CQS, CQRS, MVC, HTTP

CQS

Asking a question should not change the answer

http://en.wikipedia.org/wiki/Command-query_separation

class ProductService
{
    public function getProduct($id)
    {
        if (!$this->_productRepository->has($id)) {
            $this->_productRepository->create($id);
        }
        return $this->_productRepository->get($id);
    }
}

class ProductService
{
    public function getProduct($id)
    {
        if (!$this->_productRepository->has($id)) {
            throw new NotFoundException();
        }
        return $this->_productRepository->get($id);
    }
    
    public function createProduct($id, $data)
    {
        $this->_productRepository->create($id, $data);    
    }
}

CQRS

Command Query Responsibility Segregation

CQRS Definition?

... see CQS

NOT CQRS

CQRS

MVC

MVC

HTTP

• GET, HEAD - safe; don't change state
• POST, PUT, DELETE - unsafe; change system state

Server MVC

Wrong

Server MVC 2

Wrong

Proper Server MVC + HTTP

Proper SeRVER MVC + HTTP + CQRS