Software Development Methodologies
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Time
15 hours 43 minutes
Difficulty
Advanced
CEU/CPE
16
Video Transcription
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>> In the last section,
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we talked about some general approaches
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to creating secure software,
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just some secure design principles.
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Now, we're going to talk
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about the ways that we create the software,
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the methodologies that we follow.
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This exam is never going to
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>> ask you to look at the code,
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>> but it's going to ask you to look at the process,
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so part of that process is the methodology we use.
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We're going to talk about the traditional waterfall.
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We'll also talk about prototyping
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and spiral methodologies,
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and then ultimately getting to agile methodologies,
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which is where a lot of software development programs
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work at this point in time.
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In talking about the waterfall,
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this has been the traditional,
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it's very much a phased approach
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where you have step by step by step,
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we're going to look at these others in just one minute.
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But this is a good example of the Waterfall model,
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so we go from requirements to
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design to implementation, testing, deployment,
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maintenance, but it's step 1,
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then you move to step 2,
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then you move to step 3.
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You notice you don't see any feedback errors,
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you move from one step to the next.
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This is a very formal process that goes through,
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you have a lot of documentation,
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and what's good about it is it's formalized,
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you have processes for changes,
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you have a better control
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over the software because of
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the rigidness of the process.
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But the downside is if you have a very long project,
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by the time you develop the software,
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it's so far removed from
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its requirements that you could
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actually find the requirements have changed.
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Requirement changes can be very difficult in
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a waterfall environment because we
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move forward step by step by step,
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so if we have a change to the scope, for instance,
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we have to go all the way back to
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requirements and then move
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forward from that beginning step.
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It's very rigid. Sometimes rigidity is good if we're
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doing projects that we've managed
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the same way time and time,
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waterfall method works very well for us.
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But many of us who've done software development
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know customer requirements change very frequently,
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so we have to be able to adjust and adapt.
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Prototyping, most folks have heard of prototyping.
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The idea is you make a design,
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you build the product,
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customer gives you information,
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they give you feedback,
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and then you go back to the drawing board,
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and then you produce
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a prototype and the customer evaluates,
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gives you information back to the drawing board until
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we ultimately produce the product
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that the customer wants.
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That's good because I'm working
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closely with the customer.
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We can get feedback fairly early on in the project.
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I don't have to do a lot of work if I'm off base.
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However, many times you want to make changes.
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''Hey, can you make this one little change?"
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This looks great except and they don't always
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understand the ramifications of
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the changes that they're asking for,
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so when we keep going back from
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the customer saying this is good,
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do you want anything different?
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Then all of a sudden they can build on
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their original requirements and start
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asking for things that cause
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a tremendous amount of change in the work.
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I always think of the waterfall is going down steps.
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I think of prototyping as a circular motion.
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If you go step by step by step in a circular motion,
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you have a spiral, and that's exactly what a spiral is.
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A spiral is a combination of
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the waterfall method going step by step by step.
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But it also at each stage of the waterfall,
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at the end of each stage,
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it allows feedback from the customer,
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so you have that combination
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of prototyping and waterfall.
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But you've got the pros of each kind.
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You've also got the cons of each kind.
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You put a lot of effort into risk analysis,
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which is very helpful,
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it helps mitigate the possibility
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of failure to satisfy the customer,
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it lessens the risk of going over
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budget or over schedule.
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But it can be expensive,
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and risk analysis is not easy.
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It takes a lot of expertise in making sure that we have
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a good quantitative understanding of
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the risks associated with the modifications we make,
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that can be tricky to find.
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What most software development projects
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use today is they use agile.
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What agile does is it
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generally takes the work of a project,
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the work of an application to be built,
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and breaks it down into iterations called sprints.
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Ultimately, what we're
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going to do is we're going to take
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functionality and we're going to
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provide that with a team,
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and they're going to go through,
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and the idea is we're going to develop deliverables,
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present them to the customer early and often.
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When the customer comes back and says,
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''Oh, I don't like this piece,
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'' we're going to be able to move out
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individual pieces of the product
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without affecting the whole.
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It's really designed for very quick adaptations,
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hence the name Agile,
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specifically to customer changes.
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Those are just a handful of
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the software development methodologies,
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but they are by far the most common.
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Waterfall has been around for years and years,
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and that's been the de facto standard
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until maybe the last decade.
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We do also have prototyping and spiral,
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but really the real game-changer
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in project management friends has been
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agile because of the fact that it can
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adapt to changes and is so flexible.
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