So I've had some hairpulling experiences lately because of coming onto projects being developed using one technology (say Tomcat 6) but having to deploy to another (say Oracle 10g R3). Differing application servers aside, multiple times I've had to downgrade J2EE specs say from J2EE 5 to J2EE 1.4 and in doing, had to scour the web to figure out what versions of what APIs should exist in my build path to ensure compatibility. I started to compose a list which I hope someone will be able to help fill in or correct. Check it out:
J2EE Technology, Desc ,1.4, 5, 6
WS, Web Service API, ?, ?, 1.3
SAAJ, SOAP with Attach, 1.2, ?, ?
JAXP, XML Processing, 1.2, ?, ?
JAXB, XML Binding, ?, 2.0, 2.2
StAX, Streaming API for XML, ?, ?, ?
JAX-WS, XML Web Services, ?, 2.1, 2.2
JAX-RPC, XML Remote Procedure, 1.1, 1.1, 1.1
JAX-RS, XML RESTful Services, x, x, 1.1
JAXR, XML Registry, 1.0, ?, ?
JSF, Java Server Faces, JSP Only, 1.2, 2.0
JSP, Java Server Pages, 2.0, 2.1, 2.2
EL, Expression Lang, 2.0, 2.1, 2.2
JSTL, Standard Tag Lib, 1.1, 1.2, 1.2
Servlet, Servlet API Spec, 2.4, 2.5, 3.0
EJB, Enterprise Java Bean, 2.1, 3.0, 3.0
JPA, Persistence API, x, x, 2.0
JNDI, Naming Directory, 1.2, ?, ?
JDBC, Database Connectivity, 3.0, ?, ?
JavaMail, Email, 1.3, 1.4, ?
Connector, J2EE Connector, 1.5, 1.5, 1.6
JAF, Activation Framework, 1.0, 1.1, 1.1