View
238
Download
1
Category
Preview:
Citation preview
7/31/2019 SDLC Details
1/51
Information System for Managers
SDLC Details
7/31/2019 SDLC Details
2/51
Content
Requirements
Analysis
Design
Development
Implementation
Operations & Maintenance
Review
7/31/2019 SDLC Details
3/51
Requirements
Handles What Part Requirements define what the deliverable will look
like and what it will do
Implied needs vs. Stated Needs (Requirements)
Objective: Project includes all the work required and
only the work requiredGetting clear requirements, is most critical and is key
to success / main reason to failure of the project
Requirements from all stakeholders
Functional
Technical
Cost
Quality
7/31/2019 SDLC Details
4/51
Pitfalls in Defining Needs
Inherently Fuzzy Needs
Identifying solutions before needs defined fully
Addressing needs of wrong customers
Multiple customer - Multiple needsSol: Establish priorities and need hierarchy. Finalize
priority with customer
Distorting Customer Needs
Gold-Plating of needs
Selective Filtering of customer needs
Father-knows-best approach
7/31/2019 SDLC Details
5/51
Pitfalls in Defining NeedsInherently Fuzzy Needs
Needs are dynamic (Changing players, budget,technology, business environment)
Customer not understanding / articulating
Customers know what they need, after they see it
Even if customer say they know exactly what they
need, they probably dontAs the deliverable develops and takes on a tangible
form, customers see new possibilities and try tochange the project accordingly
Customer must be taken seriously a project fails if
the deliverable is not used, underused, or misused bythe customer
Sol: Work closely with customer, involve customer inneed articulation, educate, proto-type / other model,
Awareness, Flexible Project Plan, Anticipated needs,
7/31/2019 SDLC Details
6/51
Scope Verification and ScopeChange
Scope Verification: Verifying actual product componentvs. scope baseline
Scope Change: Controlling changes to project scope.
Change control process, configuration management,version control
7/31/2019 SDLC Details
7/51
Questions
Who carries out the activities?What is carried out?
How is it carried out?
What is the output?What tools are used?
7/31/2019 SDLC Details
8/51
Requirements
Requirements and Test Plan: Verifiable Requirements Requirements Management
Requirements: Static and Evolving, Project Vs Product,
etc.
BRS (Business Requirements Specification), FS(Functional Specification) and SRS (System
Requirements Specification)
7/31/2019 SDLC Details
9/51
Table of Contents - BRS
1 Introduction1.1 Purpose of Document
1.2 Audience
1.3 Document Organization1.4 References
7/31/2019 SDLC Details
10/51
Table of Contents - BRS
2 Overview2.1 Business Description
2.2 Stakeholders Requests
2.2.1 Establish Stakeholder Profile
2.2.2 Establish User or Customer Profile
2.2.3 Assessing the Problem
2.2.4 Understanding the User Environment
2.3 Process Schematic
7/31/2019 SDLC Details
11/51
Table of Contents - BRS
3 Business Requirements3.1 Functional Requirement One
3.1.1 Description
3.1.2 Rationale
3.1.3 Source
3.1.4 Dependencies / Conflicts / Assumptions
3.1.5 Priority
3.1.6 Verification
3.1.7 Use Cases
3.2 Other Implicit Functionality
7/31/2019 SDLC Details
12/51
Table of Contents - BRS
4 Technical Requirements4.1 Usability
4.2 Reliability
4.3 Performance
4.4 Security / Privacy4.5 Portability / Migration
4.6 Supportability
5 External Interfaces
7/31/2019 SDLC Details
13/51
Table of Contents - BRS
Appendix A: Assumptions and DependenciesAppendix B: Glossary
Appendix C: Business Rules
Appendix D: UI Screens
Appendix E: Requirements Summary
7/31/2019 SDLC Details
14/51
STRUCTURED AND OBJECT ORIENTED MODELS
Events andEvent table
Things
Class diagramEntity-
relationshipdiagram
Interaction
Statechartdiagrams
Other OOmodels
Use casediagrams
Contextdiagram
DFD fragmentsOther
definitions
Diagram 0
Object-orientedapproach
Traditionalapproach
Nodes and locations diagram
Pseudocode
System controls
User-interface dialog, forms, and reports
Hybrid relational database scheme
Analysis
Design
System flowchart
Structure chart
Relationaldatabasescheme
Packagediagram
Designclass
diagram
Objectdatabasescheme
7/31/2019 SDLC Details
15/51
15
Systems Analysis
Detailing RequirementsSSAD
ERD
DFD
Input / output details
OO Analysis
7/31/2019 SDLC Details
16/51
Modern Structured Analysis
1. Draw a context DFD to establish initial project scope.2. Draw a functional decomposition diagram to partition
the system into subsystems.
3. Create an event-response or use-case list for thesystem to define events for which the system must havea response.
4. Draw an event DFD (or event handler) for each event
5. Merge event DFDs into a system diagram
6. Draw detailed, primitive DFDs for the more complex
event handlers.7. Document data flows and processes in the data
dictionary.
7/31/2019 SDLC Details
17/51
Step 1: Context Diagram
Payroll SystemPersonnelDept
EmployeeDetail
EmployeeSalarySlip
F16
FinanceDept
SalarySummary
Tax Slab
TaxRate
7/31/2019 SDLC Details
18/51
Step 2: Functional Decomposition
Payroll System
MaintainEmployee Master Process Payroll Calculate Tax
AddEmployee
UpdateEmployee
DeleteEmployee
Calculate Salary
Salary Slip
7/31/2019 SDLC Details
19/51
Step 3 Event List
Actor Trigger Event /
Use Case
Response
Personnel New Employee
fill joining form
Create
Employee
Employee record
created in Employee
Master
(Time) 1st of Month Calculate
Salary
Salary calculated,
salary slip printed
Finance Ask for
summary
Generate
Summary
Salary Summary
generated for a period
(Time) 1st of Year Calculate
Tax
Tax calculated, F16
printed
St 4 D t di f
7/31/2019 SDLC Details
20/51
Step 4 Draw event diagram foreach event
Event: 1st of Month
EmployeeMaster
Salary File
CalculateSalary
1st of Month
Print SalarySlip
Salary
Slip
Employee
7/31/2019 SDLC Details
21/51
Step 5 DFD Level 1
Personnel
MaintainEmployee
Master
Employee
Master
Employee
Detail
Tax SlabCalculate Tax
Salary File
1st of year
F16 Emp
ProcessPayroll
1st
ofMonth SalarySlip
ProcessPayrollGenerateSummary
Finance
SalarySummary
Step 6 DFD Le el 2 for Maintain
7/31/2019 SDLC Details
22/51
Step 6 DFD Level 2 for MaintainEmployee Master
PersonnelAdd
Employee
Employee
Master
New EmpRecord
Update
Employee
DeleteEmployee
ChangedDetail
7/31/2019 SDLC Details
23/51
23
Systems Design
Answers the question: how will the informationsystem solve a problem?
Results in a technical design
Details system outputs, inputs, and user interfaces
Specifies hardware, software, databases,
telecommunications, personnel, and procedures
Shows how these components are related
7/31/2019 SDLC Details
24/51
System Design
High Level Design Application Design(cont) Common Functionality
Functional Decomposition
System Flow
System Chart
File / Table Design
User Interface Design Detailed Design- Program Specification
Pseudo code Flow ChartDecision Table
7/31/2019 SDLC Details
25/51
25
Interface Design and Controls
Table 13.1: The Elements of Good Interactive Dialogue
Design of System Security and
7/31/2019 SDLC Details
26/51
26
Design of System Security and
Controls
Preventing, detecting, and correcting errors Enterprise-rights management software
Disaster planning and recovery Disaster planning:process of anticipating and
providing for disasters Disaster recovery: implementation of disaster plan
Approaches
Hot site
Cold site Incremental backup
Image log
7/31/2019 SDLC Details
27/51
27
The Design Report
Figure 13.9: A Typical Table of Contents for a Systems Design Report
Implementation
7/31/2019 SDLC Details
28/51
ImplementationContext
Implementation
Operations &Maintenance
In-HouseDevelopment
Acquisition
7/31/2019 SDLC Details
29/51
29
Systems Implementation
Figure 13.10: Typical Steps in Systems Implementation
Acquiring Hardware from an IS
7/31/2019 SDLC Details
30/51
30
Acquiring Hardware from an IS
Vendor
BuyingPurchasing used computer equipment
Leasing
RentingApplication service provider (ASP)
7/31/2019 SDLC Details
31/51
31
Acquiring Software: Make or Buy?
Make-or-buy decision: decision regardingwhether to obtain software from external or
internal sources
Acquiring Software: Make or Buy?
7/31/2019 SDLC Details
32/51
32
Acquiring Software: Make or Buy?
(continued)
Table 13.5: Comparison of Off the Shelf and Developed Software
7/31/2019 SDLC Details
33/51
33
User Preparation
Readying managers, decision makers,employees, other users, and stakeholders for
new systems
Training users
7/31/2019 SDLC Details
34/51
34
IS Personnel: Hiring and Training
Personnel that might be needed for new system IS manager
Systems analysts
Computer programmers
Data-entry operators
Training programs should be conducted for IS
personnel who will be using the system
7/31/2019 SDLC Details
35/51
35
Site, Data Preparation & Installation
SITE PREPARATION Preparation of the location of a new system. May involve
Making room for a computer in an office
Special wiring and air conditioning
Renovation of entire room Special floor
Additional power circuits
DATA PREPARATION (Data Entry & Conversion)
Ensuring all files and databases are ready to be usedwith new computer software and systems
INSTLLATION
Process of physically placing computer equipment on thesite and making it operational
7/31/2019 SDLC Details
36/51
36
Testing
Unit testing: testing of individual programsInterface testing:
System: testing all related systems together
Acceptance testing: conducting any testsrequired by user
Alpha testing: testing an incomplete or earlyversion of system
Beta testing: testing a complete and stablesystem by end users
7/31/2019 SDLC Details
37/51
37
Start-Up
Process of making the final tested informationsystem fully operational
Approaches
Direct conversion (plunge, direct cutover)
Phase-in approach (piecemeal)
Module-wise
Functionality-wise
Customer Segment-wise Parallel start-up
7/31/2019 SDLC Details
38/51
38
Start-Up (continued)
Figure 13.13: Start-Up Approaches
7/31/2019 SDLC Details
39/51
39
Start-Up (continued)
Figure 13.13: Start-Up Approaches (continued)
7/31/2019 SDLC Details
40/51
40
User Acceptance
User acceptance document: formal agreementsigned by user that states that a phase of
installation or the complete system is approved
Legal document that removes or reduces IS vendors
liability
Maintenance
7/31/2019 SDLC Details
41/51
MaintenanceContext
Maintenance
Implementation
ObjectiveSatisfied?
Review
Y N
Develop &ImplementNew System
RetireThisSystem
Systems Operation and
7/31/2019 SDLC Details
42/51
42
Systems Operation and
Maintenance
Systems operation: use of a new or modifiedsystem
Help desk provides support
Systems maintenance: checking, changing,and enhancing the system to make it more
useful in achieving user and organizational goals
S t M i t (C t)
7/31/2019 SDLC Details
43/51
System Maintenance (Cont)
Maintenance Manage Changes - Requires high discipline (Strict
SCM including Change Control, Testing) Involves error correction & enhancements
Longest Phase (Hopefully!)
All Benefits in this phase Major cost in this phase Stable & Profitable business for third party Most time critical and demanding
Hated by many developers
R f M i t
7/31/2019 SDLC Details
44/51
44
Reasons for Maintenance
Changes in business processesNew requests from stakeholders, users, and
managers
Bugs or errors in program
Corporate mergers and acquisitions
Government regulations
Change in operating system or hardware on
which the application runs
Unexpected events
T f M i t
7/31/2019 SDLC Details
45/51
45
Types of Maintenance
Slipstream upgrade: minor upgrade
Patch: fix a problem or make small
enhancement
Release: significant program change requiringnew documentation
Version: major program change with new
features
Ch C t l P d
7/31/2019 SDLC Details
46/51
46
Change Control Procedure
Change Request FormReview
Identifies programs to be changed
Determines programmer to be assigned to task
Estimates expected completion date
Develops a technical description of change
Approval
Check-out, Do changes, Testing, Check-inImplement Changes
The Financial Implications of
7/31/2019 SDLC Details
47/51
47
The Financial Implications of
Maintenance
Total maintenance expenditures increase in timeand money as programs age
For older programs, total cost of maintenance can be
up to five times greater than total cost of development
Determining factor in decision to replace asystem
Costs more to fix than replace system
The Financial Implications of
7/31/2019 SDLC Details
48/51
48
e a c a p cat o s oMaintenance (continued)
Figure 13.14: Maintenance Costs as a Function of Age
The Relationship Between
7/31/2019 SDLC Details
49/51
49
pMaintenance and Design
Figure 13.15: The Value of Investment in Design
More time and money spent on design means less
time and money spent on maintenance
S stems Re ie
7/31/2019 SDLC Details
50/51
50
Systems Review
Analysis of systems to make sure that they areoperating as intended
Often compares performance and benefits of
designed system with actual performance and
benefits of operational system
Types of Review Procedures
7/31/2019 SDLC Details
51/51
Types of Review Procedures
Table 13.6: Examples of Review Types
Recommended