Download - MIS (19.01.2011)
-
8/2/2019 MIS (19.01.2011)
1/49
Modern Systems Analysis & Design
-
8/2/2019 MIS (19.01.2011)
2/49
The Systems Development Environment
Complex organisational process in which informationsystems are developed and maintained
Result of systems analysis & design is usually development
of application/systems software
Systems development methodologies - systematic
approach..science
Systems development techniques - art of applying
methodologies
Primary responsibility of systems analyst and related teams
-
8/2/2019 MIS (19.01.2011)
3/49
Systems
Group of related parts that function as a Unit collection of people, machines & methods to accomplish
specific objectives
In Computer parlance..
Collection of hardware, software, data Beginning in 1950s. Emphasis was on..
Processes
Automating single function e.g. purchasing or payroll
Considered more as an art and less as science
-
8/2/2019 MIS (19.01.2011)
4/49
System Software
Performs basic functions toestablish and maintain operatingenvironment (Co-ordinates &controls the running of thecomputer)
Works with the computer and notwith the end-user
Operating systems like DOS,UNIX, OS-400 etc. whichperform functions like memorymanagement, secondarystorage management
Device management driverslike printer drivers, mouse
drivers, modem s/w etc. Utilities and editors like filecompression, defragmentationetc.
Language compilers like BASIC,C, COBOL, FORTRAN
Software packages like xBase,
Business Application Software
Uses the environment provided bySystems Software to perform
functions directly needed by end-
users
Generic programs such as Word
processors, electronic spreadsheets,
e-mail etc. Programs to support specific business
functions like TBA, Financial
Accounting packages etc.
Software Systems
-
8/2/2019 MIS (19.01.2011)
5/49
Hardware
O.S.
Systems S/W
Application S/W
Data.
Hardware
Application S/W
Data.
Structure of systems
How it is How it should be
-
8/2/2019 MIS (19.01.2011)
6/49
Business Application Software Phases in Business Application Software
Systems Development Life Cycle (SDLC) Feasibility Study Systems Requirements Specifications Systems Design Programming / Construction
Testing Implementation / Commissioning
Entering history / master data User Training Implementation / commissioning
Live working Post implementation support / modifications
Towards next maturity level
-
8/2/2019 MIS (19.01.2011)
7/49
Feasibility Study
-
8/2/2019 MIS (19.01.2011)
8/49
To set priority of Areas / departments to computerise vis--
vis business focus..TBA vs. Fixed Assets Accounting To finalise overall direction of the Computerisation..
Centralised vs. decentralised, Web-enabled or non-web-enabled
Make or Buy Decision Make.. In house or Outsourcing
Buy..off the shelf with customisation
To gather information about various aspects of
computerisation e.g. hardware, software, information about
about vendors etc.
To finalise Terms-of-reference / time and cost estimates A Feasibility Study Report is the outcome of this phase
Feasibility Study
-
8/2/2019 MIS (19.01.2011)
9/49
Make or BuyMake..In-House
A team of Project Leader, systems analysts, programmers etc. will berequired (may be difficult)
Resulting software would cover most of the user needs with properintegration within the modules.(Advantage)
Complete control and ownership of the resulting software. (Advantage) Less technically and professionally competent software than developed
by outsourced vendor whose main business is software development.(Disadvantage)
Integration with other bought out systems may be difficult e.g. TBAslinkage with voice-mail recognition s/w
Due to high employee turn over in IT field, difficulty in retaining IT staff.This could pose problems for maintaining software and developing newmodules. (Disadvantage)
The time frame required to form such team and developing software maybe more. (Disadvantage) Due to rapid technological advancement in computer field, the IT staff will
have to undergo continuous training in new areas and technologies.
-
8/2/2019 MIS (19.01.2011)
10/49
Make or Buy
Make..Outsourcing Expert team having state-of-the-art knowledge would be involved
in the development (Advantage)
Deliverables by outsourced vendor must be clearly specified.
Rigorous acceptance testing is necessary.(May be difficult)
If more than one vendor, then integration amongst vendors is akey factor.(May be difficult)
Likelihood of vendor/s misusing the source code elsewhere
(Disadvantage) .. IPR issues are to be looked into and involves
lot of legal documentation.
For replication of the software fresh licensing issues & cost may
not be involved (Advantage)
Senior management involvement will be more
-
8/2/2019 MIS (19.01.2011)
11/49
Make or Buy
Buy.. Off the shelf No plug-and-play.. Customisation is necessary. Some product
deficiencies, if any, will have to be accepted.(Disadvantage)
Market research and comparative analysis of different vendors
and their products will have to carried out. Vendors specifications
need to be brought down to a common scalable platform. (May bedifficult).
Vendors capability of providing continuous support must be
ensured.
Software escrow agreement must be entered into and all the legal
documents need to be reviewed by legal counsel.
Total dependability on the vendor(Disadvantage)
Senior management involvement will be more
-
8/2/2019 MIS (19.01.2011)
12/49
Systems Requirement
Specifications (SRS)
-
8/2/2019 MIS (19.01.2011)
13/49
To set Terms-of-reference (TOR) for Software Development (objective
scope and deliverables)
Existing operations along with users additional requirements with
running description and system flow diagrams Interview / meetings with users at various levels along with / observation of
users at work
Document / register / report forms collection and analysis Existing Work flow analysis
BPR requirements
Volume of data, frequency of transactions, entry points are decided
Analysis of authorities / roles / responsibilities of users at various levels
Analysis of locations of computers
Many-a-times Feasibility is merged into this phase and therefore SRSmust be carried out irrespective of Make or Buy decision.
A Systems Requirements Specifications Report is the outcome of this
phase
Systems Requirement Specifications - SRS
-
8/2/2019 MIS (19.01.2011)
14/49
Systems Design
-
8/2/2019 MIS (19.01.2011)
15/49
Organisation of data (temp files, report files) / programs(Source code,
executables, DLLs) on computer is designed
Business rules / requirements of validation of data are specified and
designed as per the analysis done
Various types of charts are prepared such as Systems Flow Chart
(Function wise), Work flow Charts (Actor wise), Data Flow Diagrams,
Decision tables(Business Rules) etc. Design of Database.. E.g. Single / Multiple database, Tables
(Normalisation), relations between tables, Primary / Foreign keys
User interfaces (Screens / Views) / report formats etc are designed
Controls start getting built-up..Authority / security requirements are
specified / designed Users involvement in this phase is minimal but necessary
Plan to convert legacy system to new system
Systems Design
-
8/2/2019 MIS (19.01.2011)
16/49
Types of Systems Operational Information Systems - OIS
e.g. stand-alone and small systems where individual functions ortheir integration is established
Transactions Processing Systems - TPS High-volume..similar to OIS but focus is on capturing data for
entire transaction
Management Information Systems - MIS Usually built on OIS and/or TPS.. Helps enabling management
reporting / decision taking
Decision Support Systems - DSS involves semi-structured problems, requires iterative development,
may not be well-structured
Expert Systems - ES for providing expert advise based on pre-captured knowledge-
base
-
8/2/2019 MIS (19.01.2011)
17/49
CASE TOOLS Computer Aided Software Engineering tools
Refers to the use of s/w packages to aid in the development of allphases of Information Systems I.e. SDLC
Aids designers / programmers to prepare business models and
various flow diagrams
Aids in designing and providing relationships amongst data entities
Changes introduced in one CASE diagram will automatically updateall relevant diagrams
Helps in documentation
Use of CASE tools by developers shall give primary comfort to IS
auditors in respect of standard and consistent methodology followed
Some of the CASE TOOLs : Rational Rose, Systems Architect, Visual
UML etc.
-
8/2/2019 MIS (19.01.2011)
18/49
Client-Server Computing
All client access points should be identified Application code and data may not be located on a single
machine
Mixed platforms (h/w, s/w, networking) may lead to
compatibility problems and confusion
Security issues need to be considered for multiple process
layers in hardware, operating systems, telecommunication
systems, database systems etc.
Version control and program change control may
become complex Testing of system is a complex process
-
8/2/2019 MIS (19.01.2011)
19/49
Web-enabled Software - Some issues More stringent user identification and authentication is required
Use of fire-walls in case of internet applications
Data encryption needs to be built-in to avoid data exposure to
unauthorized users (hackers)
Telecommunication band-width problems leading to slower system
response
Mixed platforms lead to compatibility problems Due to browser based user interfaces, server side processing is done
for allowing access through any browser
Form Fill - submit methodology needs to be adopted to avoid sluggish
response
Performance profile of site needs to be built-up in respect of following Pages visited most often and average visit length
Most typical traffic pattern with peak traffic occurrence
-
8/2/2019 MIS (19.01.2011)
20/49
Programming / Construction
-
8/2/2019 MIS (19.01.2011)
21/49
The Systems Design is converted into Source Programs (Source
Code - human readable form). Source Code is then compiled into Executable Code (Machine
readable form)
Executable code resides on secondary storage and loaded into
memory when executed
Executable cannot be modified. If source code is unavailable,modification to software is not possible.
Programming documentation needs to be done
Two Methodologies Procedural Programming - past trend e.g. COBOL, BASIC, Foxpro - 3
GL
Object Oriented Programming(OOPs) - current trend Visual versions
of BASIC, Foxpro, SQL, C++, JAVA etc. - 4 GL
Programming / Construction
-
8/2/2019 MIS (19.01.2011)
22/49
Procedural ProgrammingAddition Program
Accept A (variable 1), B
(variable 2) from user
C (variable 3) = A + B
Display C as answerFeatures
Each task needs to be
programmed
Less re-usablility
Usually one executable
Procedural Programming vs. OOPs
OOPsAddition Object
Call Accept object
Call summation object
Call display object
Features
Re-usability of objects
Modular(not procedure wise)
development
Unrestricted data types Inheritance, encapsulation,
polymorphism
-
8/2/2019 MIS (19.01.2011)
23/49
Sequence check
Control number follows sequentially and any out-of-sequence number is eitherrejected or reported as an exception
Limit Check Data should not exceed a pre-determined number or range
Validity check
Checking data validity in accordance with pre-determined criteria..e.g. Male /Female check for Sex code
Logical relationship check Checks logical relationship between two data entities.. E.g. relation between
joining date and retirement date
Table look-ups Input data is checked against master data already stored..e.g. Account number
entered gives details of account holder from master data
Few Validation checks
-
8/2/2019 MIS (19.01.2011)
24/49
Testing
-
8/2/2019 MIS (19.01.2011)
25/49
Unit testing ( testing)
Individual function / object / program is tested Normally carried out by programmers / QC
Integration testing Linkages between all related programs is tested for interfaces and overall
functioning
Normally carried out by senior programmers / QC
System testing ( testing) Completed modules are tested for interfaces and overall functioning
Normally carried out by Project Leaders / QC
Regression testing Any changes in coding needs to be tested again in isolation as well as with all
linkages Acceptance testing
Done by users, QC, IS auditors
Testing
-
8/2/2019 MIS (19.01.2011)
26/49
Black-box testing
Internal logic of programs is not examined.. Product is examined and not theprocess
White-box testing Internal logic of programs is examined.. Process is examined and not the
product
Top-down testing Top-level modules are tested first and then explored further into lower levelmodules / programs
Bottom-up testing Lower level modules / programs are tested first and graduated to higher level
modules / programs
The objective of testing is to make the system fail Debugging .. removing the errors
Bebugging .. planting the errors to gauge system response
Approaches to Testing
-
8/2/2019 MIS (19.01.2011)
27/49
Water-fall model (Linear Sequential Model)
Analysis >> Design >> Coding >> Testing
Spiral Model Analysis >> Design >> Coding >> Testing >> Review >>
Prototyping Model
Uses 4GL programming languages which enable faster development Controlled trial & error method Emphasis is on screens and reports acceptable to users Users are misled into believing that the complete system is ready
(processing, transaction volumes, security & controls, back-up &
recovery etc will have to be built later)
Likelihood of resulting system not having proper controls Seldom documented / approved because of the fast development Significant cost & time saving is possible
SDLC Methodologies
-
8/2/2019 MIS (19.01.2011)
28/49
Rapid Application Development Model (RAD) Strategically important systems are developed faster
Well-defined methodology
Reduction in development cost / time while maintaining
quality
Small well-trained development teams are used
Integrated RAD tools(e.g. VB, Magic) are required
Central repository of objects / functions is developed
Rigid limits on development time frames are set
SDLC Methodologies
-
8/2/2019 MIS (19.01.2011)
29/49
Joint Application Development Model (JAD) Introduced by IBM in late 70s
users , managers and analsysts/programmers, scribe, IS
staff work together
usually requires a sponsor JAD session leader is required
disadvantages similar to those of group meetings
Participatory Development (PD)
alternative approach to SDLC
users involvement is more
SDLC Methodologies
-
8/2/2019 MIS (19.01.2011)
30/49
Improper SDLC - Risks
System may not meet end-users needs May exceed financial budget
May exceed budgeted project time
May result into inefficient product
Promote poor or mismanagement of project
Incompatibility with existing systems
Missed business opportunities
Reduced credibility of IS department
Demotivation of staff
-
8/2/2019 MIS (19.01.2011)
31/49
Modern Systems Analysis & Design
-
8/2/2019 MIS (19.01.2011)
32/49
To set priority of Areas / departments to computerise vis--
vis business focus..TBA vs. Fixed Assets Accounting To finalise overall direction of the Computerisation..
Centralised vs. decentralised, Web-enabled or non-web-enabled
Make or Buy Decision Make.. In house or Outsourcing
Buy..off the shelf with customisation To gather information about various aspects of
computerisation e.g. hardware, software, information about
about vendors etc.
To finalise Terms-of-reference / time and cost estimates
A Feasibility Study Report is the outcome of this phase
Feasibility Study
-
8/2/2019 MIS (19.01.2011)
33/49
To set Terms-of-reference (TOR) for Software Development
Existing operations along with users additional requirements withrunning description and system flow diagrams Interview / meetings with users at various levels along with / observation of
users at work
Document / register / report forms collection and analysis
Existing Work flow analysis
BPR requirements
Volume of data, frequency of transactions, entry points are decided
Analysis of authorities / roles / responsibilities of users at various levels
Analysis of locations of computers
Many-a-times Feasibility is merged into this phase and therefore SRS
must be carried out irrespective of Make or Buy decision. A Systems Requirements Specifications Report is the outcome of this
phase
Systems Requirement Specifications - SRS
-
8/2/2019 MIS (19.01.2011)
34/49
Project Identification and Selection
Project Initiation and Planning
Analysis
Logical Design
Physical Design
Implementation
Maintenance
SDLC
SRS
-
8/2/2019 MIS (19.01.2011)
35/49
Accounting Systems
Creating & processing documents Book keeping / filing / register updating
Posting in subsidiary and general ledger
Reconciliation of ledger with all sub-ledgers
Preparation of trial balance
Preparing financial statements such as P & L account, balance sheet, income
statement, cash-flow statement Analysis of authorities / roles / responsibilities of users at various levels
Analysis of locations of computers
Operational Systems Production / Project planning / Scheduling etc. 3 Ms
Inventory / raw material / WIP / finished goods .. JITs etc. Purchase systems
Commercial Systems
-
8/2/2019 MIS (19.01.2011)
36/49
Human Resource Systems
Personnel Administration Payroll and associated processing
Employee performance tracking
Marketing Systems Customer Billing
Accounts receivables
Supply chain management
Customer service management
Banking Systems
Portfolio management systems / Shares accounting systems
School / College / results processing systems
Many more.
Commercial Systems
-
8/2/2019 MIS (19.01.2011)
37/49
Five generally observed types..these are logical types and not physical
Transaction files Master Files
Master files..can also contain transaction data
Reference or Parameter files
System files
Summary files
Temporary files
Reports Printed Reports.. Can be on plain or pre-printed stationery
Display Reports
Queries processing leading to display or printed reports
Types of Files
-
8/2/2019 MIS (19.01.2011)
38/49
Systems Analysis Systems Analysis involves
Study of existing system Study the product and information(data) flows
Formulate strategic requirements for the new system
Evaluate the present system (mainly reassessment)
---------------------------------------------------------------------------------------------
Business Objectives Find out, decompose and document..obtain from stakeholders
Organisation and Job Design Organisation structure
Bifurcation into roles / responsibilities / authorities
Project Management
Study throughobservation, interviews, meetings, reading, presentation,collecting documents etc.
Making use of computer based tools and techniques
-
8/2/2019 MIS (19.01.2011)
39/49
Systems Analysis Techniques Effective Interviewing
Plan your interview Do your homework .. Clients brochures, web-sites, balance sheet
Observe necessary protocols
Know your subject very well
Unstructured interviews Convey your subject/s that this is an unstructured interview
Be very informal / casual and do not interrogate your subject too much
You may not be specific about a topic
Make notes of discussion points in brief
Structured Interviews should follow unstructured interview Convey your subject/s that this is a structured interview
Ask very specific questions Take detailed notes.. If required take a steno or record interview with permission
After the interview, circulate minutes and take formal / informal approval
-
8/2/2019 MIS (19.01.2011)
40/49
Organisation of data (temp files, report files) / programs(Source code,
executables, DLLs) on computer is designed Business rules / requirements of validation of data are specified and
designed as per the analysis done
Various types of charts are prepared such as Systems Flow Chart
(Function wise), Work flow Charts (Actor wise), Data Flow Diagrams,
Decision tables(Business Rules) etc. Design of Database.. E.g. Single / Multiple database, Tables(Normalisation), relations between tables, Primary / Foreign keys
User interfaces (Screens / Views) / report formats etc are designed
Controls start getting built-up..Authority / security requirements are
specified / designed
Users involvement in this phase is minimal but necessary
Plan to convert legacy system to new system
Systems Design
-
8/2/2019 MIS (19.01.2011)
41/49
Process Modeling
Involves graphical representation of functions / processes Functions or processes .. Capture, manipulate, store and distribute data
within or outside of the systems
DFD is a Structured Analysis Technique Out of Requirements Determination, Requirements
Structuring and Alternative generation and selction.. DFD isfor requirements structuring Context data flow diagram DFDs of current physical system DFDs of current logical system
DFDs of proposed logical system DFDs of proposed physical system
Data Flow Diagrams - DFDs
-
8/2/2019 MIS (19.01.2011)
42/49
Data Flow
Data in motion e.g. customer order form, Invoice, Paycheque
Data store is data at rest e.g. a file folder, computer file
Process is work performed to transform, store or distribute
data
Source / Sink is origin and / or destination of the data We do not consider.. Interactions between source & sinks
What a source or sink does with the data
How to control or redesign source or sink
How to provide direct access to source and sinks
Data Flow Diagrams - DFDs
-
8/2/2019 MIS (19.01.2011)
43/49
Process
Data Store
Source/Sink
Data FlowDeMarco & Yourdon symbols Gane & Sarson symbols
Context Diagram
-
8/2/2019 MIS (19.01.2011)
44/49
0
Customer
Customer Order
Receipt
Food Order
Management
Reports
Kitchen
Context Diagram
Rules of DFD
-
8/2/2019 MIS (19.01.2011)
45/49
A B
C
D
E
Rules of DFD
FSource Sink
Rules of DFD
-
8/2/2019 MIS (19.01.2011)
46/49
G
H
I
J
Rules of DFD
A
B
A
A
A
B
A
A
A
AA
C
B
A
Update
Retrieval
K
L
DFD Improper way
-
8/2/2019 MIS (19.01.2011)
47/49
Customer
Record
Payment
Make
BankDeposit
Bank
CustomerMaster
Accounting
Department
Payment
Payment Data
Receipt
Credit Data
Deposit Data
Payment
Data
1.0
2.0
D1
DFD Improper way
DFD Proper way
-
8/2/2019 MIS (19.01.2011)
48/49
Customer
Record
Payment
Make
BankDeposit
Bank
CustomerMaster
Payment
Payment Data
Receipt
Credit Data
Deposit Data
Payment
Data
1.0
2.0
D1
DFD Proper way
Update
Customer
Master
3.0
Level-0 diagram
-
8/2/2019 MIS (19.01.2011)
49/49
Level 0 diagram
Goods Sold FileD2
Inventory FileD1
1.0Customer
Kitchen
Receive and
Transform
Customer
Food Order
Food Order
Update
Goods SoldFile
Formatted
Goods Sold Data
Inventory
Data
3.0
2.0
RestaurantManager
ProduceManagement
Report
4.0
Management
Reports
Daily Inventory Depletion Quantity
Update
Inventory
File
Customer Order
Receipt