Coupling a SQL database through a urllib2 to a Python application - python

Momentarily I am creating a python based application through the programme Ren'py. Now I have to couple the game with a SQL database. The admin on the board of the programme recommended using urllib to do this.
http://lemmasoft.renai.us/forums/viewtopic.php?f=8&t=29954
This is my thread. Now, I've managed to succesfully add the urllib to the program, but I'm lost at the entire "talk to a web service, which would then talk to the sqlite database" segment. Could you perhaps provide any hints/ tips?
I've never worked with Python before, so it's kind of challenging.

The answer you got on that forum isn't very helpful, in that the poster didn't really explain what they meant.
urllib is really the most minor component of the solution they're suggesting. What they actually mean is that you set up an entire web service, hosted on a URL somewhere, which talks to its own database. Your local installations of the app would then use a Python web library to communicate with that remote database over the web.
While this isn't particularly difficult, it is a fair amount of work, especially if you don't have any experience in doing this. You'll need a Python web framework and somewhere to host it. Since you talk about admins needing to log in and view data, you might want to explore Django, which comes with a built-in admin interface.
You'll then need to design an API to allow your Ren'py app to communicate with that web service, and you might want to look at the Django REST framework for that. The final part is getting your app to talk to the web service, which is where the recommendation of urllib comes in - but to be honest, that isn't even a very good recommendation here: the third-party library requests would be much better.
As I say, there's quite a lot of work. A much simpler solution would be to use Python's built-in sqlite3 library to talk to a local database via SQL, but that wouldn't do anything to make people's data available in a central location and would be open to anyone who worked out how to query the database.

Related

How to run a server in the cloud

Im creating a server in Python that receives POST requests, process the information in the request using some scripts (sometimes using a database) and send back a answer in JSON format. Im searching for a way to run this server and code in the cloud, in a way that i dont need my PC turned on for it to work, because my connection is very unstable.
There are a lot of web hosting companies out there, you just need to find the one that is right for you.
My personal favorite for python apps is heroku, but there are many out there. AWS is another popular one.
In future when asking questions, try to do more research before hand, and try to be more specific with questions. It would have been useful to know what kind of database you are using, or whether you're using flask or django.

Desktop Python App with Online Storage

I am looking for a 'sanity check' before I start working on this, as I'm new to writing server-side code. I want to stick to Python if possible, since that's what I'm used to!
I have written a desktop app (wxPython) that allows offsite employees to record their working times, the results of which they currently email to the company. I want to be able to have them save data directly to an 'online' location, from which the company can get summary data.
From what I have read (mostly here on StackOverflow) leads me to think I should do the following:
Run a database on the server with local access only (I'm favouring RethinkDB...)
Write a Python server app that can access the database but only exposes the functionality needed per user. Probably with different ports for users, payroll, and admin (me). Secure the sockets with TLS.
Add code to the desktop app to access the server.
Is this a good approach, or am I reinventing wheels and should learn to use Django or some other web framework?
As Paulo Almeida suggested in the comments making a REST application you interface with your wxPython application is probably the way to go. For this django may be a solution but it is probably an overkill microframework such as web.py, flask or bottle is enough and more easier to grasp

Python application communicating with a web server? Ideas?

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.

Good resources to start python for web development?

I'm really interested in learning Python for web development. Can anyone point me in the right direction? I've been looking at stuff on Google, but haven't really found anything that shows proper documentation and how to get started. Any recommended frameworks? Tutorials?
I've been doing PHP for 5 years now, so I just want to try something new.
Django is probably the best starting point. It's got great documentation and an easy tutorial (at http://djangoproject.com/) and a free online book too (http://www.djangobook.com/).
Web Server Gateway Interface
About
http://www.wsgi.org/en/latest/index.html
http://en.wikipedia.org/wiki/Web_Server_Gateway_Interface
Tutorials
http://webpython.codepoint.net/wsgi_tutorial
http://lucumr.pocoo.org/2007/5/21/getting-started-with-wsgi/
http://archimedeanco.com/wsgi-tutorial/
There are three major parts to python web frameworks, in my experience. From the front to back:
Views/Templates: Application frameworks don't function as independent scripts - instead, you map paths to python functions or objects which return html. To generate the html you probably need templates (aka views). Check out Cheetah.
Application framework/Server: There are plenty. CherryPy is my favorite, and is good for understanding how a python application server works because a) it's simple and b) unlike django and others, it is just the application server and doesn't include a templating engine or a database abstraction layer.
Database layer: I've actually never used it, but everyone seems to like SQLAlchemy. I prefer, in simple applications, executing SQL directly using a tool like psycopg2 (for postgres).
You can try Django. It's easy to learn, and it works with GAE (though the default version is 0.96, a little bit old, but you can change it). And there's a video about rapid development (by Guido Van Rossum) that goes through the basics of setting up a Django project in App Engine.

Feedback on using Google App Engine? [closed]

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Closed 11 years ago.
Looking to do a very small, quick 'n dirty side project. I like the fact that the Google App Engine is running on Python with Django built right in - gives me an excuse to try that platform... but my question is this:
Has anyone made use of the app engine for anything other than a toy problem? I see some good example apps out there, so I would assume this is good enough for the real deal, but wanted to get some feedback.
Any other success/failure notes would be great.
I have tried app engine for my small quake watch application
http://quakewatch.appspot.com/
My purpose was to see the capabilities of app engine, so here are the main points:
it doesn't come by default with Django, it has its own web framework which is pythonic has URL dispatcher like Django and it uses Django templates
So if you have Django exp. you will find it easy to use
But you can use any pure python framework and Django can be easily added see
http://code.google.com/appengine/articles/django.html
google-app-engine-django (http://code.google.com/p/google-app-engine-django/) project is excellent and works almost like working on a Django project
You can not execute any long running process on server, what you do is reply to request and which should be quick otherwise appengine will kill it
So if your app needs lots of backend processing appengine is not the best way
otherwise you will have to do processing on a server of your own
My quakewatch app has a subscription feature, it means I had to email latest quakes as they happend, but I can not run a background process in app engine to monitor new quakes
solution here is to use a third part service like pingablity.com which can connect to one of your page and which executes the subscription emailer
but here also you will have to take care that you don't spend much time here
or break task into several pieces
It provides Django like modeling capabilities but backend is totally different but for a new project it should not matter.
But overall I think it is excellent for creating apps which do not need lot of background processing.
Edit:
Now task queues can be used for running batch processing or scheduled tasks
Edit:
after working/creating a real application on GAE for a year, now my opnion is that unless you are making a application which needs to scale to million and million of users, don't use GAE. Maintaining and doing trivial tasks in GAE is a headache due to distributed nature, to avoid deadline exceeded errors, count entities or do complex queries requires complex code, so small complex application should stick to LAMP.
Edit:
Models should be specially designed considering all the transactions you wish to have in future, because entities only in same entity group can be used in a transaction and it makes the process of updating two different groups a nightmare e.g. transfer money from user1 to user2 in transaction is impossible unless they are in same entity group, but making them same entity group may not be best for frequent update purposes....
read this http://blog.notdot.net/2009/9/Distributed-Transactions-on-App-Engine
I am using GAE to host several high-traffic applications. Like on the order of 50-100 req/sec. It is great, I can't recommend it enough.
My previous experience with web development was with Ruby (Rails/Merb). Learning Python was easy. I didn't mess with Django or Pylons or any other framework, just started from the GAE examples and built what I needed out of the basic webapp libraries that are provided.
If you're used to the flexibility of SQL the datastore can take some getting used to. Nothing too traumatic! The biggest adjustment is moving away from JOINs. You have to shed the idea that normalizing is crucial.
Ben
One of the compelling reasons I have come across for using Google App Engine is its integration with Google Apps for your domain. Essentially it allows you to create custom, managed web applications that are restricted to the (controlled) logins of your domain.
Most of my experience with this code was building a simple time/task tracking application. The template engine was simple and yet made a multi-page application very approachable. The login/user awareness api is similarly useful. I was able to make a public page/private page paradigm without too much issue. (a user would log in to see the private pages. An anonymous user was only shown the public page.)
I was just getting into the datastore portion of the project when I got pulled away for "real work".
I was able to accomplish a lot (it still is not done yet) in a very little amount of time. Since I had never used Python before, this was particularly pleasant (both because it was a new language for me, and also because the development was still fast despite the new language). I ran into very little that led me to believe that I wouldn't be able to accomplish my task. Instead I have a fairly positive impression of the functionality and features.
That is my experience with it. Perhaps it doesn't represent more than an unfinished toy project, but it does represent an informed trial of the platform, and I hope that helps.
The "App Engine running Django" idea is a bit misleading. App Engine replaces the entire Django model layer so be prepared to spend some time getting acclimated with App Engine's datastore which requires a different way of modeling and thinking about data.
I used GAE to build http://www.muspy.com
It's a bit more than a toy project but not overly complex either. I still depend on a few issues to be addressed by Google, but overall developing the website was an enjoyable experience.
If you don't want to deal with hosting issues, server administration, etc, I can definitely recommend it. Especially if you already know Python and Django.
I think App Engine is pretty cool for small projects at this point. There's a lot to be said for never having to worry about hosting. The API also pushes you in the direction of building scalable apps, which is good practice.
app-engine-patch is a good layer between Django and App Engine, enabling the use of the auth app and more.
Google have promised an SLA and pricing model by the end of 2008.
Requests must complete in 10 seconds, sub-requests to web services required to complete in 5 seconds. This forces you to design a fast, lightweight application, off-loading serious processing to other platforms (e.g. a hosted service or an EC2 instance).
More languages are coming soon! Google won't say which though :-). My money's on Java next.
This question has been fully answered. Which is good.
But one thing perhaps is worth mentioning.
The google app engine has a plugin for the eclipse ide which is a joy to work with.
If you already do your development with eclipse you are going to be so happy about that.
To deploy on the google app engine's web site all I need to do is click one little button - with the airplane logo - super.
Take a look the the sql game, it is very stable and actually pushed traffic limits at one point so that it was getting throttled by Google. I have seen nothing but good news about App Engine, other than hosting you app on servers someone else controls completely.
I used GAE to build a simple application which accepts some parameters, formats and send email. It was extremely simple and fast. I also made some performance benchmarks on the GAE datastore and memcache services (http://dbaspects.blogspot.com/2010/01/memcache-vs-datastore-on-google-app.html ). It is not that fast. My opinion is that GAE is serious platform which enforce certain methodology. I think it will evolve to the truly scalable platform, where bad practices simply not allowed.
I used GAE for my flash gaming site, Bearded Games. GAE is a great platform. I used Django templates which are so much easier than the old days of PHP. It comes with a great admin panel, and gives you really good logs. The datastore is different than a database like MySQL, but it's much easier to work with. Building the site was easy and straightforward and they have lots of helpful advice on the site.
I used GAE and Django to build a Facebook application. I used http://code.google.com/p/app-engine-patch as my starting point as it has Django 1.1 support. I didn't try to use any of the manage.py commands because I assumed they wouldn't work, but I didn't even look into it. The application had three models and also used pyfacebook, but that was the extent of the complexity. I'm in the process of building a much more complicated application which I'm starting to blog about on http://brianyamabe.com.

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