Software Engineering Practices and Issues.pptx

Managerial issues
Managerial activities are as important as the
technical activities for the success of a software
product.
Managers control the resources and the
environment in which technical activities occur.
Managers also have the responsibility for
ensuring that software products are delivered on time
and within cost estimates and that products exhibit the
functional and quality attributes desired by the
customer.
Other management responsibilities include
developing business plans, recruiting the customers,
developing marketing strategies and recruiting and
training employees.

MANAGEMENT PROBLEMS
 Planning for software engineering projects.
 Procedures and techniques for the selection of
project managers are poor.
 The accountability of many software engineering
projects is poor leaving some question as to who is
responsible for various project functions.
 The ability to accurately estimate the resources
required to accomplish a software development
project is poor.
 Success criterion for software development projects
are frequently inappropriate. This results in software
products that are unreliable difficult to use and
difficult to maintain.

Decision rules to aid in selecting the proper organizational
structure are not available.
Decision rules to aid in selecting the correct management
techniques for . software engineering projects are not available.
Procedures methods and techniques for designing a project
control system that will enable project managers to successful
control their project are not readily available.
Procedures, techniques, strategies and aids that will provide
visibility of progress to the project manager are not available.
Standards and techniques for measuring the quality of
performance and the quality of production expected from
programmers and data processing analysts are not available.

SOLUTION TO THE
PROBLEMS
 Educate and train top management project managers and
software developers.
 Enforce the use of standards, procedures and documentation.
Analyze data from prior software projects to determine effective
methods.
 Define objectives in terms of quality desired.
 Define quality in terms of deliverable.
 Establish success priority criteria.
 Allow for contingencies.
 Develop truthful, accurate cost and schedule estimates that are
accepted by management and customer and manage to them.
Select project managers based on ability to manage software
projects rather than on technical ability or availability.
Make specific work assignments to software developers and
apply job performance standards.

• Planning a Software Project
• Defining the problem
• Goals and Requirements
1

2
Introduction
Lack of planning : a primary cause of schedule
slippage, cost overruns, poor quality, and high
maintenance
Careful planning : is required for both devlopment
process and
work products
Major purpose of planning : to clarify goals, needs, and
constraints
Preliminary plans will be modified as the workproducts
evolve Planning for change is one of the key aspects of
successful planning

3
Defining the problem
Every man-made entry is first a concept in
someone’s mind.
Computing systems, like other products of
technology, are developed in response to
perceived needs.
Sources of software product ideas include :
• externally generated customer
requirements,
• internal organizational requirements,
• marketing plans, and
• organizational mission plans.

Stepsin Planninga SoftwareProject
4
Defining the problem
1. Developing a definitive statement of the problem to be
solved.
Include a description of the present situation, problem
constraints, and a statement of the goals to be achieved.
2.Justify a computerized solution strategy for the problem.
3. Identify the functions to be provided by, and the
constraints on, the hardware subsystem, the software
subsystem, and the people subsystem.
4. Determine the system-level goals and requirements for
the development process and the work products.
5. Establish high-level acceptance criteria for the system.

5
Developing a solution strategy
6.Outline several solution strategies, without
regard for constraints.
7.Conduct a feasibility study for each strategy.
8.Recommend a solution strategy, indicating why
other strategies were rejected.
9.Develop a list of priorities for product
characteristics.

Planning the developmentprocess
6
10.Define a life-cycle model and an organizational structure for the
project.
11.Plan the configuration management, quality assurance, and
validation activities.
12.Determine phase-dependent tools, techniques, and notations
to be used.
13.Establish preliminary cost estimates for system
development.
14.Establish a preliminary development schedule.
15.Establish preliminary staffing estimates.
16.Develop preliminary estimates of the computing resources
required to operate and maintain the system.
17.Prepare a glossary of terms.
18.Identify sources of information, and refer to them
throughout the project plan.

7 Goals andRequirements
 Given a concise statement of the problem
and an indication of the constraints that
exist for its solution, preliminary goals
and requirements can be performed.
¶ Goals
 Goals are targets for achievement, and
serve to establish the framework for a
software development project.
 Goals apply to both development process
and work
products.

8
Goals can be either:
QUALITATIVE OR QUANTITATIVE
A qualitative process goal
A quantitative process goal
A qualitative product goal
A quantitative product goal

9  A qualitative process goal
o The development process should enhance the
professional skills of quality assurance
personnel.
 A quantitative process goal
o The system should be delivered within 12
months.
 A qualitative product goal
o The system should make user’s job more
interesting.
 A quantitative product goal
o The system should reduce the cost of a
transaction by 25 percent

10
 Some goals apply to every project and every
product.
 For e.g.
• Every project and every product should be useful,
reliable, understandable, and cost-effective.
• Every development process should deliver work
products
on time and within cost estimates.
• Every development process should
provide project personnel with the
opportunity to learn new skills.
 Other goals include : transportability, early delivery
of subset capabilities and ease of use by
nonprogrammers

11
Requirements
 Requirements specify capabilities that a system
must provide in order to solve a problem.
 Requirements include functional requirements,
performance requirements, and requirements
for the hardware, firmware, software, and user
interfaces.
 Requirements may also specify development
standards and
quality assurance standards for both project and
product.

 Requirements should be quantified whenever
possible.
 Quantified requirements such as :
 Phase accuracy shall be within 0.5 degrees,
 Response to external interrupts shall be 0.25
second
maximum,
 System shall reside in 50K bytes of primary
memory, excluding file buffers,
 System shall be fully operational 95 percent of
each 24-
hour period, can be used as the basis for
acceptance testing of the delivered system.

 Qualitative requirements such as :
 Accuracy shall be sufficient to support mission,
 System shall provide real-time response,
 System shall make efficient use of primary memory,
 System shall be 99 percent reliable,
are often meaningless and can result in
misunderstandings
and disagreements between developers and customers.

High-level goals and requirements can often be
expressed in terms of quality attributes
 Glossary of QualityAttributes
 Portability :
 The ease with which software can be transferred from
one computer system to another.
 Reliability :
 The ability of a program to perform a required function
under stated conditions for a stated period of time.

 Efficiency :
 The extent to which software performs its
intended functions with a minimum
consumption of computing resources.
 Accuracy :
 A qualitative assessment of freedom fromerror.
 A quantitative measure of the magnitude of error,
preferably expressed as a function of the relative
error.
 Error :
 A discrepancy between a computed value or
condition and the true, specified, or theoretically
correct value or condition.

 Robustness :
 The extent to which software can combine to
operate correctly despite the introduction of
invalid inputs.
 Correctness :
 The extent to which software is free from design
defects
and from coding defects, that is fault-free.
 The extent to which software meets its
specified requirements.
 The extent to which software meets user
expectations.
 These high-level quality attributes can in turn be
expressed in terms of attributes that can be built into the
work products.

 Plans describe the mechanisms to be used in
achieving goals and requirements.
 For e.g.
 The goal of delivering work products on time can be
expressed in terms of reaching each project milestone
on time.
 A milestone is a significant event in the software product
life-cycle.
 Examples of milestones include completion of
requirements analysis, completion of design,
and integration and successful testing of all
system components.

Software Engineering Practices and Issues.pptx

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Software Engineering Practices and Issues.pptx