Transcript Systems Analysis I Introduction and Fundamentals ISYS 200 Glenn Booker ISYS 200 Week #1 Systems Analysis I  This course is an introduction to the process used to.

Systems Analysis I
Introduction and Fundamentals
ISYS 200
Glenn Booker
ISYS 200
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Systems Analysis I
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This course is an introduction to the process
used to create an information system
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Much of it also applies to creating any other
kind of software
We’ll focus on the relational model for
designing the data structure of a system
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In contrast, ISYS 355 uses object-oriented
methods
Both are useful approaches
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Systems Analysis I
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This course provides an overview of many
topics which are examined in more detail
in subsequent courses
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Relational modeling is covered in ISYS 210
Interface design is covered in ISYS 110 and 310
Project management is covered in ISYS 420
Systems analysis starts with the concept for
a system, and produces the blueprints to be
able to implement it
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The Life Cycle
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We use one or more life cycle models to help
structure the tasks needed to create a system
Key activities we’ll examine include
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Determine if system is feasible
Gather information to determine requirements
Model processes with a Data Flow Diagram; and
model data with an Entity Relationship Diagram
Design outputs, inputs, and the user interface
Implement the system
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Syllabus
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Note the office hours; other than that, email
is the best way to contact me
Participation isn’t graded per se, but you are
responsible for the contents of the lectures,
and they will help clarify the assignments
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About the Text
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We’re skipping five chapters of the text, since
700 pages in ten weeks is a bit much
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There’s still a lot of reading, but most of it goes
pretty quickly
Be sure to read the text and review the lecture
notes before class
You’re responsible for printing the lecture notes
after this set 
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My Background
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Come from 18 years of system analysis,
design and maintenance for various
government agencies (mostly FAA & DOD)
Teaching for Drexel since 1998
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Predominantly graduate students for the first
six years
Have been known to use acronyms, so be
sure to stop me if I forget to define one
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Industry Focus
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Keep in mind that information systems are
used to support nearly every industry
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Banking, real estate, manufacturing,
pharmaceuticals, logistics, retail sales, service
fields (auto repair, restaurant, dry cleaner’s, etc.),
legal offices, transportation, etc.
Are there any you’re particularly
interested in?
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Why Bother?
Why do we need information systems?
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There’s too much data to reliably track and
manage manually
Why bother with analysis and design?
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To prevent joining the third of major software
projects that fail
By doing analysis and design properly, we will
be much more likely to create a system which
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Meets user’s and the organization’s needs, and
Is developed on time and within budget
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A Bit of Review
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The first chapter should be a review of what
you covered in ISYS 102 – the types of
information systems
From a systems analyst perspective, we
might be involved in the development,
maintenance, or reengineering of any of
these kinds of systems
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Types of Systems
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From most basic to most complex, we have
many types of info systems
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Transaction processing systems (TPS) process
data for routine business functions – sales,
payroll, inventory, etc.
Office automation systems (OAS) manage or
organize information
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Includes MS Office applications, desktop publishing,
scheduling, voice or email, video conferencing
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Types of Systems
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Knowledge work systems (KWS) are used by
various professionals to help them create new
knowledge and share it with their organization
or profession
Management information systems (MIS) take
input from TPS and helps analyze that data to
make better decisions
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Typically uses models of business processes or rules
Decision support systems (DSS) are more
customized systems to help make good decisions
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Types of Systems
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Artificial intelligence (AI) refers to a set of
techniques for creating complex systems, whether
they perform mundane tasks or expert tasks
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Knowledge-based systems (KBS) are AI systems
that represent knowledge explicitly
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AI also includes natural language processing (NLP),
neural networks, and other approaches
Expert systems are the first KBS methodology;
they go beyond DSS to create new rules or select
from existing rules to make their own decisions
KBS may use statistical approaches to deal with
uncertainty, or apply fuzzy set theory
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Types of Systems
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Computer-supported collaborative work (CSCW)
is a relatively new field to help groups of people
work together on a project, whether in the same
room or on different continents
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Group decision support systems (GDSS) is a subset
of CSCW used to focus on group decision-making
Executive support systems (ESS) help top
management levels evaluate the overall status
of an organization, often drawing from many
TPS or MIS
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Technologies
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All of these types of systems can be
supported by various kinds of technology
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E-commerce has had a profound influence on the
way businesses reach clients
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Web-based systems are becoming universal
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Nothing else has had global impact on marketing at
such small cost
From four computers in 1969, the Internet protocols
have provided a common language for almost every
computer, and many devices
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Technologies
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Enterprise resource planning (ERP) systems are
designed to integrate what were separate
systems (manufacturing, payroll, logistics, etc.)
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Wireless networks are common now
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SAP is a big local player
Oracle just bought PeopleSoft
JD Edwards is also in the field
Wireless LANs (WLANs), Bluetooth, or generic
Wi-Fi (802.11g)
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Technologies
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Handheld devices (PDAs) are increasingly
common too
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Open source software has emerged in the last
decade from a geek oddity to a significant force
in the market
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Blackberry, Palm, etc.
GNU and Linux are big players
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The Systems Analyst
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The role of the systems analyst is part
detective, part translator
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Detective to seek out the requirements from the
various stakeholders and reconcile them
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What’s a stakeholder?
Why might you need to reconcile requirements?
Translator to translate those requirements into a
design which will fulfill them, and be intelligible to
the people who implement the system
(programmers, etc.)
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The Systems Analyst
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An analyst might be called on for an
objective opinion on a system elsewhere
in the organization
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Hence keeping current with HW and SW
trends and technologies is critical
Implementing or modifying information
systems also changes an organization,
so the analyst must also plan and support
those changes
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The SDLC
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A Software Development Life Cycle (SDLC)
is used to systematically get from a need to
an implemented system
How do you solve a big problem? Break it
into little problems and solve them
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That’s what the SDLC does, by breaking
development into life cycle phases
There are many types of life cycles; we’re
focusing on a basic ‘waterfall’ model
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Typical SDLC Phases
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Creating any kind of software system typically
involves these phases
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Identify problems and opportunities
Determine information requirements
Analyze system needs
Design the system
Develop the system
Test the system
Implement the system
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Identify problems and
opportunities
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Creating an information system is expensive
Therefore, we must prove that doing so is
worth our while (and money)
Start by identifying
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What problems are there with the current system
(whether manual or automated)? Is it slow,
expensive, error-prone, …what?
What new features or capabilities could we put in
the new system?
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Identify problems and
opportunities
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Based on the problems and opportunities,
define objectives for the new system
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Estimate the percent improvement in processing
speed, market share, data accuracy, etc.
Put the description of problems, opportunities
and objectives into a feasibility study
Then some higher manager decides if the
project is worth pursuing
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Determine information
requirements
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Then determine the existing information
requirements, by studying the users of the
existing system, and the system itself
Interviews, data sampling, questionnaires,
observation, and prototyping are methods
typically used for gathering requirements
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People, data, and procedures
Look for ways to improve existing procedures
and data
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Analyze system needs
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Based on the information needs, determine
the requirements for your system
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Often this phase is combined with the previous
We’ll use a Data Flow Diagram (DFD) to
capture the data needs for a system
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A data flow diagram shows the types of users
of the system, the processes which can be
performed, and the types of data needed for
each process
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Design the system
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Then the system is designed to accomplish
the processes described in the DFD
This includes
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Design of data structure using an entityrelationship diagram (ERD)
Design of the user interface
Design of data entry procedures (won’t cover
in class)
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Develop the system
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Then the analyst supports the programmers
and database analysts who develop the
system itself
Includes documentation of the code, which
is increasingly done automatically by the
development environment
Requirements and design may be refined
during development
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Test the system
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The system is tested before being put into
production
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Unit level testing is done by the programmers
Integration and system testing are often done by
a separate testing organization
Independent testers or customers may also
perform testing
Maintenance of the system begins here
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Implement the system
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Implementation is when the system is put into
routine use (also called ‘deployed into a
production environment’)
Planning for implementation includes
choosing a deployment strategy, data
conversion and loading (DC&L), and training
users and support staff
Now determine if system met its objectives
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Maintenance
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After the development life cycle, maintenance
of the system begins
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Maintenance can cost 50% to 200% of the cost
of developing a system
Tasks are
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Fix bugs in the existing system
Make minor improvements
Update commercial components (OS patches,
apply service packs, product upgrades, etc.)
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CASE Tools
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Computer-Aided Software Engineering
(CASE) tools are big, fancy software
applications designed to help create other
software applications
First used in the mid-80’s, CASE tools help
manage the complexity in large scale
software development
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CASE Tools
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Used properly, they can help:
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Increase productivity, by automating boring and
error-prone tasks (generating diagrams,
documenting code)
Improve communication with users, by speeding
updates to diagrams, models, and prototypes
Integrate life cycle activities, by providing a
common platform for exchanging work products
Help assess maintenance changes, by identifying
the impact of changes across the system
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CASE Tools
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There are upper and lower CASE tools
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Upper CASE tools focus on the start of the life
cycle – requirements and design of the system
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Lower CASE tools, therefore, focus on the end of
the life cycle – coding and testing
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Some help do prototyping too
Automatic generation of code, and automated testing
are key features here
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CASE Tools
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Some CASE tools can reverse engineer or
help reengineer code
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Reverse engineering code is to input the source
code, and generate the design drawings from it
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Is code generation run backwards
Reverse compilation is also possible
Reengineering code often refers to rethinking
how business processes work, and restructuring how the applications support them
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Extreme Programming (XP)
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Extreme programming, agile programming,
scrum, DSDM, and other variations are used
to speed traditional development methods,
but keep enough structure to maintain control
XP, for example, features
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Short release schedules
A 40-hour work week
Having the customer onsite
Programming by pairs of people
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The Systems View
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There are two major aspects to what we’re
calling ‘the systems view’
In dealing with the information system, we
need to recognize that it consists of much
more than just software or a database
It will include
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Hardware (the servers and networking equipment
it runs on)
Training materials (for users, support staff, etc.)
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The Systems View
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Documentation, such as
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User manual
Installation manual
Work products from development
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Feasibility study
Requirements document
Design documents
Implementation plan
Processes used by the development team
Commercial components (e.g. the operating
system, database system, … )
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The Systems View
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When we create an information system,
we create all these things, not just
some software
The second perspective is to realize that the
organization’s top management doesn’t care
about any of the previous components of our
system – they think of it in terms of how it
helps perform business functions
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Organizations as Systems
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Organizations typically have three levels
of management focus
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Strategic – what lines of business are we in?
Middle management – what projects within our
line of business do we pursue?
Operations – how can I manage this project well?
Hopefully, all of them are working to
achieve common goals or objectives
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Usually, the goal is ‘make money’
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Organizations as Systems
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The levels of management tend to need
different time scales of data from information
systems
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Strategic – long term trends and competitive
information, lots of predictions
Middle management – short and medium term
performance information, some historical data
Operations – repetitive, low level data on their
project; current and past performance
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Organizations as Systems
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Each organization is broken into parts (e.g.
divisions or departments) to help achieve
different functions to meet that goal
Each part, or functional area, might be
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Purchasing
Finance
Production
Marketing
Distribution
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Organizations as Systems
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Information systems typically serve more
than one functional area of an organization
Hence to determine the information needs of
your system, you first need to identify what
areas are affected by it
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Who will generate input for your system?
Who will use outputs from your system?
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Organizations as Systems
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Identify how those areas affect each other
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Does output from one area become an input for
another area?
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Marketing results in production and then distribution
Purchasing provides materials for production
Finance pays for purchasing and marketing
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Organizations as Systems
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Look for feedback mechanisms to help
improve your system
Any process exists to take some input(s)
and create some output(s)
What kind of outputs from other systems
could influence your system, either as a
direct input, or change the rules your
system uses?
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Organizations as Systems
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Look for outside influences on your
organization and system
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Export laws and tariffs may affect distribution
Production may be limited by labor laws
Finance should comply with accounting practices
and tax laws
Marketing might be limited by truth-in-advertising
laws, intellectual property rights, and competition
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Organizations as Systems
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Look for how open your system’s
organization is
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Is information encouraged to flow freely?
Are there a lot of approvals and checks &
balances?
Who is allowed to communicate with whom?
Trouble is, everyone tends to think their
organization is the most important one
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Virtual Organizations
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Organizations don’t have to be physically
located together
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If not, they are a virtual organization
Could save money on facilities or travel
Social aspects are unclear
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Harder to form identity with a virtual team
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Context Diagram
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The context diagram (called in the text a
‘context-level data flow diagram’) is the
highest level view of the data needs for
a system
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At its center is a rounded box which represents
your entire system
Around that box are square boxes representing
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1) The types of users of your system, and
2) External systems with which your system interacts
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Context Diagram
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Show only users who interact directly with
your system
Lines between your system and the other
boxes are labeled to identify the types of
data which flow between them
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If data flow goes both directions, use separate
lines for each direction to distinguish inputs
from outputs
Example on page 33, figure 2.5
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Context Diagram
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The context diagram is also handy for
defining system requirements
Consider each type of user or external
system separately, and ask:
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What kind of inputs and outputs would they
want from this system?
What kind of processes would they expect to
be able to perform?
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Entity-Relationship Model
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The Entity-Relationship Model will be
refined later to show the data structure
for our system
For now, we can use the same notation to
indicate early results of system analysis
Each entity represents some key concept
related to your system – a user, event, thing,
etc. that you want to keep information about
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Transient or temporary data aren’t kept in entities
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Entity-Relationship Model
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A line between entities is labeled with verb
phrases to identify what kind of relationship
exists between those entities
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Employee ‘is assigned to’ Office
Passenger ‘is flying to’ Destination
The ends of the line are marked to show the
“cardinality” – how many of one thing could
be associated with the other?
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Cardinality and Relationships
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To determine the cardinality shown, ask “for
one example of entity A, how many possible
entries could exist in entity B?”
A
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B
Consider extreme cases; a Customer may
have zero Orders briefly, before their first
order is completed
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Cardinality and Relationships
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Relationships are described by how many
records of each entity may be related: 0
(shown by a ‘0’), 1 (shown with a single or
double line), or many (shown by a trident)
• Here we are using the Martin notation; many others exist
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Cardinality of zero implies the relationship
is optional in that direction
One-to-one is a unique relationship
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Cardinality and Relationships
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Cardinality conveys the minimum and maximum
number of relationships, and must be defined in
both directions for all relationships:
 Only one
 Zero or one
 One or many (more)
 Zero, (one), or many
 Many (only >1)
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Associative Entity
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In discussion, cardinality is often abbreviated
to “one to one”, “one to many”, or “many to
many”
“Many to many” relationships are bad; break
them up with an associative entity
An associative entity is an entity that shares
traits from two other entities, because it is
associated with both of them
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Associative Entity
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The example in the text (p. 37) is breaking up
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With the associative entity Reservation, to
become
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Patron – Concert
Patron – Reservation – Concert
Another example is
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Employee – Employer
Becomes Employee – Contract – Employer
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Associative Entity
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An associative entity must also have some
characteristics which are unique to it (e.g.
data)
The symbol for an associative entity has a
diamond in it
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