JavaWorld has an article entitled JBoss, Geronimo, or Tomcat? Three open source Java application servers compared. It's unfortunate that they did not include GlassFish but Masoud has attempted to address that through his latest blog entry; Check it out!

We probably should write some comparison articles of our own and submit them for publication. Maybe after GFv2 UR1 goes out we will find the time to do it.

Added: Also see the discussion at TheServerSide.COM, and the comparisons at TSS and Wikipedia.

Julien (at Aubiere) provides an evaluation of the main Open Source AppServers: Apache Geronimo, GlassFish, JBoss and Jonas and his choice is GlassFish. He mentions the usual reasons (documentation, console, RI) but also one that is less common: domains which turn to be very useful for teaching a class.

Julien also mentions jRuby and GlassFish v3 support as additional reasons. Check the details at his Blog entry.

News.Com has a nice Interview with Marc Fleury that is worth a read. With my GlassFish hat on, I specially like this quote: ... we were seriously stressed when IBM declared war with Geronimo, and then HP got in the game against us, too. Red Hat and JonAS didn't scare us at all (really - not at all), nor did we worry about Sun's foray into the market. Oddly enough, of that group only Sun has managed to mount serious competition to JBoss.

Marc has a keen understanding of the industry and the whole interview is worth a read.

Apache Geronimo has passed all the tests in the JavaEE 5 CTS test suite. Geronimo is pursuing two Web Services stacks (report card); these results used CXF. According to the announcement, "the official 2.0 release is anticipated at the end of June / early July", which puts it very close to Eclipse 3.3 (Europa). Congratulations to the Apache community! Competition and options are good for customers, we welcome Geronimo to the Java EE 5 Compatibility party.

One of the benefits of using an OpenSource license is to simplify adoption by other F/OSS groups, and, slowly we are getting more customers.

In the case of Geronimo their Report Card shows a plan to use JAXB 2.0 (or 2.1?). Other modules are listed as multiple options, including JSF 1.2, TopLink Essentials, and JSP 2.1 (used by Jetty). The table is probably not up-to-date; for example, check this Thread on JSTL 1.2.