ROME is an open source tool to
parse, generate and publish RSS and Atom feeds. Using Rome you can
parse the available
RSS and Atom feeds. Without bothering about format and version of RSS feed. The core library depends on the JDOM XML parser. Atom is on the similar lines of RSS is another kind of feed. But it’s different in some aspects as protocol, payloads. RSS is a method to share and publish contents. The contents may be any things from news to any little information. The main component is xml. Using xml you can share your contents on web. At the same time you are free to get what you like from others.
Why use Rome instead of other available readers
The Rome project started with the motivation of ‘ESCAPE’ where each letter stands for: E – Easy to use. Just give a URL and forget about its type and version, you will be given a output in the format which you like. S – Simple. Simple structure. The complications are all hidden from developers. C – Complete. It handles all the versions of RSS and Atom feeds. A – Abstract. It provides abstraction over various syndication specifications. P – Powerful. Don’t worry about the format let Rome handle it. E – Extensible. It needs a simple pluggable architecture to provide future extension of formats.
Dependency
Following are few dependencies: J2SE 1.4+, JDOM 1.0, Jar files (rome-0.8.jar, purl-org-content-0.3.jar, jdom.jar)
Using Rome to read a Syndication Feed
Considering you have all the required jar files we will start with reading the
RSS feed.
ROME represents syndication feeds (RSS and Atom) as instances of the
com.sun.syndication.synd.SyndFeed interface. ROME includes
parsers to process
syndication feeds into SyndFeed instances. The SyndFeedInput class handles the parsers using the correct one based on the syndication feed being processed. The developer does not need to worry about selecting the right parser for a syndication feed, the SyndFeedInput will take care of it by peeking at the syndication feed structure. All it takes to read a syndication feed using
ROME are the following 2 lines of code:
SyndFeedInput input = new SyndFeedInput();
SyndFeed feed = input.build (new XmlReader (feedUrl));
Code language: Java (java)
Now it’s simple to get the details of Feed. You have the object. The sample code is as follows.
package com.infosys.hanumant.rome;
import java.net.URL;
import java.util.Iterator;
import com.sun.syndication.feed.synd.SyndEntry;
import com.sun.syndication.feed.synd.SyndFeed;
import com.sun.syndication.io.SyndFeedInput;
import com.sun.syndication.io.XmlReader;
public class Reader {
public static void main(String[] args) throws Exception {
URL url = new URL("https://www.viralpatel.net/feed");
XmlReader reader = null;
try {
reader = new XmlReader(url);
SyndFeed feed = new SyndFeedInput().build(reader);
System.out.println("Feed Title: "+ feed.getAuthor());
for (Iterator i = feed.getEntries().iterator(); i.hasNext();) {
SyndEntry entry = (SyndEntry) i.next();
System.out.println(entry.getTitle());
}
} finally {
if (reader != null)
reader.close();
}
}
}
Code language: Java (java)
Understanding the Program
Initialize the URL object with the
RSS Feed or Atom url. Then we will need XMLReader object which will then take URL object, as its constructor argument. Initialize the SyndFeed object by calling the build(reader) method. This method takes the XMLReader object as an argument.
References
https://rome.dev.java.net/ http://www.intertwingly.net/wiki/pie/Rss20AndAtom10Compared http://www.rss-specifications.com
View Comments
Really thanks for this... This really saved me out after struggling for hours with other parsers.
you welcome Venkatesan.. :)
Hay, i have an error reading the RSS feeds which are generated from google groups. I guess google is blocking requests from other applications than the browsers. Can you please help me on this
Hi Dinesh,
You can set User-Agent of your http request to any of the bot's user-agent so that Google treat it as a bot. To change the user agent of request use XmlReader(java.net.URLConnection conn) constructor of XmlReader class. Pass the conn object which has the user agent set to proper value.
conn.setRequestProperty(”User-Agent”,”whateveryouwant”);
Hope this works
It worked. Thank you very much
I treid your example and got:
Invalid XML: Error on line 10: The element type "META" must be terminated by the matching end-tag "".
[Thrown class com.sun.syndication.io.ParsingFeedException]
Hi Bradford, I suggest you to validate the xml before you parsing it using ROME. Check the source RSS and see if it does not contain any error. There are online tools to validate RSS. Search on Google and you will get lot of such online utilities.
generates this error why?
Exception in thread "main" java.lang.NoClassDefFoundError: org/jdom/input/JDOMParseException
at com.sun.syndication.io.SyndFeedInput.(SyndFeedInput.java:58)
at com.sun.syndication.io.SyndFeedInput.(SyndFeedInput.java:48)
at feedrss.Main.main(Main.java:27)
Caused by: java.lang.ClassNotFoundException: org.jdom.input.JDOMParseException
at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
... 3 more
Java Result: 1
you may want to look at vtd-xml, the latest and most advanced xml processing api
vtd-xml
Rome 1.0 doesn't have a build method who takes a XmlReader. this tutorial needs to be updated.
Sorry 'bout that. the solution was to load jdom lib, nothing wrong with example.
Jnew: that should solve your problem aswell