Blogging Roller

Elliot Rusty Harold: I just realized something: Java 1.5, being covered at JavaOne, is code named Tiger. Mac OS X 10.4, being announced across the hall in Moscone is code named Tiger. And I've heard a couple of hints that there's something big and unexpected being announced by Sun next week with regard to Java. Could there be some as yet unreleased big news about a Sun-Apple collaboration?

Prompted by the news of the Rome effort, I started taking a serious look at the various Java based Weblog and Wiki libraries last night. Starting with the list compiled by the Rome guys in What's wrong with other existing RSS parsing libraries, I started to build my own list. I expanded my list to include not only newsfeed parsing libraries, but also blog/wiki API server and client libraries. I also added a couple of clarifications and a couple of categories: 1) newsfeed parsing and producing, 2) server-side libraries, 3) client-side libraries.

It is interesting that there are two Atom API server libraries, but no Atom API client library (except for Gilmore which is just getting started). This illustrates the fact that the Atom API is new, still in flux, and interesting only to server developers at this point. Also interesting: all of the newsfeed parsing libraries parse news feeds as XML, there is no Java equavalent to Mark Pilgrim's Universal Feed Parser.

One question that crossed my mind: should Rome include a blogging client library? Posting, updating, and deleting posts via the XML-RPC based Blogger API or the REST-based Atom API is not exactly easy to do. Wouldn't it be nice to have a client library with an easy-to-use set of interfaces for this.

Here is my list of Open source Java libraries for Weblogs, Wikis, and Newsfeeds.:

Newsfeed parsers and generators

• Informa - library for parsing and producing RSS, RDF, and very soon, Atom. Also includes database persistence layer. Established May 2002, under active development, latest release 0.5.
• Rome - library for parsing and producing all flavors of RSS and Atom. New effort started June 2004, latest release 0.2.
• RSSLibJ - primarily for generating RSS. Development stalled?
• <a href= "http://java.sun.com/developer/technicalArticles/javaserverpages/rss_utilities/"> RSS Utilities - JSP tags for parsing and displaying RSS presented in a java.net article.
• RSS4J - parser for RSS and RDF. Development stalled?
• FeedParser - Kevin Burton's parser, drives Newsmonster.

Server libraries

• Sandler - toolkit for implementing Atom API in a web application, includes an Atom parser. Used by Blojsom.
• Atom4J - toolkit for implementing Atom API in a web application, includes an Atom parser. Used by Roller.

Client libraries

• <a href= "http://www.javaslash.org/blog/?permalink=ADF02966A9EFE9FD2275BE52CCFB72C7.txt"> Gilmore - soon to be a full function Atom API client library, under development. Sister project to Sandler.
• Hula - client library for programming Wikis that implement WikiRPCInterface. Associated with JSPWiki
• Apache XML-RPC - good do-it-yourself starting point for implementing a Blogger API or a WikiRPCInterface client.

- according to Time Magazine

- Redhat frees Eclipse from the VM, via Scott Delap

- Sam Newman's take on Rome

- via Oleg Proudnikov

- ending syndication feed hell, at least for Java developers

- The Global Assembly Cache

- from Ben Hammersley

- Thirsty Bear. Be there and/or be square.

- via Erik

I'm messing around with HSQLDB because I need to create an easy-to-install demo-only version of Roller. I want to bundle everything needed to run Roller and make it drop-dead simple to try Roller on your own machine. All that you, the potential Roller user, will have to do is to unzip the distribution file and run a startup script.

To make this work I need Roller, a database, and a Web app server, all bundled together into one downloadable file. That is easy to do: I start with a Tomcat distribution and drop Roller into the webapps directory. When Tomcat starts, Roller will start. Roller won't function without a database, so I need to add the tiny pure-Java HSQLDB database to the mix. I need to get HSQLDB started before Roller starts. This part is not so easy: after looking at the HSQLDB docs I found that I have at least three options:

1. Use the "in-memory" version of HSQLDB. With this approach, no HSQLDB starter is necessary. If you use a JDBC connect string of the form jdbc:hsqldb:filepath instead of the normal jdbc:hsqldb:hsql://host:port form, then HSQLDB will start itself inside your process (is that cool - or what!). The problem with this approach is that it requires the person who installs my demo to edit a file - they have to set the path to the HSQLDB, or I have to rely on an unreliable relative path. Another problem is that, in this mode, HSQLDB will not accept JDBC connections from other clients - such as the HSQLDB database manager.


2. Add a ServletContextListener to Roller that starts the "standalone" server version of HSQLDB on it's own thread when my Web app starts, on contextInitialized(), and shuts down when my Web app stops, on contextDestroyed(). There are a couple of problems with this approach. First, I don't want to add anything to Roller. Second, I want the database to be available for other Web apps - like JSPWiki which I will include in the demo - to do authentication. Finally, after some experimentation I could not get HSQLDB starting ServletContextListener to start before the other parts of Roller that need a database connection.


3. Add a LifecycleListener to the Tomcat server.xml to start the "standalone" server verion of HSQL on it's own thread when Tomcat starts. To enable this, I also add some -D startup parameters to catalina.sh to tell my listener where the database file is and what port to use.

Approach #3 seems to be the best option for the Roller Demo and it's working for me. Here is the code for the lifecycle listener that starts and stops HSQLDB:

import org.apache.catalina.Lifecycle;
import org.apache.catalina.LifecycleEvent;
import org.apache.catalina.LifecycleListener;
import org.roller.util.HSQLDBUtility;

public class TomcatHSQLDBPlugin implements LifecycleListener {
   public void lifecycleEvent(LifecycleEvent event) {		
      if (event.getType().equals(Lifecycle.START_EVENT)) {
         HSQLDBUtility.start();
      }
      else if (event.getType().equals(Lifecycle.STOP_EVENT)) {
         HSQLDBUtility.stop();
      }
      else {
         System.out.println(getClass().getName()+": Not handling LifecycleEvent: "+event.getType());
      }
   }
}

To plug-in to the Tomcat startup and shutdown process, I had to do two things. First, I placed a jar with my TomcatHSQLDBPlugin and HSQLDBUtility classes in a jar in tomcat/server/lib. Second, I added the following XML to the tomcat/conf/server.xml file along side the listeners already in the file:

    <Listener className="org.roller.tomcat.TomcatHSQLDBPlugin" debug="0"/>

That's that. I've got this stuff working now. Next up: JSPWiki integration and then I'll make Roller-Demo available for download on SourceForge.

I'll be at JavaOne this year, my first time ever. I haven't been to a real conference or to San Franciso in a couple of years, so I am pretty excited about the whole deal. I'm looking forward to meeting the Java bloggers, too. For example, I've never met Matt Raible or Russell Beattie or Simon Brown, or any of the other Java bloggers and I hope to change that next week. I also hope to hook up with some of the Sun Bloggers to talk about Roller at Sun. Along those lines: Atlassian is organizing a meetup that looks to be interesting.

I noticed that MyEclipse now supports Eclipse 3.0 RC1, so I downloaded both last night. I must say, I'm impressed. Eclipse looks and feels much better than before on the Mac. Font sizes are reasonable and the theme looks better in some way, but I can't quite put my finger on exactly what it is. Code folding is sweet!

- A Bug Pattern Detector for Java (via Rusty)

- Java based

I found an interesting article on Embedding HSQLDB in Eclipse, but what I really want to do is to embed HSQLDB in Tomcat. Is there an easy way to add a "lifecycle" plugin to Tomcat so that HSQLDB is started by Tomcat startup and shutdown by Tomcat shutdown .