Simple App on Google App Engine using Python

Hi,
Today we'll try to make a simple App on Google App Engine in Python which just says 'YourName Rulz!!' and we'll upload it on Google App Engine :)

To get what I am saying, goto this page and check it out :)


That's what we are going to make today. Isn't that cool! You are about to write your name in history! Well on the web and as long as the sever lasts but it still rocks! :)

Once you are done with this tutorial, you can try and solve this activity at reliscore - 
Google AppEngine using Python to see how much you really understood :)

Now what is Google App Engine? Simply, its a way to deploy your web apps and let google's infrastucture do all the hard work for you! It will do all the cloud computing *cool* stuff for you!

So Let's get started.

Go to this url and download the app engine for your OS. I am using Fedora 15 KDE for it. And I recommend you do start using linux if you haven't. Here's a link to my friend's blog post on Getting Started with linux . Its a tutorial for the absolute newbies.

Okay Back to the game. So now that you have downloaded it. For Windows/Mac please check the installations note.

For linux you just have to unzip the folder somewhere, lets say /home/yourusername/workspace/gapp

Fire up your terminals and move into the directory using cd command.
just in case you don't know



$ cd /home/yourusername/workspace/gapp


create a new directory called hello
and inside that directory
write a file called hello.py
and in that file
write these contents


------------hello.py------------
print 'Content-Type: text/plain'
print ''
print 'yourname Rulz'
------------X--X---------------


save it.
Note1 : Make sure you have an empty line After Content-Type else you will have issues.

Note2: Replace yourname with YOUR name :p ... Incase you haven't figured that out ;)

open another file and call it app.yaml
and write these contents

------------app.yaml------------
application: helloworld
version: 1
runtime: python
api_version: 1

handlers:
- url: /.*
  script: hello.py
------------X--X---------------





Note: Make sure url and script are aligned. I had issues when they were not aligned.

Basically, this is like the app configuration file. Simply put, this tells that the application name is helloworld (we will change this later, why we will see that), the version is 1, you are using python as a language. And the handlers just says simply right now is that whatever sub url you give, all will be handled by the script hello.py given by us. If you don't get it, its okay...

and save it.

to test it run this command

$ /home/yourusername/gapp/dev_appserver.py /homeyourusername/hello/ 

(Note: You don't need to give full path, but to keep it simple and universal, I am writing full path. You can write it whatever way you like as long as its correct.)

Once it works, open your favourite browser and check it aout! :)


http://localhost:8080/




Ta ra! :)

"Hey, but thats not deployed on the web" you say! Aye. That's Next ;)

Okay go to this site and login with your google account.

Once you are done, choose create application. Choose a nice "Application Identifier" as thats what you will be sharing it with others. In my case it was firesofmay

Fill in the Application title and let other things be default and click "Create Application".

Now go back to the hello folder and open up the app.yaml file and modify the
"application: helloworld" to whatever your application identifier was. In my case it was
"application: firesofmay"

Once you are done issue this command :)


$ /home/yourusername/workspace/gapp/appcfg.py update /home/yourusername/workspace/helloworld/




If you have done everything correctly you should see something like this as output...

-------------------------
Application: firesofmay; version: 1
Host: appengine.google.com

Starting update of app: firesofmay, version: 1
Scanning files on local disk.
Cloning 2 application files.
Compilation starting.
Compilation completed.
Starting deployment.
Checking if deployment succeeded.
Deployment successful.
Checking if updated app version is serving.
Will check again in 1 seconds.
Checking if updated app version is serving.
Will check again in 1 seconds.
Checking if updated app version is serving.
Completed update of app: firesofmay, version: 1
-------------------------

Open up your URL and check it out... isn't that super cool!! :)
It's time for you to go to your facebook and post some cool stuff online and show it off to your friends!

Here are the references :-

• Google App Engine - Intro
• Google App Engine - Basics
• Google App Engine - Hello
• Google App Engine - Uploading
• Google's Python Class
• Google AppEngine using Python - Problem Challenge @ Reliscore

I want to thank Navin Kabra, for being a great support and starting such a cool website - reliscore for programmers like you and me who love coding real world problems. And its a Kick Ass Website for those who wanna show off and get job for it too ;) Now Go and sharpen your coding skills on that website.

Cya :)