SOFTWARE DEVELOPMENT LIFE CYCLE
Software Elements Analysis: The most important task in
creating a software product is extracting the
requirements. Customers typically know what they want,
but not what software should do, while incomplete, ambiguous
or contradictory requirements are recognized by skilled and
experienced software engineers. Frequently demonstrating
live code may help reduce the risk that the requirements are
Requirements (Requirements Specification): There is the task of precisely
describing the software to be written, possibly in a
rigorous way. In practice, most successful requirements
are written to understand and fine-tune applications that
were already well-developed, although safety-critical
software systems are often carefully specified prior to
application development. Requirements are most
important for external interfaces that must remain stable.
Software architecture: The architecture of a software
system refers to an abstract representation of that system.
Architecture is concerned with making sure the software
system will meet the requirements of the product, as well as
ensuring that future requirements can be addressed. The
architecture step also addresses interfaces between the
software system and other software products, as well as the
underlying hardware or the host operating system.
Implementation (or coding): Reducing a design to code
may be the most obvious part of the software engineering
job, but it is not necessarily the largest portion.
Testing: Testing of parts of software, especially where
code by two different engineers must work together, falls to
the software engineer.
Documentation: An important (and often overlooked) task
is documenting the internal design of software for the
purpose of future maintenance and enhancement.
Documentation is most important for external interfaces.
- Software Training and Support: A large percentage of
software projects fail because the developers fail to
realize that it doesn't matter how much time and planning a
development team puts into creating software if nobody in an
organization ends up using it. People are occasionally
resistant to change and avoid venturing into an unfamiliar
area, so as a part of the deployment phase, its very
important to have training classes for the most enthusiastic
software users (build excitement and confidence), shifting
the training towards the neutral users intermixed with the
avid supporters, and finally incorporate the rest of the
organization into adopting the new software. Users will have
lots of questions and software problems which leads to the
next phase of software.
Maintenance: Maintaining and enhancing software to cope
with newly discovered problems or new requirements can take
far more time than the initial development of the software.
Not only may it be necessary to add code that does not fit
the original design but just determining how software works
at some point after it is completed may require significant
effort by a software engineer. About ⅔ of all software
engineering work is maintenance, but this statistic can be
misleading. A small part of that is fixing bugs. Most
maintenance is extending systems to do new things, which in
many ways can be considered new work. In comparison, about ⅔
of all civil engineering, architecture, and construction
work is maintenance in a similar way.