Websockets

• 2013 - New way for javascript to open a tcp connection back to the server for data transfer.
• Here is some notes as I struggled to get the first examples to work.
  • Errors in apache log files

    1.  Exception: ('PythonOption mod_pywebsocket.handler_root is not defined', 3)  

    2.  AttributeError: object has no attribute  "APLOG_DEBUG" 

  • Cause was that i had to have the websocket config above the default virtual server in my apache2 config file.

  ##PES 2013 pywebsocket
  <IfModule python_module>
    PythonPath "sys.path+['/mod_pywebsocket']"
    PythonOption mod_pywebsocket.handler_root /var/www
    PythonOption mod_pywebsocket.handler_scan /var/www/ws
    #PythonOption mod_pywebsocket.allow_draft75 On
    <Location /ws>
      PythonHeaderParserHandler mod_pywebsocket.headerparserhandler
    </Location>
  </IfModule>  
  
  <VirtualHost *:80>
  
          ServerAdmin webmaster@localhost
  
          DocumentRoot /var/www
          <Directory />
                  Options FollowSymLinks
                  AllowOverride None
          </Directory>
          <Directory /var/www/>
                  Options Indexes FollowSymLinks MultiViews
                  AllowOverride None
                  Order allow,deny
                  allow from all
          </Directory>
          ErrorLog ${APACHE_LOG_DIR}/error.log
          LogLevel debug
          CustomLog ${APACHE_LOG_DIR}/access.log combined
  </VirtualHost>

• To test

  1. copy file echo_wsh.py into /var/www/ws

  2. open webpage to test file:///usr/share/doc/python-mod-pywebsocket/examples/console.html in browser

  3. test by entering in webpage abe the url ws://localhost/ws/echo

  4. on web page in display window you should see message Connect ws://localhost/ws/echo

...

CategoryDevelopement