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  • pierrepureur 12:11 am on February 18, 2016 Permalink | Reply
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    Requirements in Continuous Architecture: Let’s Clarify! 

    CA Book Cover Small 2

    Clarifying Requirements is Important

    In the previous installment of our “Continuous Architecture” blog as well as in our book, we discussed an effective approach for capturing requirements. We suggested that thinking in terms of testable hypotheses instead of traditional requirements enables teams following the Continuous Architecture approach to quickly deliver systems that evolve in response to users’ feedback and meet or even exceed users’ expectations. But are we sure that we always understand what the system stakeholders want, even when they are able to precisely quantify those requirements?

    Philippe Kruchten tells the following story about the importance of clarifying requirements. Back in 1992, Philippe was leading the Architecture team for the Canadian Air Traffic Control System (CAATS), and the team had a requirement of “125 ms time to process a new position message from the Radar Processing System, from its arrival entry in the Area Control Center till all displays are up-to-date”.

    Here is how Philippe tells the story: “After trying very hard to meet the 125 ms for several months, I was hiking one day, looking at a secondary radar slowly rotating (I think it was the one on the top of Mount Parke on Mayne island, just across from Vancouver Airport). I thought … “mmm, there is already a 12-20 second lag in the position of the plane, why would they bother with 125ms…?”

    radar

    Note: primary radar uses an echo of an object. Secondary radar sends a message “who are you?” and the aircraft respond automatically with its ID and its altitude (http://en.wikipedia.org/wiki/Secondary_surveillance_radar). It looks like this: https://www.youtube.com/watch?v=Z0mpzIBWVG

    I knew all this because I am myself a pilot…

    Then I thought:  “in 125ms, how far across the screen can an aircraft go, assuming a supersonic jet… and full magnification”. Some back of the envelope computation gave me…about 1/2 pixel! When I had located the author of the requirement, he told me: “mmm, I allocated 15 seconds to the radar itself (rotation), 1 second for the radar processing system, 4 seconds for transmission, through various microwave equipment, that left 1 second in the ACC, breaking this down between all equipment in there, router, front end, etc.., it left 125ms for your processing, guys, updating and displaying the position…” These may not have been his exact words as this happened a long time ago, but this was the general line… Before agile methodologies made it a “standard”, it was useful for the architects to have direct access to the customer, often on site… And in this case being able to speak the same language (French)”.

    Philippe’s story clearly stresses that it is important for an Architect to question everything, and not to assume that requirements as stated are absolute.

     

    Please check our blog at https://pgppgp.wordpress.com/ and our “Continuous Architecture” book (http://www.store.elsevier.com/9780128032848) for more information about Continuous Architecture

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  • pierrepureur 12:10 am on February 8, 2016 Permalink | Reply  

    Continuous Architecture and Requirements 

    Source: Continuous Architecture and Requirements

     
  • pierrepureur 12:09 am on February 8, 2016 Permalink | Reply
    Tags: , , , ,   

    Continuous Architecture and Requirements 

    CA Book Cover Small 2

    Don’t Think Functional Requirements, Think Faster Time to Feedback

    As we discussed in Chapter 1 of the “Continuous Architecture” book and elsewhere in this blog, capturing and managing requirements accurately and timely  – especially Quality Attribute Requirements – is an essential part of the Continuous Architecture approach. Traditionally, the approach to capturing and managing requirements has been based on conducting interviews of subject matter experts (SMEs) in order to document  requirements that the system must satisfy, often documented in voluminous documents which are hard to read and analyze. Ideally, the interviewees should be actual or prospective users of the system being developed, but in practice the interviewers often have to settle for representatives from the business who believe that they are familiar with the way the system is (or will be) used.

    Requirements Interviews Dilbert

    Collecting requirements from user representatives who attempt to guess the needs of real users as well as the best ways to satisfy those needs often result in systems that fall short of real users’  expectations. In addition there is often a significant time interval between the interviews and the delivery of the system, and this may lead to further disappointment as requirements  may change due to evolving business conditions.

    As Forrester Research Principal Analyst Kurt Bittner states, “The problem is the SME paradigm itself. No one person can represent the needs of all users, no matter how hard they try. The problem goes deeper: The conscious mind often cannot express what is really needed, and only knows what it doesn’t like when it sees it. As a result, the surest path to success is to put something out there that minimally satisfies some need, sometimes called a minimum viable product, and then improve upon that in rapid cycles.”

    The objective of the Continuous Architecture approach is to enable the rapid delivery of a minimum viable product that may be designed to satisfy some need or validate some hypothesis, and will continuously evolve as feedback from the users is received. As we describe in the book and in this blog, we achieve this objective by creating a “minimum viable architecture” that also continuously evolve as user feedback is received, and enables the delivery of a system that meets or even exceeds its users’ expectations.

    Please check our blog at https://pgppgp.wordpress.com/ and our “Continuous Architecture” book (http://www.store.elsevier.com/9780128032848) for more information about Continuous Architecture.

     
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