Helicon Zoo

Tornado

Installation

  1. Open Web Platform Installer and install "Python project":
  2. Follow steps in "Creating Tornado project":

  3. Create server.py file with the following content:
    import tornado.ioloop
    import tornado.web
    
    from tornado.options import define, options
    
    define("port", default=8888, help="run on the given port", type=int)
    
    class MainHandler(tornado.web.RequestHandler):
        def get(self):
            self.write("Hello, world")
    
    application = tornado.web.Application([
        (r".*", MainHandler),
    ])
    
    if __name__ == "__main__":
        tornado.options.parse_command_line()
        application.listen(options.port)
        tornado.ioloop.IOLoop.instance().start()
    Output of sample Tornado application:

Deployment

To deploy Python Tornado application you will need to install Python Hosting Package on a target server. Then just copy IIS web site from one machine to another.

web.config example

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
  <system.webServer>
    <heliconZoo>
      <application name="tornado.project" >
        <environmentVariables>
          <add name="PYTHONPATH" value="%APPL_PHYSICAL_PATH%;%APPL_PHYSICAL_PATH%\python_modules\Lib\site-packages;%PYTHONPATH%" /> 
          <add name="APP_WORKER" value="%APPL_PHYSICAL_PATH%\server.py" />
          <add name="DEPLOY_FILE" value="deploy.py" />
          <add name="DEPLOY_LOG" value="log\deploy.log" />
        </environmentVariables>
      </application>
    </heliconZoo>
    <handlers>
      <add name="tornado.project#x86" scriptProcessor="python.2.7.http"
           path="*" verb="*" modules="HeliconZoo_x86"
           preCondition="bitness32" resourceType="Unspecified" requireAccess="Script" />
      <add name="tornado.project#x64" scriptProcessor="python.2.7.http"
           path="*" verb="*" modules="HeliconZoo_x64"
           preCondition="bitness64" resourceType="Unspecified" requireAccess="Script" />
    </handlers>
  </system.webServer>
</configuration>

Environment variables

  • PYTHONPATH — path to Python modules. In the example it points to application root, the python_modules\Lib\site-packages subfolder and also includes value defined by user.
  • APP_WORKER — path to Tornado application’s worker script.
  • WATCH_FILE_CHANGES_MASK — optional files mask to watch for changes. Worker is restarted every time a file of specified type changes. In the example all .py files are watched.

web.config in directory with static files

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
  <system.webServer>
    <handlers>
      <!-- 
      This removes Helicon Zoo handler and makes IIS processing static files.
      -->
      <remove name="tornado.project#x64" />
      <remove name="tornado.project#x86" />
    </handlers>
  </system.webServer>
</configuration>

deploy.py file example

Deploy file is used to execute commands, such as components installations or database migrations, on a server when the application initially starts or updated. The following code is only an example. We recommend you to use deploy.py file that comes with the Python project template.

# This file is example of deploy.py
# The file is executed once on the first request after every restart of IIS application.
# The file output is redirected to log file described in DEPLOG_LOG environment variable.

import sys
import os
import os.path

PROJECT_DIR = os.path.dirname(__file__)
os.chdir(PROJECT_DIR)

PIP_EXE = os.path.join(os.path.dirname(sys.executable), 'scripts\\pip.exe')

# update APPDATA env for pip
os.environ['APPDATA'] = os.path.join(PROJECT_DIR, 'python_modules')

# install requirements to local folder
os.system('{0} install --install-option="--prefix={1}" --requirement=requirements.txt'.format(PIP_EXE, os.path.join(PROJECT_DIR, 'python_modules')))