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Standards

The language and the JVM standards can be found at: http://docs.oracle.com/javase/specs/ Those only contain the language specification, not the Java Class Library.

Note that they are two separate standards:

  • the Java language specification (JLS), which determines on a high level what the language does
  • the JVM specification specifies (JVMS), which determines on a lower level how the bytecode is interpreted

Java Community Process

JCP

https://jcp.org

The Java standard is not completely controlled by Oracle, but maintained by a committee composed of many large organizations: http://en.wikipedia.org/wiki/Java_Community_Process

JSR

Java Specification Requests

RFC of the JCP. E.g., Servlets are specified in JSR 315: https://jcp.org/aboutJava/communityprocess/final/jsr315/

Documentation

Tutorials: http://docs.oracle.com/javase/tutorial/ Download them under the downloads section.

Docs: http://docs.oracle.com/javase/7/docs/ see under the downloads section.

JCL reference: http://docs.oracle.com/javase/7/docs/api/ TODO: is that official?

JRE vs JDK

The JVM is included in the Java Runtime Environment (JRE), which also contains things like all the compiled standard library .class files. JRE does not contain for example javac which is only needed by developers: it is an end user package.

For development, one must have the Java Developer Kit (JDK), which includes things like:

  • javac which transforms .java files into .class files,
  • javadoc which generates HTML documentation from comments. JDK also includes the JRE.

Java was present in LSB, but got removed from LSB 4.1 because of licensing issues. Source.

JCL

Java Class Library.

http://en.wikipedia.org/wiki/Java_Class_Library

Name of the stdlib .class implementation. Present in the JRE.

Editions

Java comes different forms for different applications.

Both the libraries and the JVM change between those implementations.

  • SE: standard edition. Intended for for personal desktops / laptops.
  • EE
  • ME: micro edition. For portable devices such as cell phones.

Each of those has their own implementations. Oracle implements all.

Source: http://stackoverflow.com/questions/2857376/difference-between-java-se-ee-me

EE

Contains "Enterprise" APIs, which is a generic term for APIs mostly useful for large enterprises.

http://stackoverflow.com/questions/106820/what-is-java-ee

Sources:

Implementations include:

  • GlassFish
  • TomEE
  • WildFly (old JBoss)
  • IBM Websphere
  • Oracle Weblogic

Tomcat

Apache Tomcat implements only JavaServer Pages and Servlets, which are only a part of the full EE.

Jetty

http://eclipse.org/jetty/

Like Tomcat, an implementation of Servlets.

Seems to be easier to deploy than Tomcat, and specially good as a development server.

http://stackoverflow.com/questions/302977/tomcat-vs-jetty

GlassFish

GlassFish is the reference implementation of many parts of the API, but not all. This table summarizes reference implementations.

For example, GlassFish is the reference for Servlets, but not for JSONP.

It is open source, started by Sun, and sponsored by Oracle.

Oracle has dropped support for it in 2013 in favor of it's Oracle Weblogic, but it still is the reference implementation. TODO does it still support?

WildFly

JBoss

JBoss, now renamed as WildFly is another open source EE implementation http://en.wikipedia.org/wiki/WildFly TODO why another? Maintained by RedHat.