CS1353-SOFTWARE ENGINEERING
TWO MARKS
1. What is software engineering?
Software engineering is a discipline in which theories, methods
and tools are applied to develop professional software.
2. What is Software ?
Software is nothing but a collection of computer programs that are
related documents that are indented to provide desired features,functionalities
and better performance.
3. What are the characteristics of the software?
·
Software is engineered,not manufactured.
·
Software does not wear out.
·
Most software is custom built rather than
being assembled from components.
4. What are the various categories of software?
·
System software
·
Application software
·
Engineering/Scientific software
·
Embedded software
·
Web Applications
·
Artificial Intelligence software
5. What are the challenges in software?
·
Copying with legacy systems.
·
Heterogeneity challenge
·
Delivery times challenge
6. Define software process.
Software process is defined as the structured set of activities
that are required to develop the software system.
7. What are the fundamental activities of a software process?
·
Specification
·
Design and implementation
·
Validation
·
Evolution
8. What are the umbrella activities of a software process?
Software project tracking and control.
Risk management.
Software Quality Assurance.
Formal Technical Reviews.
Software Configuration Management.
Work product preparation and production.
Reusability management.
Measurement.
9. What are the merits of incremental model?
i. The incremental model can be adopted when tere are less number
of
people involved in the project.
ii. Technical risks can be managed with each increment.
iii. For a very small time span,at least core product can be
delivered to the
customer.
10. List the task regions in the Spiral model.
Customer communication – In this
region it is suggested to establish customer communication.
Planning – All planning activities
are carried out in order to define resources timeline and other project related
activities.
Risk analysis – The tasks
required to calculate technical and management risks.
Engineering – In this the task
region,tasks required to build one or more representations of applications are
carried out.
Construct and release – All the
necessary tasks required to construct,test,install the applications are
conducted.
Customer evaluation – Customer’s
feedback is obtained and based on the customer evaluation required tasks are
performed and implemented at installation stage.
11. What are the drawbacks of spiral model?
i. It is based on customer communication. If the communication is
not proper then the software product that gets developed will not be the up to
the mark.
ii. It demands considerable risk assessment. If the risk
assessment is done properly then only the successful product can be obtained.
12. What is System Engineering?
System Engineering means designing, implementing, deploying and operating
systems which include hardware,software and people.
13. List the process maturity levels in SEIs
CMM.
Level 1:Initial – Few processes
are defined and individual efforts are taken.
Level 2:Repeatable – To track
cost schedule and functionality basic project management processes are
established.
Level 3:Defined – The process
is standardized, documented and followed.
Level 4:Managed – Both the
software process and product are quantitatively understood and controlled using
detailed measures.
Level 5:Optimizing – Establish
mechanisms to plan and implement change.
14. What is an effector process?
The effector process is a process that verifies itself. The
effector process exists in certain criteria.
15. Define the computer based system.
The computer based system can be defined as “a set or an
arrangement of elements that are organized to accomplish some predefined goal
by processing information”.
16. What does Verification represent?
Verification represents the set of activities that are carried out
to confirm that the software correctly implements the specific functionality.
17. What does Validation represent?
Validation represents the set of activities that ensure that the
software that has been built is satisfying the customer requirements.
18. What are the steps followed in testing?
i. Unit testing – The individual components are tested in this type of testing.
ii. Module testing – Related
collection of independent components are tested.
iii. Sub-system testing – This is a
kind of integration testing.Various modules are integrated into a subsystem and
the whole subsystem is tested.
iv. System testing – The whole
system is tested in this system.
v. Acceptance testing – This type of testing involves testing of the system with customer
data.If the system behaves as per customer need then it is accepted.
19. What is the use of CMM?
Capability Maturity Model is used in assessing how well an
organisation’s processes allow to complete and manage new software projects.
20. Name the Evolutionary process Models.
i. Incremental model
ii. Spiral model
iii. WIN-WIN spiral model
iv. Concurrent Development
21. What is requirement engineering?
Requirement engineering is the process of establishing the
services that the customer requires from the system and the constraints under
which it operates and is developed.
22. What are the various types of traceability in software
engineering?
i. Source traceability – These are
basically the links from requirement to stakeholders who propose these
requirements.
ii. Requirements traceability – These
are links between dependant requirements.
iii. Design traceability – These are links from requirements to design.
23. Define software prototyping.
Software prototyping is defined as a rapid software development
for validating the requirements.
24. What are the benefits of prototyping?
i. Prototype serves as a basis for deriving system specification.
ii. Design quality can be improved.
iii. System can be maintained easily.
iv. Development efforts may get reduced.
v. System usability can be improved.
25. What are the prototyping approaches in software process?
i. Evolutionary prototyping – In
this approach of system development, the initial prototype is prepared and it
is then refined through number of stages to final stage.
ii. Throw-away prototyping – Using this approach a rough practical implementation of the system
is produced. The requirement problems can be identified from this
implementation. It is then discarded. System is then developed using some
different engineering paradigm.
26. What are the advantages of evolutionary prototyping?
i. Fast delivery of the working system.
ii. User is involved while developing the system.
iii. More useful system can be delivered.
iv. Specification,design and implementation work in co-ordinated
manner.
27. What are the various Rapid prototyping techniques?
i. Dynamic high level language development.
ii. Database programming.
iii. Component and application assembly.
28. What is the use of User Interface prototyping?
This prototyping is used to pre-specify the look and feel of user
interface in an effective way.
29. What are the characteristics of SRS?
i. Correct – The SRS should be made
up to date when appropriate requirements are identified.
ii. Unambiguous – When the
requirements are correctly understood then only it is possible to write an
unambiguous software.
iii. Complete – To make SRS
complete, it should be specified what a software designer wants to create
software.
iv. Consistent – It should
be consistent with reference to the functionalities identified.
v. Specific – The requirements should
be mentioned specifically.
vi. Traceable – What
is the need for mentioned requirement? This should be correctly identified.
30. What are the objectives of Analysis modeling?
i. To describe what the customer requires.
ii. To establish a basis for the creation of software design.
iii. To devise a set of valid requirements after which the
software can be built.
31. What is data modeling?
Data modeling is the basic step in the analysis modeling. In data
modeling the data objects are examined independently of processing. The data
model represents how data are related with one another.
32. What is a data object?
Data object is a collection of attributes
that act as an aspect, characteristic, quality, or descriptor of the object.
33. What are attributes?
Attributes are the one, which defines the
properties of data object.
34. What is cardinality in data modeling?
Cardinality in data modeling, cardinality
specifies how the number of occurrences of one object is related to the number
of occurrences of another object.
35. What does modality in data modeling indicates?
Modality indicates whether or not a
particular data object must participate in the relationship.
36. What is ERD?
Entity Relationship Diagram is the graphical
representation of the object relationship pair.It is mainly used in database
applications.
37. What is DFD?
Data Flow Diagram depicts the information
flow and the transforms that are applied on the data as it moves from input to
output.
38. What does Level0 DFD represent?
Level0 DFD is called as ‘fundamental system
model’ or ‘context model’. In the context model the entire software system is
represented by a single bubble with input and output indicated by incoming and
outgoing arrows.
39. What is a state transition diagram?
State transition diagram is basically a
collection of states and events. The events cause the system to change its
state.It also represents what actions are to be taken on the occurrence of
particular event.
40. Define Data Dictionary.
The data dictionary can be defined as an
organized collection of all the data elements of the system with precise and
rigorous definitions so that user and system analyst will have a common
understanding of inputs,outputs,components of stores and intermediate
calculations.
41. What are the elements of Analysis model?
i. Data Dictionary
ii. Entity Relationship Diagram
iii. Data Flow Diagram
iv. State Transition Diagram
v. Control Specification
vi. Process specification
42. What are the elements of design model?
i. Data design
ii. Architectural design
iii. Interface design
iv. Component-level design
43. Define design process.
Design process is a sequence of steps carried
through which the requirements are translated into a system or software model.
44. List the principles of a software design.
i. The design process should not suffer from “tunnel vision”.
ii. The design should be traceable to the analysis model.
iii. The design should exhibit uniformity and integration.
iv. Design is not coding.
v. The design should not reinvent the wheel.
45. What is the benefit of modular design?
Changes made during testing and maintenance
becomes manageable and they do not affect other modules.
46. What is a cohesive module?
A cohesive module performs only “one task” in
software procedure with little interaction with other modules. In other words
cohesive module performs only one thing.
47. What are the different types of Cohesion?
i. Coincidentally cohesive –The modules
in which the set I\of tasks are related with each other loosely then such
modules are called coincidentally cohesive.
ii. Logically cohesive – A module
that performs the tasks that are logically related with each other is called
logically cohesive.
iii. Temporal cohesion – The module
in which the tasks need to be executed in some specific time span is called
temporal cohesive.
iv. Procedural cohesion – When
processing elements of a module are related with one another and must be
executed in some specific order then such module is called procedural cohesive.
v. Communicational cohesion – When the processing elements of a module share the data then such
module is called communicational cohesive.
48. What is Coupling?
Coupling is the measure of interconnection
among modules in a program structure. It depends on the interface complexity
between modules.
49. What are the various types of coupling?
i. Data coupling – The data
coupling is possible by parameter passing or data interaction.
ii. Control coupling – The modules
share related control data in control coupling.
iii. Common coupling – The common
data or a global data is shared among modules.
iv. Content coupling – Content coupling occurs when one module makes use of data or
control information maintained in another module.
50. What are the common activities in design process?
i. System structuring – The system is subdivided into principle subsystems components
and communications between these subsystems are identified.
ii. Control modeling – A model of control relationships between different parts of the
system is established.
iii. Modular decomposition – The
identified subsystems are decomposed into modules.
51. What are the benefits of horizontal partitioning?
i. Software that is easy to test.
ii. Software that is easier to maintain.
iii. Propagation of fewer sideeffects.
iv. Software that is easier to extend.
52. What is vertical partitioning?
Vertical partitioning often called factoring
suggests that the control and work should be distributed top-down in program
structure.
53. What are the advantages of vertical partitioning?
i. These are easy to maintain changes.
ii. They reduce the change impact and error propagation.
54. What are the various elements of data design?
i. Data object – The data
objects are identified and relationship among various data objects can be
represented using ERD or data dictionaries.
ii. Databases – Using
software design model, the data models are translated into data structures and
data bases at the application level.
iii. Data warehouses – At the business level useful information is identified from
various databases and the data warehouses are created.
55. List the guidelines for data design.
i. Apply systematic analysis on data.
ii. Identify data structures and related operations.
iii. Establish data dictionary.
iv. Use information hiding in the design of data structure.
v. Apply a library of useful data structures and operations.
56. Name the commonly used architectural styles.
i. Data centered architecture.
ii. Data flow architecture.
iii. Call and return architecture.
iv. Object-oriented architecture.
v. Layered architecture.
57. What is Transform mapping?
The transform mapping is a set of design
steps applied on the DFD in order to map the transformed flow characteristics
into specific architectural style.
58. What is a Real time system?
Real time system is a software system in
which the correct functionalities of the system are dependent upon results
produced by the system and the time at which these results are produced.
59. What is SCM?
Software Configuration Management is a set of
activities carried out for identifying, organizing and controlling changes
throughout the lifecycle of computer software.
60. What is SCI?
Software Configuration Item is information
that is carried as part of the software engineering process.
61. Define software testing?
Software testing is a critical element of
software quality assurance and represents the ultimate review of specification,
design, and coding.
62. What are the objectives of testing?
i. Testing is a process of executing a program with the intend of
finding an error.
ii. A good test case is one that has high probability of finding
an undiscovered error.
iii. A successful test is one that uncovers as an-yet undiscovered
error.
63. What are the testing principles the software
engineer must apply while performing the software testing?
i. All tests should be traceable to customer requirements.
ii. Tests should be planned long before testing begins.
iii. The pareto principle can be applied to software testing-80%
of all errors uncovered during testing will likely be traceable to 20% of all
program modules.
iv. Testing should begin “in the small” and progress toward
testing “in the large”.
v. Exhaustive testing is not possible.
vi. To be most effective, an independent third party should
conduct testing.
63. What are the two levels of testing?
i. Component testing
Individual components are tested. Tests are
derived from developer’ s experience.
ii. System Testing
The group of components are integrated to
create a system or sub-system is done.These tests are based on the system specification.
64. What are the various testing activities?
i. Test planning
ii. Test case design
iii. Test execution
iv. Data collection
v. Effective evaluation
65. Write short note on black box testing.
The black box testing is also called as
behavioral testing. This method fully focus on the functional requirements of
the software. Tests are derived that fully exercise all functional
requirements.
66. What is equivalence partitioning?
Equivalence partitioning is a black box
technique that divides the input domain into classes of data. From this data
test cases can be derived. Equivalence class represents a set of valid or
invalid states for input conditions.
67. What is a boundary value analysis?
A boundary value analysis is a testing
technique in which the elements at the edge of the domain are selected and
tested. It is a test case design technique that complements equivalence
partitioning technique. Here instead of focusing on input conditions only, the
test cases are derived from the output domain.
68. What are the reasons behind to perform white box testing?
There are three main reasons behind
performing the white box testing.
1. Programmers may have some incorrect assumptions while designing
or implementing some functions.Due to this there are chances of having logical
errors in the program.To detect and correct such logical errors procedural
details need to be examined.
2. Certain assumptions on flow of control and data may lead programmer
to make design errors.To uncover the errors on logical path,white box testing
is must.
3. There may be certain typographical errors that remain
undetected even after syntax and type checking mechanisms.Such errors can be uncovered
during white box testing.
69. What is cyclomatic complexity?
Cyclomatic complexity is a software metric that gives the
quantitative measure of logical complexity of the program.
The Cyclomatic complexity defines the number of independent paths
in the basis set of the program that provides the upper bound for the number of
tests that must be conducted to ensure that all the statements have been
executed at least once.
70. How to compute the cyclomatic complexity?
The cyclomatic complexity can be computed by any one of the
following ways.
1. The numbers of regions of the flow graph correspond to the
cyclomatic complexity.
2. Cyclomatic complexity,V(G),for the flow graph,G,is defined as:
V(G)=E-N+2,
E -- number of flow graph edges,
N -- number of flow graph nodes
3. V(G)=P+1
Where P is the number of predicate nodes contained in the flow
graph.
71. Distinguish between verification and validation.
Verification refers to the set of activities that ensure that
software correctly implements a specific function.
Validation refers to a different set of activities that ensure
that the software that has been built is traceable to the customer requirements.
According to Boehm,
Verification:” Are we building the product right?”
Validation:” Are we building the right product?”
72. What are the various testing strategies for conventional
software?
i. Unit testing
ii. Integration testing.
iii. Validation testing.
iv. System testing.
73. Write about drivers and stubs.
Drivers and stub software need to be
developed to test incompatible software.
·
The “ driver” is a program that accepts the test data and prints the relevant
results.
·
The “ stub” is a subprogram that uses the module interfaces and performs the
minimal data manipulation if required.
74. What are the approaches of integration testing?
The integration testing can be carried out using two approaches.
1. The non-incremental testing.
2. Incremental testing.
75. What are the advantages and disadvantages of big-bang?
Advantages: This approach is
simple.
Disadvantages:
It is hard to debug.
It is not easy to isolate errors while testing.
In this approach it is not easy to validate test results.
After performing testing, it is impossible to form an integrated
system.
76. What are the benefits of smoke testing?
Integration risk is minimized.
The quality of the end-product is improved.
Error diagnosis and correction are simplified.
Assessment of program is easy.
77. What are the conditions exists after performing validation
testing?
·
After performing the validation testing there
exists two conditions.
·
The function or performance characteristics
are according to the specifications and are accepted.
·
The requirement specifications are derived
and the deficiency list is created.
·
The deficiencies then can be resolved by
establishing the proper communication with the customer.
78. Distinguish between alpha and beta testing.
Alpha and beta testing are the types of acceptance testing.
Alpha test: The alpha testing is
attesting in which the version of complete software is tested by the customer
under the supervision of developer. This testing is performed at developer’ s
site. Beta test:
The beta testing is a testing in which the version of the software is tested by
the customer without the developer being present. This testing is performed at
customer’ s site.
79. What are the various types of system testing?
1. Recovery testing – is intended to check the system’ s ability to recover from
failures.
2. Security testing – verifies that system protection mechanism prevent improper
penetration or data alteration.
3. Stress testing – Determines breakpoint of a system to establish maximum service
level.
4. Performance testing – evaluates the run time performance of the software, especially
real-time software.
80. Define debugging.
Debugging is defined as the process of removal of defect. It
occurs as a consequence of successful testing.
81. What are the common approaches in debugging?
Brute force method: The memory
dumps and run-time tracks are examined and program with write statements is
loaded to obtain clues to error causes.
Back tracking method: The source
code is examined by looking backwards from symptom to potential causes of
errors.
Cause elimination method: This method
uses binary partitioning to reduce the number of locations where errors can exists.
82. Write about the types of project plan.
Quality plan – This plan describes the
quality procedures and standards that will be used in a project.
Validation plan – This plan
describes the approach, resources and schedule required for system validation.
Configuration management plan – This
plan focuses on the configuration management procedures and structures to be
used.
Maintenance plan – The purpose
of maintenance plan is to predict the maintenance requirements of the system,
maintenance cost and efforts required.
Staff development plan – This plan
describes how to develop the skills and experience of the project team members.
83. Define measure.
Measure is defined as a quantitative
indication of the extent, amount, dimension, or size of some attribute of a
product or process.
84. Define metrics.
Metrics is defined as the degree to which a
system component,or process possesses a given attribute.
85. What are the types of metrics?
Direct metrics – It refers
to immediately measurable attributes.
Example – Lines of code, execution speed.
Indirect metrics – It refers
to the aspects that are not immediately quantifiable or measurable. Example –
functionality of a program.
86. What are the advantages and disadvantages of size measure?
Advantages:
·
Artifact of software development which is
easily counted.
·
Many existing methods use LOC as a key input.
·
A large body of literature and data based on
LOC already exists.
Disadvantages:
·
This method is dependent upon the programming
language.
·
This method is well designed but shorter
program may get suffered.
·
It does not accommodate non procedural languages.
·
In early stage of development it is difficult
to estimate LOC.
·
87. Write short note on the various estimation techniques.
Algorithmic cost modeling – the cost
estimation is based on the size of the software.
Expert judgement – The experts
from software development and the application domain use their exoerience to
predict software costs.
Estimation by analogy – The cost of
a project is computed by comparing the project to a similar project in the same
application domain and then cost can be computed.
Parkinson’s law – The cost is
determined by available resources rather than by objective assessment.
Pricing to win – The project
costs whatever the customer ready to spend it.
88. What is COCOMO model?
Constructive Cost Model is a cost model,
which gives the estimate of number of man-months it will take to develop the
software product.
89. Give the procedure of the Delphi method.
1. The co-ordinator presents a specification and estimation form
to each expert.
2. Co-ordinator calls a group meeting in which the experts discuss
estimation issues with the coordinator and each other.
3. Experts fill out forms anonymously.
4. Co-ordinator prepares and distributes a summary of the
estimates.
5. The Co-ordinator then calls a group meeting.In this meeting the
experts mainly discuss the points where their estimates vary widely.
6. The experts again fill out forms anonymously.
7. Again co-ordinator edits and summarizes the forms,repeating
steps 5 and 6 until the co-ordinator is satisfied with the overallprediction synthesized
from experts.
90. What is the purpose of timeline chart?
The purpose of the timeline chart is to emphasize the scope of the
individual task. Hence set of tasks are given as input to the timeline chart.
91. What is EVA?
Earned Value Analysis is a technique of
performing quantitative analysis of the software project.It provides a common
value scale for every task of software project.It acts as a measure for
software project progress.
92. What are the metrics computed during error tracking activity?
·
Errors per requirement specification page.
·
Errors per component-design level
·
Errors per component-code level
·
DRE-requirement analysis
·
DRE-architectural analysis
·
DRE-component level design
·
DRE-coding.
93. Why software change occurs?
·
Software change occurs because of the
following reasons.
·
New requirements emerge when the software is
used.
·
The business environment changes.
·
Errors need to be repaired.
·
New equipment must be accommodated.
·
The performance or reliability may have to be
improved.
94. Write about software change strategies.
The software change strategies that could be applied separately or
together are:
Software maintenance – The changes
are made in the software due to requirements. Architectural
transformation – It is the process of changing one architecture
into another form. Software re-engineering – New features can be added to existing system and then the system
is reconstructed for better use of it in future.
95. What is software maintenance?
Software maintenance is an activity in which
program is modified after it has been put into use.
96. Define maintenance.
Maintenance is defined as the process in
which changes are implemented by either modifying the existing system’ s
architecture or by adding new components to the system.
97. What are the types of software maintenance?
Corrective maintenance – Means the
maintenance for correcting the software faults.
Adaptive maintenance – Means
maintenance for adapting the change in environment. Perfective maintenance – Means
modifying or enhancing the system to meet the new requirements.
Preventive maintenance – Means
changes made to improve future maintainability.
98. What is architectural evolution?
Architectural evolution is the process of
changing a system from a centralized architecture to a distributed architecture
like client server.
99. How the CASE tools are classified?
CASE tools can be classified by
a. By function or use
b. By user type (e.g. manager, tester),or
c. By stage in software engineering process (e.g. requirements, test).
100. What are the types of static testing tools?
There are three types of static testing tools.
Code based testing tools – These tools
take source code as input and generate test cases.
Specialized testing tools – Using this
language the detailed test specification can be written for each test case.
Requirement-based testing tools – These tools help in designing the test cases as per user
requirements.
SIXTEEN MARKS
1. Explain iterative waterfall and spiral model
for software life cycle and
various activities in each phase.
Answer: Iterative waterfall model
The iterative waterfall model is as shown in the following figure.
· Requirement gathering phase in which all requirements are
identified.
· The deign phase is responsible for creating architectural view of
the software.
· The implementation phase in which the software design is
transformed into coding.
· Testing is a kind of phase in which the developed software
component is fully tested.
· Maintenance is an activity by which the software product can be maintained.
Requirements
Design
Implementation
Testing
Maintenance
SPIRAL MODEL
· The spiral model is divided into number of frame works. These
frameworks are
denoted by task regions.
· Usually there are six task regions. In spiral model project entry
point axis is
defined.
· The task regions are:
Customer communication
Planning
Risk analysis.
Engineering.
Construct and release.
Customer evaluation.
Drawbacks
· It is based on customer communication.
· It demands considerable risk assessment.
2. Explain about the incremental model.
· Have same phases as the waterfall model.
· Phases are
Analysis.
Design.
Code.
Test.
· Incremental model delivers series of releases to customers called
as increments.
· The first increment is called as core product. Here only the
document processing facilities are available.
· Second increment, more sophisticated document producing and
processing facilities are available.
· Next increment spelling and grammar checking facilities are given.
Merits
· This model can be adopted when there is less number of people involved
in the project.
· Technical risks can be managed with each increment.
· For a very small time span, at least core product can be delivered
to the customer.
RAD Model
· Rapid Application Development Model is the type of incremental model.
· Achieves the high speed development using component based construction.
Phases
· Business modeling
· Data modeling
· Process modeling
· Application generation.
· Testing and turnover.
3. Explain in detail about the software process.
· It is defined as the structured set of activities that are
required to develop the software system.
Fundamental activities
· Specification
· Design and implementation
· Validation
· Evolution
Common Process Framework
· Process framework activities
Communication
Planning
Modeling
Construction
Deployment.
· Task Sets
Defines the actual work to achieve the
software objective.
· Umbrella activities
Software
project tracking and control
Risk
management
Software
quality assurance
Formal
technical reviews
Software
configuration management
Work
product preparation and production
Reusability
management.
Measurement.
Capability Maturity Model(CMM)
Level 1:Initial – Few
processes are defined and individual efforts are taken.
Level 2:Repeatable – To track
cost schedule and functionality basic project management processes are
established.
Level 3:Defined – The process
is standardized, documented and followed.
Level 4:Managed – Both the
software process and product are quantitatively understood and controlled using
detailed measures.
Level 5:Optimizing – Establish
mechanisms to plan and implement change.
4. Explain in detail about the life cycle process.
Fig: System engineering process
· System engineering process follows a waterfall model for the
parallel development of different parts of the system.
System requirements definition
· Three types of requirements
Abstract functional requirements.
System properties.
Undesirable Characteristics.
· System objectives
· System requirement problem.
The system design process Process steps
· Partition requirements
· Identify sub-systems.
· Assign requirements to sub-systems.
· Specify sub-system functionality.
· Define sub-system interfaces.
Requirement
Definition
definition
System
Design
Sub-system
Design
System
Integration
System
decommissioning
System
evolution
System
Installation
Sub-System development process
· After system design it starts.
· Involve use of COTS (Commercial-Off-The-Shelf).
System Integration
· It is the process of putting hardware, software and people
together to make a system.
System Installation
Issues are
· Environmental assumptions may be incorrect.
· There may be human resistance to the introduction of anew system.
· System may have to coexist with alternative systems for some
period.
· There may arise some physical installation problems (e.g. cabling
problem).
· Operator training has to be identified.
System evolution
· The lifetime of large systems is too long. They must evolve to
meet change requirements.
· The evolution may be costly.
· Existing systems that must be maintained are sometimes called as
legacy systems.
System Decommissioning
· Taking the system out of service after its useful lifetime is
called as System Decommissioning.
5. Explain the prototyping approaches in software process.
Two approaches
i. Evolutionary prototyping – In
this approach of system development, the initial prototype is prepared and it
is then refined through number of stages to final stage.
ii. Throw-away prototyping – Using this approach a rough practical implementation of the system
is produced. The requirement problems can be identified from this
implementation. It is then discarded. System is then developed using some
different engineering paradigm.
Evolutionary prototyping
Objective:
· The principal objective of this model is to deliver the working
system to the end-user.
· Example-AI systems.
Advantages
· Fast delivery of the working system.
· User is involved while developing the system.
· More useful system can be delivered.
· Specification, design and implementation work is co-ordinated
manner.
Problems
· Management problems
· Maintenance problem
· Verification
Incremental Development
· After designing the overall architecture the system is developed
and delivered in series of increments.
Throw-away prototyping
Objective:
· The principal objective of this model is to validate or to derive
the system requirements.
· It is developed to reduce requirement risks.
Advantages
· Requirement risks are very less.
Problems
· It can be undocumented.
· Changes made during the software development proceed may degrade the
system structure.
· Sometimes organizational quality standard may not be strictly
applied.
6. Explain about
rapid prototyping techniques.
Executable specification languages.
· Used to animate the system specification.
· It is expressed in a formal, mathematical language to provide a
system prototype.
Very high level languages.
· These are programming languages which include powerful data management
facilities.
· They simplify program development.
Application generators and fourth-generation languages.
· These are successful languages because there is a great deal of
communality across data processing applications.
7. Explain in detail about data modeling.
· Data modeling makes use of the ERD.
· Consists of 3 interrelated information.
The data object.
Attributes.
Relationships.
Cardinality and Modality
· Cardinality is the specification of the number of occurrences of
one object that can be related to the number of occurrences of another object.
· One-to-one cardinality.
· One-to-many cardinality.
· Many-to-Many cardinality.
· Modality of a relation is 0 if there is no explicit relationship
or relation is
optional.
· Modality is 1 if an occurrence of relationship is mandatory.
Entity/Relationship Diagrams
· Components are
Data Objects.
Attributes.
Relationships.
Various type indicators.
8. Explain in detail about Functional Modeling.
· This model describes the computations that take place within a
system.
· This model is useful when the transformation from the inputs to
outputs is complex.
· The functional model of a system can be represented by a data Flow
Diagram(DFD).
Data Flow Diagrams/Data Flow Graph/Bubble chart
· A DFD is a graphical representation that depicts the information
flow and the transforms that are applied as the data move from input to output.
· Level 0 DFD also called as fundamental system model or context
model represents the entire software as a single bubble with input and output
data indicated by incoming and outgoing arrows.
· Level 1 DFD contains 5 or 6 bubbles. Each bubbles can be refined
at Layers to depict more details.
Extensions to Real Time Systems
· Ward and Meller extensions
· Hatley and Pirbhai extension.
9. Explain in detail about Structural Modeling.
· Structural model includes a detail refinement of ERD,data flow
model and control flow model.
· Creating an ERD.
· Example: Safe Home Security System.
· Developing relationships and cardinality/Modality.
· Creating a data flow model using the guidelines.
· Creating a control flow model which describes the structural
connection of Processes
Control flows
Control stores.
· State automation
· Process activation table.
10. Explain in detail the design concepts.
Abstraction
· Functional abstraction
· Data abstraction
· Control abstraction
Information hiding
· Each module in the system hides the internal details of its processing
activities and modules communicate only through over defined interfaces.
Structure
· It permits the decomposition of a large system into smaller, more manageable
units with well defined relationships to the other units in a system.
· Network is the most general form of structure.
Hierarchical Structures/Structure Charts
· It depicts the structure of subroutines in a system, the data
passed between routines, can be indicated on the arcs connecting routines.
Modularity
· Modular system consists of well-defined, manageable units with well
defined interfaces among units.
Concurrency
· Independent processes that can be activated simultaneously if multiple
processors are available.
Coupling and Cohesion
· Data coupling – The data
coupling is possible by parameter passing or data interaction.
· Control coupling – The modules
share related control data in control coupling.
· Common coupling – The common
data or a global data is shared among modules.
· Content coupling – Content
coupling occurs when one module makes use of data or control information
maintained in another module.
11. Explain the design principles.
· The design process should not suffer from tunnel vision.
· The design should be traceable to the analysis model.
· Design should not reinvent the wheel.
· The design should minimize the intellectual distance between the
software and problem as it exists in the real world.
· The design should be structured to degrade gently, even when
aberrant data, events or operating conditions are encountered.
· Design is not coding, coding is not design.
· The design should be assessed for quality as it is being created,
not after the fact.
· The design should be reviewed to minimize conceptual (semantic)
errors.
12. Explain the design steps of the transform mapping.
· Review the fundamental model.
· Review and refine the DFD for the software.
· Determine whether the DFD has the transform or transaction
mapping.
· Isolate the transform center by specifying incoming and outgoing
flow boundaries.
· Perform first-level factoring.
· Perform second-level factoring.
· Refine the first iteration architecture using design heuristics
for improved software quality.
13. Explain the design steps in transaction mapping.
· Review the fundamental model.
· Review and refine the DFD for the software.
· Determine whether the DFD has the transform or transaction
mapping.
· Identify transaction center and the flow characteristics along
each of the action paths.
· Factor and refine the transaction structure and the structure of
each action path.
· Refine the first iteration architecture using design heuristics
for improved software quality.
14. Explain in detail about the real time systems.
· Hard and soft real time systems.
· Real time and high performance.
· Real-Time control.
· Real time software design
Periodic Stimuli – Occur at predictable time intervals.
Aperiodic Stimuli – Occur regularly
15. Explain the types of software testing.
· Unit testing
· System testing
· Integration testing
· User-acceptance testing
· End-to-End testing
· Regression testing
· Exception testing
· Destructive testing
16. Explain in detail about Black box testing.
· Black box or behavioral testing focuses on the functional
requirements of the software.
· It is applied during the last stage of testing.
· Syntax driven testing is suitable for the specification which are described
by a certain grammar.
· Decision table based testing is implemented when the original
software requirement have been formulated in the format of “ if-then” statements.
· Liquid level control is the study of a simple control problem
which is designed to check the liquid level. It has 2 sensors.
· Cause effect graphs in functional testing.
17. Explain about the software testing strategies.
· A strategic approach to software testing.
· Verification and Validation.
Verification refers to the set of activities that ensure that
software correctly implements a specific function.
Validation refers to a different set of activities that ensure
that the software that has been built is traceable to the customer requirements.
According to Boehm,
Verification:” Are we building the product right?”
Validation:” Are we building the right product?”
· Organization for software testing
· A software testing strategy.
· Criteria for completion of testing.
18. Explain in detail about Integration testing.
· It is a systematic technique for constructing the program
structure.
· Incremental integration – The program
is constructed and tested in small increments.
Top-down integration
· It is an incremental approach.
· Modules are integrated by moving downward through the control hierarchy
beginning with the main control module(main program).
· Subordinate modules are incorporated by depth-first or
breadth-first manner.
Bottom-up integration
· This testing begins construction and testing with the components
at the lowest levels in the program structure.
Regression testing
· It is the re-execution of some subset of tests that have already
been conducted to ensure the changes that have not been propagated unintended
side effects.
Smoke testing
· It minimizes the integration risk.
· Error diagnosis and correction are simplified.
19. Explain in detail about system testing.
· System testing
· Stress testing
· Security testing.
· Performance testing
20. Explain in detail about SCM.
· Software Configuration Management is an umbrella activity that is applied
throughout the software process.
SCM Activities
· Identify change.
· Control change.
· Ensure the change is properly implemented.
· Report change to others.
Need for SCM
· When you build computer software change happens, you need to control
it effectively.
SCI
· Software Configuration Item is information that is carried as part
of the software engineering process.
21. Explain about software cost estimation.
· Major factors are:
Programme ability.
Product Complexity.
Product size.
Available time.
Required reliability.
22. Explain in detail about COCOMO model.
· Constructive Cost Model.
· Software cost estimation gives the estimation of how much months a
man take to develop a software product.
· Application Composition Model.
· Early design stage model
· Post-architecture stage model.
· COCOMO II application composition uses object points.
· NOP=(object point)X[100-%reuse)/100]
NOP-New Object Point.
· Productivity Rate, PROD=NOP/person-Month.
23. Explain in detail about Delphi Method.
Procedure
· The co-ordinator presents a specification and estimation form to
each expert.
· Co-ordinator calls a group meeting in which the experts discuss estimation
issues with the coordinator and each other.
· Experts fill out forms anonymously.
· Co-ordinator prepares and distributes a summary of the estimates.
· The Co-ordinator then calls a group meeting.In this meeting the experts
mainly discuss the points where their estimates vary widely.
· The experts again fill out forms anonymously.
· Again co-ordinator edits and summarizes the forms,repeating steps
5 and 6 until the co-ordinator is satisfied with the overall prediction synthesized
from experts.
24. Explain in detail about software Maintenance.
· Software maintenance is an activity in which program is modified after
it has been put into use.
· Maintenance is defined as the process in which changes are implemented
by either modifying the existing system’ s architecture or by adding new
components to the system.
Different aspects of maintenance
· The bug-fixing view
· The need-to-adapt view
· The user-support view
Need for software maintenance
· To provide continuity of service
· To support mandatory upgrades.
· To support user requests for improvements.
· To facilitate future maintenance work.
25. Explain about CASE tools.
· Computer Aided Software Engineering.
· Business Process Engineering Tools.
· Process Modeling and Management Tools.
· Project Planning Tools.
· Risk analysis tools.
· Project management tools.
· Requirement tracing tools.
· Metrics and management tools.
· Documentation tools.
· System Software tools.
· Quality Assurance tools.
· Database management tools.
· SCM tools.
· Analysis and design tools.
· PTO/SIM tools.
· Interface design and development tools.
· Prototyping tools.
· Programming tools.
· Web development tools.
· Integration and testing tools.
· Static analysis tools.
· Dynamic analysis tools.
· Test management tools.
· Client/server tools.
· Re-engineering tools.
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