Parsing and Writing RSS Using Jython and Project ROME

Submitted By: Josh Juneau

Introduction

RSS and Jython Using Project ROME

RSS is an old technology now...it has been around for years. However, it is a technology which remains very useful for disseminating news and other information. The ROME project on java.net is helping to make parsing, generating, and publishing RSS and Atom feeds a breeze for any Java developer.

Since I am particularly fond of translating Java to Jython code, I've taken a simple example from the Project ROME wiki and translated a Java RSS reader into Jython. It is quite easy to do, and it only takes a few lines of code.

Keep in mind that you would still need to build a front-end viewer for such an RSS reader, but I think you will get the idea of how easy it can be just to parse a feed with Project ROME and Jython.

Setting Up The CLASSPATH

In order to use this example, you must obtain the ROME and JDOM jar files and place them into your CLASSPATH.

Windows:

set CLASSPATH=C:\Jython\Jython2.2\rome-0.9.jar;%CLASSPATH%
set CLASSPATH=C:\Jython\Jython2.2\jdom.jar;%CLASSPATH%

Parsing Feeds

Parsing feeds is easy with ROME. Using ROME with Jython makes it even easier with the elegant Jython syntax. I am not a professional Python or Jython programmer, I am a professional Java programmer and DBA by profession, so my Jython interpretation may be even wordier than it should be.

I took the FeedReader example from the ROME site and translated it into Jython below. You can copy and paste the following code into your own FeedReader.py module and run it to parse feeds. However, the output is unformatted and ugly...creating a good looking front end is up to you.

FeedReader.py

########################################
# File:  FeedReader.py
# Author: J. Juneau 
# 
# This module can be used to parse an RSS feed
########################################
from java.net import URL
from java.io import InputStreamReader
from java.lang import Exception
from java.lang import Object
from com.sun.syndication.feed.synd import SyndFeed
from com.sun.syndication.io import SyndFeedInput
from com.sun.syndication.io import XmlReader

class FeedReader(Object):
   def __init__(self, url):
      self.inUrl = url

   def readFeed(self):
      ok = False
      #####################################
      # If url passed in is blank, then use a default
      #####################################
      if self.inUrl != '':
         rssUrl = self.inUrl
      else:
         rssUrl = "http://www.dzone.com/feed/frontpage/java/rss.xml"
      #####################################
      # Parse feed located at given URL
      #####################################
      try:
         feedUrl = URL(rssUrl)
         input = SyndFeedInput()
         feed = input.build(XmlReader(feedUrl))
         ####################################
         # Do something here with feed data
         ####################################
         print(feed)
         ok = True
      except Exception, e:
         print 'An exception has occurred', e
      if ok != True:
         print 'An error has occurred in this reader'

if __name__== "__main__":
    reader = FeedReader('')
    reader.readFeed()
    print '*******************Command Complete...RSS has been parsed***********************'

Creating Feeds

Resources