There have been a number of approaches proposed to design and develop object-oriented systems.

An object-oriented system is composed of objects.

Each thread - with its associated 'method'(location address, data route and other information)- can be regarded as an object in an object-oriented system.

Objects are the run time entities in an object-oriented system.

In contrast, most object-oriented systems at the time that it was created used large virtual machine runtimes.

Creation of objects is one of the most common activities in an object-oriented system.

In the early 1990s other object-oriented systems analysis methods were proposed.

The book is very focused on describing the domain layer as one of the common layers in an object-oriented system with a multilayered architecture.

It is also an excellent validation of object-oriented systems.

Henry Lieberman: Using prototypical objects to implement shared behavior in object-oriented systems.