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Module 6: Beginning Physical Design

178 Module 6: Beginning Physical Design




Module Overview

Module 3: A Services-Based
Approach to Solution Design
Module 4: Business Solution
Conceptual Design
Module 5: Business Solution
Logical Design
Module 6: Beginning Physical
Design
Module 1: Course Overview
Module 2: Solution Design Using
the MSF
Module 7: Selecting Solution
Technologies
Module 8: Solution Design and the
Component Object Model
Module 9: Designing Solutions with
Microsoft Technologies
Module 10: Completing the
Physical Design
Module 11: Designing the
Presentation Layer

Module 12: Introduction to
Functional Specifications
Designing Business
Solutions
Physical Design
Basics
Activity 6.2: Risks in
Requirements and Constraints
Physical Design
Analysis
Review
Activity 6.1: Risks of
Skipping the Physical Design
Physical Design
Process
Physical Design
Research
Activity 6.3: Determining a Preliminary
Distribution of Components Across a
Network Topology
Module 6:
Beginning Physical
Design
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Module 6: Beginning Physical Design 179

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Overview
In this module
In this module
" Physical Design Basics
" Activity 6.1: Risks of Skipping Physical Design
" Physical Design Process
" Physical Design Research
" Activity 6.2: Risks in Requirements and Constraints
" Physical Design Analysis
" Activity 6.3: Determining a Preliminary
Distribution of Services Across a
Network Topology
" Review


The last phase of the design process is the physical design. Physical design
begins after logical design has started, and the project team agrees that there is
sufficient information to begin the physical design.
Because the physical design evolves from the conceptual and logical designs, it
relies on the successful performance of the first two design phases for its own
success. This reliance helps ensure that the physical design for a solution is one
that the development team can complete successfully, while addressing both
business and user requirements.
In this module, you will begin learning about the physical design phase of the
Microsoft
®

Solutions Framework (MSF) Process Model. First, you will learn
the basics of physical design. You will then learn about physical design in
greater detail through the use of examples and activities based on the Ferguson
and Bardell, Inc. case study.
After completing this module, you will be able to:
"
Explain the need for physical design in the process of designing a business
solution.
"
Describe the role of physical design in the MSF Design Process.
"
Describe the steps of physical design.
"
Create a preliminary services topology.
"
Identify the risks in conflicts between solution requirements and physical
constraints.

Slide Objective
To provide an overview of
the module topics and
objectives.
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180 Module 6: Beginning Physical Design




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Physical Design Basics
In this section
In this section
" Physical Design in the Design Process
" Physical Design: The Search for Structure
" Goals of Physical Design
" Perspective of Physical Design
" Perspective Captured in Component
Specifications
" Clarifying Physical Design
" Value of Physical Design


During physical design, you will apply real-world technology considerations
and constraints to the designs and models that you created during conceptual
and logical designs.
Before delving into the technology aspects, however, you must first learn the
basics of the physical design phase.
In this section, you will begin to learn about the physical design phase. You will
learn about the perspective that should be used during physical design and its
value. You will continue learning about physical design through Modules 7, 8,
and 9 and will complete physical design in Module 10: Completing Physical
Design.
Slide Objective
To provide an overview of
the topics and activities in
this section.

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Module 6: Beginning Physical Design 181




Physical Design in the Design Process
Conceptual Design
Logical Design
Physical Design
Components,
User Interface, and
Physical Database
Scenarios
Services and Objects,
User Interface, and
Logical Database


Physical design is the third phase of the MSF Design Process Model. Physical
design involves clearly defining the components and their location so that the
development team can begin to develop. Its inputs are the business object
model and the other supporting information created in logical design. Its output
is the solution deployment model, the component specification, and a list of
candidate implementation technologies.
Slide Objective
To place physical design in
context with the rest of the
design process.

Lead-in
As you learned in Module 2,
physical design is the third
phase in the MSF Design
Process.
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182 Module 6: Beginning Physical Design




Physical Design: The Search for Structure
"
Definition
The process of describing components,
services, and technologies of the
solution from the perspective of the
development team
"
Purpose
To apply real-world technology
constraints to the logical model,
including implementation and
performance considerations
"
Output
A set of components, user interface
design for a particular platform, and a
physical database design

Physical Design
Components,
User Interface, and
Physical Database


Physical design is the process of describing the components, services, and
technologies of the solution from the perspective of the development team.
Physical design takes into account performance and implementation issues, and
applies technology and technology constraints to a logical design.
Physical design can be likened to the third stage of designing a house. After the
basic architectural plan is complete, the plans for wiring, plumbing, heating,
and ventilation — the internals of the house — are created for the contractors.

This module does not address user-interface design or data-store design.
The user-interface design is presented in Module 11: Designing the
Presentation Layer, and the data-store design is covered in a separate course,
Course 1609: Designing Data Services and Data Modeling.

Slide Objective
To explain physical design,
its purpose, and its output.
Lead-in
Physical design is the
process of describing
components, services, and
technologies of the solution
from the perspective of the
development team.
Note

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Module 6: Beginning Physical Design 183




Goals of Physical Design
"
Transform the logical design into a set of component
candidates
"
Provide a baseline for evaluating implementation design
opportunities
"
Determine the implementation technologies and
strategies
"
Create a structural view of the solution from the
development team’s perspective
"
Articulate the solution design at the level of detail
required for development


Physical design uses the outputs of logical design to produce a component
specification for the proposed solution. This specification describes the
application from the development team’s perspective and will be used by the
development team to create the actual components for the application.
Physical design also provides a baseline that leads to the development of the

application. This baseline provides opportunities for developing prototypes and
beginning the Developing Phase of the MSF Design Process.
During physical design, the project team will evaluate candidate technologies to
determine the technologies that should be used to develop the solution.
Physical design should describe the solution in sufficient detail so that the
development team can create the application that the design describes. The
physical design phase leads to the functional specification, which is the primary
source of information for the development team.
Slide Objective
To describe some of the
goals of the physical design
phase.
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184 Module 6: Beginning Physical Design




Perspective of Physical Design
The physical design
perspective is from the
point of view of the
developers
Conceptual
Logical
Physical
Business
Solution

The physical design is from the perspective of the development team. This
perspective allows the design to begin to take a form that a development team
can use to create the solution by using specific technologies. In this sense,
physical design looks at the design from a more technical viewpoint. Basically,
physical design provides a bridge between logical design and implementation.
Slide Objective
To explain the perspective
that should be used during
the physical design phase.
Lead-in
Whereas logical design
viewed the problem from the
perspective of the project
team, physical design views
the problem from the
perspective of the
development team.
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Module 6: Beginning Physical Design 185




Perspective Captured in Component Specifications
"
Describes the solution at a greater level of detail
"
Defines the internal structure of the components

"
Applies physical constraints to the solution
"
Provides:
$
A bridge between logical design and implementation
$
Implementation clarity for the developers
$
Simplified work estimation and segmentation


Because physical design is from the development team's perspective, this
perspective is captured in a format that is most useful to a developer — that of a
component specification.
The component specification contains the level of detail that developers require
to begin building the components of the business solution. The component
specification defines how those components should be built and determines
what technologies and constraints are applicable to the development.
The component specification provides the transition from the logical design and
its models to the actual implementation. It clearly states what must be built,
how much effort it should take, and how the development effort should be
divided.
Slide Objective
To introduce component
specifications and their use
during physical design.
Lead-in
Physical design involves
reaching a level of detail

that is appropriate for
implementation. Component
specifications are one part
of this process, because
they define how the
individual components are
to be developed.
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186 Module 6: Beginning Physical Design




Clarifying Physical Design
Physical design is not
Coding
Technology deployment
But it enables you to
Create detailed component
specifications for development
Determine where the components
should reside
Choose technologies


During the physical design phase, the project team produces component
specifications and deployment topologies that the development team will use to
create the solution.
It is important to realize that this phase is still part of designing the solution and

not developing the deployable release.
Slide Objective
To further explain the
physical design phase by
giving examples of what
physical design is and is
not.
Lead-in
To further clarify what
physical design entails, let
us look at some examples of
what it is and is not.
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Module 6: Beginning Physical Design 187




Value of Physical Design
"
Evaluates implementation options
"
Provides a flexible design that is based on components
"
Becomes the basis for cost, schedule, and resource
estimates
"
Seeks compatibility with the enterprise architecture
"

Can be traced to usage scenarios through the logical
design


During physical design, you begin to look at candidate technologies that may be
used to develop the solution. You also begin designing the components that the
development team will create.
While you are considering technologies and development options during
physical design, you can also begin to determine more accurately the costs and
schedule for implementation of the project.
During physical design, you can determine how different implementation
options fit within the enterprise architecture. In this stage of development, you
can eliminate gaps and conflicts with the business environment before those
conflicts have a negative impact on the project schedule or project cost.
Physical design is the final step in the path from the original scenarios
developed in conceptual design, through logical design, to implementation. The
final implementation can be traced all the way back to the original business
goals and the vision statement.
Slide Objective
To describe the value that
the physical design phase
brings to the overall MSF
Design Process.
Lead-in
The physical design phase
brings great value to the
overall design in many
ways, including the
following.
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188 Module 6: Beginning Physical Design




Activity 6.1: Risks of Skipping Physical Design


In this activity, based on the course material preceding this activity, you will
take part in a class discussion to identify what the possible risks are of not
doing physical design.
After completing this activity, you will be able to:
"
Articulate the value of doing physical design and the risks of not doing
physical design.

Slide Objective
To introduce the activity.
Module 6: Beginning Physical Design 189

Module 6: Beginning Physical Design 189




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Physical Design Process
"
Physical Design and the MSF Process Model
"
Physical Design Steps
"
Deliverables of Physical Design
In this section
In this section


In this section, you will learn when the physical design phase takes place in the
overall MSF Design Process Model. You will also learn of the separate steps
that make up the physical design phase. Finally, you will look at some concepts
related to the physical design and the actual implementation of the solution.
Slide Objective
To provide an overview of
the topics and activities in
this section.
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190 Module 6: Beginning Physical Design




Physical Design and the MSF Process Model
Vision
Approved
Vision

Approved
Project Plan
Approved
Project Plan
Approved
Conceptual Design
Logical Design
Physical Design
Baseline
Physical design begins before the team baselines logical
design and baselines before the team reaches the Project Plan
Approved Milestone


Physical design begins before the project team has baselined the logical design
and is baselined before the team reaches the Project Plan Approved Milestone.
Physical design should begin when the project team agrees that logical design
has produced the outputs for it to use. As soon as portions of the logical design
have been completed, those portions can be taken into the physical design
phase.
Slide Objective
To explain where the
physical design phase takes
place in the overall MSF
Design Process.
Module 6: Beginning Physical Design 191

Module 6: Beginning Physical Design 191

Physical Design Steps
Although portrayed
sequentially, these
steps are iterative and
overlapping
Physical Design
Specification
Rationalization
Baseline
Analysis
Baseline
Research
Baseline
Research
Analysis
Rationalization
Physical Design
Baseline
Specification
Baseline


The physical design phase of the MSF Design Process has four steps and
associated baselines.
"
Research
• Determine physical constraints and requirements.
• Identify the infrastructure.

"
Analysis
• Develop a preliminary deployment model.
• Select candidate technologies.
"
Rationalization
• Determine a packaging and deployment strategy.
• Transform business objects into services-based components.
• Distribute components across the network topology.
"
Specification
• Determine a programming model.
• Specify component interfaces, attributes, and services.

The specification baseline leads into the baseline of the physical design.
Slide Objective
To explain the separate
steps in the physical design
phase: research, analysis,
rationalization, and
specification.
Lead-in
Physical design has four
distinct steps.
Delivery Tip
Do not spend too much time
here on the details of the
steps. Tell students that the
details will be presented
over the next several

modules.
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192 Module 6: Beginning Physical Design




Deliverables of Physical Design
"
Technology selections
"
Baseline deployment model, comprising network, data,
and component topologies
"
Packaging and distribution strategies
"
Programming models
"
Component specifications


At the physical design baseline, you will have enough information to begin
developing a solution. This information should include the following:
"
Technology selection
Knowing what technology to use to implement certain components based on
solution requirements
"
Baselined deployment model:

• The network topology that indicates hardware locations and
interconnections
• The data topology that indicates data store locations in relation to the
network topology
• The component topology that indicates the locations of components and
their services in relation to the network topology
"
Packaging and distribution strategy
Identifying what services will be packaged together in a component and
how those components will be distributed across the network topology
"
Programming model
Identifying how the solution will be coded as well as identifying guidelines
and specifications regarding development issues
"
Component specification
Identifying the internal structure of the components as well as the
component interfaces

Slide Objective
To introduce the final
outputs that a physical
design should produce.
Delivery Tip
Do not spend too much time
here on the details of the
deliverables. Tell students
that the details will be
presented over the next
several modules.

Module 6: Beginning Physical Design 193

Module 6: Beginning Physical Design 193




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Physical Design Research
In this section
In this section
"
Deliverables of the Research Baseline
"
Sources of Physical Requirements and Constraints
"
Examples of Physical Requirements and Constraints
"
Determining Gaps and Trade-Offs
"
Options for Handling Gaps


In the research step of physical design, you should begin to consider two things.
First, you should look at the actual physical requirements of the new solution.
This could be in terms of performance (for example, transactions per second),
reliability (for example, 99 percent uptime), or other factors. These

requirements should be evident from the conceptual and logical design phases,
but you should now translate these requirements into physical requirements.
Second, you should look at the infrastructure that already exists within the
organization.

Keep in mind during the following slides that each of the considerations
applies to not only the new solution that is being designed but also to the
existing business environment. Conflicts or gaps between the two must be
resolved before implementation.

Slide Objective
To provide an overview of
the topics and activities in
this section.
Tip
194 Module 6: Beginning Physical Design

194 Module 6: Beginning Physical Design




Deliverables of the Research Baseline
Task
Determining physical constraints
and requirements
Identifying risks from conflicts between
constraints and requirements
Deliverable
"

Current network topology
"
Current data topology
"
Current component
topology
"
Physical application
requirements
Risk assessment and mitigation plan
Research Baseline
Research


The deliverables of the research baseline of physical design provide the
foundation for the analysis, rationalization, and specification steps. These
deliverables describe the current infrastructure of the business.
Slide Objective
To explain the deliverables
of the research baseline.
Module 6: Beginning Physical Design 195

Module 6: Beginning Physical Design 195




Sources of Physical Requirements and Constraints
"
Usage scenarios

"
Team experience
"
Management
"
Proof of concepts
"
Vision document
"
Current environment
"
Enterprise architecture


Throughout the design process, you gather and analyze information on the
requirements and constraints of the business. During physical design, you focus
on the physical requirements and constraints, those that will affect the
development of the solution.
The sources of this information include the outputs of conceptual and logical
design as well as the business environment and enterprise architecture.
Be sure to identify both the obvious and hidden constraints and requirements.
Slide Objective
To identify some of the
sources for physical
requirements and
constraints.
Lead-in
The project team’s design
can be greatly affected by
physical requirements and

constraints, both obvious
and hidden. Some of the
sources that should be
investigated include the
following.
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196 Module 6: Beginning Physical Design




Examples of Physical Requirements and Constraints
"
Requirements
$
Performance
$
Cost/benefit
$
Ease of use
$
Deployability
$
Supportability
$
Reliability
$
Reusability
"

Constraints
$
Budget
$
Schedule
$
Network topology
$
Data topology
$
Component topology
$
Technology guidelines
$
Security


Just as requirements and constraints influenced the conceptual and logical
designs, they also influence the physical design.
Often, the requirements and constraints conflict with each other. By identifying
these conflicts early in the design, and addressing them, you can mitigate much
of the risk of developing an unsuccessful solution.
Slide Objective
To reinforce the concept of
requirements and
constraints.
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Module 6: Beginning Physical Design 197

Determining Gaps and Trade-Offs
"
Identify where infrastructure constraints conflict with
application requirements
"
Perform a preliminary assessment to highlight the gaps
"
Prioritize the trade-offs to determine which aspects are
more important
"
Brainstorm initial solutions with the team
"
Identify associated risks


When the physical requirements of the application are compared with the
physical constraints of the infrastructure, some will be in conflict, some will not
be in conflict, and some will be immaterial. For example, the application may
require 100 megabits per second (Mbps) of bandwidth on the network, whereas
the existing network infrastructure supports only 10 Mbps.
In the preliminary assessment of the gaps, you must determine if a gap requires
some sort of choice to resolve the conflict. In the previous example, you may
choose to upgrade the network to support 100 Mbps speeds. Choices such as
these must be made before the project is implemented to ensure that there are
no items that will cause the project to fail later.
Next, you must determine which requirements are absolutely necessary for the
project. When prioritizing, be sure to review the business requirements for

supporting information.
Finally, you can brainstorm separate solutions with individuals from each of the
perspectives: business, user, project team, and development team.
Slide Objective
To explain gaps that occur
during the design process
and the trade-offs that are
required to resolve those
gaps.
Lead-in
Often in the design process,
conflict occurs between the
physical requirements and
the constraints under which
they must be met.
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198 Module 6: Beginning Physical Design




Options for Handling Gaps
"
Accept the gap without doing anything
"
Work around the gap
"
Change the source of the gap

There are three ways to address the gaps:
"
Accept the gap without doing anything.
This implies that the gap is acceptable for the initial release of the solution.
The consequences should be clearly identified, and all stakeholders must
reach a consensus that this is the appropriate choice.
"
Design a way to work around the gap.
Workarounds are often not the optimal solution in the long term, but they
may be necessary because of constraints such as limited project resources.
"
Change either the requirement or the constraint.
Finally, the project team can change one, or both, of the sources of the gap.
This involves changing either the requirement, the constraint, or both. The
team can modify constraints by providing a business case for the change and
identifying the impact of the change. Alternately, the project team can adapt
the requirement to the constraint and still provide adequate service for the
users.

Slide Objective
To explain several options
for dealing with gaps.
Module 6: Beginning Physical Design 199

Module 6: Beginning Physical Design 199

Activity 6.2: Risks in Requirements and Constraints


In this activity, you will participate in a class discussion about the implications
of the constraints and requirements in the Ferguson and Bardell, Inc. case study.
After completing this activity, you will be able to:
"
Articulate the type of risks that become evident when requirements are not
aligned with the physical constraints of the solution.

Slide Objective
To introduce the activity.
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200 Module 6: Beginning Physical Design




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Physical Design Analysis
In this section
In this section
"
Deliverables of the Analysis Baseline
"
Preliminary Deployment Model

"
Example: Network Topology
"
Example: Data Topology
"
Example: Component Topology
"
Selecting Implementation Technologies


In this section, you will learn about the analysis step of physical design. The
focus of the analysis step is on selecting candidate technologies for the
implementation, based on the application requirements. In evaluating candidate
technologies, you should first address business considerations and then take
into account business environment considerations.
Slide Objective
To provide an overview of
the topics and activities in
this section.
Module 6: Beginning Physical Design 201

Module 6: Beginning Physical Design 201




Deliverables of the Analysis Baseline
Task
Drafting a preliminary deployment
model

Selecting candidate implementation
technologies
Deliverable
Preliminary deployment model
"
Proposed network topology
"
Proposed data topology
"
Proposed component
topology
List of candidate
technologies
Analysis Baseline
Analysis


The analysis baseline leads to several deliverables. Whereas the research
baseline contained deliverables for the current network, data, and component
topologies, the analysis baseline should contain proposed network, data, and
component topologies.
The analysis baseline should also include a list of candidate technologies for
implementing the solution.

Slide Objective
To describe the deliverables
of the analysis baseline.
Lead-in
The analysis baseline
results in a set of

deliverables.
Delivery Tip
Candidate technology
issues will be discussed in
the next three modules.