Introduction
In the late 1990s,
the widespread availability of low-cost computers and access to global
connectivity have fueled the demand for a new kind of application: the
highly distributed application. Highly distributed applications are used by
extremely large numbers of people around the world who are connected to many
application and data servers via nonpermanent or slow links. These
characteristics create application requirements that strain the capabilities
of traditional application architectures.
The Microsoft
Windows Distributed interNet Applications (DNA) architecture represents
Microsoft's approach to creating highly distributed applications. DNA
applications use a logical, three-tier, component-based architecture.
Microsoft system services provide the infrastructure needed by this type of
application. The key infrastructure services are the Component Object Model
(COM), which provides the basic mechanism for component interaction, and
Microsoft Transaction Server (MTS), which provides an execution environment
for building scalable server applications.
This book is
intended to help you succeed in building your first distributed three-tier
application based on COM and MTS. It does not attempt to address every issue
you will encounter when writing enterprise-wide applications. It does not
attempt to define a methodology that will work for every development team.
It does give you practical advice that will help you design, develop,
test, and deploy three-tier applications based on the Microsoft Windows DNA
technologies. The primary focus will be on the middle tier, or business
logic, where you will use COM and MTS.
The
recommendations in this book are based on experience gained from Microsoft's
3-2-1 program. "3-2-1" stands for three-tier application,
two developers, one month—in other words, a project in which two
developers work for one month to write a three-tier application. 3-2-1
projects are a way to get started with MTS. For more information, see the
Appendix.
Who
Should Read This Book?
The primary
audience for this book is the full-time professional developer who is
familiar with an object-based programming language such as Microsoft C++,
Java, or Microsoft Visual Basic. Some familiarity with the Internet and
general database concepts, while not required, will be helpful. Several of
the topics covered here will be of interest to system administrators as
well.
Some portions of
the sections of this book assume that you have some experience using Visual
Basic or Visual C++. I also assume that you don't need a zillion screen
shots to figure out how to install an application or use a development
environment and that you understand how to use the documentation that comes
with your tools. Pages of screen shots and step-by-step instructions for
selecting a menu option bore me; I expect they bore you as well.
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