Improving Polymorphism and Concurrency in Common Object Models

Abstract

<p>

Most common object models of distributed object systems have a limited

set of object-oriented features, lacking the advanced features of

`polymorphism' (an abstraction mechanism that represents a quality or

state of being able to assume different forms) and `concurrency' (the

ability to have more than one thread of execution in an object

simultaneously). The lack of support for advanced features is a

serious limitation because it restricts the development of new

components and limits reuse of existing of components that use these

advanced features. As a result, wrappers must be used that hide the

advanced features or components must be re-implemented using only the

features of the common object model.

<p>

In this dissertation, a new direction of research centered on a subset

of object-oriented languages, specifically statically typed languages,

is considered. One of the major drawbacks of existing distributed

object systems is that they cater to a broad domain of programming

languages including both object-oriented as well as non object-oriented

languages. Mapping an object model into a non object-oriented language

is a complex task and it does not appear natural to a native language

user.

<p>

The interoperable common object model (ICOM) proposed in this

dissertation is an attempt to elevate common object models (with the

advanced features of polymorphism and concurrency) closer to the object

models of statically typed object-oriented languages. Specific

features of the ICOM object model include: remote inheritance, method

overloading, parameterized types, and guard methods. The actor

model and reflection techniques are used to develop a uniform

implementation framework for the ICOM object model in C++ and

Modula-3. Prototype applications were implemented to demonstrate the

utility of the advanced features of the ICOM object model.

<p>

The main contributions of this dissertation are: design and

implementation of a powerful common object model, an architecture for

distributed compilation, and an implementation of a distributed object

model using the actor model.