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Planning!

When I travelled from home to Saudi Arabia in May, 2006, I planned ahead. Flights were booked, course manuals printed, Visa obtained, contacts established, deposit paid (to us for courses), travel insurance in place before I even left home. "Of Course" or "Prudent", I expect you'll say. And I agree with you.

So why is it that when people start on a major software project, they're tempted to jump in and start writing code from an early point? Shouldn't there be a great deal of planning done before the first programming - checks that what they want to achieve is fully understood, and that it will work and there will be few hidden surprises? Well - it's a very brave analyst / programmer who, half way through a six week project, hasn't written a line of code ;-). But is CAN work.

I recall the "Bill of Materials" module of our "Designer I" CAD product (written by myself, David, Julie and Adam in the 1980s in Fortran, C and Assembler, running on PCs, Linux, Sintran, RSX11M ...) which was specified down to the extent of the user manual being complete before a line of code was written. An excellent module, which did what is said on the box, and worked well for our customers. Th eonly problem I recall was that - having put the manual into the hands of our sales person - we also had orders (and with an impossible tight timescale promised) before any code was in place.

I was reminded of this yesterday, when I was helping with the design of a new project for one of our friends and customers, and although the project will be in PHP, we didn't write a line of PHP all day.

We started off with "Use Case" - looking at what the data held by the system will be, who provides it, who uses it. We extended "use case" somewhat by adding in weights to the various users, both in terms of how much traffic each role will generate, and how sensitive that role is to a 'good' or 'bad' system - the user profile.

Alongside "Use Case", we thought of key features and extensions, looking to think well ahead at an early stage of what the system must do at day 1, what would be really helpful in terms of extra features that will help it be accepted / used / strongly taken up from day 1, what will help make it usable, secure, extensible, manageable and profitable. In my own mind (though not, I will admit, on the paper), I was thinking through how each user will walk through the system - "State Diagrams", and at lunch we talked though with a potential user of such a system about what when would like to see in it / how it could work for her. That's an unscientifically small sample size, I know - but never the less, a first sanity check to say "have we overlooked anything serious here?".

Towards the end of the day, we moved on to a more detailed look at the data to beheld - the structure of the tables. And, in this case, we chose to write the description down in the form of MySQL CREATE TABLE commands, to see how it would work, together with some INSERT commands to actually add data in to the tables. We preceded these commands with a DROP DATABASE and a CREATE DATABASE so that we could try it out, time and again, and we added in a handful of SELECTs so that we can see how - when code is eventually written - the data will be accessed. The file (as it was by the end of the day) is here.

With a solid, tested, thought ahead design for the database, this system can be a big success. Design issues considered / resolved very early include:

a) The main tables, and how they are normalised to avoid data duplication, to avoid multiple values in a single field, and to avoid the storage of calculated results.

b) Table and field names based on a consistent convention so that coding will not be held back by "what did we call that field" or confusion between multiple fields of the same name.

c) Deciding the data types for the central fields early on, and allowing for additional fields to be added easily into each table, preferably getting most of them specified and 'in' early on.

Although each table has an auto_increment id field, we specified record IDs manually in our test data, using a different range of integers for each of the id sets. Thus, the categories of course are numbered from 200 upwards, individual courses from 300 upwards. This is purely for early 'Spike solution' testing so that we can easily see and work through the database logic; come the live system, they'll all start automatically at 1.

I hope to be able to bring you updates on this project from time to time, and perhaps to be a consumer myself in the (not too distant) future - I know it is something I would use if easily available here in Melksham. And it's good to be reminded that the chapter in our Perl Programming Course that's headed "Design Matters" is actually capitalised / styled as "Design MATTERS" - in other words, remember the importance of getting the specification right to begin with!
(written 2009-08-08)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
Q101 - Object Orientation and General technical topics - Programming Principles
  [4645] What are callbacks? Why use them? An example in Python - (2016-02-11)
  [4632] Remember to ask the question before you listen for the answer - (2016-01-26)
  [4611] Hungarian, Camel, Snake and Kebab - variable naming conventions - (2016-01-03)
  [4325] Learning to program - what are algorithms and design patterns? - (2014-11-22)
  [4206] Writing the perfect program in Tcl? - (2013-11-13)
  [4153] Rooms available tonight - how to code an algorithm from first principles - (2013-08-19)
  [4118] We not only teach PHP and Python - we teach good PHP and Python Practice! - (2013-06-18)
  [4090] Test Driven Development in Python - Customer Comes First - (2013-05-16)
  [4061] Seamless, integrated IT - we have a long way to go! - (2013-04-11)
  [4003] Web and console - same principle, same code - Ruby example - (2013-02-14)
  [3954] Lesson 1 in programing - write clean, reuseable and maintainable tidy code - (2012-12-16)
  [3928] Storing your intermediate data - what format should you you choose? - (2012-11-20)
  [3878] From Structured to Object Oriented Programming. - (2012-10-02)
  [3673] Object oriented or structured - a comparison in Python. Also writing clean regular expressions - (2012-03-26)
  [3551] Some terms used in programming (Biased towards Python) - (2011-12-12)
  [3548] Dark mornings, dog update, and Python and Lua courses before Christmas - (2011-12-10)
  [3542] What order are operations performed in, in a Perl expression? - (2011-12-07)
  [3456] Stepping stones - early coding, and writing re-usable code quickly - (2011-09-24)
  [3026] Coding efficiency - do not repeat yourself! - (2010-11-02)
  [2964] An introduction to file handling in programs - buffering, standard in and out, and file handles - (2010-09-21)
  [2915] Looking up a value by key - associative arrays / Hashes / Dictionaries - (2010-08-11)
  [2878] Program for reliability and efficiency - do not duplicate, but rather share and re-use - (2010-07-19)
  [2769] Easy - but for whom? - (2010-05-18)
  [2737] Improving your function calls (APIs) - General and PHP - (2010-04-24)
  [2586] And and Or illustrated by locks - (2010-01-17)
  [2550] Do not copy and paste code - there are much better ways - (2009-12-26)
  [2510] The music of the stock market - (2009-11-22)
  [2415] Variable names like i and j - why? - (2009-09-22)
  [2310] Learning to write high quality code in Lua - (2009-07-30)
  [2228] Where do I start when writing a program? - (2009-06-11)
  [2022] Pre and post increment - the ++ operator - (2009-02-03)
  [2001] I have not programmed before, and need to learn - (2009-01-19)

Q904 - Object Orientation and General technical topics - Analysing a Programming Task
  [3895] Flowchart to program - learning to program with Well House - (2012-10-14)
  [3461] From flowchart to program - code design for the newcomer - (2011-09-29)
  [3366] Specification, Design, Implementation, Testing and Documentation - stages of a (Java) programming project - (2011-07-21)
  [3329] Perl from basics - (2011-06-20)
  [2834] Teaching examples in Perl - third and final part - (2010-06-27)
  [2715] Uploading an image, document or pdf via a browser (php) - (2010-04-10)
  [1853] Well structured coding in Perl - (2008-10-24)
  [1850] Daisy the Cow and a Pint of Ginger Beer - (2008-10-21)
  [1607] Learning to program in Perl - (2008-04-11)
  [1513] Perl, PHP or Python? No - Perl AND PHP AND Python! - (2008-01-20)
  [1345] Perl and Shell coding standards / costs of an IT project - (2007-09-11)
  [747] The Fag Packet Design Methodology - (2006-06-06)

Q907 - Object Orientation and General technical topics - Object Orientation: Design Techniques
  [4628] Associative objects - one object within another. - (2016-01-20)
  [4449] Spike solution, refactoring into encapsulated object methods - good design practise - (2015-03-05)
  [4430] The spirit of Java - delegating to classes - (2015-02-18)
  [4374] Test driven development, and class design, from first principles (using C++) - (2014-12-30)
  [4098] Using object orientation for non-physical objects - (2013-05-22)
  [3978] Teaching OO - how to avoid lots of window switching early on - (2013-01-17)
  [3887] Inheritance, Composition and Associated objects - when to use which - Python example - (2012-10-10)
  [3844] Rooms ready for guests - each time, every time, thanks to good system design - (2012-08-20)
  [3798] When you should use Object Orientation even in a short program - Python example - (2012-07-06)
  [3763] Spike solutions and refactoring - a Python example - (2012-06-13)
  [3760] Why you should use objects even for short data manipulation programs in Ruby - (2012-06-10)
  [3607] Designing your application - using UML techniques - (2012-02-11)
  [3454] Your PHP website - how to factor and refactor to reduce growing pains - (2011-09-24)
  [3260] Ruby - a training example that puts many language elements together to demonstrate the whole - (2011-04-23)
  [3085] Object Oriented Programming for Structured Programmers - conversion training - (2010-12-14)
  [3063] Comments in and on Perl - a case for extreme OO programming - (2010-11-21)
  [2977] What is a factory method and why use one? - Example in Ruby - (2010-09-30)
  [2953] Turning an exercise into the real thing with extreme programming - (2010-09-11)
  [2889] Should Python classes each be in their own file? - (2010-07-27)
  [2865] Relationships between Java classes - inheritance, packaging and others - (2010-07-10)
  [2785] The Light bulb moment when people see how Object Orientation works in real use - (2010-05-28)
  [2747] Containment, Associative Objects, Inheritance, packages and modules - (2010-04-30)
  [2741] What is a factory? - (2010-04-26)
  [2717] The Multiple Inheritance Conundrum, interfaces and mixins - (2010-04-11)
  [2523] Plan your application before you start - (2009-12-02)
  [2501] Simples - (2009-11-12)
  [2380] Object Oriented programming - a practical design example - (2009-08-27)
  [2170] Designing a heirarcy of classes - getting inheritance right - (2009-05-11)
  [2169] When should I use OO techniques? - (2009-05-11)
  [1538] Teaching Object Oriented Java with Students and Ice Cream - (2008-02-12)
  [1528] Object Oriented Tcl - (2008-02-02)
  [1435] Object Oriented Programming in Perl - Course - (2007-11-18)
  [1224] Object Relation Mapping (ORM) - (2007-06-09)
  [1217] What are factory and singleton classes? - (2007-06-04)
  [1047] Maintainable code - some positive advice - (2007-01-21)
  [836] Build on what you already have with OO - (2006-08-17)
  [831] Comparison of Object Oriented Philosophy - Python, Java, C++, Perl - (2006-08-13)
  [656] Think about your design even if you don't use full UML - (2006-03-24)
  [534] Design - one name, one action - (2005-12-19)
  [507] Introduction to Object Oriented Programming - (2005-11-27)
  [236] Tapping in on resources - (2005-03-05)
  [80] OO - real benefits - (2004-10-09)


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This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

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