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SYSTEM ANALYSIS : :fire: - Coggle Diagram
SYSTEM ANALYSIS : :fire:
1)SYSTEM REQUIREMENT :star:
a)Outputs
The purchasing system must provide suppliers with up-to-date specifications.
b)Inputs
Student grades must be entered on machine-scannable forms prepared by the instructor.
c)Processes
The student records system must calculate the GPA at the end of each semester.
d)Performance
The system must support 25 users online simultaneously.
e)Controls
An employee record must be added, changed, or deleted only by a member of the human resources department.
2)FACT FINDING TECNIQUES :fire:
4W1H :black_flag:
a)Who
Who performs each of the procedures within the system?
b)What
What is being done?
c)Where
Where are operations being performed?
d)when
When is a procedure performed?
e)How
How is a procedure performed?
TECHNIQUES :black_flag:
a)Interview :check:
An interview is a planned meeting during which you obtain information from another person.
seven steps for each interview:
Step 1 : Determine the people to interview.
Step 2 : Establish objectives for the interview.
Step 3 : Develop interview questions.
Step 4 : Prepare for the interview.
Step 5 : Conduct the interview.
Step 6 : Document the interview.
Step 7 : Evaluate the interview.
b)Documentation review :check:
Document review can help you understand how the current system is supposed to work.
c)Observation :check:
Seeing the system in action gives you additional perspective and a better understanding of the system procedures
d)Questionnaires :check:
Open-ended-questions
Close-ended question
A questionnaire, also called a survey, is a document containing a number of standard questions that can be sent to many individuals.
e)Sampling :check:
Systematic
Stratified
Random
The samples might include records, reports, operational logs, data entry documents, complaint summaries, work requests, and various types of forms.
f)Research :check:
Your research can include the Internet, IT magazines, and books to obtain background information, technical material, and news about industry trends and developments.
3)MODELING TOOLS AND TECHNIQUES : :fire:
a)Functional Decomposition Diagrams(FDD)
-A functional decomposition diagram (FDD) is a top-down representation of a function or processt.
b)Unified Modeling language Diagram(UML)
-use case diagrams
-sequence diagrams
The Unified Modeling Language (UML) is a widely used method of visualizing and documenting software systems design.
Steps to analyze the gathered information;
: :black_flag:
Step 1 : Review the questions
Step 2 : Organize the information
Step 3 : Decide how to analyze the information
Step 4 : Analyze quantitative information
Step 5 : Analyze qualitative information
Step 6 : Integrate the information
Data & Process Modelling :forbidden:
A)Data Flow Diagram
B)Data Dictionary
C)Process Description
A)Data Flow Diagram :warning:
A data flow diagram (DFD) shows how data moves through an information system but does not show program logic or processing steps( flow of data between process).
DFD Symbols :<3:
-process symbols
Receives input data and produces output that has a different content, form, or both
-data flow symbol
-Represents one or more data items
-The symbol for a data flow is a line with a single or double arrowhead
Avoid
-Spontaneous generation
-Black hole
-Gray hole
-data store symbol
-Represent data that the system stores
-The physical characteristics of a data store are unimportant because you are concerned only with a logical model
-entity symbol
-Name of the entity appears inside the symbol
-Shows only external entities that provide data to the system or receive output from the system.
Creating a set of DFD
-Create a graphical model of the information system based on your fact-finding results
-First, you will review a set of guidelines for drawing DFDs. Then you will learn how to apply these guidelines and create a set of DFDs using a three-step process
Guidelines for drawing DFD
Draw the context diagram so that it fits on one page
Use the name of the information system as the process name in the context diagram
Use unique names within each set of symbols
Do not cross lines
Provide a unique name and reference number for each process
Obtain as much user input and feedback as possible
3 step
step 1 : draw a context diagram
step 2 : draw a diagram 0 DFD
step 3 : draw the lower-level diagrams
B)Data Dictionary :warning:
A data dictionary, or data repository, is a central storehouse of information about the system’s data
Using CASE Tools for Documentation
:explode:
The more complex the system, the more difficult it is to maintain full and accurate documentation
Modern CASE tools simplify the task
A CASE repository ensures data consistency
Documenting the Data Elements
:explode:
The following attributes usually are recorded and described
-Data element name and label
-Alias
-Type and length
-Default value
-Acceptable values - Domain and validity rules
-Source
-Security
-Responsible user(s)
-Description and comments
Documenting the Data Stores
:explode:
Typical characteristics of a data store are :star:
-Data store name or label
-Description
-Alternate name(s)
-Attributes
-Volume and frequency
Typical characteristics of a process :star:
-Process name or label
-Description
-Process number
-Process description
Typical characteristics of an entity include :star:
-Entity name
-Description
-Alternate name(s)
-Input data flows
-Output data flows
Typical characteristics of a record include :star:
-Record or data structure name
-Definition or description
-Alternate name(s)
-Attributes
C)Process Description :warning:
A process description documents the details of a functional primitive, which represents a specific set of processing steps and business logic
Process specification
Modular design
Structured English
Decision Table
Modular design
:checkered_flag:
-Modular design is based on combinations of three logical structures, sometimes called control structures, which serve as building blocks for the process.
-Each logical structure must have a single entry and exit point.
The three structures are called
sequence
selection
iteration
Structure English
:checkered_flag:
Must conform to the following rules
Use only the three building blocks of sequence, selection, and iteration
Use indentation for readability
Use a limited vocabulary, including standard terms used in the data dictionary and specific words that describe the processing rules
Decision Tables
:checkered_flag:
Types of tables;
Tables with one condition
Tables with two condition
Tables with three condition
Table with multiple outcomes
Logical & Physical Model : : :checkered_flag:
Sequence of Models
Many systems analysts create a physical model of the current system and then develop a logical model of the current system before tackling a logical model of the new system
Performing that extra step allows them to understand the current system better
Four-Model Approach
Develop a physical model of the current system, a logical model of the current system, a logical model of the new system, and a physical model of the new system
The only disadvantage of the four-model approach is the added time and cost
