O-S

---

Object Oriented Programming

Programming in a language that supports objects.

Object Reuse

Extracting commonality in a program that requires some state to be maintained, and using an object to maintain that state.

Parent Thread

The thread that started the current thread.

Passive Object

An object used to control interactions between active objects. Because it runs only when a service is requested by an active object, this type of object is often called a reactive object. Passive objects are generally components.

Procedural

Executing serially (step by step).

Procedural Reuse

Extracting commonality in a program and putting it in a procedural method.

Process

The heap, method area, and program contexts for all threads needed to run a program. Often it is the program being run.

Program Context

The stack, PC, and state stored in memory and used to define a thread.

Program Counter (PC)

The address of the current instruction to execute next. In the SVM this is a line of code, as it does not contain instruction addresses.

Program Stack

A FIFO list of information (activation records) to execute methods. This is contained in the program context.

Propagating an Exception

Allowing an exception to continue up the call stack until it is caught in a catch block.

Race Condition

A condition where, if a thread can complete a critical section without interference, the program will be correct, but the possibility exists that interference can occur, in which case the program would be incorrect.

Reactive Object

An object that "reacts" to messages from active objects. Also often called a passive object.

Ready (thread state)

A state of a thread that says the thread can be run when the CPU is available.

Refactoring

Modifying the code base to ensure that each thing is done once and only once.

Reuse

The abstracting of common code and applying it to several situations in a program or programs.

Reuse by Copy

When a block of code is copied within, or between, programs and modified to fit the current needs of a program.

Running (thread state)

A state of a thread that says the thread is currently executing on the CPU.

Safety

A property of a program that says if a concurrent program finishes, the answer produced will be correct. This normally means that the program does not contain race conditions.

Servlets

A way to use Java to process requests from the Web in a Web server using threads instead of processes.

Simple Memory Model (SMM)

The simple model of memory used by the SVM.

Simple Virtual Machine (SVM)

A simple computer architecture used to explain how concurrent programs run.

Stateless Methods

Methods that do not have to maintain state (i.e., keep variables with values) between invocations.

Synchronization

When two or more asynchronous activities coordinate.

Synchronized Blocks

A block of code that can only be entered (or executed) by one method at a time.

Synchronous Activity

An activity where the order of the steps is determined by a single activity.

---