Open Source Application servers

A number of free, or nearly free, application servers are available from open source groups.

To find out whether an open source product fits the needs of your organization, start by checking out a few of these better-known open source application servers:

• Enhydra, from Enhydra.org. Originally developed by Lutris Technologies, Open Source Enhydra is a Java/XML application server. It supports Sun Microsystems' J2EE standards for Java servlets and JavaServer Pages (JSP) and includes useful features such as an XML engine, object-to-relational mapping and database connection pooling.
  
• jBoss Group's jBoss server. jBoss is a J2EE Web application server that jBoss Group claims competes directly with BEA Systems' WebLogic and IBM's WebSphere. According to the jBoss Web site, 50,000 copies of the application server are downloaded each month. JBoss includes the JBossServer, which is the basic EJB container and JMX (Java Management eXtension) infrastructure; JBossMQ for JMS messaging; JBossMX for mail; JBossTX for JTA/JTS (Java Transaction API and Java Transaction Service) transactions; JBossSX for security; JBossCX for JCA (Java Connector Architecture) connectivity; and JBossCMP for container managed persistence.
  
• JOnAS, from ObjectWeb and Evidian. JOnAS is an implementation of the EJB specification. It's one of the projects of the ObjectWeb open source initiative (www.objectWeb.org), although tech support is available from Evidian (formerly BullSoft). JOnAS includes such features as JMX management, support for the JCA specification, a transaction manager, a database manager and an embedded implementation of JMS.
  
• PHP, from the Apache Software Foundation. PHP was developed by Zend Technologies and is now a project of the Apache folks. While not technically an application server, PHP acts much like one. It's a scripting language and environment that generates dynamic pages. Unlike an application server, notes Jean-Christophe Cimetiere, CEO of TechMetrix Research, a PHP server isn't an always-on process but is only activated when a request for a dynamic page is made.
  

• Resin, from Caucho. Resin is a servlet and JSP engine that has load-balancing capability and includes an HTTP/1.1 Web server. It's available under the Caucho Developer Source Licens
  
• Tomcat, from the Apache Software Foundation. Tomcat is the servlet container used in the official reference implementation for Sun's Java servlet and JSP technologies. Tomcat is released under the Apache Software License.