Get Started with Pylons

The following tutorial will walk you through the steps to create a new Entourage-powered web application for the Python-based Pylons web application framework.

Prerequisites

Before you get started, you will need to download and install Python, Pylons, and Paste. The best resource for installing these items can be found at the Pylons website.

Create a new project

Download the Entourage Service Broker implementation for Pylons and unzip it in the directory in which you would like to develop your application. In the application directory, rename all directories marked with _rename_to_your_app_ with the name of your top-level application directory. Next, you must peform the same replacement in a few configuration files in your app's home directory:

Once this is done, you should be able to start your new Pylons application using the paster command from your project home directory: paster serve development.ini http_port=4000.

Hello World

Let’s start by creating a simple user interface that will test remote messaging. Lets create [project root]/public/hello_world.html and replace the body contents with the following: 

<html>
<head>
  <title>Appcelerator Entourage&trade; Hello World</title>
  <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
  <script src="/javascripts/entourage.js" type="text/javascript"></script>
</head>
<body style="visibility:hidden" on="l:app.compiled then visible">
 
  <!-- generate request -->
  <textarea id="your_message" fieldset="hello_world">type something</textarea>
  <div>
    <input type="button" value="click me" fieldset="hello_world"
       on="click then r:hello.request"/> 
  </div>
 
  <!-- display response -->
  <div>
    You typed: 
    <span on="r:hello.world.response then value[message]"
        style="color:blue">
      nothing yet
    </span>  
  </div>
 
  <!-- mock service -->
  <script type="text/javascript">
    $MQL("r:hello.world.request", function(message) {
      $MQ({
        name: "r:hello.response",
        payload: {
          message: message.payload.your_message
        }
      });
    });
  </script>
 
</body>
</html>

Test out your new application by accessing it at the following url: http://localhost:4000/hello_world.html

User Interface Explanation

There are several basic concepts covered in this example. First, we use the fieldset attribute to link the TEXTAREA with the INPUT button. When a click event is generated by an element with a fieldset, Appcelerator will look for other input elements with the same fieldset value, and it will include their values in the message generated by the click event. This feature is very useful when creating forms.

Second, we show how an element can subscribe to a message and set its value based on an attribute in the message payload - in this case the message attribute.

Finally, we show an example of how to create a mock service. A mock service is a SCRIPT widget that subscribes to a remote request and responds with a remote response. This is a powerful capability because it enables you to create fully functional user interfaces (UI) without writing a single line of service code. These UIs are also 100% reusable. Once you finish your UI, you can remove your mock services as you create the remote service implementations. We call this Interactive Use Case development. You can learn more about Interactive Use Cases in the Best Practices section of this documentation.

Service

Now we’re ready to implement the service for our Hello World example. First, remove (or comment out) the mock service that you created above. Next, open [project root]/[your app name]/app/services/hello_service.py and create a new service method like the one below: 

@Service(request='hello.request', response='hello.response')
def hello(params, session, msgtype):
    message = params.get('message', 'World')
    return {'message': message, 'success': 'true'}

You should now be able to open your example HTML page and run the code against our new service method.