Requirements the Last Bottleneck

Requirements: the Last Bottleneck Bill Karwin ZendCon • Santa Clara • 2010/11/3

Me • Software developer • C, Java, Perl, PHP, Ruby • SQL maven • Author of new book SQL Antipatterns

the greatest single cost in producing software is programmer time

code faster!

Tools for reducing programmer time • Dynamic languages • IDE’s • Lots of functions • Frameworks • OO design • Source control • Code reuse • Test automation • Code generation • Agile development

• Tools help productivity for coding and error removal • But not so much for requirements management

Error removal is the most time- consuming part of development Facts and Fallacies of Software Engineering, Robert L. Glass

Cost to ﬁx a defect Software Requirements, Karl E. Wiegers Code Complete, Steve McConnell

code faster?

code less!

Front-load the project Facts and Fallacies of Software Engineering, Robert L. Glass

managing requirements reduces project cost

so why don’t we do it?

Really? “We practice Agile Development, so we don’t need requirements.”

Agile Manifesto? Principle #2: “Welcome changing requirements, even late in development.” http://www.agilemanifesto.org/

Test-Driven Design? “TDD is very good at detailed speciﬁcation and validation, but not so good at thinking through bigger issues such as the overall design, how people will use the system, or the UI design (for example).” Introduction to Test-Driven Design, Scott W. Ambler http://www.agiledata.org/essays/tdd.html

Extreme Programming? Testing Coding If you don’t test, you don’t If you don’t code, you know when you are done haven’t done anything. coding. Listening Design If you don’t listen you So you can keep coding don’t know what to code and testing and listening or what to test. indeﬁnitely. Extreme Programming Explained: Embrace Change, Kent Beck

Scrum? • Product Backlog: the prioritized list of desired project outcomes/features http://www.scrumalliance.org/learn_about_scrum

Repeat for each Agile iteration

“Every time the design changes, we have to update the requirements doc.”

“Requirements are not architecture. Requirements are not design, nor are they interface. Requirements are need.” The Pragmatic Programmer: From Journeyman to Master, Andrew Hunt and David Thomas

do not dictate the implementation in the requirements

Decoupling • Familiar principle of OO design • Interface vs. implementation • Design patterns (Strategy, Bridge, etc.)

Decouple requirements from solutions Solution 1 Java, Spring ☒ Require- ments Solution 2 C#, .NET ☒ Solution 3 PHP ☑

“How much detail is enough?”

Really? “If it takes more than 15 minutes to determine what it is that you’re building, the spec wasn’t done properly.”

• Imagine your boss has a great idea • He’s going to describe his idea to you • You’re to code it while he’s gone • He has to leave in 15 minutes • Here’s his vision...

How much is enough? • Probably a bit more than 15 minutes • But not a whole book • Focus on goals to satisfy, not design or implementation

“No one reads requirements docs anyway.”

• Right—if the docs aren’t helpful • Make the docs helpful to developers • Describe what to build, not how

SMART goals

speciﬁc measurable achievable results-oriented timely

Speciﬁc • Be concrete; use action verbs ☒ • Users will have an intuitive experience using our software. ☑ • Users will be able to post textual content of 140 characters or fewer, and to search the content posted by others.

Speciﬁc • Also specify what the project does not need ☒ • Support all browsers, full stop. It doesn’t matter how obscure or how old. ☑ • Test the browser brands/versions used by 97% of the target market.

Measurable • Describe testable or quantiﬁable goals ☒ • The web site will work at web scale. ☑ • The web site will serve up to 10 million users; up to 10 thousand posting simultaneously; up to 500 thousand reading content stream.

Measurable • Measure progress as well as ﬁnal result ☒ • The whole site must have no security issues. ☑ • Certify that each application use case is secure.

Achievable • Set goals that are feasible and possible; stay appropriate to scope ☒ • Our site will change the way people communicate on the web. ☑ • Our site will let users contribute bite-sized content and search the content stream by users, by lists of users, or by tags or trends.

Results-oriented • Describe outputs or results—not activities ☒ • Developers will always strive to achieve optimal performance. ☑ • The landing page will respond in ~0.5 sec; other pages will respond in ~1.0 sec.

Results-oriented • Describe outputs or results—not activities ☒ • The developers will use LAMP stack, REST architecture, scrum methodology, and git. ☑ • Don’t dictate technology choices, design, or methodology in requirements.

Time-related • Use speciﬁc, realistic deadlines; include milestones, schedule ☒ • We need our web site to go live sooner rather than later. ☑ • Four weeks for design; three weeks for developing prototype; one week for performance testing; three weeks for refactoring; one week for ﬁnal work and deployment.

Evaluation • Often forgotten phase • Testing is part of this of course • Other review of how well you met the requirements • In Agile terms, delivery to customer • Spell out evaluation criteria in requirements

manage requirements to develop more efﬁciently

decouple requirements from solutions

be SMART

SQL Antipatterns: Avoiding the Pitfalls of Database Programming http://www.pragprog.com/titles/bksqla/

Copyright 2010 Bill Karwin www.slideshare.net/billkarwin Released under a Creative Commons 3.0 License: http://creativecommons.org/licenses/by-nc-nd/3.0/ You are free to share - to copy, distribute and transmit this work, under the following conditions: Attribution. Noncommercial. No Derivative Works. You must attribute this You may not use this work You may not alter, work to Bill Karwin. for commercial purposes. transform, or build upon this work.

Requirements the Last Bottleneck

by Karwin Software Solutions LLC on Nov 04, 2010

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