Symfony2 hold behavior when extending DefaultAuthenticationSuccessHandler - authentication

Question

I want to be able to login in my app via the usual login form and using AJAX directly sending the user/password to the login_check path.
The idea is when user access via AJAX return Response with code 200 or 400 depending if the login success or fails.
Looking at other threads I finally decide to extend the default handlers DefaultAuthenticationSuccessHandler and DefaultAuthenticationFailureHandler to achieve this, export as services and specify in the success_handler property in my secure area.
File service.yml
services:
authentication.success_handler:
class: %mycustom.authentication.success_handler.class%
arguments: ['#security.http_utils', {} ]
public: false
tags:
- { name: 'monolog.logger', channel: 'security' }
authentication.failure_handler:
class: %mycustom.authentication.failure_handler.class%
arguments: ['#http_kernel', '#security.http_utils', {}, '#logger' ]
public: false
tags:
- { name: 'monolog.logger', channel: 'security' }
File security.yml
secured_meems_area:
pattern: ^/somrurl/
form_login:
login_path: /somrurl/login
check_path: /somrurl/api/login_check
success_handler: authentication.success_handler
failure_handler: authentication.failure_handler
require_previous_session: false
All this seems to work, except the behaviour of my extendend handler isn't like the original one. In the default implementation used by Symfony if you access a page/A and you are not logged on, Symfony redirects to the login page and after it you are redirected again to page/A. But this not occurs with my extended handler.
To solve it, I can specify a default_target_path when registering the handler as a service, but I want to understand why it doesn't follow the "normal" behavior.
Any ideas out there.
Thanks in advance.
SOLUTION !!!
After looking and test I found a solution here Symfony2 extending DefaultAuthenticationSuccessHandler
The idea is override the default symfony success/failure handlers instead of define my own and apply in the security.yml file.
File security.yml
secured_meems_area:
pattern: ^/somrurl/
form_login:
login_path: /somrurl/login
check_path: /somrurl/api/login_check
#
# DON'T USE !!!
#
# success_handler: authentication.success_handler
# failure_handler: authentication.failure_handler
#
require_previous_session: false
File service.yml. (NOTE the security. in the service name)
services:
security.authentication.success_handler:
class: %mycustom.authentication.success_handler.class%
arguments: ['#security.http_utils', {} ]
public: false
tags:
- { name: 'monolog.logger', channel: 'security' }
security.authentication.failure_handler:
class: %mycustom.authentication.failure_handler.class%
arguments: ['#http_kernel', '#security.http_utils', {}, '#logger' ]
public: false
tags:
- { name: 'monolog.logger', channel: 'security' }
This way we are overriden the default implementation with our own and don't need to specify the handlers in the security area.