . Consider it as a software application sitting in between the Django app and Nginx . uWSGI and Nginx communicate using WSGI but there is no communication interface between Django and uWSGI . Check out this video https://www.youtube.com/watch?v=WqrCnVAkLIo
In simple terms, just think of an analogy where you are running a CGI or PHP application with Nginx web server. You will use the respective handlers like php-fpm to run these files since the webserver, in its native form doesn't render these formats.
Closed. This question needs details or clarity. It is not currently accepting answers.
Want to improve this question? Add details and clarify the problem by editing this post.
Closed 7 years ago.
Improve this question
I built an application on my local machine with Python and Django. Its working fine. Now, I would like to automate the process to start my Django application on a production server.
What I have to do to achieve that?
Django documentation don't recommend to use Django built-in server on production.
DO NOT USE THIS SERVER IN A PRODUCTION SETTING. It has not gone
through security audits or performance tests. (And that’s how it’s
gonna stay. We’re in the business of making Web frameworks, not Web
servers, so improving this server to be able to handle a production
environment is outside the scope of Django.)
It's recommended to use gunicorn or uWSGI to launch your WSGI application :
- How to use Django with gunicorn
- How to use Django with uWSGI
Another good practice, it's to use supervisord to start your process, Then if it dies or get killed for some reason, supervisord will restart this process.
And to finish, use nginx or apache as proxy server, which are strong server that can handle the charge. Most of tutorials or documentations, recommend to use nginx because it's a high-performance HTTP server.
NGINX is a free, open-source, high-performance HTTP server and reverse
proxy, as well as an IMAP/POP3 proxy server. NGINX is known for its
high performance, stability, rich feature set, simple configuration,
and low resource consumption.
Check this to know how to configure them :
- Deploying Gunicorn with nginx
- Deploying uWSGI with nginx
Also before deploy your Django app, read this checklist, to make sure everything is well configured : Django - Deployment checklist
With this architecture and tools, you will be able to launch your gunicorn process with a simple supervisord command. That's all. Then gunicorn will launch your WSGI application.
Closed. This question needs to be more focused. It is not currently accepting answers.
Want to improve this question? Update the question so it focuses on one problem only by editing this post.
Closed 3 years ago.
Improve this question
I am completely new to Python-- never used it before today. I am interested in devloping Python applications for the web. I would like to check to see if my web server supports WSGI or running python apps in some way.
Let's say I have a .py file that prints "Hello world!". How can I test to see if my server supports processing this file?
FYI, this is a Mac OS X server 10.5. So I know Python is installed (It's installed on Mac OS X by default), but I don't know if it's set up to process .py files server-side and return the results.
BTW, I'm coming from a PHP background, so this is a bit foreign to me. I've looked at the python docs re: wgsi, cgi, etc. but since I haven't done anything concrete yet, it's not quite making sense.
A very basic WSGI application can look as follows:
def application(environ, start_response):
start_response('200 OK', [('content-type', 'text/html')])
return ['Hello world!']
Unfortunately, if you put this into helloworld.py on the server and then browse to URL/helloworld.py you will most likely see the code.
In general you need to add very specific configuration options to the server (or to a server configuration file) to get it to serve your python 'application' correctly. Given you are using mod_wsgi on Apache 2, a configuration could look as follows:
<VirtualHost *>
ServerName example.com
WSGIScriptAlias /server/location/address /path/to/helloworld.py
</VirtualHost>
Where /server/location/address is the endpoint of the URL you have to browse to.
This is because python WSGI catches all URLs passed to it, and pushes them to the same entry point (your application method/class). And from the information received in the parameters, the application must decide what page to return.
Since this information is so application specific there 'should' be a way to configure it on the server, however I have yet to come across a web-hosting configuration panel that allows the configuration of Python applications. This generally means you have to contact the server administrators and have them configure it for you.
However, in general, when you sign up for hosting the company generally has a page where they tell you exactly what is supported on their servers (generally: php, mysql) and how much space and bandwidth you are allowed. Thus if they do not list it on their site, it is highly likely they will not support it.
To get around this you can instead buy a VPS (Virtual Private Server) and then configure it however you want.
If you are new to Python and Python web application development, then ignore all the hosting issues to begin with and don't start from scratch. Simply go get a full featured Python web framework such as Django or web2py and learn how to write Python web applications using their in built development web server. You will only cause yourself much pain by trying to solve distinct problem of production web hosting first.