Approaches to System Development
The System Development Cycle
• The system development cycle (SDLC) is a fundamental concept in the success
of information system development projects
• A predictive approach to the SDLC assumes that the development project can
be planned and organized and that the new information system can be
developed according to the plan
• An adaptive approach to the SDLC is used when the systems requirements
and/or the users needs aren’t well understood. In this situation, project can’t be
planned completely. Some system requirements may need to be determined
after preliminary development work
• Predictive approaches were more traditional around 1970s to 1990s
• Adaptive approaches were evolved with the object-orientated technology and
web development which were created around the late 1990s
Traditional Predective Approaches to the SDLC
• In predicitive approaches, there is a group of activites that identifies the
problem and secures approval to develop a new system, this is called project
• A second group of activites, called project planning, involves planning,
organizing, and scheduling the project. These activites map out the project’s
• A third group, analysis, focuses on discovering and understanding the details
of the problem or need. The intent here is to figure out exactly what the system
must do to support the business process.
• A fourth group, design, focuses on configuring and structuring the new system
• A fifth group, implementation, includes programming and testing the system.
• A sixth group-deployment-involves installing and putting the system into
operation • These six groups of activites are sometimes reffered to phases of the system,
and they provide framework for managing the project.
• Another phase called the support phase, includes the activites needed to
upgrade and maintain the system after it has been deployed.
• The most predictive SDLC approach is called the waterfall model, with phases
of the project flowing down, one after another.
• Look at figure 8.3 page 229
• First, a detailed plan is developed, then the requirements and thoroughly
specified, then the system is designed down to the last algorithim, and then it is
programmed, tested and installed
Newer Adaptive Approaches to the SDLC
• In an adaptive approach, project activites- including plans and models are
adjusted as the project progresses
• There’re many ways to depict an adaptive SDLC, all include iterations.
• Rather than having the analysis, design and implementation phases
proceed sequentially with some overlap, instead iterations can be used to
create a series of mini-projects that address smaller parts of the
• One of the these smaller parts is analyzed, designed, built, tested during a
single iteration, then based on the results, the next iteration proceeds to
analyze, design, build, and test the next smaller part.
• Look at fig 8.6 and 8.7 pg 231
• The columns are the multiple iterations of the project
• The difference between the waterfall approach and iterative approach is
waterfall approach attempts to do all planning, all analysis, all design and
• Our iterative approach is adaptive because with each iteration analysis
design, and implementation, modifications can be made to adapt to the
changing requirements of the project. • A related concept to an iterative SDLC is called incremental development,
which is always based on a iterative life cycle. The basic idea is that the
system is built in small increments.
• An increment maybe developed within a single iteration or may require to
or three iterations.
• Another concept related on an iterative approach is a walking skeleton.
• A walking skeleton provides a complete front-to-back implementation of
the new system but with only bare bone functionality.
• The walking skeleton is developed in a few iterations early in the project.
• Later iterations then flesh out the skeleton with more functions and
The Support Phase
• The objective of the support activites is to keep the system running productively
during the years following its initial deployment.
• They begin only after the new system has been installed and put into production,
and they last throughout the productive life of the system
• During the support phase, uprgrades and enhancements maybe carried out to
expand the system’s capabilities, and these will require their own development
• Three major activites occur during support : maintaining the system, enhancing
the system, supporting the users.
• Upgrades maybe requested by major modifications that are required, may often
result in a new version of the system.
• A help desk, consisting of knowledgable technicians, is a popular method for
answering users’ questions quickly and helping increase their productivity.
Methodolgies, Models, Tools and Techniques
Methodolgies • A system development methodology provides guidelines for every facet of
the SDLC which contains models, tools and techniques
• Each project team will use a set of tools – usually computer based tools-
to build models, record information, and write the code
• The techniques, models and tools support one another to pro