I have found – by accident really! – a very interesting presentation on SlideShare concerning the different leading Open Source Application Servers on the market.

This very solid evaluation is proposed by OpenLogic.

I have summarized parts of it below.

Goal of the presentation /

Help you choose which open source application servers to evaluate more thoroughly:

• JBoss
• GlassFish
• dm Server
• Geronimo
• Tomcat

Which open source application servers are your using or considering using /

J2EE Didn’t Fill the Need /

• EJB 2 is difficult to use
  • Many people consider it unnecessary difficult
  • Entity Beans were especially problematic
  • But even session beans earned bad reputations
• The Open Source community responds
  • OSS packages mitigating the problem
    • Hibernate instead of Entity Beans
    • Spring as a component model
  • They were very successful in the marketplace
• Many Spring/Hibernate applications
  • Required only Tomcat to run but also work in full app servers

When Tomcat Is Not Enough /

• Tomcat doesn’t support
  • JMS
  • EJBs
  • Other…
• Enterprises need integration
  • The more mature the app is, the more likely it is to be added
• Add-ons
  • It was possible to add things that Tomcat was missing
  • But this became a “build your own Frankenstein” exercise

Java Enterprise Edition in the Meantime /

• Weaknesses in EJB 2 model were recognized
• Work on new specification was completed
  • J2EE → JEE 5
  • EJB 2 → EJB 3
    • Entity Beans → JPA
• EJB 3
  • Simple annotation-based programming model
  • Not everybody adopted EJB 3
• JEE 6 will embrace modularity
  • Profiles, including web profile

Choices in 2007 /

• Use Spring
  • Start with full app server
  • Start with Tomcat, build from there
• Use EJB 3
  • Requires full app servers
• Full application server
  • Pros – everything you are likely to need, could use EJB
  • Cons – complexity, might use more resources then Tomcat
• Tomcat
  • Pros – small, simple, low resource usage
  • Cons – you might need to build your own app server, no EJB

OSGi /

• Started in 1999
  • Recently got a lot of exposure
  • In particular, R 4.1
    • JSR-294
• OSGi brings
  • Dependency management and modularity
  • Ability to load only parts it needs
• OSGi currently has a lot of mindshare

The central questions /

• Decisions, decisions
  • EJB 3 or Spring
  • Spring on dm Server or on J2EE/JEE server?
  • OSGi or not OSGi
  • Do I need EJB 2 compatibility?
  • In addition, there are many “old” considerations
• Servers are not “all inclusive”
  • EJB 3 apps won’t work on SpringSource dm Server or Tomcat

Assessment JBoss /

Assessment SpringSource dm Server /

Assessment Tomcat /

Conclusions /

• App servers are not just about the JEE specs
• Make some high-level decisions before evaluation
  • Do I need EJB 2 compatibility?
  • Do I intend to follow EJB 3 and other industry standards?
  • Do I need something fast, lightweight, and easy to use?
  • Do I have a need for lifecycle management of server components (through OSGi)?
  • Do I need support for dynamic languages like Groovy and JRuby?
  • Am I an early adopter of new technology?

Recommendations /

• “I’m using EJBs and I’m conservative”
  • JBoss, GlassFish
• “I don’t need XA/JMS/EJB”
  • Tomcat, JBoss, GlassFish, dm Server
• “I’m using Spring”
  • Conservative – JBoss, Tomcat, GlassFish
  • Leading edge – dm Server
• “I need to embed an app server in my commercial code”
  • Tomcat, Geronimo
• “I use Spring heavily and I need OSGi”
  • I need it today and don’t need EJBs – dm Server
  • I need it soon and/or need EJBs – GlassFish, JBoss
• “I use Seam”
  • JBoss
• “I want ActiveMQ/Spring/Hibernate preinstalled”
  • Geronimo
• “I need dynamic language support”
  • Groovy/Grails – dm Server, JBoss, GlassFish
  • JRuby/Rails – GlassFish, Geronimo