think horizontally @codemotion

Codemotion ROME

@bit_sharkAndrea Giuliano

Think horizontallydo not use lighters to open beers

Giulio De Donato

andreagiuliano.it welcometothebundle.com

@liuggio

11-12 april 2014

Think horizontally

@bit_shark @liuggio#codemotion

hint

We won't use technicisms and acronyms. Please see the references, we have had a lot of inspiration

thinking ideal


Given an application with certain requirements which is the technology that fit the application requirements?

thinking real


Given an application with certain requirements, I’m guru on Java I’ll use Java.

think too much… … at the same technology


What’s wrong here? I’m developing a tech-centric application

I’m fitting business requirements with technical boundaries

rethink to the origin


But what about our preferred technology? Was it the coolest? The most requested for working? Or trivially the simplest?

think about laziness


A developer should choose not the simplest tech

The developer laziness drive the developer to reuse its code!

different thoughts


A language can lack on some structural characteristic (polymorphism, strong typing)

think with ease


The success of a language is it’s distributability (cheap, easy, zero-conf)?

a thought for thought


There are successful application written in lacking languages

The success of the business make the success of the application

thinking relational


EAVthousand of libraries choose the relational model instead of schemaless • simplicity to distribute and install • even though some arguable tech detail

think to aim the success


nosql

Using the right technology in some cases could lead to a wrong choice

Shaggio theorem


Hypothesis: supposing a developer knows every technology and make a good choice for a complex application

Thesis: whatever will be the choice could be the wrong choice

…we are thinking to the app as a one big global ‘entity'

think modular@bit_shark @liuggio#codemotion

we want to split the application in as many as possible modules choosing the “right” technology for each module

think…


• Split the business needs in subsets… a subset could be composed by services... • Spit and conquer and Object Oriented Design • If you have to implement a complex system, don’t implement a complex

system, implement a lot of simple systems

think procedural


developing with procedural is misleading, at the beginning you feel powerful, fast…

think WTF!


• How many times you will modify the application, did you think about Maintenance costs? • Procedural is when you create a fast program (at the beginning) but difficult to maintain.

“Tragically, the very same forces that make it so easy to add new features to a brand new Rails application are the ones that start to hold you back as the number of features grows.” cit. Matt Wynne

think connected

TimeFeature

😊😁

😰🏃


think connected

TimeFeature

😊😁

😰🏃


• The procedural code is sick with a disease called "code connected” • Object-oriented programming is not immune • Time increases exponentially with the addition of new features.

think “Operation”


All the programs are difficult to maintain, but decoupled software is easier How to understand if my code is decoupled? If you modify here and you don’t break over there.

Time

Feature

think maintainability


TDD

Time

Feature

think maintainability


TDD

• Modularity is the main concept of Object Oriented Design • The trend has changed (90 years ago), now we have to focus on maintainability • The overhead of testing before code is smaller than you think and the real adding

value is the way you develop better your application

Think back to ‘89


responsability driven approach!SOLID principles

• R. Wirfs-Brock, B. Wilkerson, “Object-Oriented Design: A Responsibility-Driven Approach” • Single responsibility principle Uncle Bob • Create a module coupling things that changes together? • Modules that communicates, but how?

think tell don’t askMatt Wayne, Uncle Bob, Alec Sharp and Martin Fowler


think behaviour


dependency injection

• Modules that communicate via protocols • Modules that exhibit a behavior not their data • Data are the guts of the module, they must not be exposed • All the public functions are API, let's take care and give them a meaning. • Each module should have its own explicit dependencies

think and code


1. An employee has always a name and a salary!

2. The salary is always greater than zero!

3. A company could add an employee

think and code


1. An employee has always a name and a salary!2. The salary is always greater than zero!3. A company could add an employee


think invariant1. An employee has always a name and a salary!2. The salary is always greater than zero!3. A company could add an employee


think consistent1. An employee has always a name and a salary!2. The salary is always greater than zero!3. A company could add an employee


think business language

3. A company could hire an employee

1. An employee has always a name and a salary!2. The salary is always greater than zero!3. A company could add an employee

think behaviour not data


Bdd!specification

thinkBehaviour Driven Development


That's why with BDD (stories and specs) you are more forced not to test the application but you focus on describe the behaviors.

With BDD you tend to describes the behavior before coding, you specify what a function should do.

think behaviour defer implementation


think onion


hexagonalDatabase as implementation detail Framework as implementation detail

think to clean the Architecture

Application goal: separation of concerns Easy substitution of obsolete elements without affecting others components of the architecture

Andrea Giuliano @bit_shark

andreagiuliano.it

Giulio De Donato @liuggio

welcometothebundle.com

T h i n k y o u !Thank

References

https://farm3.staticflickr.com/2491/4193434786_306120fe90_b.jpg https://farm8.staticflickr.com/7185/13732796883_58bb40fae9_b.jpg https://farm8.staticflickr.com/7290/12859759305_51e8685d43_b.jpg https://www.flickr.com/photos/lovezonero/5304831965/sizes/l/ http://i.imgur.com/xl9v1on.jpg https://farm4.staticflickr.com/3404/3633209399_467123a6ca_o.jpg https://farm1.staticflickr.com/188/391815999_2725ca688c_b.jpg https://farm2.staticflickr.com/1116/1486403962_d055d8b1f9_o.jpg https://farm4.staticflickr.com/3055/2852526965_bee2642e0f_o.jpg

- Growing Object-Oriented Software by Guided by Tests, Steve Freeman, Nat Pryce - Implementing Domain-Driven Design by Vaughn Vernon - Unbreakable Domain Models by Mathias Verraes - Uncle Bob the clean Architecture http://blog.8thlight.com/uncle-bob/2012/08/13/the-clean-architecture.html - DDD community - Matt Wayne GoRuCo 2012 Hexagonal Rails by Matt Wynne - Implementing Domain-Driven Design with Spring and vFabric Wes Williams, Vaughn Vernon - The RSpec Book Behaviour-Driven Development with RSpec, Cucumber, and Friends

by David Chelimsky, Dave Astels, Zach Dennis, Aslak Hellesøy, Bryan Helmkamp, Dan North

- Alberto Brandolini http://www.slideshare.net/ziobrando/

https://farm6.staticflickr.com/5134/5449083311_9a856145fa_b.jpg https://farm3.staticflickr.com/2583/3752448573_4cc6a2698a_b.jpg https://farm4.staticflickr.com/3325/3420223723_2805816861_b.jpg https://farm1.staticflickr.com/118/313590022_25c580474c_b.jpg https://farm4.staticflickr.com/3274/2886945884_8dfa5d849f_b.jpg https://farm5.staticflickr.com/4013/4290367973_c58749d73f_b.jpg https://farm9.staticflickr.com/8327/8091221482_dce187e288_b.jpg https://farm1.staticflickr.com/48/108484055_b07800b7c7_b.jpg https://farm8.staticflickr.com/7115/7445550970_32ac507395_b.jpg

Assets

https://farm8.staticflickr.com/7115/7445550970_32ac507395_b.jpg

think horizontally @codemotion

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