Richard rodger technical debt - web summit 2013

Falling in Love withTechnical Debt

@rjrodger

senecajs.org

Tuesday 5 November 2013

How did theRomans do

Long Division?Tuesday 5 November 2013

LXXII MMMDCXIIL rem XII


How did theRomans doAddition?


IV + XI = ?


1. Normalize: IV → IIII2. Concatenate: IIII + XI → IIIIXI3. Sort, descending: IIIIXI → XIIIII4. Reduce: XIIIII → XV

IV + XI = ?



Subtraction?Tuesday 5 November 2013

XXIV - XV = ?


1. Normalize: XXIV → XXIIII2. Eliminate: XXIIII - XV → XIIII - V3. Expand: XIIII - V → VIIIIIIIII - V4. Repeat 2 and 3 until no moves left5. Reduce: IIIIIIIII → IX

XXIV - XV = ?



Multiplication?Tuesday 5 November 2013

III × VI = ?


III × VI = ?bit shifting


III → 3VI → 6 → 110

III × VI = ?bit shifting


III → 3VI → 6 → 110

III × VI = ?

3 × 001 × 0 = 03 × 010 × 1 = 63 × 100 × 1 = 12 18

bit shifting


III → 3VI → 6 → 110

III × VI = ?

3 × 001 × 0 = 03 × 010 × 1 = 63 × 100 × 1 = 12 18

bit shifting


III → 3VI → 6 → 110

III × VI = ?

3 × 001 × 0 = 03 × 010 × 1 = 63 × 100 × 1 = 12 18

bit shifting


How did theRomans doDivision?



they didn't



Roman Numerals have

Technical DebtTuesday 5 November 2013

http://akvo.org/blog/the-ball-of-mud-transition/





The JavaScript Date Object

var today = new Date( 2013, 10, 30)console.log(today)

Sat Nov 30 2013 00:00:00 GMT+0000


Not allTechnical Debt

is created equalTuesday 5 November 2013

"A good plan, violently executed now,is better than a perfect plan next week."

Intentional


Unintentional


Inherent


Incidental


2x2 Matrix!

deliberate choice live with it

you are a bad person

unknown unknowns

intentional

unintentional

incidental inherent





NTSC 1941 Standard:

Black+White onlySignal encodes BrightnessEach Channel gets 6Mhz

Happy Days!


Color TelevisionThree Colors: Red, Green, Blue

Each Color needs 3MhzYou only have 6Mhzand you need 9Mhz!

Technical Debt FTW


You can't Break theold Black+White TVs


We must send the old brightness signal

White Light =30% Red

59% Green11% Blue

Send White, Red and Blue


You need to embed the color signals inside

the brightness signal


Color TV circuits aremore complicated

than they should be.


How do you ReduceTechnical Debt?


Things thatDon't Work


Unit Testing(or any other sort)


Objects


Design


Process


Mitigation As Good as it Gets


Conform


Rebel


Evolve


•Do one job•Death is natural•Use messages

•Really small

Cells


•Do one job•Death is natural•Use messages

•Really small

Micro Services•One feature•kill and restart•No shared state

•100 lines of code


ExamplesUser Data

Encrypt Password

Image Resize

SendEmail

Business Rule

Monitor

ParseFormat


how do you route messages?

Pattern MatchingTuesday 5 November 2013

// load a user's data by name{ user:"load", name:"alice" }

// login user - load and check password{ user:"login", name:"alice", pass:"123"}

The user Service

some messages

github.com/rjrodger/websummit2013senecajs.org


var users = { alice: {name:"alice", pass:"123"}, bob: {name:"bob", pass:"abc"},}

function user_load( args, done ) { // callback( err, result ) done( null, users[args.name] ) }

user_load action


function user_login( args, done ) { user_load( { name:args.name }, function(err,user){ if( err || !user ) return done(err);

if( user.pass == args.pass ) return done( null, user );

return done(); })}

user_login action


require("seneca")() .add({ user:"load" }, user_load) .add({ user:"login" }, user_login) .listen(8000)

$ node user.js

$ curl "http://localhost:8000/act ? user=login & name=alice & pass=123"

{ "name":"alice", "pass":"123" }

Run user Service using Seneca


http://localhost:8000/act?user=login&name=alice&pass=123&




•Easy to change - just rewrite!•Easy to scale - run more instances•Easy to reason about - just messages•Easy to make robust - kill and restart!•Easy to build - natural units of work

What Happens?


Technical Debt?lower interest rate!

See github forscaling and adapting

github.com/rjrodger/websummit2013senecajs.org


•Java: twitter.github.io/finagle•Ruby: sinatrarb.com•Node: senecajs.org

Try this at Home!


Technical Debt•overwhelms every other factor•should drive your architecture•can be mitigated with awareness



Thank You!@rjrodger

senecajs.org


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Richard rodger technical debt - web summit 2013

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