Contents
Overview 1
Design Patterns and Design Tools in Logical
Design 2
Technology Usage in Physical Design 7
Best Practices 13
Design Validation 14
Future Enhancements to Market Purchasing 17
Review 18

Module 12: Summary

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Module 12: Summary iii Instructor Notes
This module provides students with a summary of the important logical and
physical design considerations for each of the layers in the Enterprise template.
After completing this module, students will be able to:
!
Summarize the logical design considerations for each of the layers of the
Enterprise template and in particular the use of design patterns.
!
Summarize the physical design considerations for each of the layers of the
Enterprise template and in particular the use of technology.
!
Review the key technologies that impact multiple layers.
!
Summarize the best practices for each of the layers of the Enterprise
template.
!
Discuss future enhancements for Market Purchasing.

Materials and Preparation
This section provides the materials and preparation tasks that you need to teach
this module.
Required Materials
To teach this module, you need the following materials:

useful.
In the topic “Structural,” note that there are three design patterns—Facade,
Composite, and Adapter—that are useful.
In the topic “Behavioral,” note that there are three design patterns—
Observer, Iterator, and State—that are useful.
In the topic “Other Patterns,” note that there are two design patterns—
Authenticate and Queue—that are useful. Also note that there are two
modeling techniques that are useful: metaphor and entity relationship
diagram (ERD).
!
Technology Usage in Physical Design
The purpose of this section is to summarize the use of technology in the
three main functions of an application: external interactions, business logic,
and state management. For each technology, a summary of its advantages
and disadvantages is presented. In addition, this section reviews two
technologies that are common to the physical design of all components:
security and error handling.
In the topic “External Interactions,” note that there are six technologies
reviewed: thin client, rich client, Message Queuing, Extensible Markup
Language (XML), distributed Component Object Model (DCOM), and
Simple Object Access Protocol (SOAP).
In the topic “Business Logic,” note that there is only one technology under
consideration: COM+.
In the topic “Data Store,” note that there are only two technologies under
consideration: Microsoft SQL Server
™
and Active Directory
™
.
!

!
Future Enhancements to Market PurchasingThis module presents a summary of the Enterprise template and highlights the
important logical and physical design considerations for each of the layers in
the Enterprise template.
After completing this module, you will be able to:
!
Summarize the logical design considerations for each one of the layers of
the Enterprise template and in particular the use of design patterns.
!
Summarize the physical design considerations for each one of the layers of
the Enterprise template and in particular the use of technology.
!
Review the key technologies that affect multiple layers.
!
Summarize the best practices for each of the layers of the Enterprise
template.
!
Discuss future enhancements for Market Purchasing.

Topic Objective
To provide an overview of
the module topics and
objectives.
Lead-in
In this module, you will
review a summary of the
material presented in this

patterns in the logical design
of an application.
Module 12: Summary 3 Creational
Design PatternLayer
NoneSystem Services
NoneData Services
NoneData Access Layer
NoneBusiness Logic
NoneFacade
NoneUser ServicesThe creational design patterns that are proposed by the book Design Patterns by
Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides, which
include Abstract Factory, Builder, Factory Method, Prototype, and Singleton,
were reviewed for their application to the various Enterprise template layers.
The conclusion drawn was that none of these design patterns are necessary
because the functionality that the design patterns provide is available through
either the operating system or component services.
The only design pattern that posed an issue is the Singleton. A Singleton
ensures that a class has only one instance and provides a global point of access
to it.
After careful consideration, the use of Singleton was rejected on the basis that it
was conceptually wrong to create a logical design that would restrict
concurrency.
Topic Objective
To provide a summary of

interface allows user services to become impervious to changes in the internal
structure of applications.
The Composite structural pattern is useful when an object such as a requisition
can contain several objects, such as line item details. Composite patterns are
useful in the business logic layer and in the data access layer (DAL).
Finally, the Adapter structural design pattern is useful in the logical design of
DAL objects that need to create uniform access to different types of data. Each
DAL component translates the underlying data store into a format suitable for
use in the rest of the system.
Topic Objective
To provide a summary of
the use of structural design
patterns.
Lead-in
In this topic, you will see a
summary of the use of
structural design patterns in
the logical designs of
various architecture
template layers.