Joe-E is a subset of the Java

Java (programming language)

Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...

 programming language intended to support programming according to object-capability discipline

Object-capability model

The object-capability model is a computer security model based on the Actor model of computation. The name "object-capability model" is due to the idea that the capability to perform an operation can be obtained by the following combination:...

.

The language is notable for being an early object-capability subset language. It has influenced later subset languages, such as ADsafe and Caja/Cajita, subsets of Javascript.

It is also notable for allowing methods to be verified as functionally pure

Pure function

In computer programming, a function may be described as pure if both these statements about the function hold:# The function always evaluates the same result value given the same argument value...

, based on their method signatures.

The restrictions imposed by the Joe-E verifier include:

• Classes may not have mutable static fields, because these create global state.
• Catching out-of-memory exceptions is prohibited, because doing so allows non-deterministic execution. For the same reason, finally clauses are not allowed.
• Methods in the standard library may be blocked if they are deemed unsafe according to taming rules. For example, the constructor new File(filename) is blocked because it allows unrestricted access to the filesystem.

Cup of Joe is slang for coffee, and so serves as a trademark-avoiding reference to Java. Thus, the name Joe-E is intended to suggest an adaptation of ideas from the E programming language

E (programming language)

E is an object-oriented programming language for secure distributed computing, created by Mark S. Miller, Dan Bornstein, and others at Electric Communities in 1997. E is mainly descended from the concurrent language Joule and from Original-E, a set of extensions to Java for secure distributed...

to create a variant of the Java language.

Waterken Server is written in Joe-E.

External links

• The Joe-E project on Google Code
• Joe-E language specification