Life Cycle - ISO 12207 - Software development activities

[Marc]

Subject: Re: Q: Life cycle model/yadav/Maibor
Date: Tue, 8 Dec 1998 14:20:31 -0600
From: ISO Standards Discussion

From: MaiborD
Subject: Re: Q: Life cycle model/yadav/Maibor

<< From: Girish Yadav - tatainfotech

On behalf of one of my friend, I'm putting forward following questions
related to Software development activities

1. What is a "life cycle model" and how it relates with the life cycle
processes defined in ISO 12207:1995 (which is thoroughly referred in
ISO 9003-1:1997) ?
2. Is a life cycle model (development model) the same as a project
management methodology?
3. Do life cycle procedures (the "how") depend on the life cycle model
selected? For example, would the requirement analysis procedure be
different depending on whether we chose a waterfall model or a RAD model?

Any answers will be appreciated.

<< regards,
<< yadav

Girish,

1. A life-cycle model is the order in which a series of processes are performed to create/update a product or service. Examples of life-cylce models include a Single-Pass Waterfall, Incremental Build, and Evolutionary Build approach. The "Life Cycle Processes" of 12207 fall into three categories: Primary/Supporting/Organizational life cycle processes. The Primary/Supporting processes are organized into appropriate sequences as part of the life cycle for the project.

2. A life cycle model is not the same as a project management methodology. The 12207 view point is that project management (and its particular methodologies) is one of the process that apply to a project throughout its life cycle and is established for the entire organization (an Organizational life cycle process).

3. The life cycle processes of 12207 are mostly "the what" has to be done on a project; not "the how." The particular how (e.g., object-oriented vs. functional programming methods, waterfall vs. RAD) are implementation details when using 12207 on a project.

By the way, I am part of the U.S. Tech. Advisory Group (TAG) responsible for 12207, as well as its revisions, and 15288 (the system life cycle std.). My company has been conducting training classes and consulting on the use of these standards for twelve years.

David S. Maibor, President
David Maibor Associates, Inc.

[Marc]

Subject: Re: Q: Life cycle model/yadav/Deibler
Date: Wed, 9 Dec 1998 08:52:02 -0600
From: ISO Standards Discussion

From: Bill Deibler
Subject: Re: Q: Life cycle model/yadav/Deibler

Hello Yadav,

Some definitions....

software life cycle - The period of time that begins when a software product is conceived and ends when the software is no longer available for use. The software life cycle typically includes a concept phase, requirements phase, design phase, implementation phase, test phase, installation and checkout phase, operation and maintenance phase, and, sometimes, retirement phase. - IEEE-STD-610

Examples of software life cycles include:
- waterfall,
- overlapping waterfall,
- spiral,
- serial build, and
- single prototype/overlapping waterfall.
- incremental
- STARTS V Model

....and the list goes on. Many models are slight variants of others, for example, the V Model and spiral models exploit the waterfall model.

> 2. Is a life cycle model (development model) the same as a project
> management methodology?

No. Project management methods are typically not tied to a particular
life cycle. Good project management spans the lifecycle of product
development.

> 3. Do life cycle procedures (the "how") depend on the life cycle model
> selected? For example, would the requirement analysis procedure be
> different depending on whether we chose a waterfall model or a RAD model?

That's a great question....

Life cycles and models in general, such as ISO 9000 and the CMM are whats not hows. A requirements analysis procedure may very well be similar when used in conjunction with different lifecycles. A lot of how requirements are fleshed out depends on the type of product, for example, graphical applications may use prototypes as a method of deriving requirements, whereas prototyping may be used less in non-graphical applications.

Life cycles are useful...but well-defined and useful policies, procedures, and standards (undocumented and documented) will dictate how things are done....the nuts and bolts.....and the lifecycle models are high level enough that they won't dictate specifics and therefore will not prevent the procedures from being flexible and useful as long as they are designed that way! :}

The real challenge is to design procedures that will support projects small to large and include the challenges of software maintenance, outsourced third-party development, and other risks...but that's another topic....

Drop me a line if you need more information as we work with companies in defining the nuts and bolts of their software engineering practices.

Sincerely,

Bill Deibler

[Marc]

--> One of the most fundamental misconceptions about a
--> "life-cycle" model is that it ends with product delivery. A
--> true life-cycle model makes a realistic estimate of the
--> useful life of the product and creates a plan from birth to
--> death. How is the product delivered, installed and
--> maintained? What kinds of support would customers require, or
--> reasonably expect? I have reviewed many so-called life-cycle
--> models that failed to address any of the issues after first
--> release, or only mentioned these issues as a sketchy
--> afterthought.
-->
--> Robert Lessman

[Marc]

A response:

I am surprised. I worked with a methodology that integrates both the project management and the software development life cycle. The approach goes like this. The software development life cycle is divided into Phases\Activity\Tasks and the deliverables are placed in the Milestone sections. The Project management practices like the scheduling and tracking as well as the business case management is done accordingly based on tools like MS-Project and the practices like the cost\benefit analysis at the respective milestones. The integration of both of these methodologies depends majorly on the size of the project, precisely on the development methodology like RAD or any other. There are many tools available in the market that use the integrated methodologies like the Project Bridge Modeler and Work Bench. I believe this is what the query wished to discuss and I am not off the topic.

Regards
Peter

[w_grunfeld]

Need help,
Does anyone have the new 2008 version of ISO 12207? What is new /different from the 1995 version?
Also, is there any added value in the IEEE/EIA 12207 series 12207.0, 12207.1 and 12207.2 Industry Implementation of the ISO standard?
I don't recall any other ISO standard that has 3 other different industry standards to guide in its implementation. Can someone enlighten me if these are really needed to satisfy a customer ?
Thanks,
Willy