JOnAS is a pure Java, open source, application server conforming to the J2EE specification. However, its high modularity allows to it to be used as
– a J2EE server, for deploying and running EAR applications (i.e. applications composed of both web and ejb components),
– an EJB container, for deploying and running EJB components (e.g. for applications without web interfaces or when using JSP/Servlet engines that are not integrated as a JOnAS J2EE container),
– a Web container, for deploying and running JSPs and Servlets (e.g. for applications without EJB components).
The Java 2, Enterprise Edition (J2EE) platform is employed widely by organizations implementing enterprise applications. It is commonly used in business-to-consumer and most recently in Web service deployments. Most of the largest business organizations today have deployed applications on a J2EE platform.
While the J2EE specification is implemented by a number of large and small vendors, there is no open source J2EE container available with a BSD or BSD-derived licence nor is there an open source project today that provides a fully compliant implementation. Verifiable compliance with the J2EE specification is important to business because it ensures that applications deployed by developers are portable and interoperable across J2EE providers. As a result organizations large and small have felt compelled to pay thousands of dollars to commercial vendors in order to deploy applications based on J2EE compliant servers.
The Apache foundation supports several projects that implement pieces of the J2EE platform such as Servlets, JSP, Tag Libraries, and a Web services stack. However, Apache does not currently support a J2EE project.
The aim of the project is to produce a large and healthy community of J2EE developers tasked with the development of an open source, certified J2EE server which is ASF licensed and passes Sun’s TCK reusing the best ASF/BSD licensed code available today and adding new code to complete the J2EE stack.
Enhydra Server is the leading Open Source Java/XML application server supporting latest Servlet and Webservice standards. Enhydra Enterprise is based on JOnAS and supports the full J2EE stack.
JOnAS PKU is a light-weight application server prototype. It functions as component operating platform based on Java/J2EE technology. It aims at exploring advanced middleware features like easy of management, flexibility, and open to change.
JBoss is an application server written in Java that can host business components developed in Java. The interface and architecture of the JBoss application server, the Java business components that can be hosted inside JBoss and various protocols by which a client application (or other business components) can interact with the business components is defined by the Enterprise JavaBeans specification.
JBoss 2 is designed to be an EJB v1.1 container and server. Some parts of EJB 2.0 are supported in the 2.4.x versions, for example Message Driven Beans
JBoss 3.x supports EJB v2.0 including Container Managed Persistence.
The JBoss server is developed in the Open Source tradition by volunteers and sponsors using 100% Pure Java.
Apache Tomcat is the servlet container that is used in the official Reference Implementation for the Java Servlet and JavaServer Pages technologies. The Java Servlet and JavaServer Pages specifications are developed by Sun under the Java Community Process. Apache Tomcat is developed in an open and participatory environment and released under the Apache Software License. Apache Tomcat is intended to be a collaboration of the best-of-breed developers from around the world. Apache Tomcat powers numerous large-scale, mission-critical web applications across a diverse range of industries and organizations.