Develop Reference

Socket.io POST Requests from Socket.IO-Client-Swift

I am running socket.io on an Apache server through Python Flask. We're integrating it into an iOS app (using the Socket.IO-Client-Swift library) and we're having a weird issue.
From the client side code in the app (written in Swift), I can view the actual connection log (client-side in XCode) and see the connection established from the client's IP and the requests being made. The client never receives the information back (or any information back; even when using a global event response handler) from the socket server.
I wrote a very simple test script in Javascript on an HTML page and sent requests that way and received the proper responses back. With that said, it seems to likely be an issue with iOS. I've found these articles (but none of them helped fix the problem):
https://github.com/nuclearace/Socket.IO-Client-Swift/issues/95
https://github.com/socketio/socket.io-client-swift/issues/359
My next thought is to extend the logging of socket.io to find out exact what data is being POSTed to the socket namespace. Is there a way to log exactly what data is coming into the server (bear in mind that the 'on' hook on the server side that I've set up is not getting any data; I've tried to log it from there but it doesn't appear to even get that far).
I found mod_dumpio for Linux to log all POST requests but I'm not sure how well it will play with multi-threading and a socket server.
Any ideas on how to get the exact data being posted so we can at least troubleshoot the syntax and make sure the data isn't being malformed when it's sent to the server?
Thanks!
Update
When testing locally, we got it working (it was a setting in the Swift code where the namespace wasn't being declared properly). This works fine now on localhost but we are having the exact same issues when emitting to the Apache server.
We are not using mod_wsgi (as far as I know; I'm relatively new to mod_wsgi, apologies for any ignorance). We used to have a .wsgi file that called the main app script to run but we had to change that because mod_wsgi is not compatible with Flask SocketIO (as stated in the uWSGI Web Server section here). The way I am running the script now is by using supervisord to run the .py file as a daemon (using that specifically so it will autostart in the event of a server crash).
Locally, it worked great once we installed the eventlet module through pip. When I ran pip freeze on my virtual environment on the server, eventlet was installed. I uninstalled and reinstalled it just to see if that cleared anything up and that did nothing. No other Python modules that are on my local copy seem to be something that would affect this.
One other thing to keep in mind is that in the function that initializes the app, we change the port to port 80:
socketio.run(app,host='0.0.0.0',port=80)
because we have other API functions that run through a domain that is pointing to the server in this app. I'm not sure if that would affect anything but it doesn't seem to matter on the local version.
I'm at a dead end again and am trying to find anything that could help. Thanks for your assistance!
Another Update
I'm not exactly sure what was happening yet but we went ahead and rewrote some of the code, making sure to pay extra special attention to the namespace declarations within each socket event on function. It's working fine now. As I get more details, I will post them here as I figure this will be something useful for other who have the same problem. This thread also has some really valuable information on how to go about debugging/logging these types of issues although we never actually fully figured out the answer to the original question.

I assume you have verified that Apache does get the POST requests. That should be your first test, if Apache does not log the POST requests coming from iOS, then you have a different kind of problem.
If you do get the POST requests, then you can add some custom code in the middleware used by Flask-SocketIO and print the request data forwarded by Apache's mod_wsgi. The this is in file flask_socketio/init.py. The relevant portion is this:
class _SocketIOMiddleware(socketio.Middleware):
# ...
def __call__(self, environ, start_response):
# log what you need from environ here
environ['flask.app'] = self.flask_app
return super(_SocketIOMiddleware, self).__call__(environ, start_response)
You can find out what's in environ in the WSGI specification. In particular, the body of the request is available in environ['wsgi.input'], which is a file-like object you read from.
Keep in mind that once you read the payload, this file will be consumed, so the WSGI server will not be able to read from it again. Seeking the file back to the position it was before the read may work on some WSGI implementations. A safer hack I've seen people do to avoid this problem is to read the whole payload into a buffer, then replace environ['wsgi.input'] with a brand new StringIO or BytesIO object.

Are you using flask-socketio on the server side? If you are, there is a lot of debugging available in the constructor.
socketio = SocketIO(app, async_mode=async_mode, logger=True, engineio_logger=True)

Run Python application from browser

I'm pretty new to programming and I've been learning python in my spare time. As a challenge to myself, I created a simple text adventure for a class project. This is not for a programming class, so the professor won't know how to compile a raw Python script, let alone have a Python interpreter on their Mac.
That being said, is it possible to run python from a browser? I'm imagining some HTML file that my professor, or anyone, can click that launches a browser and they can play my game from there.
I've learned about something called Django from my research on this subject. However, I have no idea what it is, nor how to implement it. Again, I'm pretty new to programming, so if you could "explain like I'm five", that would be great.
EDIT: I found this other thread where the OP asks a similar question, but I don't fully understand the approved answer:
execution python application from browser

Well, not really. Your basic browser generally supports 1 programming language, javascript.
However, you could use pythonanywhere" which is a hosted python environment.
You could also try skulpt which is a javacript implementation of python. I have never tried this myself.

You can host a website on an internal network and run the program from there. Read more about the Python CGI programming
here to make a form that will execute your script and print the result as a html page
For example you could have a form that will ask for input in textboxes: Name: _, Value: __, SUBMIT
After they press the button, the browser will then send a request to the python program, execute it, and display the result back to the client as a html webpage.
In addition, you do not need to install any other third-party modules if you are using a school computer. However, ask you teacher before hosting the website on the school network.
The problem is that your program is a "text adventure" which requires a lot more input/output management for a CGI program.
You can use this answer for other projects.
Anyway, here are the steps to setup the server:
1) Create a folder for your website and add a "index.html" file (it can be anything)
2) Add a favicon.ico file in the folder (this will speed up the connection) You can download this one
3) Put this python program in the folder (it will be used to host the website)
import BaseHTTPServer
import CGIHTTPServer
import cgitb; cgitb.enable()
from socket import gethostbyname, gethostname
def server(port):
server = BaseHTTPServer.HTTPServer
handler = CGIHTTPServer.CGIHTTPRequestHandler
server_address = ("", port)
httpd = server(server_address, handler)
print "Server %s:%s started" % (gethostbyname(gethostname()), str(port))
httpd.serve_forever()
server(4) #You can change this. It is a port number
4) Create a cgi-bin folder
5) To make the website available, execute the program created in the step 3. To stop hosting it, just close the python console.
6) While the program is running, you can go into the browser and type the IP adress : port as the URL. You will see your index.html page and favicon.ico icon. Anyone who is connected to the same network can get to the website. You and only you can also get to the website in a browser by entering http:/localhost:port with "port" being the port you've set
7) The rest you need to manage yourself. I cannot create the full script because I do not know what is in your program. Read the link provided in the beginning and modify your program to make it work in the browser.
FYI: It is possible to host more than one website or an instance of the same website at once using different ports. And, you can set and read cookies using Python CGI
Please comment if something doesn't work because of an error in my answer. I will try to fix it.

All of the answers so far assume that your game is something that can be presented as a web app. You can only do that if you write or covert your program (or part of it) into Javascript, which may not actually work because the existing compilers (e.g. pyjs) are quite limited.
If you made your program in a GUI (using 'Tkinter', 'Pygame', wxPython, PyQt, etc.), your best option is to package your program into a Mac app using py2app or pyinstaller.

Implementing subscriber Pubsubhubbub in python

I have a bunch of Google alerts set up as rss feeds that update in real time. What I want is to be able to store the new data the rss feed is sending out in a database.
After looking around I found Google and Superfeedr both offer hubs that do most of the work for you; however they both require a callback url (obviously). I do have an Apache server running on the machine I'm working off, it already has python enabled so I can run python scripts on my server. However at the moment its only accessible from within my LAN.
What my real question is, what do I do next? I know that in php you would just have a call back file that handles requests but I'm lost as to what to do in python. Would I write a script and give the google/superfeedr services a url to that script? What would be in the script? Specific imports needed?
Also, I just read that if you use XMPP you don't need a callback url. How does that work?

For the local LAN problem, the most commonly used solution is to use tuneling solutions like Passageway. They will temporarily expose a local port of your machine to the "outer" web.
Now, as for implementation, it's fairly easy to set things up. Python is similar to PHP in the sense that you'll have to write a script that listen on networking connection and then handles the HTTP requests you're getting from Superfeedr or Google. (it looks like you're not familiar with Python, why not stick to PHP then?)
Finally XMPP is a feature that only us (Superfeedr) offer. It solves the problem of exposing local ports because it works behind the firewall.

Heroku Django Logging

I'm trying to debug an internal server error in my django app, running on heroku. I'm
completely new to all of this web server stuff so I really have no idea what to do.
It seems like the stdout output is sometimes getting logged in heroku logs and sometimes not. I was reasonably sure that the program was reaching a certain line but the prints at that point are simply not showing up.
I am seeing the 500 error in my heroku logs file, but there is no stack trace or anything else in there. I am trying to create a web server to respond to GET and POST requests from various applications I have running, meaning I don't know how to debug this in a web browser, if thats even applicable. The current error is on a POST request sent to the webserver. I can't replicate this locally because the Http module I am using, http://www.python-requests.org/en/latest/ seems to be unable to connect to a local ip address.
I have done some extensive googling for the last hour and I haven't found any help. Do I need to enable logging or something somewhere in heroku? I am completely new to this so please be explicit in your explanations. I have heard mention of a way to get stack traces emailed to you but I haven't seen an explanation of how to do that. is that possible?
Thanks!

I would recommend 2 things in this case:
First: use python's logging facility rather than print statements (http://docs.python.org/2/howto/logging-cookbook.html). This gives you much more control over where your statements end up, and allows you to filter them.
Second: use a logging add-on. This vastly increases the amount of logging you can store (loggly keeps all your logs for 24 hours even in the "free" size), so you don't have to worry about the relevant information falling out before you get around to looking at it.

Running web.py as a service on linux

I've used web.py to create a web service that returns results in json.
I run it on my local box as python scriptname.py 8888
However, I now want to run it on a linux box.
How can I run it as a service on the linux box?
update
After the answers it seems like the question isn't right. I am aware of the deployment process, frameworks, and the webserver. Maybe the following back story will help:
I had a small python script that takes as input a file and based on some logic splits that file up. I wanted to use this script with a web front end I already have in place (Grails). I wanted to call this from the grails application but did not want to do it by executing a command line. So I wrapped the python script as a webservice. which takes in two parameters and returns, in json, the number of split files. This webservice will ONLY be used by my grails front end and nothing else.
So, I simply wish to run this little web.py service so that it can respond to my grails front end.
Please correct me if I'm wrong, but would I still need ngix and the like after the above? This script sounds trivial but eventually i will be adding more logic to it so I wanted it as a webservice which can be consumed by a web front end.

In general, there are two parts of this.
The "remote and event-based" part: Service used remotely over network needs certain set of skills: to be able to accept (multiple) connections, read requests, process, reply, speak at least basic TCP/HTTP, handle dead connections, and if it's more than small private LAN, it needs to be robust (think DoS) and maybe also perform some kind of authentication.
If your script is willing to take care of all of this, then it's ready to open its own port and listen. I'm not sure if web.py provides all of these facilities.
Then there's the other part, "daemonization", when you want to run the server unattended: running at boot, running under the right user, not blocking your parent (ssh, init script or whatever), not having ttys open but maybe logging somewhere...
Servers like nginx and Apache are built for this, and provide interfaces like mod_python or WSGI, so that much simpler applications can give up as much of the above as possible.
So the answer would be: yes, you still need Nginx or the likes, unless:
you can implement it yourself in Python,
or you are using the script on localhost only and are willing to take some
risks of instability.
Then probably you can do on your own.

try this
python scriptname.py 8888 2>/dev/null
it will run as daemon