1. Structured System Analysis
•Modeling System Function
•Data Flow Diagram
•System Flowchart
•Modeling Stored Data
Entity-Relationship
Data Dictionary
2. Structured Analysis
• Throughout the phases of analysis and
design, the analyst should proceed step by
step, obtaining feedback from users and
analyzing the design for omissions and
errors.
• Moving too quickly to the next phase may
require the analyst to rework portions of the
design that were produced earlier.
3. Structured Analysis
• They Structured a project into small, well-defines
activities and specify the sequence and interaction
of these activities.
• They use diagrammatic and other modeling
techniques to give a more precise (structured)
definition that is understandable by both users and
developers.
4. Structured Analysis
• Structured analysis provides a clear
requirements statements that everyone can
understand and is a firm foundation for
subsequent design and implementation.
• Part of the problem with systems analysts
just asking ‘the right questions’ that it is
often difficult for a technical person to
describe the system concepts back to the user
can understand.
5. Structured Analysis
• Structured methods generally include the use of
easily understood, non technical diagrammatic
techniques.
• It is important that these diagram do not contain
computer jargon and technical detail that the user
wont understand – and does not need
understand.
6. Structured Analysis
Why do we use these tools?
•Use graphics whenever possible to help
communicate better with the user.
•Differentiate between logical and physical
system
•Build a logical system model to familiarize the
user with system characteristics and
interrelationships before implementation.
8. •A Data Flow Diagram (DFD) is a graphical
representation of the "flow" of data through
an information system.
•It differs from the system flowchart as it shows the
flow of data through processes instead of computer
hardware.
•Data flow diagrams were invented by Larry
Constantine, developer of structured design, based
on Martin and Estrin's "data flow graph" model of
computation.
9. •It is common practice to draw a System Context
Diagram first which shows the interaction between
the system and outside entities.
•The DFD is designed to show how a system is
divided into smaller portions and to highlight the
flow of data between those parts.
•This context-level Data flow diagram is then
"exploded" to show more detail of the system being
modeled.
10.
11.
12.
13.
14. PASSENGER
AIRLINE
RESERVATION
SYSTEM
AIRLINE
TRAVEL
AGENT
Travel Request
Preference and
Available Flights
Ticketing Information
Passenger Reservation
0
Context –level flow
diagram for an airline
reservation system
15. •A concrete, physical model that
documents, in an easily visualized,
graphical form, the system’s
discrete physical components (its
programs, procedures, files,
reports, screens, etc.).
16. •A system flowchart is a valuable presentation aid
because it shows how the system’s major components
fit together and interact.
• In effect, it serves as a system roadmap. During the
information gathering stage, a system flowchart is an
excellent tool for summarizing a great deal of technical
information about the existing system.
• A system flowchart can also be used to map a
hardware system.
17. •System flowcharts are valuable as project planning
and project management aids.
•Using the system flowchart as a guide, discrete
units of work (such as writing a program or
installing a new printer) can be identified, cost
estimated, and scheduled.
• On large projects, the components suggest how
the work might be divided into subsystems.
21. Shows one physical alternative
for implementing an inventory
system.
At the top left, a Sales receipt is
prepared as output from the Sell
appliance predefined process.
The data from the Sales
receipt are then input to
the Inventory program.
Subsequently, a printed Cash
flow report goes to the Financial
system.
22. Below the symbols that
represent the system files are
procedures to send advertising
to customers, perform a
physical inventory, process
incoming shipments from
suppliers, and reorder stock.
Except for the predefined
processes, each symbol
represents one of the system’s
discrete components at a black-box
level.
23. • Predefined process —On a system
flowchart, a high-level process that is
more fully documented in a separate,
lower-level flowchart.
• System flowchart —A tool for
documenting a physical system in which
each component is represented by a
symbol that visually suggests its
function.
25. • An entity-relationship model is a systematic way of
describing and defining a business process.
• The process is modeled as components (entities) that
are linked with each other by relationships that express
the dependencies and requirements between them,
such as: one building may be divided into zero or more
apartments, but one apartment can only be located in
one building.
• Entities may have various properties (attributes) that
characterize them. Diagrams created to represent these
entities, attributes, and relationships graphically are
called entity–relationship diagrams.
26. • The elements that make up an organizational
system can be referred to as entities.
• An Entity may be a person, a place, or a thing,
such as a passenger on an airplane, a
destination, or a plane.
• Alternatively that entity may be an event, such
as the end of the month, a sales period, or a
machine breakdown.
• A relationship is the association that describes
the interaction among entities.
30. Relationships are normally given names that are verbs, while attributes and entities are
named after nouns. This convention makes it easy to express relationships.
For example, if we name our Person/City relationship "Lives In", we can string them together
to say "A person lives in a city."
We express relationships in E-R diagrams by drawing a line between the related entities and
placing a diamond shape that contains the relationship name in the middle of the line.
Here's how our Person/City relationship would look:
31. •A structured place to keep details of
the contents of data flows,
processes, and data store.
•It is a structured repository of data
about data.
•It is a set of definitions of all DFD
elements
32. •Documentation- it is a valuable reference
in any organization.
•It improves analyst/user communication
by establishing consistent definitions of
various elements, terms and procedures
•It is important step in building a database
