This is a follow-up to two questions I asked a week or so back. The upshot of those was that I was building a prototype of an AI-based application for the web, and I wondered what language(s) to use. The conclusion seemed to be that I should go for something like python and then convert any critical bits into something faster like Java or C/C++.
That sounds fine to me, but I'm wondering now whether python is really the right language to use for building a web application. Most web applications I've worked on in the past were C/C++ CGI and then php. The php I found much easier to work with as it made linking the user interface to the back-end so much easier, and also it made more logical sense to me.
I've not used python before, but what I'm basically wondering is how easy is CGI programming in python? Will I have to go back to the tedious way of doing it in C/C++ where you have to store HTML code in templates and have the CGI read them in and replace special codes with appropriate values or is it possible to have the templates be the code as with php?
I'm probably asking a deeply ignorant question here, for which I apologise, but hopefully someone will know what I'm getting at! My overall question is: is writing web applications in python a good idea, and is it as easy as it is with php?
Python is a good choice.
I would avoid the CGI model though - you'll pay a large penalty for the interpreter launch on each request. Most Python web frameworks support the WSGI standard and can be hooked up to servers in a myriad of ways, but most live in some sort of long-running process that the web server communicates with (via proxying, FastCGI, SCGI, etc).
Speaking of frameworks, the Python landscape is ripe with them. This is both good and bad. There are many fine options but it can be daunting to a newcomer.
If you are looking for something that comes prepackaged with web/DB/templating integration I'd suggest looking at Django, TurboGears or Pylons. If you want to have more control over the individual components, look at CherryPy, Colubrid or web.py.
As for whether or not it is as "easy as PHP", that is subjective. Usually it is encouraged to keep your templates and application logic separate in the Python web programming world, which can make your life easier. On the other hand, being able to write all of the code for a page in a PHP file is another definition of "easy".
Good luck.
"how easy is CGI programming in python?" Easier than C, that's for sure. Python is easier because -- simply -- it's an easier language to work with than C. First and foremost: no memory allocation-deallocation. Beyond that, the OO programming model is excellent.
Beyond the essential language simplicity, the Python WSGI standard is much easier to cope with than the CGI standard.
However, raw CGI is a huge pain when compared with the greatly simplified world of an all-Python framework (TurboGears, CherryPy, Django, whatever.)
The frameworks impose a lot of (necessary) structure. The out-of-the-box experience for a CGI programmer is that it's too much to learn. True. All new things are too much to learn. However, the value far exceeds the investment.
With Django, you're up and running within minutes. Seriously. django-admin.py startproject and you have something you can run almost immediately. You do have to design your URL's, write view functions and design page templates. All of which is work. But it's less work than CGI in C.
Django has a better architecture than PHP because the presentation templates are completely separated from the processing. This leads to some confusion (see Syntax error whenever I put python code inside a django template) when you want to use the free-and-unconstrained PHP style on the Django framework.
linking the user interface to the back-end
Python front-end (Django, for example) uses Python view functions. Those view functions can contain any Python code at all. That includes, if necessary, modules written in C and callable from Python.
That means you can compile a CLIPS module with a Python-friendly interface. It becomes something available to your Python code with the import statement.
Sometimes, however, that's ineffective because your Django pages are waiting for the CLIPS engine to finish. An alternative is to use something like a named pipe.
You have your CLIPS-based app, written entirely in C, reading from a named pipe. Your Django application, written entirely in Python, writes to that named pipe. Since you've got two independent processes, you'll max out all of your cores pretty quickly like this.
I would suggest Django, but given that you ask for something "as easy as it is with php" then you must take a look at PSP (Python Server Pages).
While Django is a complete framework for doing websites, PSP can be used in the same way than PHP, without any framework.
It is easier to write web-apps in python than it's in php. Particularly because python is not a broken language.
Pick up some web framework that supports mod_wsgi or roll out your own. WSGI apps are really easy to deploy after you get a hold from doing it.
If you want templates then genshi is about the best templating engine I've found for python and you can use it however you like.
Related
I'm going to be writing a fairly sophisticated command line app in python. I'd like to leverage something other than just pure python, maybe a framework or something that makes the services and code management within the app easier. I guess in my mind, I'm thinking MVC, as the app will have several different commands (controllers) which call different sources for data (JSON requests, REST requests, etc., e.g. the "Models" in MVC), and then display results in different formats (the View).
I think MVC works well for this, but I'm not really doing a web app. I want something that doesn't necessarily require a web server, but has the advantages of a framework to force some coding standards.
Does anyone have any tips or suggestions? I know I could build something from scratch with Python, but I'm just curious if there's something else out there I could utilize.
Thanks,
Dustin
This is a bit late, however posting for anyone else who stumbles across this:
Cement is an Advanced CLI Application Framework for Python. Getting started is easy, and it is extremely flexible for customizing almost every piece of it from logging to config file parsing. Cement2 (code name portland) is currently in beta, but is very close to a stable release:
http://cement.readthedocs.org/en/portland/
Additionally, if you are creating a REST command line client, also checkout dRest:
http://drest.readthedocs.org/en/latest/
It too is very easy to get started with, and is also extremely flexible for customization from the request handler, to how serialization happens on both the sending and receiving ends.
I'd be happy to answer any questions about either.
To be fair to the pattern, MVC is not bound to web applications. I think because of the web-aware trend of the last couple of years this relation between MVC and web apps could have grown. Put differently, a web app can use MVC, but using MVC doesn't necessarily mean that you have a web app.
If you want to use a framework, you could try to use the one most close to your intended controller. I'm not aware of an MVC frameworks that have a command line as the interface, but some platform independent GUI frameworks that use it are for example GTK+ or QT: both have python bindings.
From a personal point of view, I've used Django for this purpose before. Although the technical purity can be a point of discussion, when selecting a framework no one forces you to use all of the framework's components. Django has a nice ORM which I've liked so much that I made it the backend for a SSH operated interface. It might be overkill, but for me had the advantage that I could reuse my knowledge about the system instead of learning a new, once-to-be-used framework.
In conclusion, it all boils down to discipline. Even the best framework cannot prevent you from violating coding standards and cutting corners...
PS if you're on Linux, you might consider using python's curses module for your command line frontend.
I'm making a simple web app where I have some simple python scripts that do the text crunchin g I need - but I'm not quite sure how to interface it with a client who'd only want to see some HTML forms.
There's so many different server side frameworks out there - but I don't think I need anything too heavy duty - just a mechanism to accept data from the forms that the user fills in, and feed it to my Python code and back.
Could someone suggest what tools I should look into and what design paradigms I should follow? Simple pointers to different references around the web with a single line about their significance would also help.
Best.
At the moment, the best lightweight and yet very powerful framework for python IMO is Flask. If you want form abstraction there is a WTFlask plugin for it which is WTForms adapted for flask - http://flask.pocoo.org/.
Web2py is also a very good framework for starters because it has helpers and wizards for creating/running an application, and also has something like an admin interface, offering an On-line IDE functionality. - http://www.web2py.com/
I proposed these two frameworks because you can start fast with them, they both have good documentation, both are powerful yet easy and they are pretty friendly for beginners.
Not normally supported with cheap hosting, but mod_python on apache might be right up your alley.
You could also have html talk to python through cgi (Which has been the way of doing it for years before php came along).
The standard Design pattern commonly seen in web apps is Model-View-Controller, so google around.
I've used Django (heavy and something of a non-trivial initial learning curve), and web.py (very small & simple), and over the past year, I've been pretty happy using tornado.
People can argue about the async details, but that's not even why I use it. It's pretty fast, it's super quick to get started with, it comes with examples that get you doing things quickly, and -- most important to me -- It's a web server and framework in one, which means you don't have to muck with mod_python vs mod_wsgi vs cgi vs fcgi vs whatever. Deployment is really easy.
Ok, so I really love HAML. Particularly, I love the integration with RedCloth and BlueCloth, so I can use Markdown and Textile intermixed with my HAML.
I also love Python and Django.
So, I would like to use HAML with Django. Now, I already understand that there are some attempts at cloning HAML-like syntax in Python (SHPAML and others). I've tried these, and while they aren't bad, I've found that I really just want the real HAML. Partially for its syntax, but also for things like RedCloth and BlueCloth.
So, my question is, how to make HAML and Django work together?
One solution, I think, would be to create HAML templates, and then compile them into HTML using the command line tool every time they're updated.
Quesiton 1: Will I run into any problems here?
I also wonder if there's a way to get Python and Ruby to play together a little more. One idea I had was actually forking out Ruby processes. This is probably a bad idea, but anyone have any thoughts about this?
Question 2: What about using Python to call the real Ruby HAML?
Finally, if anyone knows of a Python implementation of HAML that is complete, and that supports either Textile or Markdown, as well as plaintext passthru, then let me know.
Question 3: Is there a full translation of HAML to Python including Markdown or Textile support?
Thanks!
Question 1: static HTML files should work finely (unless you plan to use HAML's ruby evaluation feature to dynamically content). I use a similar way on a php website with SASS stylesheets. Just make sure you start HAML in directory watch mode before starting to hack ;)
Question 2: while forking a ruby process to create HTML code is possible, but I don't recommend it you, because initializing a ruby interpreter, and loading required files takes a lot of cpu times, so you better stick with static files. If you need the ruby evaluation feature to include runtime created data into the document, you'd better have a look at eventmachine, and make it a server (so your Django application can connect to it, and request HTML generation, without forking a new interpreter each time).
Question 3: maybe this is the hardest. There's GHRML which is abandoned; SHPAML which only implements a small subset of HAML, DMSL which is currently very experimental, but already supports most of HAML and also calling python code, but lacks Markdown or Textile support. But apparently there's no alternative (yet) to Ruby HAML that supports all the required features.
Try: http://github.com/fitoria/django-haml
I strongly recommend that you do not fork any processes out of your django views, because the overhead is significant.
You should have a persistent ruby process to serve your templates for you, and invoke it from your django code. I leave the IPC technology to you, but the obvious choices would either be some kind of message queuing technology, or speaking HTTP over a socket to the ruby process.
While this could end up being more trouble than it is worth, it is PROBABLY possible to leverage the Java or .NET platform and still run your Django application in Jython or IronPython (with some minor adjustments I'm sure) and also be able to leverage Ruby's HAML gem via jRuby or IronRuby.
I'm sure there will be some quirks in getting this to work, but I'm sure it would be possible.
Again, this is probably a lot more trouble than it's worth (considering that you'd have to move your application to a completely new platform), but it would be a pretty fun project to work on.
I'm lucky enough to have full control over the architecture of my company's app, and I've decided to scrap our prototype written in Ruby/Rails and start afresh in Python. This is for a few reasons: I want to learn Python, I prefer the syntax and I've basically said "F**k it, let's do it."
So, baring in mind this is going to be a pretty intensive app, I'd like to hear your opinions on the following:
Generic web frameworks
ORM/Database Layer (perhaps to work with MongoDB)
RESTful API w/ oAuth/xAuth authentication
Testing/BDD support
Message queue (I'd like to keep this in Python if possible)
The API is going to need to interface with a Clojure app to handle some internal data stuff, and interface with the message queue, so if it's not Python it'd be great to have some libraries to it.
TDD/BDD is very important to me, so the more tested, the better!
It'll be really interesting to read your thoughts on this. Much appreciated.
My best,
Jamie
Frameworks
OK, so I'm a little biased here as I currently make extensive use of Django and organise the Django User Group in London so bear that in mind when reading the following.
Start with Django because it's a great gateway drug. Lots of documentation and literature, a very active community of people to talk to and lots of example code around the web.
That's a completely non-technical reason. Pylons is probably purer in terms of Python philosophy (being much more a collection of discrete bits and pieces) but lots of the technical stuff is personal preference, at least until you get into Python more. Compare the very active Django tag on Stack Overflow with that of pylons or turbogears though and I'd argue getting started is simply easier with Django irrespective of anything to do with code.
Personally I default to Django, but find that an increasing amount of time I actually opt for writing using simpler micro frameworks (think Sinatra rather than Rails). Lots of things to choose from (good list here, http://fewagainstmany.com/blog/python-micro-frameworks-are-all-the-rage). I tend to use MNML (because I wrote parts of it and it's tiny) but others are actively developed. I tend to do this for small, stupid web services which are then strung together with a Django project in the middle serving people.
Worth noting here is appengine. You have to work within it's limitations and it's not designed for everything but it's a great way to just play with Python and get something up and working quickly. It makes a great testbed for learning and experimentation.
Mongo/ORM
On the MongoDB front you'll likely want to look at the basic python mongo library ( http://api.mongodb.org/python/ ) first to see if it has everything you need. If you really do want something a little more ORM like then mongoengine (http://hmarr.com/mongoengine/) might be what you're looking for. A bunch of folks are also working on making Django specifically integrate more seamlessly with nosql backends. Some of that is for future Django releases, but django-norel ( http://www.allbuttonspressed.com/projects/django-nonrel) has code now.
For relational data SQLAlchemy ( http://www.sqlalchemy.org/) is good if you want something standalone. Django's ORM is also excellent if you're using Django.
API
The most official Oauth library is python-oauth2 ( http://github.com/simplegeo/python-oauth2), which handily has a Django example as part of it's docs.
Piston ( http://bitbucket.org/jespern/django-piston/wiki/Home) is a Django app which provides lots of tools for building APIs. It has the advantage of being pretty active and well maintained and in production all over the place. Other projects exist too, including Dagny ( http://zacharyvoase.github.com/dagny/) which is an early attempt to create something akin to RESTful resources in Rails.
In reality any Python framework (or even just raw WSGI code) should be reasonably good for this sort of task.
Testing
Python has unittest as part of it's standard library, and unittest2 is in python 2.7 (but backported to previous versions too http://pypi.python.org/pypi/unittest2/0.1.4). Some people also like Nose ( http://code.google.com/p/python-nose/), which is an alternative test runner with some additional features. Twill ( http://twill.idyll.org/) is also nice, it's a "a simple scripting language for Web browsing", so handy for some functional testing. Freshen ( http://github.com/rlisagor/freshen) is a port of cucumber to Python. I haven't yet gotten round to using this in anger, but a quick look now suggests it's much better than when I last looked.
I actually also use Ruby for high level testing of Python apps and apis because I love the combination of celerity and cucumber. But I'm weird and get funny looks from other Python people for this.
Message Queues
For a message queue, whatever language I'm using, I now always use RabbitMQ. I've had some success with stompserver in the past but Rabbit is awesome. Don't worry that it's not itself written in Python, neither is PostgresSQL, Nginx or MongoDB - all for good reason. What you care about are the libraries available. What you're looking for here is py-amqplib ( http://barryp.org/software/py-amqplib/) which is a low level library for talking amqp (the protocol for talking to rabbit as well as other message queues). I've also used Carrot ( http://github.com/ask/carrot/), which is easier to get started with and provides a nicer API. Think bunny in Ruby if you're familiar with that.
Environment
Whatever bits and pieces you decide to use from the Python ecosystem I'd recommend getting to who pip and virtualenv ( http://clemesha.org/blog/2009/jul/05/modern-python-hacker-tools-virtualenv-fabric-pip/ - note that fabric is also cool, but not essential and these docs are out of date on that tool). Think about using Ruby without gem, bundler or rvm and you'll be in the right direction.
Ok, you might be making a mistake, the same one I made when I started with python.
Before you decide on a thing like django, which is an excellent, yet atypical python web framework, spend an night cuddled up with:
This, is a good start. Make sure you do A little Werkzeug watching , Then check out
some classic WebOb. Maybe, if you feel the fire in the blood, and you might, wsgi is a bit flawed, but only to the gods, check out Flask
I'm not saying use it, Django is beautiful too, but if you don't know python, and you go through django, you run the risk of learning a framework.
WSGI is super straightforward. You'll find out about Paste, and Pastescript, and Pylons.
Then, make your decision. It'll be much easier learning stuff doing bare bones wsgi or Flask, stuff like variable assignment, using the interpreter, style concerns, testing, on 3 files for a couple of nights, instead of django. Take 2 nights. Then you'll see the great similarity between python web frameworks, instead of the differences. Hell, you might even roll with Flask.
Just some advice, I did the same thing with ruby, going in through Rails, and... well, strong words were said.
Language, then basic wsgi and testing, then pick your framework and roll
I'm new to python myself, and plan to get more in depth with it this year. I've had a few false starts at this, but always professional needs bring me back to PHP. The few times I've done some development, I've had really good experiences with web2py as a python framework. It's quite well done, and complete in features, while still being extremely lightweight. The database layer seems to be very flexible and mature.
As for TDD/BDD and the rest of your questions, I don't have any experience with python options, but would be interested to hear what others say.
I am using Twisted Framework based Nevow library for python based web app.
All your criteria fit into this single framework.
What makes Python stand out for use in web development? What are some examples of highly successful uses of Python on the web?
Django is, IMHO, one of the major benefits of using Python. Model your domain, code your classes, and voila, your ORM is done, and you can focus on the UI. Add in the ease of templating with the built-in templating language (or one of many others you can use as well), and it becomes very easy to whip up effective web applications in no time. Throw in the built-in admin interface, and it's a no-brainer.
Certainly one successful use of Python on the web is Google App Engine. Site authors write code in (a slightly restricted subset of) Python, which is then executed by the App Engine servers in a distributed and scalable manner.
Quotes about Python:
"Python is fast enough for our site
and allows us to produce maintainable
features in record times, with a
minimum of developers," said Cuong Do,
Software Architect, YouTube.com.
YouTube uses a lot of Python and is probably the best example of a Python success story.
A great example of a Django success story is the Washington Post, who recently shared a big list of applications they have developed:
http://push.cx/2009/washington-post-update
www.lawrence.com and www.ljworld.com are two of the first sites to use Django (before it was even open source).
djangositeoftheweek.com has a bunch of good case studies.
www.everyblock.com is another great example.
Finally, http://www.djangosites.org/ links to nearly 2,000 other Django powered sites.
Short anwser: the diversity of tools readily available and freedom of choice.
This sounds like a simple question but which it really isn't. While Python is very good for web development and this has been shown by the, oh so famous, Google App Engine, Plone and Django. One has to point out that the development way in Python requires a lot more from the developer than PHP but it gives a lot more to the mix as well.
The entry level on actually producing something is higher. This is because there are bunch of different tools for doing web development with Python. Choosing the web development framework can be a hard decision for an inexperienced developer.
Having a lot of different tools is a two edged sword. To some extent it brings you the freedom of choice to pick the one you might want but then again how do you really know which one is good for what you're doing. This brings me to my point. Python stands out from the mass by not having a standard or de facto web development library. While this is pretty much against the principle of having only one simple way of doing on thing it also brings us a wide variety of different tools with different kind of design choices. At first this might feel very frustrating because it would be so much easier if somebody had made the choice for you but now that you're left to make the choice you actually might have to think about what you're doing and what would fit. ...or you might just end up picking one and blowing your head off after you've realized that you made the wrong choice. Anyway you end up, you've made the choice and no one else.
Furthermore,
Python is both strong in web and in data analytics and machine learning. For example scikit, sci-py and numpy are very strong. In some cases, it can be very interesting to have the both elements on the same server.
For example http://rankmytweet.com uses this a lot.
trac(bug tracker) and moinmoin(wiki) are too web based python tools that I find invaluable.
GNU Mailman is another project written in python that is widely successful.
As many have pointed out, Django is a great reason to use Python...so in order to figure out why Python is great for web development, the best bet is to look at why it is a good language to build a framework like Django.
IMHO Python combines the cleanest, or at least one of the cleanest, metaprogramming models of any language with a very pure object orientation. This not only makes it possible to write extremely general abstractions that are easy to use, but also allows the abstractions to combine relatively cleanly with others. This is harder to do in languages that take a code-generation based approach to metaprogramming (e.g. Ruby).
Dynamic languages are in general good for web apps because the speed of development. Python in particular has two advantages over most of them:
"batteries included" means lots of available libraries
Django. For me this is the only reason why i use Python instead of Lua (which i like a lot more).
Besides the frameworks...
Python's pervasive support for Unicode should make i18n much smoother.
A sane namespace system makes debugging much nicer, because it's typically easier to find where things are defined.
Python's inability to function as a standalone templating language should discourage the mixture of HTML with model code
Great standard library
Other examples of Python sites are Reddit and YouTube.