I am currently working on a project to create simple file uploader site that will update the user of the progress of an upload.
I've been attempting this in pure python (with CGI) on the server side but to get the progress of the file I obviously need send requests to the server continually. I was looking to use AJAX to do this but I was wondering how hard it would be to, instead of changing to some other framerwork (web.py for instance), just write my own web server for receiving the XML HTTP Requests?
My main problem is that sending the request is done from HTML and Javascript so it all seems like magic trickery at the moment.
Can anyone advise me as to the best way to go about receiving these requests on the server?
EDIT: It seems that a framework would be the way to go. Would web.py be a good route to take?
I would recommend to use a microframework like Sinatra for Ruby. There seem to be some equivalents for Python. What python equivalent of Sinatra would you recommend?
Such a framework allows you to simply map a single method to a route.
Writing a very basic HTTP server won't be very hard (see http://docs.python.org/library/simplehttpserver.html for an example), but you will be missing many features that are provided by real servers and web frameworks.
For your project, I suggest you pick one of the many Python web frameworks and run your application behind Apache/mod_wsgi.
There's absolutely no need to write your own web server. Plenty of options exist, including lightweight ones like nginx.
You should use one of those, and either your own custom WSGI code to receive the request, or (better) one of the microframeworks like Flask or Bottle.
Related
I have a long-running process written in Python 2.7 that I would like to send KML files to my GWT application asynchronously as the KML files are generated.
I have been trying to determine what Python web framework I could use as the back-end with the Python process that could possibly allow the webapp to be hosted on Google AppEngine.
I was able to write a simple python webserver using Cherrypy that sent the kml using JSON from the back-end to GWT using an http request; however, I would like the files to be sent to GWT as they are generated since it may be several minutes between each one. What would be a relatively simple but effective way to achieve this? (Comet? Long-polling? Websockets?)
After researching more python web frameworks, I started experimenting with Tornado because it is non-blocking and seems like it could return data as it is generated possibly using long-polling as mentioned in this answer. However, it looks like GAE requires WSGI which would not allow a Tornado webserver to be non-blocking.
I have read answers to similar questions such as this one. However, I am not sure if updates in web frameworks, GWT, or GAE has changed what is the best option today, or whether some of these answers apply to my case.
What Python web framework would you recommend I use to send data to my asynchronous GWT app using long-polling or another method relatively simply? Could I use this web framework with GAE, or would I need to use something else?
If I understood the problem correctly you might don't need any special framework and you can solve it with what you have: Tasks API and Channel API.
With Tasks API you can perform long task and when the task is complete you can get a notification. You can combine it with the Channel API to push messages directly to the client when a particular task is complete.
You could use also the deferred library to simplify your life with tasks and maybe even using the PubNub for your push notifications, since the setup is easier and you can have many subscribers at the same time.
I was wondering how to create a django webservice (responds with XML) with websockets.
I have already a django webservice which accepts xml requests, parse those requests, makes a database query, creates a response xml and send that xml back to the requester/browser. Just a normal HTTP XML request, where the response is shown as xml within the browser.
But how would i now create a websocket django webservice? Lets say i would like to send a xml response to the requester/browser with the latest data from database whenever a new magical event occurs.
I have read a lot of posts and blogs but it was kinda all too general. Can i solve this only with django + apache or do i need something else next to django and another server only to handle websockets?
I am right now using django 1.3, Apache + wsgi but i would be ready to switch any configuration that would work.
Update:
There are many possible websockets out there,
http://pypi.python.org/pypi?:action=search&term=websocket&submit=search
but which one could be used in my case?
Sorry but django handles async requests very very poorly as it is wsgi. You'll be limited by your number of parallel instance if you have to handle real users. The best solution is to use tornado or node.js.
Tornado handles websocket and long polling brilliantly. Here is my wrapper to allow getting user and sessions from a parallel tornado thread:
https://gist.github.com/1939836
It's adapted from a more complex source, I didn't tested this gist, it's long polling but tornado handlse WebSocket as well.
http://www.tornadoweb.org/documentation/websocket.html
update:
Avoid django-websocket for production use. Even the main developer recommends against it.
I recommend Tornado because it's an awesome technology which is damningly faster/lighter than django. It may be useful for some simple cases. You'll need to configure apache/nginx anyway so, at least get "faster web pages" feature available.
Django-Desktop-Notification focuses on chrome browser and require node.js.
update (01/2016):
Mozilla gave money to django in late 2015 to solve this particular issue, the current most promizing implementation made by a django core dev is this one:
https://github.com/andrewgodwin/channels
It will probably be part of django 1.11 or 2.0
Although it's a bit complicated to setup (but probably the way to go), you could use gunicorn + gevent + socket.io .
I used this article to guide my way through it.
You might also look at server sent events (the article mentioned above looks at that too). If they suit your needs, it would be a bit easier to set up - since you don't have to set up socket.io and you don't need a client library. One catch though - SSE are not supported in IE.
Yeah, django is not all that great when it comes to asynchronous stuffs. My advice for you would be to use twisted as it has a lot of websocket libraries. If you really need to use django..you can make django act just as a pass through, for all the api stuff you build using twisted.
I'm looking for a bit of web development advice. I'm fairly new to the area but I'm sure there are some gurus out there willing to part with some wisdom.
Objective: I'm interested in controlling a Python application on my computer from my personal web hosted site. I know, this question has been asked several times before but in each case the requirements were a bit different from my own. To reduce the length of this post I'll summarize my objective in a few bullet points:
Personal site is hosted by a web hosting company
Site uses HTML, PHP, MySQL, Python and JavaScript, the majority of everything is coded by me from the ground up
An application that is coded in Python will run on a PC within my home and will communicate with an Arduino board
The app will receive commands from the internet to control actuation via the Arduino, and will transmit sensor data back to the site (such as temperature)
Looking for the communication to be bi-directional, fast and secure
Securing the connection between site and Python app would be most ideal
I'm not looking to connect to the Python application directly, the web server must serve as the 'middle man'
So far I've considered HTTP Post and HTML forms, using sockets (Python app would run as a web server), an IRC bot and reading/writing to a text file stored on the web server.
I was also hoping to have a way to communicate with the Python app without needing to refresh the webpage, perhaps using AJAX or JavaScipt? Maybe with Flash?
Is there something I'm not considering? I feel like I'm missing something. Thanks in advance for the advice!
Just thinking out loud for how I would start out with this. First, regarding the website itself, you can just use what's easiest to you, or to the environment you're in. For example, a basic PHP page will do just fine, but if you can get a site running in Python as well, I'd prefer using the same language all over.
That said, I'm not sure why you would need to use a hosted website? Given that you're already forced to have a externally accessible PC at home for the communication, why not run a webserver on that directly (Apache, Nginx, or even something like CherryPy should do)? That webserver can then communicate with the python process that is running to control your Arduino (by using e.g. Python's xmlrpclib). If you would run things via the hosting company, you would still need some process that can handle external requests securely... something a webserver is quite good at. Just running it yourself gives you all the freedom you want, and simplifies things by lessening the number of components in your solution.
The updates on your site I'd keep quite basic: commands you want to run can be handled in the request handlers of the webserver by just calling the relevant (xmlrpclib) calls. Dynamically updating the page is best done by some AJAX calls I reckon. Based on your story, these updates are easily put in a JSON object, suitable for periodically updating only the relevant segments of your page.
I've written a Python application that makes web requests using the urllib2 library after which it scrapes the data. I could deploy this as a web application which means all urllib2 requests go through my web-server. This leads to the danger of the server's IP being banned due to the high number of web requests for many users. The other option is to create an desktop application which I don't want to do. Is there any way I could deploy my application so that I can get my web-requests through the client side. One way was to use Jython to create an applet but I've read that Java applets can only make web-requests to the server it is deployed on and the only way to to circumvent this is to create a server side proxy which leads us back to the problem of the server's ip getting banned.
This might sounds sound like and impossible situation and I'll probably end up creating a desktop application but I thought I'd ask if anyone knew of an alternate solution.
Thanks.
You can use a signed Java applet, they can use the Java security mechanism to enable access to any site.
This tutorial explains exactly what you have to do: http://www-personal.umich.edu/~lsiden/tutorials/signed-applet/signed-applet.html
The same might be possible from a Flash applet. Javascript is also restricted to the published site and doesn't allow being signed or security exceptions like this, AFAIK.
You probably can use AJAX requests made from JavaScript that is a part of client-side.
Use server → client communication to give commands and necessary data to make a request
…and use AJAX communication from client to 3rd party server then.
This depends on the form of "scraping" you intend to do:
You might run into problems running an AJAX call to a third-party site. Please see Screen scraping through AJAX and javascript.
An alternative would be to do it server-side, but to cache the results so that you don't hit the third-party server unnecessarily.
Check out diggstripper on google code.
I want to develop a tool for my project using python. The requirements are:
Embed a web server to let the user get some static files, but the traffic is not very high.
User can configure the tool using http, I don't want a GUI page, I just need a RPC interface, like XML-RPC? or others?
Besides the web server, the tool need some background job to do, so these jobs need to be done with the web server.
So, Which python web server is best choice? I am looking at CherryPy, If you have other recommendation, please write it here.
what about the internal python webserver ?
just type "python web server" in google, and host the 1st result...
Well, I used web frameworks like TurboGears, my current projects are based on Pylons. The last ist fairly easy to learn and both come with CherryPy.
To do some background job you could implement that in pylons too.
Just go to your config/environment.py and see that example:
(I implemented a queue here)
from faxserver.lib.myQueue import start_queue
...
def load_environment(global_conf, app_conf):
...
start_queue()
It depends on your need if you simply use CherryPy or start to use something more complete like Pylons.
Use the WSGI Reference Implementation wsgiref already provided with Python
Use REST protocols with JSON (not XML-RPC). It's simpler and faster than XML.
Background jobs are started with subprocess.
Why dont you use open source build tools (continuous integration tools) like Cruise. Most of them come with a web server/xml interface and sometimes with fancy reports as well.
This sounds like a fun project. So, why don't write your own HTTP server? Its not so complicated after all, HTTP is a well-known and easy to implement protocol and you'll gain a lot of new knowledge!
Check documentation or manual pages (whatever you prefer) of socket(), bind(), listen(), accept() and so on.