Join Java
Encyclopedia
Join Java is a programming language
that extends the standard Java programming language
with the join semantics of the join-calculus
. It was written at the University of South Australia
within the Reconfigurable Computing Lab by Dr. Von Itzstein.
Concurrency in most popular programming languages is implemented using constructs such as semaphores and monitors. Libraries are emerging (such as the Java concurrency library JSR-166) that provide higher-level concurrency semantics. Communicating Sequential Processes (CSP), Calculus of Communicating Systems (CCS) and Pi have higher-level synchronization behaviours defined implicitly through the composition of events at the interfaces of concurrent processes. Join calculus, in contrast, has explicit synchronization based on a localized conjunction of events defined as reduction rules. Join semantics try to provide explicit expressions of synchronization without breaching the object-oriented idea of modularization, including dynamic creation and destruction of processes and channels.
The Join Java language can express virtually all published concurrency patterns without explicit recourse to low-level monitor calls. In general, Join Java programs are more concise than their Java equivalents. The overhead introduced in Join Java by the higher-level expressions derived from the Join calculus is manageable. The synchronization expressions associated with monitors (wait and notify) which are normally located in the body of methods can be replaced by Join Java expressions (the Join methods) which form part of the method signature.
execute once all the fragments of the Join pattern have been called.
If the return type is a standard Java type then the leading fragment will
block the caller until the Join pattern is complete and the method has
executed. If the return type is of type signal then the
leading fragment will return immediately. All trailing fragments are
asynchronous so will not block the caller.
Example:
class JoinExample {
int fragment1 & fragment2(int x) {
//will return value of x
//to caller of fragment1
return x;
}
}
a case when multiple Join patterns are completed when a fragment is called.
Such a case could occur in the example below if B, C and D then A are
called. The final A fragment completes three of the patterns so there are
three possible methods that may be called. The ordered class
modifier is used here to determine which Join method will be called.
The default and when using the unordered class modifier is
to pick one of the methods at random. With the ordered
modifier the methods are prioritised according to the order they are declared.
Example:
class ordered SimpleJoinPattern {
void A & B {
}
void A & C {
}
void A & D {
}
signal D & E {
}
}
return type. This has the same characteristics as the void
type except that the method will return immediately. When an asynchronous
method is called a new thread is created to execute the body of the method.
Example:
class ThreadExample {
signal thread(SomeObject x) {
//this code will execute in a new thread
}
}
is the closest related language.
Hardware Join Java language further extended Join Java to implement Hardware semantics. This language extended the semantics of Join Java to FPGA applications.
Programming language
A programming language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely....
that extends the standard Java programming language
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...
with the join semantics of the join-calculus
Join-calculus
The join-calculus is a process calculus developed at INRIA. The join-calculus was developed to provide a formal basis for the design of distributed programming languages, and therefore intentionally avoids communications constructs found in other process calculi, such as rendezvous communications,...
. It was written at the University of South Australia
University of South Australia
The University of South Australia is a public university in the Australian state of South Australia. It was formed in 1991 with the merger of the South Australian Institute of Technology and Colleges of Advanced Education. It is the largest university in South Australia, with more than 36,000...
within the Reconfigurable Computing Lab by Dr. Von Itzstein.
Language characteristics
The Join Java extension introduces three new language constructs:- Join methods
- Asynchronous methods
- Order class modifiers for determining the order that patterns are matched
Concurrency in most popular programming languages is implemented using constructs such as semaphores and monitors. Libraries are emerging (such as the Java concurrency library JSR-166) that provide higher-level concurrency semantics. Communicating Sequential Processes (CSP), Calculus of Communicating Systems (CCS) and Pi have higher-level synchronization behaviours defined implicitly through the composition of events at the interfaces of concurrent processes. Join calculus, in contrast, has explicit synchronization based on a localized conjunction of events defined as reduction rules. Join semantics try to provide explicit expressions of synchronization without breaching the object-oriented idea of modularization, including dynamic creation and destruction of processes and channels.
The Join Java language can express virtually all published concurrency patterns without explicit recourse to low-level monitor calls. In general, Join Java programs are more concise than their Java equivalents. The overhead introduced in Join Java by the higher-level expressions derived from the Join calculus is manageable. The synchronization expressions associated with monitors (wait and notify) which are normally located in the body of methods can be replaced by Join Java expressions (the Join methods) which form part of the method signature.
Join methods
A Join method is defined by two or more Join fragments. A Join method willexecute once all the fragments of the Join pattern have been called.
If the return type is a standard Java type then the leading fragment will
block the caller until the Join pattern is complete and the method has
executed. If the return type is of type signal then the
leading fragment will return immediately. All trailing fragments are
asynchronous so will not block the caller.
Example:
class JoinExample {
int fragment1 & fragment2(int x) {
//will return value of x
//to caller of fragment1
return x;
}
}
Ordering modifiers
Join fragments can be repeated in multiple Join patterns so there can bea case when multiple Join patterns are completed when a fragment is called.
Such a case could occur in the example below if B, C and D then A are
called. The final A fragment completes three of the patterns so there are
three possible methods that may be called. The ordered class
modifier is used here to determine which Join method will be called.
The default and when using the unordered class modifier is
to pick one of the methods at random. With the ordered
modifier the methods are prioritised according to the order they are declared.
Example:
class ordered SimpleJoinPattern {
void A & B {
}
void A & C {
}
void A & D {
}
signal D & E {
}
}
Asynchronous methods
Asynchronous methods are defined by using the signalreturn type. This has the same characteristics as the void
type except that the method will return immediately. When an asynchronous
method is called a new thread is created to execute the body of the method.
Example:
class ThreadExample {
signal thread(SomeObject x) {
//this code will execute in a new thread
}
}
Related languages
Polyphonic C sharpPolyphonic C sharp
Polyphonic C# is an extension of the C# programming language.It includes a new concurrency model in which objects can have both synchronous and asynchronous methods...
is the closest related language.
Hardware Join Java language further extended Join Java to implement Hardware semantics. This language extended the semantics of Join Java to FPGA applications.