Showing Revision 11 created 09/03/2017 by Dejan Trajkovic.

1. Title:
   Hello Webapp World - Web Development
2. Description:

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   Okay, so let's move on to some live web applications.

   ¶

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   So, at the end of your last homework, you should have
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   Google App Engine running on your machine, and you should have a basic site online.
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   We're going to start with basically the simple hello world example
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   that Google has on their site, which I have.
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   This is the main hello world Python file from the Google App Engine example page,
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   and it's got 2 main sections.
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    We'll start with this section down here at the bottom.
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    This is the URL mapping section, and in this case,
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    we have 1 URL, slash, and it maps to a handler called MainPage.
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    MainPage is defined in this class called MainPage.
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    It inherits from webapp to RequestHandler, which is the generic
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    request handler from Google.
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    If you don't know what classes are, you can learn about them offline.
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    It's basically a convenient way for grouping together
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    functions and data that are all related to the same thing.
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    We're not going to spend a whole lot of time on it here,
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    but you should be able to keep up just fine.
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    Our class has a function called get, which takes a parameter called self,
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    which is the common first parameter to most Python methods.
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    So, this function does 2 things.
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    First, it takes self.response, which is the kind of global response object
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    that this framework uses, and it sets a header.
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    It sets the Content-Type header to equal text/plain.
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    By default, the content type is text/html, but in this case it's setting it to text/plain,
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    and then it's writing the string "Hello, webapp World!"
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    If we start up Google App Engine, I'll start Google App Engine in my terminal here,
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    and then I'll go to my browser and load the page, and this is what we see.
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    We see that string that our program was writing out in our browser, "Hello, webapp World!"
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    Pretty neat.