fos_rest.yml

# config.yml
fos_rest:
    format_listener:
        rules:
          - { path: ^/, priorities: [ json, xml, html ], fallback_format: ~, prefer_extension: false }
    view:
        view_response_listener: force

sensio_framework_extra:
    view:    { annotations: false }
    router:  { annotations: true }
    
# routing.yml
products:
    type:     rest
    resource: Acme\StoreBundle\Controller\RestController
    defaults: {_format: json}
    prefix: /api