Appendix A: Key Words

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Activation Record: A record for each method call on the program stack.
Active Object: An object that is an asynchronous activity. In terms of threads it is an object that has a run method and is run as a thread.
Activity: A series of steps that is implemented to do a task.
Adapter: Software that provides an interface allowing a component to be used in a manner.
Animation: A technique where pictures are changed slightly and displayed on a terminal so fast that the eye perceives movement.
Asynchronous Activity: When the steps involved in the two or more sub-tasks are being executed independently, or asynchronously, from each other.
Born (thread state): The initial state of a thread before it can be run.
Cache: A special place to store data, often hidden from either the other objects or in some cases the program. In the case of computer architecture, it is very fast memory that the program cannot directly manipulate. In a sense it is hidden from the program.
Checked Exception: An exception that the compiler forces the program to explicitly handle in either a try block or by using a throws clause in the current method. These exceptions extend Exception.
Child Thread: A thread that was started by the current thread.
Classification: An OOP design methodology where objects are designed by extending other objects, using the "extends" clause in Java. Classification is also called inheritance.
Cohesion: The degree that an object or method does a specific task, and only that task.
Common Gateway Interfaces (CGI): A way to process Web requests that was initially dependent on using a separate process for each request.
Competitive Synchronization: When two or more asynchronous activities coordinate around a resource.
Complete Synchronization: An object with all of its methods synchronized and no waits in any methods.
Component: Used in this text to mean concurrent component.
Composition: An OOP design methodology where objects are created by using instances of other objects or primitives, hence they are "composites" of other objects.
Concurrency: The presence of asynchronous activities that interact and thus must at some point in their execution implement either competitive or cooperative synchronization.
Concurrent Component: A passive object that controls interactions between two or more asynchronous activities.
Concurrent Programming: A program that contains asynchronous activities which synchronize at one or more points or on one or more resources during execution.
Confinement: Complete encapsulation of an object inside of another object.
Context Switch: The switching between the thread to be run.
Control Object: An object used to build all the active and passive objects in a concurrent program and start them.
Cooperative Synchronization: When two or more asynchronous activities coordinate around an event.
Coupling: How tightly integrated two objects or methods are integrated together.
Critical Section: A section of a program (for example a method) where the existence of a race condition could cause the program to be incorrect.

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A-C