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Construction Planning and Construction Planning and PrerequisitePrerequisite

Measure Twice, Cut OnceMeasure Twice, Cut Once

Chapter 3Chapter 3

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Importance of PrerequisiteImportance of Prerequisite

Earlier parts of projects are “Earlier parts of projects are “PrerequisitePrerequisite”.”.

Projects run best if appropriate preparation Projects run best if appropriate preparation activities are done before constructionactivities are done before construction

Removing an error by the beginning of Removing an error by the beginning of construction allows rework to be done 10 to construction allows rework to be done 10 to 100 times less expensively 100 times less expensively

33

44

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Problem-Definition Prerequisite Problem-Definition Prerequisite

Is clear statement of the problemIs clear statement of the problem Does Not indicate to any possible solutionDoes Not indicate to any possible solution One or two pages and sounds like problemOne or two pages and sounds like problem Should be in user language and described from Should be in user language and described from

user’s point of viewuser’s point of view

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Good Example:Good Example:

““We can’t keep up with orders for Giant”We can’t keep up with orders for Giant”

Bad ExampleBad Example

““We need to optimize our automated data-We need to optimize our automated data-entry system to keep up with orders for the entry system to keep up with orders for the GiantGiant““

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Requirements PrerequisiteRequirements Prerequisite

Contains what a software system is supposed to Contains what a software system is supposed to dodo

The first step toward a solutionThe first step toward a solution Helps user derive system’s functionalitiesHelps user derive system’s functionalities User can review and agree on requirementsUser can review and agree on requirements Keep programmer of guessing what the user Keep programmer of guessing what the user

wantswants

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Architecture PrerequisiteArchitecture Prerequisite

High level part of software designHigh level part of software design Known as “system architecture” or “high-level Known as “system architecture” or “high-level

design” or “top-level design”design” or “top-level design” Good architecture makes construction easyGood architecture makes construction easy Architecture changes are expensive to make Architecture changes are expensive to make

during construction or laterduring construction or later

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Typical architecture componentsTypical architecture components Program OrganizationProgram Organization

Defining major building blocks Defining major building blocks Might be class, group of classes (subsystem)Might be class, group of classes (subsystem) Includes communication rules with other blocks, Includes communication rules with other blocks,

Major ClassesMajor Classes Responsibilities of major classes and interaction with other Responsibilities of major classes and interaction with other

classesclasses Data DesignData Design

High level of file and table designHigh level of file and table design Specify if single or multiple database to be usedSpecify if single or multiple database to be used

Business RulesBusiness Rules Must be mentioned and describe the impact of the rules on Must be mentioned and describe the impact of the rules on

system designsystem design

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Typical architecture components .. Typical architecture components .. continuecontinue User Interface DesignUser Interface Design

Usually specified at requirements timeUsually specified at requirements time Major elements of web page format, GUIs, command line Major elements of web page format, GUIs, command line

interface ..interface .. Recourse Management Recourse Management

How managing resources such as database connections, How managing resources such as database connections, threads, memory ..threads, memory ..

SecuritySecurity High level and code level securityHigh level and code level security Handling un-trusted data (such as user data, cookies, Handling un-trusted data (such as user data, cookies,

configuration data), encryption, detail in error messages.configuration data), encryption, detail in error messages. Protecting secret data in memoryProtecting secret data in memory

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Typical architecture components .. Typical architecture components .. continuecontinue

ScalabilityScalability The ability of a system to grow to meet future The ability of a system to grow to meet future

demandsdemands Plan to handle growth of users, servers, number Plan to handle growth of users, servers, number

and size of database records, transaction volumeand size of database records, transaction volume InteroperabilityInteroperability

How data or resources will be shared with other How data or resources will be shared with other software or hardwaresoftware or hardware