Enough suffering, fix your architecture!

Luís Cobucci 
@lcobucci
fix your architecture!
Enough suffering,

Inexperience and
lack of discipline

“ does it
have to be
hard ?Frederik Brooks
No Silver Bullet - 1986

Complexity
essential accidental

“ I need a scalable
API that stores and
retrieves the medical
history of patients in
order to help doctors
create an accurate
diagnosis
The client

“ Woe is the architect
who prematurely
decides on a database,
and then finds that flat
files would have been
sufficient.
Robert C. Martin

BCE
DCI
Onion
architecture
Hexagonal
architecture
Clean
architecture

“ To communicate
effectively, the code must be
based on the same language
used to write the
requirements — the same
language that the developers
speak with each other and
with domain experts.
Eric Evans

USER INTERFACE
APPLICATION
DOMAIN
INFRA

USER INTERFACE
APPLICATION
DOMAIN
INFRA
Request
model

USER INTERFACE
APPLICATION
DOMAIN
INFRA
Response
model

USER INTERFACE
APPLICATION
DOMAIN
INFRA
HTML/JSON/*

function createBook( 
Isbn $isbn, 
Author $author, 
string $title 
): Book { 
$book = new Book($isbn, $author, $title); 
 
$this->collection->add($book); 
 
return $book; 
}

Isbn $isbn, 
Author $author, 
string $title 
): void { 
$this->collection->add( 
new Book($isbn, $author, $title) 
); 
} 
 
function findBook(Isbn $isbn): ?Book 
{ 
return $this->collection->find($isbn); 
}

Isbn $isbn, 
Author $author, 
string $title 
): void { 
); 
} 
 
{ 
}
Command 
method

Isbn $isbn, 
Author $author, 
string $title 
): void { 
); 
} 
 
{ 
}
Command 
method
Query 
method

Command Query
Responsibility Segregation

Isbn $isbn, 
Author $author, 
string $title 
): void { 
$this->library->add( 
); 
} 
 
function findBook(Isbn $isbn): ?BookModel 
{ 
return $this->inventory->find($isbn); 
}

Isbn $isbn, 
Author $author, 
string $title 
): void { 
); 
}

Isbn $isbn, 
Author $author, 
string $title 
): void { 
); 
}
Intent

Isbn $isbn, 
Author $author, 
string $title 
): void { 
); 
}
Intent
Data

Isbn $isbn, 
Author $author, 
string $title 
): void { 
); 
}
Intent
Data
Processing

Intent + Data = Message
class CreateBook 
{ 
private $isbn, $author, $title;
 
public function isbn(): Isbn {}
public function authorId(): AuthorId {}
public function title(): string {} 
}

function handle(CreateBook $message): void 
{ 
new Book( 
$message->isbn(), 
$this->authors->get($message->authorId()), 
$message->title() 
) 
); 
}

{ 
new Book( 
) 
); 
}
Message

{ 
new Book( 
) 
); 
}
Message
Processing

$serviceBus->handle( 
new CreateBook($isbn, $authorId, $title) 
);

“ One of our difficulties
will be the maintenance of
an appropriate discipline, so
that we do not lose track of
what we are doing
Alan Turing 1945

Enough suffering, fix your architecture!

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Enough suffering, fix your architecture!