After suggesting to my AHO class that they consider using RSS feeds in Processing, I realized that there is actually no built-in functionality to do so. The XML class built into Processing is too basic to handle feeds, it seems. To remedy the situation I’ve cooked up a quick hack using the ROME library for RSS / Atom syndication.

To run the code below you’ll need to download ROME and JDOM. Make a “code” subfolder in your sketch and paste “jdom.jar” and “rome-*.jar” into it, then run the code as given. The FeedReader and FeedEntry convenience classes take care of parsing the feed and returning the entries with the most common fields included. Error checking is rudimentary, however.

// feedParser.pde
//
// Reads RSS and Atom feeds. Requires ROME
// (https://rome.dev.java.net/)
// and JDOM (http://www.jdom.org/), just make
// a code folder and copy "jdom.jar" and "rome-*.jar"
// into it.
//
// Marius Watz - http://workshop.evolutionzone.com

import com.sun.syndication.feed.synd.*;
import com.sun.syndication.io.*;

FeedReader feed;
String feedurl;

void setup() {
  size(200, 200);

  // load feed
  feedurl="http://feeds.feedburner.com/CodeForm";
  println("Loading feed: "+feedurl);
  feed=new FeedReader(feedurl);

  // print feed data
  println("Feed: "+feed.title);
  println("------------------------------");
  println("Description: "+feed.description);
  println("\nNumber of entries: "+feed.numEntries);
  println("------------------------------");

  // print feed entries
  for(int i=0; i< feed.numEntries; i++) {
    println(i+": "+feed.entry[i]);
  }
}

class FeedReader {
  SyndFeed feed;
  String url,description,title;
  int numEntries;
  FeedEntry entry[];

  public FeedReader(String _url) {
    url=_url;
    try {
      feed=new SyndFeedInput().build(new XmlReader(new URL(url)));
      description=feed.getDescription();
      title=feed.getTitle();

      java.util.List entrl=feed.getEntries();
      Object [] o=entrl.toArray();
      numEntries=o.length;

      entry=new FeedEntry[numEntries];
      for(int i=0; i< numEntries; i++) {
        entry[i]=new FeedEntry((SyndEntryImpl)o[i]);
        println(i+": "+entry[i]);
      }
    }
    catch(Exception e) {
      println("Exception in Feedreader: "+e.toString());
      e.printStackTrace();
    }
  }

}

class FeedEntry {
  Date pubdate;
  SyndEntryImpl entry;
  String author, contents, description, url, title;
  public String newline = System.getProperty("line.separator");

  public FeedEntry(SyndEntryImpl _entry) {
    try {
      entry=_entry;
      author=entry.getAuthor();
      Object [] o=entry.getContents().toArray();
      if(o.length>0) contents=((SyndContentImpl)o[0]).getValue();
      else contents="[No content.]";

      description=entry.getDescription().getValue();
      if(description.charAt(0)==
        System.getProperty("line.separator").charAt(0))
          description=description.substring(1);

      url=entry.getLink();
      title=entry.getTitle();
      pubdate=entry.getPublishedDate();
    }
    catch(Exception e) {
      println("Exception in FeedEntry: "+e.toString());
      e.printStackTrace();
    }

  }

  public String toString() {
    String s;

    s="Title: "+title+newline+
      "URL: "+url+newline+
      "Date: "+pubdate.toString()+newline;

    if(description.length()>50)
      s+="Descr: ["+description.substring(0,50)+
        "...]"+newline;
    else s+="Descr: ["+description+"]"+newline;

    if(contents.length()>50)
      s+="Contents: ["+contents.substring(0,50)+
        "...]"+newline;
    else s+="Contents: ["+contents+"]"+newline;
    return s;
  }
}