Channel plugins

The simplest kind of plugin is a channel plugin, so we'll start with one of those. We'll write it in Python, since it's very easy to see what's happening, even if you don't know the language.

Running a simple channel plugin

Start Awasu, open the Channel Wizard and select the script file Samples/SamplePythonChannel/SamplePythonChannel.py. When you have finished going through the wizard, Awasu will call this script to generate a feed and show you the results.

The script looks like this:

HOME_URL = "http://www.test.com"
NFEEDITEMS = 10 

# generate the RSS feed 
print "<rss>" 
print "<channel>" 
print 
print "<title>Sample Python Channel</title>" 
print "<link>" + HOME_URL + "</link>"
print "<description>This is a dummy RSS feed generated by the sample Python channel plugin.</description>" 
print 
for i in range(1,NFEEDITEMS+1) :
    print "<item>" 
    print "    <title>Item " + str(i) + "</title>" 
    print "    <link>" + HOME_URL + "/item" + str(i) + ".html</link>" 
    print "    <description>This is a dummy description for item " + str(i) + "</description>" 
    print "</item>" 
    print 
print "</channel>" 
print "</rss>"

That's it! Plugins just print out their feed to the console and Awasu will take it from there. We won't go into the details of the exact format of an feed here but it's easy to see how things are organized. You will find an example feed in the Samples/ directory. Most of the time, you won't need anything more than this.

How plugins are run

A few notes about how plugins are run:

• Awasu determines which program to run by checking the script's file extension and looking up the appropriate association in the Windows Registry. Most of the time, the scripting engine will set this up for you when it is installed but it is possible to override this or define new associations if necessary. You should definitely read this section if you are writing plugins in Java.
• If the plugin writes anything to the error output (stderr) or returns a non-zero exit code, this will be treated as an error by Awasu and processing will be aborted. In the example above, we simply run off the end of the script, which will return a zero exit code by default.
• The plugin will be run in the directory in which the script resides. For a stand-alone script this is not important but will be relevant if the script needs to locate data files or other helper scripts.