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== Does or did the waterfall model ever even exist? ==
==todo==
I still think it would be good to have a remark in the beginning that the waterfall model is the methodology which was used in softwre development before there was much debate on different methodologies. That is why I inserted a small remark some weeks ago ("It was the first and only wide spread software development process in the 1970ies before Agile software development came in the 2000 decade."). This insertion was reverted by WalterGörlitz, so the gap is open again, I think.


While the term "waterfall" certainly exists, none of the references on the page support that it was ever an actual project management approach. It seems to be nothing more than a pejorative term. A sort of bucket into which all bad project management approaches can be put. Is there any evidence that the "waterfall model" ever existed? [[User:Twasonasummersmorn|Twasonasummersmorn]] ([[User talk:Twasonasummersmorn|talk]]) 18:27, 6 March 2021 (UTC)
I have looked up what was our "Bible of software methodology" at that time:
Schnupp, Peter / Christiane Floyd: Software. Programmentwicklung und Projektorganisation.
Publishing company: Berlin de Gruyter, (1976), ISBN 10: 3110059533 ISBN 13: 9783110059533.


:Yes, it absolutely existed. I first started doing software development in the 1980's at Accenture (then Andersen Consulting). The SDLC we were all taught at the time was called Method/1 and it was a classic waterfall model. Ironically, I did a lot of research work for the DoD and we had to use the same methodology for research as all other DoD software developers did. I think it was called Mil Standard 2167a. In any case it was absolutely a waterfall model. In both cases we always filled out the required forms and made the required project plans and then essentially ignored them. One of my bosses had a great name for them: "Write Only Documentation" which was what they were. We did things using what is now called Agile because we just knew that was the better way to do it. [[User:MadScientistX11|MadScientistX11]] ([[User talk:MadScientistX11|talk]]) 19:46, 26 April 2023 (UTC)
Basically, you see the phases of the waterfall model there, but not the name "waterfall model". There was no need for a name of the methodology, as it was the only one, besides "naive development"; in much the same way as a steam locomotive was simply called a locomotive before electric or diesel locomotive existed. ([[User:MatEngel|MatEngel]] ([[User talk:MatEngel|talk]]) 15:57, 20 October 2014 (UTC))


Having looked more deeply at the references on this page, they're dreadful. Royce (the reference on which the whole article almost depends) does not say what he's supposed to have said in the referenced paper and the rest of the references are full of "some say". If no-one has better references I'm going to do a pretty tight cropping of the whole article. [[User:Twasonasummersmorn|Twasonasummersmorn]] ([[User talk:Twasonasummersmorn|talk]]) 20:41, 15 March 2021 (UTC)
== Peer review ==
{{Old peer review|archive=1}}


Still no satisfactory references on here. The article seems to be based on misquoting a few articles - generally from very long ago - and then claiming (without reference) that the "waterfall" approach so demonized in previous years as a counterpoint to Agile, existed. [[User:Twasonasummersmorn|Twasonasummersmorn]] ([[User talk:Twasonasummersmorn|talk]]) 15:34, 26 March 2021 (UTC)
Just added a lot of material, I'd like to make sure that it's all correct... [[User:GeorgeBills|GeorgeBills]] 14:57, 17 November 2005 (UTC)
: Perhaps it's the question that is lacking. The "model" adjective is shorthand and synonymous with approach. Feel free to correct the term or make adjustments, but the tags of shame you've place are childish. [[User:Walter Görlitz|Walter Görlitz]] ([[User talk:Walter Görlitz|talk]]) 15:55, 26 March 2021 (UTC)


This definately exists, it's a recommended product development process by the FDA in https://www.fda.gov/media/116573/download linked from https://www.fda.gov/regulatory-information/search-fda-guidance-documents/design-control-guidance-medical-device-manufacturers. [[User:Poisonadder1|Poisonadder1]] ([[User talk:Poisonadder1|talk]]) 09:21, 2 June 2021 (UTC)
* I briefly scanned the article, and (IMHO) it's technically correct. I may tweak some stuff if I get some time, but the general sense of the article looks right. [[User:Jim Huggins|Jim Huggins]] 22:39, 18 November 2005 (UTC)


That paper mentions waterfall, but doesn't recommend it. Nor does it give any reason to believe they're not just talking about something everyone seems to have heard of but perhaps never actually existed. [[User:Twasonasummersmorn|Twasonasummersmorn]] ([[User talk:Twasonasummersmorn|talk]]) 21:12, 9 October 2021 (UTC)
I wonder if a link to Tarmo's blog counts as vanity link... Tarmo is a journalist for the biggest computers related magazine in Finland, but still... :/ I'm not very familiar with Wiki customs. --''sigmundur'' <small>—The preceding [[Wikipedia:Sign your posts on talk pages|unsigned]] comment was added by [[User:194.86.94.11 |194.86.94.11 ]] ([[User talk:194.86.94.11 |talk]] • [[Special:Contributions/194.86.94.11 |contribs]]) 26 June 2006.</small>


Seriously - this whole article is cantering around almost without any decent references. Should the whole page be just blanked out until some can be found? The ones I've found would indicate that the term is largely a bogey man term and that the method never actually existed. But I'm not sure they prove the negative either. [[User:Twasonasummersmorn|Twasonasummersmorn]] ([[User talk:Twasonasummersmorn|talk]]) 23:35, 2 January 2023 (UTC)
* Blogs by notable authorities are generally acceptable, at least in the absence of a better citation. - [[User:Jmabel|Jmabel]] | [[User talk:Jmabel|Talk]] 17:51, 3 July 2006 (UTC)


:Agreeed - Waterfall was only a software industry thing. Everyine who was an engineering the 1980's knows this.
==Image==
:And nobody outside of Software industry has ever heard the word "Waterfall" untiil somebody tried to sell them Agil.
:Again we have the critical flaw in Wikipedia. How do you prove something didn't exit? THere's no references for things that didn't happen. Waterfall outside of Siftware never happened. People can post that it's a thing and it stays in. you post that it never happened with referenecs. And it gets taken out.
:Wikipedia admins are not checking references in edits [[Special:Contributions/2601:286:C200:1E90:447B:B3AC:AEDD:EDD1|2601:286:C200:1E90:447B:B3AC:AEDD:EDD1]] ([[User talk:2601:286:C200:1E90:447B:B3AC:AEDD:EDD1|talk]]) 22:54, 14 December 2023 (UTC)


== the article fails to explain most fundamental thing ==
I can't draw at all, it would be nice if someone could whip up the coloured boxes in a slightly nicer form and replace Image:Waterfall_model.jpg. [[User:GeorgeBills|GeorgeBills]] 04:57, 18 November 2005 (UTC)


[[File:GanttProject_2.8.5.png|thumb|waterfall on a timeline, as seen in project management application]]
* In the meantime, "maintenance" is mis-spelled ... :) [[User:Jim Huggins|Jim Huggins]] 22:33, 18 November 2005 (UTC)
the waterfall model exists on a timeline, it's not some random bunch of boxes in a drawing. i couldn't figure this out when i was first reading the article, thus, the article is quite worthless, because it fails to actually inform the reader of what the waterfall model actually means. this article doesn't look like it was written for encyclopedia. [[Special:Contributions/5.184.25.166|5.184.25.166]] ([[User talk:5.184.25.166|talk]]) 13:23, 17 October 2021 (UTC)


== Waterfall project management ==
I created a replacement diagram: Image:Waterfall_model.png. I'll leave the 'reqimage' tag above for now, in case someone thinks this article needs more diagrams. [[User:PaulHoadley|PaulHoadley]] 03:29, 25 November 2005 (UTC)


Waterfall model help to restraint required analysis and definitions on system and software development by implementing the specific units of testing and execution of operations and maintenance as itself shows to be cumbersome and liable to cause application delivery lag. [[Special:Contributions/2405:201:C00F:60AF:251B:472B:6159:E14A|2405:201:C00F:60AF:251B:472B:6159:E14A]] ([[User talk:2405:201:C00F:60AF:251B:472B:6159:E14A|talk]]) 18:21, 19 December 2022 (UTC)
:Nobody seems to have thought so in almost the last year, so looks like it's all good. -[[User:Stellmach|Stellmach]] 17:49, 12 October 2006 (UTC)


== The waterfall model ==
The image ( http://upload.wikimedia.org/wikipedia/commons/e/e2/Waterfall_model.svg )currently show the phases overlapping. This should probably be changed so the are aligned at the ends of each box or so they have a bit of space between each to. This would make it clear that the phases do not overlap in the unmodified waterfall model. [[Special:Contributions/62.107.105.61|62.107.105.61]] ([[User talk:62.107.105.61|talk]]) 19:54, 21 February 2014 (UTC)
: That image is in wikicommons, [[:commons:File:Waterfall model.svg]]. There are two earlier versions there. Feel free to change it. [[User:Walter Görlitz|Walter Görlitz]] ([[User talk:Walter Görlitz|talk]]) 20:05, 21 February 2014 (UTC)


Waterfall Model Description
==Previous discussion...==


''In practice, the process rarely proceeds in a purely linear fashion. Iterations, by going back to or adapting results of the precedent stage, are common.''
The waterfall model


The waterfall model is a software development methodology that follows a linear, sequential approach. It is named after the way in which tasks flow, like a waterfall, from one phase to the next in a predetermined order. The waterfall model is also sometimes referred to as the "linear-sequential" model.
Would it be correct to state that this actually mutates the waterfall model into a [[spiral model]]? (and hence, waterfall method is *almost never* used in its "pure state"? ) [[User:80.126.238.189|80.126.238.189]] 13:13, 15 Feb 2004 (UTC)


In the waterfall model, the development process is divided into distinct phases, each of which must be completed before moving on to the next. The phases of the waterfall model are:
* In my opinion ... almost, but not quite. In the waterfall model, the end of each iteration is (supposedly) a fully-functional, deployable, saleable product. In the spiral model, the end of each iteration (except the last) is never intended to be fully-functional; it merely finishes the goals laid out for that particular iteration. [[User:Jim Huggins|Jim Huggins]] 04:40, 3 Apr 2005 (UTC)


1.Requirements gathering and analysis: In this phase, the project requirements are gathered and documented.
== POV check ==


2. Design: In this phase, the system is designed based on the requirements gathered in the previous phase.
This article seems to focusses on the disadvantages of the model, rather than explaining just what the model is. --[[User:Huwr|huwr]] 01:28, 8 October 2005 (UTC)


3.Implementation: In this phase, the code is written based on the design created in the previous phase.
:It is recognized that the model does not work in reality and indeed it wasn't even proposed by Royce which as the article explains advocated iterative development. It has never been anything more than a straw man model. The only people who advocate anything like it are [[Dilbert]]'s pointy haired boss and his real life counterparts. If the article simply presents the model without explaining the well known problems with it which are historically the very motivation for developing more workable approaches, this would be a violation of neutrality. I can't see why anyone would want to leave out the facts unless they are embarrassed by the fact that they themselves have been using a waterfall approach without knowing better. [[User:Kuratowski's Ghost|Kuratowski's Ghost]] 11:41, 18 October 2005 (UTC)


4.Testing: In this phase, the system is tested to ensure it meets the requirements and functions correctly.
:It might be nice to add some of the reasons why people think that BDUF and the waterfall model work "in theory" and then point out why they don't in practice. Maybe with some references to publications supporting this; would Parnas' "a rational design process (and how to fake it)" be suitable? There's no way a page on this could omit to mention that the waterfall model is widely regarded as fatally flawed though. :S [[User:GeorgeBills|GeorgeBills]] 03:58, 17 November 2005 (UTC)


5.Deployment: In this phase, the system is deployed and made available for use.
:I've added a lot of stuff to try and get in a better explanation of what waterfall actually is and explain the thinking behind it (and to try and clarify the objections raised against it for people who haven't heard this all before). Can someone please check over what I've written? Thanks. [[User:GeorgeBills|GeorgeBills]] 04:43, 17 November 2005 (UTC)


6.Maintenance: In this phase, the system is maintained and any necessary updates or changes are made.
:OK, I've just added a fair bit of work on what the waterfall method actually is, and arguments for it, including a supporting quote for BDUF from someone who gets a fair bit of respect in software circles (as far as I can see). I feel that both views on the waterfall models usefulness are now included, and that neither argument can be removed in the interests of NPoV. Maybe some clarification of points. As per [[Wikipedia:POV_check]] ("may be removed by anyone if they feel that the issue has been resolved") I'm going to delete the "PoV check" template. Feel free to argue here or replace it with a "NPoV" template if you feel that this was bad. [[User:GeorgeBills|GeorgeBills]] 12:58, 17 November 2005 (UTC)


The waterfall model is a linear approach to software development and is well-suited to projects with well-defined requirements and a clear understanding of the problem to be solved. However, it can be inflexible and may not be the best choice for projects with rapidly changing or complex requirements [[Special:Contributions/106.78.85.100|106.78.85.100]] ([[User talk:106.78.85.100|talk]]) 11:25, 27 December 2022 (UTC)
== NPOV violation - add pros ==


:Ehm...where's that from? [[User:Twasonasummersmorn|Twasonasummersmorn]] ([[User talk:Twasonasummersmorn|talk]]) 23:27, 2 January 2023 (UTC)
this article should first simply present what the methodology is.
The negative aspects of this model should be listed but balanced with the positive, even if the positives are from circa 1970 and the negatives circa 1990.
What it "is" should be the bulk of the article, the negative and positive should be a foot note.


== The waterfall ==
:That would make sense if it was a real methodology that was actually advocated by methodologists, but it isn't. "Waterfall" has always been used as a straw man example of how not to do software development, even Royce who coined the term never proposed such a methodology he proposed iterative development. It only occurs in practice by accident in companies that know little about formal methodologies in general but which try to institute formal processes and they typically don't know the term "Waterfall" or that their processes are doomed (although they quickly discover it). [[User:Kuratowski's Ghost|Kuratowski's Ghost]] 21:56, 28 October 2005 (UTC)


The waterfall model is a breakdown of project activities into linear sequential phases, meaning they are passed down onto each other, where each phase depends on the deliverables of the previous one and corresponds to a specialization of tasks.[1] The approach is typical for certain areas of engineering design. In software development,[1] it tends to be among the less iterative and flexible approaches, as progress flows in largely one direction ("downwards" like a waterfall) through the phases of conception, initiation, analysis, design, construction, testing, deployment and maintenance.[2][better source needed] The waterfall model is the earliest SDLC approach that was used in software development.[citation needed]
::Unfortunately you are wrong, the "waterfall model" in the common use of the term (i.e. not the originally intended use) has only recently been recognized as being completely unsuitable for actual software development. In fact, it has been intentionally used, and is currently intentionally used. I've personally worked on projects that utilze it (one project in college and one project for with the government). Agile, iterative software development methodologies are having a difficult time gaining foothold because everyone "knows" that software should be designed once, then implemented. Entire university textbooks are written every year citing the waterfall (and similar methods of linear, monolithic, inflexible design methods) as being a "classic" methodology, and teach it in its misrepresented form. The fact of the matter is: the Waterfall Methodology as it is commonly perceived against the original intentions of W. W. Royce, is a *real* software engineering methodology, with a lot of history.


The waterfall development model originated in the manufacturing and construction industries,[citation needed] where the highly structured physical environments meant that design changes became prohibitively expensive much sooner in the development process.[citation needed] When first adopted for software development, there were no recognized alternatives for knowledge-based creative work.[3][better source needed] [[Special:Contributions/103.255.145.74|103.255.145.74]] ([[User talk:103.255.145.74|talk]]) 14:15, 8 January 2023 (UTC)
:::I don't know if you call 1989 "recently", but here is a refernce to a paper whose authors deeply believe that the Waterfall model of software development does not work: Floyd, C., Reisin, F.-M., Schmidt, G., STEPS to Software Development with Users., In: C. Ghezzi, J.A. McDermid (Eds.). ESEC '89, Lecture Notes in Computer Science no. 387. Berlin, Heidelberg: Springer, 1989. 48–64. -- Nevertheless, I do fear that many people still believe that the Waterfall model is the ideal model for software development that one should strive for. <small>—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/85.177.207.189|85.177.207.189]] ([[User talk:85.177.207.189|talk]]) 16:40, 14 February 2008 (UTC)</small><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->


== Removing Sentences on RUP ==
::: I don't think college examples count; my university did the same thing, but that's not 'real usage' (by industry). But I'd be interested if anyone has any concrete evidence of experienced developers with a history of successful projects behind them actually choosing waterfall, or alternately projects that consciously chose waterfall and succeeded. Caveat: teams of at least 5 developers, more developers better, with project lengths of at least six months, more duration better. If someone has no clue how to do it, and says "oh, I'm doing the pinkrainbows methodology", that doesn't mean the pinkrainbows methodology page should talk about the postives balanced with the negatives. Articles about dysfunctions should talk about the dysfunction at a meta-level, about their role in society and why they exist. If, on the other hand, waterfall actually works for some significantly-difficult projects, then maybe there are some positives which could be discussed. --[[User:JHolman|jholman]] ([[User talk:JHolman|talk]]) 19:19, 9 November 2010 (UTC)


At the end of the Criticism section it says: "[[Rational Unified Process]] (RUP) phases acknowledge the programmatic need for milestones, for keeping a project on track, but encourage iterations (especially within Disciplines) within the Phases. RUP Phases are often referred to as waterfall-like" There is a citation needed next to this but I've used and read about RUP a lot and I have never heard it "referred to as waterfall-like". What the RUP books say is that you can use it in different ways. I.e., you can use it in an iterative manner (which is how it is mostly intended to be used) or you can use it in a waterfall manner. But that is not at all the same as saying the methodology is "Waterfall-like". I'm going to be bold and just delete that part. [[User:MadScientistX11|MadScientistX11]] ([[User talk:MadScientistX11|talk]]) 19:52, 26 April 2023 (UTC)
== Still too POV ==


== Another Questionable Claim in Criticism Section ==
As an Extreme Programming practitioner and coach, I personally believe that the waterfall model is generally unworkable. However, quite a lot of people don't, and I don't think the article reflects that. For example, the phrase, "The waterfall model however is widely believed to be a bad idea in actual practice" seems overly strong to me. Ditto value-laden terms like "inflexible". The organization and writing are very good, though! --[[User:William Pietri|William Pietri]] 15:58, 17 November 2005 (UTC)


The ending of the Criticism section currently says: "While advocates of [[agile software development]] argue the waterfall model is an ineffective process for developing software, some sceptics suggest that the waterfall model is a false argument used purely to market ''alternative'' development methodologies" There are plenty of valid criticisms of Agile but the idea that Agile is just a marketing ploy is one I've never heard anyone seriously make. I went to check that reference and it goes to a dead link. Given that there is no actual source information anyway (there is an author but nothing like the name of the source cite, it looks like just a URL to the site: http://get.syr.edu/ which is no longer a site at all). The link is archived to Wayback but still goes to a dead link. Given that this looks to me like it isn't a valid source even if we could find it in the bowels of the web and that this is not what in my experience constitutes a serious argument (anymore than I would consider the same argument applied to Waterfall to be a serious argument) I'm going to delete that claim. [[User:MadScientistX11|MadScientistX11]] ([[User talk:MadScientistX11|talk]]) 01:32, 2 May 2023 (UTC)
:OK, made some changes but it might need more. I changed "The waterfall model however is widely believed to be a bad idea in actual practice" to "The waterfall model however is believed by many to be a bad idea in practice, mainly because of the belief that it is impossible to get one phase of a software products lifecycle "perfected" before moving on to the next phase (or at least, the belief that this is impossible for any non-trivial program)". Now it doesn't imply that ''everyone'' dislikes the waterfall model, just that ''many'' people believe that it isn't the best model available. I've added some counter-arguments to some of the criticisms of the waterfall model, and I've tried to make it more clear that many of the arguments for and against the waterfall model presented here are opinions. Thanks heaps for the help, it seems that it's hard to spot PoV when you don't realise that you're biased. :S Feel entirely free to jump in and correct me if I'm still not being NPoV enough. :D [[User:GeorgeBills|GeorgeBills]] 04:14, 18 November 2005 (UTC)


== Waterfall was limited to the Software industry ==
== User "72.244.140.113" ==


Having lived in engineering and consulting industry for 47 years. Waterfall is a software industry only term. Nobody outside of the software industry ever used it in the 20th century. It's only used to describe "everything note agile is waterfall". Which is obviously not true. [[Special:Contributions/2601:286:C200:1E90:447B:B3AC:AEDD:EDD1|2601:286:C200:1E90:447B:B3AC:AEDD:EDD1]] ([[User talk:2601:286:C200:1E90:447B:B3AC:AEDD:EDD1|talk]]) 22:15, 14 December 2023 (UTC)
Hi to "72.244.140.113".


:The article must be based on sources, you cannot make additions based on your personal opinions. That is called 'original research' here and is prohibited by a core policy, which you can read at [[WP:OR]]. Wikipedia's not a place for ediorializing. [[User:MrOllie|MrOllie]] ([[User talk:MrOllie|talk]]) 00:17, 15 December 2023 (UTC)
You've just deleted a large chunk of text which could have remained in the article - I would kind of prefer it if you could have just moved it in order to remove the implication that Joel uses the waterfall model (edit summary was "It is extremely misleading to describe Joel Spolsky as a "user of the waterfall model.") For now I'll re-include the text somewhere other than under the heading "users of the waterfall model".

I also note for future reference that your only edits concern Joel Spolsky and projects managed and worked upon by Joel Spolsky. I'd like to ask that PoV be kept out of this, and the text be allowed to stay.

He has argued in favour of Big Design Up Front (see the quote you deleted...), and Big Design Up Front is what many people think is wrong with the waterfall model. :S Is there any way you would like this to be phrased? I'd like the quote to stay, because it's one of the few arguments in favour of Big Design Up Front, and this article needs them for NPoV. Thanks. [[User:GeorgeBills|GeorgeBills]] 15:48, 18 November 2005 (UTC)

OK, I've moved that text, added a new reference, and added some clarification to remove the mistaken implication (my bad) that Spolsky is a user of the waterfall model. [[User:GeorgeBills|GeorgeBills]] 16:05, 18 November 2005 (UTC)

== Peer review, redux ==

I started out thinking I would do a copy edit, but the issues are bigger, so I'll just comment.

# Wikipedia itself is a poorly chosen example of what is being specified and built. It's not quite a violation of "no self-references", but it is still going to be very unfriendly to anyone who wants to reuse the content. At the very least, this should be "an online encyclopedia". More likely, we should pick another example entirely.
# Most of the criticisms are uncited.
# If we are going to use phrases like "&hellip;followed perfectly in order&hellip;" (is that yours or Royce's?), we should make it clear that this is a "[[straw man]]" model.
# While the spiral model is, indeed, an alternative, probably more relevant are the models that Steve McConnell (''Rapid Development: Taming Wild Software Schedules'', Microsoft Press, 1996, ISBN 1-55615-900-5) calls "modified waterfalls" (see especially p.143-147): Peter DeGrace's "sashimi model" (waterfall with overlapping phases), waterfall with subprojects, and (my own personal favorite) waterfall with risk reduction (living in the Pacific Northwest, I like to think of it as letting salmon jump up the waterfall and carry information: the volume of salmon will never be nearly as much as the volume of water, but, hey, information doesn't weigh much).

If you want to see my own writing on the topic (from a few years back), see [http://www.lux-seattle.com/about/whitepapers/waterfall.asp], a whitepaper for a company I was helping through a transition on the tech side. -- [[User:Jmabel|Jmabel]] | [[User talk:Jmabel|Talk]] 20:09, 19 November 2005 (UTC)

:OK, those are good points, thanks for the review. :)
:I was thinking that to fix them:
:#Change the Wikipedia example to an example based on another well known software program; in order for the "requirements explanation example" to work it needs to be something that most people recognize as having multiple components that seperate teams work on - maybe if we said the "Microsoft Office" project, with the "Word" and "Excel" teams needing to integrate their components? This might not be the right thing though, as Word and Excel could still work as seperate components. This example might not indicate how difficult it is to integrate example component pieces. :S What was that "baggage handling" program that had large integration problems? I seem to remember it being touted as an example of bad project management around three months ago...
:#Find citations - I think Parnas covers most of them, and Code Complete and some Agile / XP bibles might cover the others. I guess the counter-arguments need citing too, and they might be hard to find reputable references for given the academic stigma of arguing for the waterfall model. :S
:# Make this more clear, got it. Something like "in the so called "pure" waterfall model (Royces first example) people do this...however, there are various "modified" waterfall models (including Royces final model) that may include slight or major variations (see the modifed waterfall models section below)"
:# A modified waterfall models section, incorporating all of your examples. Some help here would be great, because you seem to be pretty well read on the topic. It probably has to come after the "criticisms" section because it might need to refer to it - as an example, we might need to write "the sashimi model handles criticisms x, y and z by blah blah blah". Unfortunately, if it comes after the criticism section people might think that we're biasing people against the modified models by dumping all of these criticisms on them before we cover models that the criticism may not apply to. :S
:[[User:GeorgeBills|GeorgeBills]] 12:35, 20 November 2005 (UTC)

::Essentially all modern methodologies are "modified waterfall", all agree that you have to have some sort of requirement first (e.g. user story in XP), some sort of design and then code and then a test (even if the unit test was developed before the code its applied after). [[User:Kuratowski's Ghost|Kuratowski&#39;s Ghost]] 14:44, 20 November 2005 (UTC)

::Just included a modified waterfalls section; as per "Ghosts" comments, I've tried to make it clear that all models bear at least some similarity to the waterfall model, but that this article will only deal with the waterfall models closest neighbours. Everything else can be found under the software project lifecycle article. I'm not sure of my information on both "waterfall model with subprojects" and "waterfall model with risk reduction" as I'm going off google only on these two. :S Can someone look at these? I'll try and find some reputable books for checking when I get back from holidays... Actually, scratch that, I'm not going to include info I don't have a reasonable amount of confidence in. Can someone else who knows the exact meaning of these terms add and fill in the subheadings "the waterfall model with subprojects" and "the waterfall model with risk analysis" under the "modified waterfall models" section? Thanks. [[User:GeorgeBills|GeorgeBills]] 16:19, 20 November 2005 (UTC)

::: You don't need to find online sources for what I can cite from McConnell. If you get the rest of this in order, I'll gladly add that. -- [[User:Jmabel|Jmabel]] | [[User talk:Jmabel|Talk]] 04:14, 21 November 2005 (UTC)

==Focus of article==
* (I don't know where to put my comments!) This article puts forth a lot of solid info. Thanks! However the focus is constantly on what's wrong with the waterfall model... frankly, this author is not the right person to write this article. Lastly, the amount of 5th grade mistakes is just sad - grammar, capitalization, layout, clarity, typos.
* And finally, just as a "small world" side note, I worked with Joel Spolsky for the past two years. But that's not why I'm writing. It's just a small world.
* Okay one more thought! BDUF is only good for shrink wrappers (like Joel), anyone doing consulting or in-house work (i.e. anyone who has to listen to their clients) has to use an iterative approach. I didn't see this basic distiction in the article and I think it is essential and supports a more balanced POV. [[User:Dkalmar|Dkalmar]] 22:37, 27 November 2005 (UTC)

:Thanks for the comments Dkalmar. It would be great if you could add some more information, particular improving and expanding upon the arguments for the waterfall model if you feel the article is still biased. Fell free to fix any spelling or grammar mistakes you see too. :) [[User:GeorgeBills|GeorgeBills]] 09:20, 28 November 2005 (UTC)

== Daily builds ==

The article remarks that daily builds are "a practice not used within the waterfall model." True engough, in a straw-man version of the model where (probably unlike any practice ever known in the history of computing) you completely build the system before you begin any verification. Carried to a logical extreme, one could imagine coding the whole system before attempting to compile. But, of course, no one ever does this. Daily builds are completely compatible with any reasonable real-world version of the waterfall model. To say that they are not would be like saying that someone doing [[Extreme Programming]] would never be allowed to go off for a couple of hours and think about a data structure. -- [[User:Jmabel|Jmabel]] | [[User talk:Jmabel|Talk]] 05:44, 7 December 2005 (UTC)

== Dead Link ==

Noting that the link http://asd-www.larc.nasa.gov/barkstrom/public/The_Standard_Waterfall_Model_For_Systems_Development.htm was dead on May 04 2006. I may or may not be back after some time to update remove this. Someone more familiar with this page is invited to correct this. - [[User:Cullen|Cullen]]

== Kruchten Reference ==
This article by Kruchten lists some situations in which use of the Waterfall model is likely to be successful: [http://www-128.ibm.com/developerworks/rational/library/4626.html Going Over the Waterfall with the RUP] (See the paragraph titled "When Is a Waterfall Approach Suitable.") It is one of the few articles I have seen by an authoritative sources seems to at least grudgingly support the use of waterfall in some situations. However, I think in the corporate domain there are many software projects that meet the Kruchten's list of constraints, which may help explain why Waterfall continues to be widely used. --[[User:GFLewis|GFLewis]] 13:27, 9 July 2006 (UTC)

== "Change of naming description" ==

The following was edited into the page by [[User:Iftikharzafar]]; I'm guessing he wants to start a discussion so I'm moving it here and notifying him on his talk page...

:Inspite of the fact that I am interested in implementing this model in many of my projects, I still believe that name of this model should be modified in order to incorporate the changes in the new waterfall model. Waterfall can't come back after hitting ground to enough extent to be named in a case where we have fair bit of iteration involved. I just suggest that name should be rather Tennis Ball Modeling Method. Atleast, it sounds slightly more reasonable. <''[email protected]''>

== Iterative = Waterfall ? ==

Hello, once I read the Waterfall and the Iterative methods and I understood that iterative method was equal or an specialization of a waterfall method. But, reading Agile method article, I found an ASCII diagram where iterative and waterfall methods are distinguished.
What are the relation and differences between iterative and waterfall methods?
I think it would help to add some additional information about it in waterfall and iterative method articles. <small>—The preceding [[Wikipedia:Sign your posts on talk pages|unsigned]] comment was added by [[User:62.43.153.45|62.43.153.45]] ([[User talk:62.43.153.45|talk]] • [[Special:Contributions/62.43.153.45|contribs]]) August 26, 2006.</small>

:Prob wrong in theory but right in practice, since I've seen, in real reality, Waterfall models with a lot of backloops and the whole bunch of steps bended into a V form. Those who use Waterfall that way, prob don't follow the initial philosophy, but yet peruse the conceptual steps and a rule chain that traffic concepts to grow modules in the allowed stream direction in the original Waterfall, i.e. much more like a [[waterfall]] than the original Waterfall. ... said: [[User:Rursus|Rursus]] ([[User talk:Rursus|'''<span style="color: #CC0044; background: #CCFF88"><sup>m</sup><u>bork³</u></span>''']]) 16:20, 21 November 2009 (UTC)

== Iterative = Waterfall ? (v2) ==

Sorry, I am the "Iterative = Waterfall ?" writer. I got confused, the models that seem to be equal but have different names are iterative and spiral, not iterative and waterfall. <small>—The preceding [[Wikipedia:Sign your posts on talk pages|unsigned]] comment was added by [[User:62.43.153.45|62.43.153.45]] ([[User talk:62.43.153.45|talk]] • [[Special:Contributions/62.43.153.45|contribs]]) August 26, 2006.</small>

== what is a water fall model ==

what are the advantages of using waterfall model . which development model is more advantageous? {{subst:undigned|61.95.205.43|10 November 2006}}

: The advantages are discussed in the article. As for "more advantageous": for what? The issue is to match an appropriate development lifecycle model to a particular project, not that one model will somehow be best for all projects. - [[User:Jmabel|Jmabel]] | [[User talk:Jmabel|Talk]] 21:48, 12 November 2006 (UTC)

== Benington ==

In a Software Project Management book, the waterfall approach is described by the author as having its roots in "Production of Large Computer Programs" by H. D. Bennington in 1956. From what I understood, it not the term "Waterfall" but the aproach itself.
I was not able to find the article so I could not confirm this. As anyone have any knowledge of this? [[User:Theups|Theups]] 14:22, 26 November 2006 (UTC)

: Only that a quick Google turned up
:*Bennington H D, Production of Large Computer Programs, Proc. Symp. on Advanced Computer Programs for Digital Computers, sponsored by ONR, June 1956, Republished in ''Annals of the History of Computing'', Oct. 1983,350 - 361
:A good computer science library should have the republished version; I don't know where you are geographically, so I don't have any specific recommendations. - [[User:Jmabel|Jmabel]] | [[User talk:Jmabel|Talk]] 23:57, 28 November 2006 (UTC)

::I got a paper copy of the republication already in 90's (from the library of Helsinki University of Technology, which apparently qualifies as a good computer science library). Now I stumbled on this page and looked up both the paper copy and Google found it for me at http://sunset.usc.edu/csse/TECHRPTS/1983/usccse83-501/usccse83-501.pdf. I think this definitely should be in the article as well as the reference to [[SAGE]]. At least [[History of software engineering]] should also mention this. [[User:Kohtala|Marko]] ([[User talk:Kohtala|talk]]) 20:13, 21 March 2011 (UTC)

== "Waterfall" misunderstood? ==

To me it seeems that the waterfall model has been misunderstood and teached wrong by quite a big audience(-including me). When thinking about the flow of actions in software development( and furthermore, any system development)-I just can't think of any other way to model the flow of actions in the development process than the one suggested by the waterfall model. To me the waterfall model does not seem a model that applies to only software systems-but any system development.

How could any other action of the waterfall be performed without taking the the previous action? Some examples:
:*how would anyone be able to design and model something without knowing what is the problem/requirement? Just start drawing models and boxes without any context?
:*what about implementation without design? Just open up some editor and start programming? Write a mixture of instructions mixing any programming languages you know? And not even knowing what the system should do eventually?
:*How could something have a verification without knowing what it should do, having no design how the system would do it -and finally having nothing implemented?
:*...
Considering these issues, the waterfall model looks like a pretty perfect model.

I would separate the business and project management issues, which (as I nowadays see it...) has nothing to do with the waterfall model. I would consider that the project size, amount of requirements, the way of organizing work, overlapping the work of different subproject and phases, prioritizing requirements, etc, was never insisted or dominated by the waterfall model -these issues have been brought up by the people using the model for their purposes. Hmmm... maybe I'm suggesting that waterfall is not a process but a model about the actions that follow each other when developing systems. Putting it that way, all system development processes actually use the waterfall model

I was happy to find some similar thoughts in the links of the article:
Conrad Weisert at http://www.idinews.com/waterfall.html:
<blockquote>
There's no such thing as the Waterfall Approach!(and there never was)
</blockquote>

Alistair Cockburn at http://members.aol.com/acockburn/papers/vwstage.htm:
<blockquote>
For all that, it is safe to say that the subsystem does not ship without being validated, cannot be validated until it the bugs are removed, cannot be tested until it is built, cannot be built without design, is not designed without requirements.
</blockquote>

I think this is one way waterfall could be understood nowadays: not as a process that tells how tho manage work and business -but a model about sequential actions in system development. [[User:KariJaakkoNiemi|KariJaakkoNiemi]] 10:40, 11 February 2007 (UTC)

: Right, up to a point, but what characterizes the "waterfall" model is the emphasis on performing these phases sequentially, rather than moving back and forth in a more experimental and experiential manner. Imagine trying to build the first guitar by starting out specifying how you want it to sound (requirement); then indicating the technique of playing (functional specification); then determining exactly what type of wood you would need, how thick the strings should be, where the frets should be positioned etc. (technical specification); then building it (implementation); and only trying to make any sounds with it once it is finished (testing). - [[User:Jmabel|Jmabel]] | [[User talk:Jmabel|Talk]] 20:19, 3 March 2007 (UTC)

== risky and invites failure ==

The "risky and invites failure" citation from Royce's paper is actually about an iterative approach, and not anything like the waterfall model. Do others agree? If so, the first paragraph should be changed.
[[User:Yaxu|Yaxu]] 19:15, 8 April 2007 (UTC)

I removed a sentence accordingly.
[[User:Yaxu|Yaxu]] 18:35, 11 April 2007 (UTC)

== code monkeys ==

Wouldn't the word coder suffice as denoting someone specialized in coding (whereas the word programmer has conotations with design or at least is more general)?
Is it just me or does anyone else find the term code monkey a little derogatory? Otherwise I propose the term "design orangutans". ;)
[[User:Kuroboushi|Kuroboushi]] 12:45, 10 July 2007 (UTC)

Replaced as proposed.
[[User:Kuroboushi|Kuroboushi]] 18:39, 11 July 2007 (UTC)

== Contradiction in first paragraph ==
The last two sentences of the very first paragraph are contradictory (unbelievable!). The first states (or at least heavily implies) that the term "waterfall" was originated by Royce. The very next sentence states that he never used the term. It is hard to imagine how someone could have originated a '''term''' without ever using it. Perhaps he originated the idea rather than the term? I don't know which sentence is correct, but they can't both be correct without further explanation. -pgenty [[User:198.81.125.18|198.81.125.18]] 17:37, 2 August 2007 (UTC)

== Comments ==

Hello everyone, the following are my comments on the waterfall model. Waterfall model can only be applied to the systems that are developed from scratch. It has several disadvantages. For example, if the system's analyst fails to capture the customer requirements corretly, then this will have an impact on the following phases : Design, Implementation, Testing, and so on. --[[User:Wikiuser183|Wikiuser183]] ([[User talk:Wikiuser183|talk]]) 18:56, 17 June 2008 (UTC)
:''"Waterfall model can only be applied to the systems that are developed from scratch."'' Line a new project on a green field? That's not true: faterfall can be used for continuous enhancementing repeatadly, even for already existyng SW, not from scratch.
:''"if the system's analyst fails to capture the customer requirements corretly, then this will have an impact on the following phases: Design, Implementation, Testing, and so on."'' Yes, that's the disadvantage of this methodology, but can be tamed, in practice. ...I am QA, so that's a piece of my everyday bread. ;) [[User:Oashi|Franta Oashi]] ([[User talk:Oashi|talk]]) 15:25, 29 June 2009 (UTC)

== Origin? ==
"It should be readily apparent that the waterfall development model has its origins in the manufacturing and construction industries; highly structured physical environments in which after-the-fact changes are prohibitively costly, if not impossible. Since no formal software development methodologies existed at the time, this hardware-oriented model was simply adapted for software development. Ironically, the use of the waterfall model for software development essentially ignores the 'soft' in 'software'."

I believe the whole paragraph above is not encyclopedic. First, I believe the waterfall model follows the basic problem solving approach. Secondly this whole paragraph seems to be supposition, with no references or citations. finally the whole 'soft' in 'software' part is presumptive and trite.

I will delete this paragraph next month unless it is adjusted to be more encyclopedic. [[User:Tee Owe|Tee Owe]] ([[User talk:Tee Owe|talk]]) 22:11, 12 April 2009 (UTC)

:I agree with you on this. I was going to tag:fact this, but I noticed your comment. I will tag it with a note that the issue was opened for discussion and is pending removal. [[User:Gendut|Gendut]] ([[User talk:Gendut|talk]]) 01:25, 24 May 2009 (UTC)

== Kissu Hoi nai, vandalism? ==

I have noticed there a new edit: "Kissu Hoi nai"... Is it a vandalism? [[User:Oashi|Franta Oashi]] ([[User talk:Oashi|talk]]) 15:17, 29 June 2009 (UTC)

== Phases of waterfall modell wrong? ==
The waterfall model as described by Royce has the following phases (just like he describes them in his paper "Managing the development of large software systems"):
#System Requirements
#Software Requirements
#Analysis
#Program Design
#Coding
#Testing
#Operations
I therefore think that all reference to Royce should cite the above model and the beginning of the Model chapter starts witha wrong citation. When you cite Rocye you have to use the model from his paper without changes, simplifications, etc. period. <span style="font-size: smaller;" class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/195.212.29.187|195.212.29.187]] ([[User talk:195.212.29.187|talk]]) 13:22, 19 May 2010 (UTC)</span><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->

This issue also annoyed me. The article cites Royce but doesn't IMHO quote "Managing the development of large software systems" correctly. Royce's paper illustrates several waterfall-like approaches (Royce's Figs. 2, 3 and 4), none of which appear here. The waterfall concept has evolved over time. One approach for handling this in the article might be to summarize Royce's original material followed by summaries of more recent viewpoints. Comments/critique? [[User:Conr2286|Conr2286]] ([[User talk:Conr2286|talk]]) 00:25, 11 August 2010 (UTC)

== An Apparent Agenda ==

Although there are some more-or-less objective parts to this article, most of it appears to be a straw-man presentation by someone (or perhaps multiple people) whose agenda is to denigrate the idea of designing software ahead of coding it. Consider the following paragraph:

''This is the central idea behind Big Design Up Front (BDUF) and the waterfall model: time spent early on making sure requirements and design are absolutely correct saves you much time and effort later. Thus, the thinking of those who follow the waterfall process goes, make sure each phase is 100% complete and absolutely correct before you proceed to the next phase. Program requirements should be set in stone before design begins (otherwise work put into a design based on incorrect requirements is wasted). The program's design should be perfect before people begin to implement the design (otherwise they implement the wrong design and their work is wasted), etc.''

The word "absolutely" (used twice -- I took the liberty of removing one of them from the article itself, it's just left in here as it was when I found it) adds no information and has no real meaning. I submit it is there just to illustrate how inflexible and unreasonable those people are who advocate a period spent designing before any period spent coding.

Likewise, consider "The program's design should be perfect..." -- The only people I've ever heard use the term perfect to refer to software design are people who are trying to make it sound like an unreasonable thing to do.

I think the same people were helping with the article on software engineering: that used to say that the two most common software development methodologies were Waterfall and Agile; they didn't give a reference, which isn't surprising since the statement was patently false. But that's another article (which doesn't say that any more -- I changed it to list the 4 methods that have their own sections in Wikipedia's software methodology section).

I think it would be good if the article made clear that BDUF and Waterfall are not the same thing; that, in fact, doing a design phase before coding starts is one but not the primary characteristic of the Waterfall Model.

Does anyone have a reference of a major project that actually used an unmodified Waterfall Model for its development?

[[User:Ralphcook|rc]] ([[User talk:Ralphcook|talk]]) 20:51, 25 September 2010 (UTC)

==== agenda, or reality? I'm curious too! ====

I too am curious about your final question ("Does anyone have a reference of a major project that actually used an unmodified Waterfall Model for its development?").

If "pure waterfall" means Royce's parody of a no-feedback waterfall, then how could anyone ship a project like this? What happens if a problem is found during verification, the code is shipped anyway? So, when other writers (on this discussion page and elsewhere) say that people really do use waterfall, what are they talking about? This can't be right!

On the other hand, I agree with you that BDUF shouldn't be absolutely equated with "pure waterfall". BDUF might be the '''right''' approach for some systems (space vehicles seem to be a common and plausible example given, e.g. google for 'they write the right stuff'). And I'm sure it '''is''' used for lots of projects, correctly or not, some of which are probably even successful (perhaps in spite of BDUF).

I wonder if the key point here is that "pure waterfall" is arguable an endpoint on a continuum, and the endpoint is clearly undesirable and impossible (again, if there's no feedback from verification to implementation, why verify?), but that moving toward that endpoint along the continuum may be desired by some stakeholders (wisely or unwisely).

All that said, I almost feel like the article isn't sufficiently clear that pure waterfall is incoherent. If you're casting around for a methodology, putting '''pure''' waterfall on your list of options is not a sane move, any more than putting "get on knees and pray until software appears full-formed by divine intervention" is a sane option, and this is more than an opinion (isn't it? I'm experiencing POV-anxiety!).

--[[User:JHolman|jholman]] ([[User talk:JHolman|talk]]) 19:35, 9 November 2010 (UTC)

== Royce 1970 citation ==

Not sure that the link to [http://www.cs.umd.edu/class/spring2003/cmsc838p/Process/waterfall.pdf "Managing the Development of Large Software Systems"] paper used in this wiki article is actually the original paper published in 1970. It looks to me that the destination document is in fact this one:

''W. W. Royce. 1987. Managing the development of large software systems: concepts and techniques. In Proceedings of the 9th international conference on Software Engineering (ICSE '87). IEEE Computer Society Press, Los Alamitos, CA, USA, 328-338.''

Check the pdf that is being opened from this link: http://portal.acm.org/citation.cfm?id=41801 <span style="font-size: smaller;" class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/194.80.32.8|194.80.32.8]] ([[User talk:194.80.32.8|talk]]) 21:41, 16 November 2010 (UTC)</span><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->

== Shrink Wrap Software ==

The article currently contains a link to [[shrink wrap contract]] under the name "shrink wrap software" in the section "[[Waterfall model#Supporting_arguments|Supporting arguments]]" in the following sentence:
:"It is argued that the waterfall model and Big Design up Front in general can be suited to software projects that are stable (especially those projects with unchanging requirements, such as with [[Shrink wrap contract|shrink wrap software]]) and where it is possible and likely that designers will be able to fully predict problem areas of the system and produce a correct design before implementation is started."

The article for shrink wrap contract, however, does not appear to explain what a "project with unchanging requirements" is. Since it seems that this might be a fairly important part of why someone might support the Waterfall Model, could someone add some information on this? (I myself don't know enough.) [[User:Raptortech97|Raptortech97]] ([[User talk:Raptortech97|talk]]) 00:08, 3 April 2013 (UTC)

== Disputed ==

Great article, one would almost start to believe there ever was such a thing as a watterfall model.
Problem is, it does not exist, nor has any project aver used such a model.
The whole waterfall model in the original article started its life as a strawman, and has seen many
incarnations that have repeatedly been used again and again to attack older aging models.
Models that one or two decades ago were advocated using the watterfall stwaman model are ironically
today being attacked using the same strawman fallicy. I believe this artiocale should be deleted and
replaced with a proper analysis of the decades old strawman falicy that the waterfall model represents. <span style="font-size: smaller;" class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/2001:980:4962:1:5604:A6FF:FEF1:6202|2001:980:4962:1:5604:A6FF:FEF1:6202]] ([[User talk:2001:980:4962:1:5604:A6FF:FEF1:6202|talk]]) 00:32, 9 February 2014 (UTC)</span><!-- Template:Unsigned IP --> <!--Autosigned by SineBot-->
: If you can provide any [[:WP:RS|reliable sources]] to support your opinion, then we should certainly add a discussion about this in a criticisms section, but the sources clearly show that it does exist and is not a straw man. [[User:Walter Görlitz|Walter Görlitz]] ([[User talk:Walter Görlitz|talk]]) 01:04, 9 February 2014 (UTC)

::The point is that (AFAICS) all of the references in the article are either 'in contrast' mentions or are 'historic' analisis quoting these 'in contrast' papers. Development processes have always been itterative, even those that define phases have explicit or implicit feedback loops. AFAIK there are no documented examples of processes in practice using a true waterfall model where the phases are frozen once the next phase begins. The burdon of the proof should not be with me, but with the people claiming that the waterfall model has ever actualy been used as a real model in practice. I would thus sugest both adding a 'quotations needed' in the parts that claim that the model has actualy ever been used AND adding criticisms section mentioning the posibility of the model being nothing but a stwawman. <span style="font-size: smaller;" class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/2001:980:4962:1:5604:A6FF:FEF1:6202|2001:980:4962:1:5604:A6FF:FEF1:6202]] ([[User talk:2001:980:4962:1:5604:A6FF:FEF1:6202|talk]]) 09:59, 9 February 2014 (UTC)</span><!-- Template:Unsigned IP --> <!--Autosigned by SineBot-->
::I would like to refer to Profesor Dischave who a few years back stated
:::"For those information technology professionals and other interested parties I encourage you to do some research. Look for the seminal work that introduces a “waterfall” methodology to the discipline. If you find it please share it with this community. I would like to read it, but in the meantime please read Winston Royce’s, “Managing the Development of Large Software Systems.”[i] I think you will find Royce does a nice job proving that the “Waterfall” systems development methodology is indeed a myth."

:: http://get.syr.edu/news_alt.aspx?recid=401
:: I don't think adding a 'criticisms section' is sufficient, but it might be a start. I maintain that there is no actual proof to be found that shows that a real development method ever existed that could truly be considered waterfall. From this I challenge the legitimacy of this article. <span style="font-size: smaller;" class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/92.70.45.2|92.70.45.2]] ([[User talk:92.70.45.2|talk]]) 06:24, 16 June 2014 (UTC)</span><!-- Template:Unsigned IP --> <!--Autosigned by SineBot-->

== Controversy ==

Controversy[edit]
Although many references to the waterfall model exist, and while many methodologies could be qualified as 'modified' waterfall, the key aspect of waterfall as being a non-iterative process, and lack of citations regarding the actual use of such a non-iterative waterfall model have made one critic,[17] among many, pose the thesis that the waterfall model itself, as a non-iterative development methodology, is in fact a myth and a straw-man argument used purely to advocate alternative development methodologies.

I write novels (4 of them). I've written reams of user manuals. I've read dozens of books on computer programming, (I'm a 30 year programmer.) It is my semi professional opinion that the above section, titled 'Controversy,' is nearly all gibberish and virtually indecipherable. <small class="autosigned">—&nbsp;Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/69.148.33.25|69.148.33.25]] ([[User talk:69.148.33.25|talk]]) 15:51, 24 March 2015 (UTC)</small><!-- Template:Unsigned IP --> <!--Autosigned by SineBot-->
: Be [[:WP:BOLD]] and remove it. It does appear to be rambling. [[User:Walter Görlitz|Walter Görlitz]] ([[User talk:Walter Görlitz|talk]]) 04:19, 25 March 2015 (UTC)

== EITVOX criteria not been talked both in Waterfall Model & modified Waterfall Model ==

Entry, Input, Task, Validation, Output, Exit criteria is very standard one whether it is Waterfall Model or any Modern modified Waterfall Model. This needs to be discussed in a generic nature, in both of the page [[Waterfall model|Waterfall Model]] and [[Modified_waterfall_models|Modified Waterfall Models]] regardless whether it gets into any specific development model page or not,- as AI - Artificial Intelligence involved nowadays rather not by any human effort in which not all its counterparts of EITVOX has a criteria as its logistics is in a quantum ride. <small><span class="autosigned">—&nbsp;Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[User:Ansathas|Ansathas]] ([[User talk:Ansathas|talk]] • [[Special:Contributions/Ansathas|contribs]]) 06:35, 9 April 2015 (UTC)</span></small><!-- Template:Unsigned --> <!--Autosigned by SineBot-->

== Leprechauns of Software Development research into the history ==

I found this interesting. It's samples from a book in progress about how to apply skepticism to claims in software engineering. One of the sample chapters is a worked example of debunking the origin myths (for and against are both myths) of the waterfall development methodology. [https://leanpub.com/leprechauns/read#leanpub-auto-chapter-7-whos-afraid-of-the-big-bad-waterfall] The author does some research, complete with citation graphs for the original paper. Probably not ready to use as a source itself, but a good pointer for what to research for a good wikipedia summary - [[User:David Gerard|David Gerard]] ([[User talk:David Gerard|talk]]) 09:31, 29 April 2015 (UTC)

== External links modified ==

Hello fellow Wikipedians,

I have just added archive links to {{plural:1|one external link|1 external links}} on [[Waterfall model]]. Please take a moment to review [https://en.wikipedia.org/w/index.php?diff=prev&oldid=703531119 my edit]. If necessary, add {{tlx|cbignore}} after the link to keep me from modifying it. Alternatively, you can add {{tlx|nobots|deny{{=}}InternetArchiveBot}} to keep me off the page altogether. I made the following changes:
*Added archive https://web.archive.org/20140702113551/http://get.syr.edu/news_alt.aspx?recid=401 to http://get.syr.edu/news_alt.aspx?recid=401

When you have finished reviewing my changes, please set the ''checked'' parameter below to '''true''' to let others know.

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Cheers.—[[User:Cyberbot II|<sup style="color:green;font-family:Courier">cyberbot II]]<small><sub style="margin-left:-14.9ex;color:green;font-family:Comic Sans MS">[[User talk:Cyberbot II|<span style="color:green">Talk to my owner]]:Online</sub></small> 02:02, 6 February 2016 (UTC)

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Does or did the waterfall model ever even exist?

[edit]

While the term "waterfall" certainly exists, none of the references on the page support that it was ever an actual project management approach. It seems to be nothing more than a pejorative term. A sort of bucket into which all bad project management approaches can be put. Is there any evidence that the "waterfall model" ever existed? Twasonasummersmorn (talk) 18:27, 6 March 2021 (UTC)[reply]

Yes, it absolutely existed. I first started doing software development in the 1980's at Accenture (then Andersen Consulting). The SDLC we were all taught at the time was called Method/1 and it was a classic waterfall model. Ironically, I did a lot of research work for the DoD and we had to use the same methodology for research as all other DoD software developers did. I think it was called Mil Standard 2167a. In any case it was absolutely a waterfall model. In both cases we always filled out the required forms and made the required project plans and then essentially ignored them. One of my bosses had a great name for them: "Write Only Documentation" which was what they were. We did things using what is now called Agile because we just knew that was the better way to do it. MadScientistX11 (talk) 19:46, 26 April 2023 (UTC)[reply]

Having looked more deeply at the references on this page, they're dreadful. Royce (the reference on which the whole article almost depends) does not say what he's supposed to have said in the referenced paper and the rest of the references are full of "some say". If no-one has better references I'm going to do a pretty tight cropping of the whole article. Twasonasummersmorn (talk) 20:41, 15 March 2021 (UTC)[reply]

Still no satisfactory references on here. The article seems to be based on misquoting a few articles - generally from very long ago - and then claiming (without reference) that the "waterfall" approach so demonized in previous years as a counterpoint to Agile, existed. Twasonasummersmorn (talk) 15:34, 26 March 2021 (UTC)[reply]

Perhaps it's the question that is lacking. The "model" adjective is shorthand and synonymous with approach. Feel free to correct the term or make adjustments, but the tags of shame you've place are childish. Walter Görlitz (talk) 15:55, 26 March 2021 (UTC)[reply]

This definately exists, it's a recommended product development process by the FDA in https://www.fda.gov/media/116573/download linked from https://www.fda.gov/regulatory-information/search-fda-guidance-documents/design-control-guidance-medical-device-manufacturers. Poisonadder1 (talk) 09:21, 2 June 2021 (UTC)[reply]

That paper mentions waterfall, but doesn't recommend it. Nor does it give any reason to believe they're not just talking about something everyone seems to have heard of but perhaps never actually existed. Twasonasummersmorn (talk) 21:12, 9 October 2021 (UTC)[reply]

Seriously - this whole article is cantering around almost without any decent references. Should the whole page be just blanked out until some can be found? The ones I've found would indicate that the term is largely a bogey man term and that the method never actually existed. But I'm not sure they prove the negative either. Twasonasummersmorn (talk) 23:35, 2 January 2023 (UTC)[reply]

Agreeed - Waterfall was only a software industry thing. Everyine who was an engineering the 1980's knows this.
And nobody outside of Software industry has ever heard the word "Waterfall" untiil somebody tried to sell them Agil.
Again we have the critical flaw in Wikipedia. How do you prove something didn't exit? THere's no references for things that didn't happen. Waterfall outside of Siftware never happened. People can post that it's a thing and it stays in. you post that it never happened with referenecs. And it gets taken out.
Wikipedia admins are not checking references in edits 2601:286:C200:1E90:447B:B3AC:AEDD:EDD1 (talk) 22:54, 14 December 2023 (UTC)[reply]

the article fails to explain most fundamental thing

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waterfall on a timeline, as seen in project management application

the waterfall model exists on a timeline, it's not some random bunch of boxes in a drawing. i couldn't figure this out when i was first reading the article, thus, the article is quite worthless, because it fails to actually inform the reader of what the waterfall model actually means. this article doesn't look like it was written for encyclopedia. 5.184.25.166 (talk) 13:23, 17 October 2021 (UTC)[reply]

Waterfall project management

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Waterfall model help to restraint required analysis and definitions on system and software development by implementing the specific units of testing and execution of operations and maintenance as itself shows to be cumbersome and liable to cause application delivery lag. 2405:201:C00F:60AF:251B:472B:6159:E14A (talk) 18:21, 19 December 2022 (UTC)[reply]

The waterfall model

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Waterfall Model Description

[email protected] The waterfall model

The waterfall model is a software development methodology that follows a linear, sequential approach. It is named after the way in which tasks flow, like a waterfall, from one phase to the next in a predetermined order. The waterfall model is also sometimes referred to as the "linear-sequential" model.

In the waterfall model, the development process is divided into distinct phases, each of which must be completed before moving on to the next. The phases of the waterfall model are:

1.Requirements gathering and analysis: In this phase, the project requirements are gathered and documented.

2. Design: In this phase, the system is designed based on the requirements gathered in the previous phase.

3.Implementation: In this phase, the code is written based on the design created in the previous phase.

4.Testing: In this phase, the system is tested to ensure it meets the requirements and functions correctly.

5.Deployment: In this phase, the system is deployed and made available for use.

6.Maintenance: In this phase, the system is maintained and any necessary updates or changes are made.

The waterfall model is a linear approach to software development and is well-suited to projects with well-defined requirements and a clear understanding of the problem to be solved. However, it can be inflexible and may not be the best choice for projects with rapidly changing or complex requirements 106.78.85.100 (talk) 11:25, 27 December 2022 (UTC)[reply]

Ehm...where's that from? Twasonasummersmorn (talk) 23:27, 2 January 2023 (UTC)[reply]

The waterfall

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The waterfall model is a breakdown of project activities into linear sequential phases, meaning they are passed down onto each other, where each phase depends on the deliverables of the previous one and corresponds to a specialization of tasks.[1] The approach is typical for certain areas of engineering design. In software development,[1] it tends to be among the less iterative and flexible approaches, as progress flows in largely one direction ("downwards" like a waterfall) through the phases of conception, initiation, analysis, design, construction, testing, deployment and maintenance.[2][better source needed] The waterfall model is the earliest SDLC approach that was used in software development.[citation needed]

The waterfall development model originated in the manufacturing and construction industries,[citation needed] where the highly structured physical environments meant that design changes became prohibitively expensive much sooner in the development process.[citation needed] When first adopted for software development, there were no recognized alternatives for knowledge-based creative work.[3][better source needed] 103.255.145.74 (talk) 14:15, 8 January 2023 (UTC)[reply]

Removing Sentences on RUP

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At the end of the Criticism section it says: "Rational Unified Process (RUP) phases acknowledge the programmatic need for milestones, for keeping a project on track, but encourage iterations (especially within Disciplines) within the Phases. RUP Phases are often referred to as waterfall-like" There is a citation needed next to this but I've used and read about RUP a lot and I have never heard it "referred to as waterfall-like". What the RUP books say is that you can use it in different ways. I.e., you can use it in an iterative manner (which is how it is mostly intended to be used) or you can use it in a waterfall manner. But that is not at all the same as saying the methodology is "Waterfall-like". I'm going to be bold and just delete that part. MadScientistX11 (talk) 19:52, 26 April 2023 (UTC)[reply]

Another Questionable Claim in Criticism Section

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The ending of the Criticism section currently says: "While advocates of agile software development argue the waterfall model is an ineffective process for developing software, some sceptics suggest that the waterfall model is a false argument used purely to market alternative development methodologies" There are plenty of valid criticisms of Agile but the idea that Agile is just a marketing ploy is one I've never heard anyone seriously make. I went to check that reference and it goes to a dead link. Given that there is no actual source information anyway (there is an author but nothing like the name of the source cite, it looks like just a URL to the site: http://get.syr.edu/ which is no longer a site at all). The link is archived to Wayback but still goes to a dead link. Given that this looks to me like it isn't a valid source even if we could find it in the bowels of the web and that this is not what in my experience constitutes a serious argument (anymore than I would consider the same argument applied to Waterfall to be a serious argument) I'm going to delete that claim. MadScientistX11 (talk) 01:32, 2 May 2023 (UTC)[reply]

Waterfall was limited to the Software industry

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Having lived in engineering and consulting industry for 47 years. Waterfall is a software industry only term. Nobody outside of the software industry ever used it in the 20th century. It's only used to describe "everything note agile is waterfall". Which is obviously not true. 2601:286:C200:1E90:447B:B3AC:AEDD:EDD1 (talk) 22:15, 14 December 2023 (UTC)[reply]

The article must be based on sources, you cannot make additions based on your personal opinions. That is called 'original research' here and is prohibited by a core policy, which you can read at WP:OR. Wikipedia's not a place for ediorializing. MrOllie (talk) 00:17, 15 December 2023 (UTC)[reply]
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