Talk:Spiral model
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Hmm, is Spiral model synonymous with Agile Methods, or is it an example of an agile method or is it something else entirely? I haven't heard of spiral model in real world programming before. Seems like it's an expressly chosen opposite to waterfall model or so. 80.126.238.189 17:20, 12 Feb 2004 (UTC)
Found it elsewhere in the wikipedia. It influenced the development of Agile Methods. 80.126.238.189 17:35, 12 Feb 2004 (UTC)
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[edit] spiral model example
Can you have sample documents of spiral model software engineering? for example, the information that should be included and how to construct a spiral model methodology?
hope to here from you soon... thank you!
EDIT:
1 - basic info which should be included in "spiral documentation" would include application name, purpose, functionality, architecture/component info, interface/networking considerations (either with other applications and/or customers) etc...but I question the value of having sample documents, as they can and do vary a great deal.
2 - you do not 'constuct a spiral model methodology' as it is a methodology in itself, albeit a high-level one.
[edit] Not just in software
Future Combat Systems also uses spiral development. I'm formatting with that in mind. Are we sure it was first applied in the software field?
- Well, I imagine that you could see NASA's efforts with the Mercury, Gemini, and Apollo programs as a form of spiral development, although it may not have been given that name. Then NASA fell victim to Big Design Up Front with the space shuttle... --Allan McInnes (talk) 17:39, 26 April 2006 (UTC)
[edit] But INTENDED for software
The spiral model recognizes the benefit of rapid prototyping, wherein the "bottom-up" people gain insight at a rapid rate that the "top-down" people can learn from. Thus a cycle of continuously improving the design requirements becomes possible during the design itself. It is thought to allow a more optimal final design, based on the notion that there are no suitable experts that can write the requirements at the start of a design exercise that will lead the team to an optimal design.
This is a critical aspect of invention, where something totally new is being considered. In this situation, specific expertise is limited or unavailable (and therefore disvalued) during the early stages of design (but ye must have faith that expertise is developing). This is known to work well on small scale projects, where all team members are in close contact and work in a flexible manner. Rapid prototyping is after all unencumbered by massive documentation requirements and free of production constraints.
A real concern with the application of the spiral model outside of the software world is one of design efficiency of large scale projects: this may challenge the very business case that makes the project possible. Great leadership is required if the spiral model is to be used with thousands of people writing design and test requirements simultaneously with thousands of others optimizing the design and planning design upgrades before new requirements are captured. Chaos can result, leading to a gap between a few great prototypes and high quality production parts.
Consider two examples. NASA's JPL was tasked to land on Mars and drive a vehicle around. At the program initiation, there were no experts as this was never accomplished before. A few years and many dollars were invested, and a few highly optimized vehicles landed and roved the surface of Mars. Each vehicle had differing malfunctions, but the fact remains that the mission overall was accomplished and stands as a great scientific achievement. The spiral model might have been very successfully employed here, where one might expect that optimization of the design was one of the most important aspects to the success of the program.
In another example, let's say GM is tasked with developing a new mini-van. The task is to build the best design achievable but also reach mass production (which requires long term planning for substantial tooling, quality and safety testing, and a business plan for costs risks and returns). The success of the program will be judged on the execution of the business case, where costs must be controlled carefully: these costs are heavily dependant upon avoiding schedule delays, avoiding quality problems, avoiding tooling errors, avoiding safety compliance shortcomings, and meeting the needs and desires of sufficient customers who can choose not to buy the mini-van at all. The spiral model is a risk here. While a good design is needed, the optimal design is less important than a brilliant execution of top down design to achieve a high quality production product on time and within budget (especially if designing something substantially more complicated than a mini-van).
If there was a linear scale, with invention or experimentation on one end (like the Mars project) and with mass production programs which expect world class quality of its products (like a new GM mini-van) at the other end, then we might be able to appreciate the applicability of the spiral model outside of the software world: its suitability depends upon the intended project goals. An experiment in state of the art (research?) projects may benefit from a spiral process that favors a more optimal final design rather than a cost-effective design process. A production project on the other hand cannot trade off the cost-effective process for a more optimized design: when the design is close, it is close enough. It may be more important to keep the thousands of people working in unison on clear requirements that freeze in time for tooling and specification writing and prototype testing to complete itself exactly when needed. To delay the program at any time may very well be as to cancel the program.
To consider the spiral model, you must intimately know just how serious you are about going to production, be you a scientist or a businessman. Mbbradford 06:39, 8 November 2006 (UTC)
[edit] Peer review requested for waterfall model.
Hi, I've just requested peer review for waterfall model. I'd really appreciate if some people could review the changes I've made. Thanks. :) GeorgeBills 15:03, 17 November 2005 (UTC)
[edit] "This persisted until the year 2000?"
In the second paragraph, last sentence, what persisted until the year 2000? A 6 to 2 year iteration cycle, and all iterations stopped then? Did a shorter or longer iteration cycle become accepted as a new standard? If someone can clarify, it would be an improvement (I would clarify, except I have no idea what the sentence means.) Chris van Hasselt 20:01, 12 January 2006 (UTC)
- I don't know what was supposed to be meant by this phrase, and I came in here to post just such a question. Since over four months have passed since the above question was asked, I removed the offending sentance. If anyone wants to restore it, please indicate what "this" refers to. Keithmahoney 20:49, 27 May 2006 (UTC)
[edit] clean up
I just did a lot of clean up to the physical appearance of this article, and it looked as though someone copied and pasted all the information from another pre-formatted location (aka plagiarism). Anyone know where the info might have come from?--Jude 04:05, 31 January 2007 (UTC)
- http://scitec.uwichill.edu.bb/cmp/online/cs22l/spiralmodel.htm The copyrighted content should be removed immediately. 71.240.184.133 18:14, 31 January 2007 (UTC)
- Thanks for finding the source! I removed everything that was added to the article by whomever.--Jude 10:28, 2 February 2007 (UTC)
