Comparison of Waterfall vs Life Cycle in Software Development Methods

[RosieA]

Can anyone provide comparison of the waterfall method of software development vs the Life Cycle method?

Pros and Cons?

RosieA said:

Can anyone provide comparison of the waterfall method of software development vs the Life Cycle method?

Pros and Cons?

Rosie -- that’s a big (and very interesting) question – this is just a quick starter answer.

The Waterfall is just one method of organising a software development life cycle – see a basic overview of approaches here: http://www.augustana.ab.ca /~mohrj/courses/2000.winter/csc220/presentations/ch12lect/

Two ISO standards apply:

ISO/IEC 12207 Software Lifecycle Processes --
overview at http://www.stsc.hill.af.mil/crosstal.../08/isoiec.asp

ISO 9000-3 (application of ISO9000:2000 to software)

I hope that helps a little!!!

[RosieA]

The first site, in particular...I appreciate the direction.

I have ordered ISO 12207 and the Tickit Guide, but plainly written overviews with positives and negatives really help a lot.

Rosie

[RosieA]

I have received a copy of ISO 12207 on Life Cycle Processes, and have a semantic question.

In section 5.3.1.1 the standard states that the developer shall define or select an appropriate software life cycle model

Under definitions, a life cycle model is defined as a framework containing processes, activities, and tasks involved in the development, operation and maintenance of a software product.

Then there's a graphic in section 4 showing Primary Life Cycle Processes. Are these primary processes what they're talking about selecting? I'm confused by the terminology...is a process the same as a model?

It seems to me that I'd choose the Development Process as my model...is that correct?

Sorry to be thick...reading standards can be confusing.
Thanks,
Rosie

[Godfrey Partridge]

When aquiring software you need to consider the steps or milestones involved in the process. A simple process would be
"enter shop, see boxed software, purchase, install, operate

a More complicated process would be

Specify aplication, develope purchase/aquisition specification, develop contract enquiry, selection of vendors, place contract, commence development high level design, modul design, software item design program assembly, test prescription, installation, test commission, delivery support, maintenance and operation.

Someware between the two an option suitable for a given aplication exists and it is required of the purchaser to determin what items should make up the process when initialy developing a software aquisition project.

This is what ISO12207 and Tickit are driving at when they call for selection of life cycle.

Hope this helps.

Enjoy

Godfrey

[mdumont]

I usually make the following difference between a process and a lifecycle, based on the state/transition diagram and Object Oriented technoogy.

A process is a suite of interrelated activities that create or transform a "product". A product may be a request document, a written document, a mechanichal part, a software, and so on.

The life cycle describes the successive states of the product as it is transformed by one or several successive processes, from an initial to a finished state.

In the software industry, the "software development process" transform a set of requirements into an executable application. Just identify the software as a product and transform it from its initial state "requirements" into a finished state "application". You have intermediate state like "designed", "coded", "tested",...

If you represent that in a diagram, with boxes and arrows linking the boxes, the process diagram represents activities in the boxes and the product in specific states in arrows. The lifecycle diagram repersents product states in boxes and transformation activities in arrows.

In the software methodology litterature unfortunately, when you see a "waterfall lifecycle", it's generally the description of a process, not a life cycle. (at least in my opinion).

To answer your question on the term "model", it is the description of a generic "process" or "lifecycle" that is customized to represent your particular needs. You plan your activities with one model or the other but you keep the model in mind.

Does it help?