CIS 321

1
CIS 321IS Analysis Design

• Chapter 6 The Traditional Approach to
  Requirements

2
Traditional vs. OO

• This chapter focuses on what the system does
  when an _______ occurs activities and
  interactions.
• This chapter follows the traditional approach.
• The traditional approach to systems involves
  processes, stored data, inputs, and ________.
• The OO approach to systems involves a collection
  of interacting objects with attributes and
  __________.
• See diagram on p. 201 for comparisons.

3
Data Flow Diagrams (DFD)

• DFDs are very common in the traditional
  approach.
• DFD A graphical ______ that shows requirements
  for inputs, outputs, processes and data storage.
• Five symbols
• process
• data flow
• external agent
• data store
• real-time link

This diagram corresponds to the first event on p.
168. and the data entities on p. 180
4
Context Diagrams

• DFDs can show high-level or low-level processing
  (levels of ____________).
• A single process in a higher level DFD can be
  decomposed into an entirely new DFD at a lower
  level.
• A ________ diagram shows the complete view of a
  system at the highest level of abstraction.
• A context diagram would only show data stores
  shared with other systems.
• A context diagram can be created from an event
  table.

5
Diagram 0

• A DFD __________ is created for each event in the
  event table.
• All DFD fragments are drawn after the event table
  and the context diagram are complete.
• All the DFD fragments can be combined in a single
  DFD called the ______-partitioned system model or
  diagram 0.
• Diagram 0 shows the entire system in greater
  detail than the context diagram.
• Diagram 0 may be too complex for large systems.

6
Logical and Physical DFDs

• A logical DFD assumes perfect technology with no
  specific technology implementations.
• perfect technology implies no ______ checking
• this models the way things should ideally be done
• a logical DFD is best for ______ analysis
• A physical DFD contains some technology
  implementations.
• hardware, data files, user interface, manual
  processes
• this may model the way things are done now
• a physical DFD is best for late analysis or early
  _______

7
DFD Quality

• Minimize complexity
• avoid information __________
• keep chunks of information to 7 /- 2
• processes in a DFD
• data flows entering or leaving a process
• Ensure data flow consistency
• balancing
• data flow at a higher level DFD should match
  those at the lower level
• ______ hole
• data entering a process are not needed
• miracle
• data leaving a process have insufficient sources

8
Documentation of DFD Components

• Process descriptions
• process decomposed in a lower level DFD
• eventually, a process must be defined
• structured ________ (similar to pseudocode,
  preferred, p. 219)
• decision tables and decision trees for complex
  logic (p. 221)
• Data dictionary
• Data flow definitions
• lists all the data elements (_______) in the flow
• corresponds to attributes of data entities in the
  ERD
• Data store definitions (s/b included in ERD)
• Data element definitions (data types, length of
  strings, )
• DFD Summary

9
Information Engineering Models

• In the early 1980s SD and ID were competitors.
• IE SDLC
• Systems planning (focus on __________ and stored
  data)
• Business area analysis (focus on each business
  area)
• System design (describe processes in detail)
• System construction (using _______ tools)
• SD vs. IE
• IE focuses on the entire enterprise, SD does not
• IE phases are tightly coupled, SD more moderately
  so
• IE models
• process decomposition diagram (p. 229)
• process dependency diagram (p. 230)

10
Locations and Networks

• Where will processing and data stores be located?
• This information may be useful in analysis to
• generate and evaluate _____________
• review recommendations with management
• A location diagram summarizes locations (p. 232)
• The activity-location matrix (p. 233)
• lists event table __________ in rows
• lists locations in columns
• The activity-data matrix (p. 234)
• lists event table activities in rows
• lists data stores in columns