Question

From all the tutorials I’ve read the service layer only seems to only have one or two methods in it so I am unsure whether services are only supposed to be lightweight/skinny as opposed to fat with as many methods as you need

If I have a Post domain object and have a PostService class is this what you are ment to do from within a controller if you wanted to delete a post:

$postService = $this->serviceFactory->build('post');
$postService->deletePost($id);

and the deletePost() method inside the PostService is something like:

$postMapper = $this->dataMapperFactory->build('post');
$post = $postMapper->fetchById($id);
// Check if the post exists
// Check if it belongs to this user
// Some other checks
$postMapper->delete($post);

Is that correct? Essentially are domain objects just value objects and all the work gets done in the service layers?

Any help would be great thanks.

Answer 1

It seems, that part of your problem is actually in the mappers. IMHO, mappers should not be responsible for creating the domain objects. So, your example code actually should look more like:

$mapper = $this->dataMapperFactory->build('post');
$post = $this->domainObjectFactory->build('post');

$post->setId( $id );
$mapper->fetch($post);
// Check if the post exists
// Check if it belongs to this user
// Some other checks
$postMapper->delete($post);

Also, most of those "other checks" are actually done on the domain object. For example:

if ( $post->belongsTo($user) )
{
    ...
}

The role of the service is "application logic", which is a term to describe interaction between domain objects and the mappers. It is also common that service interact with other services.

As a side-note

Having a PostService makes no sense to me. Service are supposed to represent major segments of domain business logic in the model layer.

• you have Recognition service instead of UserService and LoginService.
• you have Content service instead of DocumentService and CommentService and UserService

Oh.. and also, you to not need to add ..Service or ..Controller postfixes anymore. PHP has namespaces now.