A fundamental concept in software engineering is the
software lifecycle
Software is second developed by a group of developers
T or F
F
Software is first developed by a group of developers
The two steps continue until the software becomes obsolete
use and modify,
and use before modify necessary
By “obsolete”, we mean
1- the software loses its validity because of inefficiency
2-obsolescence of the language,
3- major changes in user requirements
4- other factors.
is a standard process followed in an organization to conduct all the steps necessary to analyze, design, implement, and maintain information systems.
System Development Methodology
list the Phases in SDLC:
Planning
Analysis
Design
Implementation
Maintenance
an organization’s total information system needs are identified, analyzed, prioritized, and arranged.
system requirements are studied and structured.
a description of the recommended solution is converted into logical and then physical system specifications.
all functional features of the system chosen for development in analysis are described independently of any computer platform.
Logical design
– the logical specifications of the system from logical design are transformed into the technology-specific details from which all programming and system construction can be accomplished.
Physical design
the information system is coded, tested, installed and supported in the organization
implementation
an information system is systematically repaired and improved
naitenance
There are several models for the development process
1- waterfall model
2- incremental model
is a very popular model for the software development process.
waterfall model
the development process flows in only one direction. This means that a phase cannot be started until the previous phase is completed
the pros(advantages) for waterfall model
1- Each phase is completed before the next phase starts
2- The testing phase can test the whole system because the entire system under development is ready
the cons (disadvantages) for waterfall model
1- System requirements “locked in” after being determined (can't change)
2- Limited user involvement (only in requirements phase)
3- The difficulty in locating a problem: if there is a problem in part of the process, the entire process must be checked.
software is developed in a series of steps.
incremental model
The developers first complete a complicated version of the whole system
The developers first complete a simplified version of the whole system
what the version represents the entire system but does not include the details
simplfied version or first version
In the second version, more details are added, while some are left unfinished, and the system is tested again.
T OR F
T
If there is a problem, the developers know that the problem is with the new functionality and thay dont add more functionality until the existing system works properly.
The development process for incremental model starts with the
analysis phase.
The analysis phase can use one separate approaches, depending on whether the implementation phase is done using an object-oriented language.
The analysis phase can use two separate approaches, depending on whether the implementation phase is done using a procedural programming language or an object-oriented language.
: the analysis process used if the system implementation phase will use a procedural language
Procedure-oriented analysis
show the movement of data in the system.
Data Flow Diagrams (DFD)
Data Flow Diagrams (DFD) use four symbols:
1- A square box shows the source or destination of data,
2- A rectangle with rounded corners shows the process (the action to be performed on the data),
3- An open-ended rectangle shows where data is stored,
4- Arrows shows the flow of data.
provide another useful tool that is normally used when the state of the entities in the system will change in response to events.
State diagrams
State is represented by……………… in the state diagram
rounded rectangle
is the analysis process used if the implementation uses an object-oriented language
Object-oriented analysis
gives the user’s view of a system: it shows how users communicate with the system.
use-case diagram
A use-case diagram uses four components:
system,
use cases,
actors
relationships
defines how the system will accomplish what was defined in the analysis phase.
The design phase
. In the ……., all components of the system are defined
design phase
, the whole system is divided into a set of procedures or modules
In procedure-oriented design
the design phase continues by elaborating the details of classes.
object-oriented design
when the implementation phase can start?
In the waterfall model, after the design phase is completed
In a procedure-oriented development, the project team needs to ?
choose a language or a set of languages
a good testing strategy is the one that finds most errors.
the testing phase
There are two types of testing:
glass-box and black-box.
is based on knowing the internal structure of the software.
Glass-box testing (or white-box testing)
Glass-box testing assumes that the tester knows everything about the……..
software
gets its name from the concept of testing software without knowing what is inside it and without knowing how it works.
Black box testing
is an ongoing process
Documentation
, three separate sets of documentation are prepared for software:
1- user documentation
2- system documentation
3- technical documentation
Documentation only stops when the package becomes obsolete
To run the software system properly, the users need documentation, traditionally called a
user guide
that shows how to use the software step by step
It should be written so that the software can be maintained and modified by people other than the original developers
System documentation defines the software itself and should exist for all four phases of system development
describes the installation and the servicing of the software system.
Technical documentation
defines how the software should be installed on each computer
Installation documentation
how the system should be maintained and updated if necessary
Service documentation defines
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