code: function trigger_service_login (msg, respond) {
      var seneca = this
  
      if (!msg.user) {
        return respond(null, {ok: false, why: 'no-user'})
      }
  
      var user_data = msg.user
      var q = {}
      if (user_data.identifier) {
        q[msg.service + '_id'] = user_data.identifier
        user_data[msg.service + '_id'] = user_data.identifier
      }
      else {
        return respond(null, {ok: false, why: 'no-identifier'})
      }
  
      seneca.act("role: 'user', get: 'user'", q, function (err, data) {
        if (err) return respond(null, {ok: false, why: 'no-identifier'})
  
        if (!data.ok) return respond(null, {ok: false, why: data.why})
  
        var user = data.user
        if (!user) {
          seneca.act("role:'user',cmd:'register'", user_data, function (err, out) {
            if (err) {
              return respond(null, {ok: false, why: err})
            }
  
            respond(null, out.user)
          })
        }
        else {
          seneca.act("role:'user',cmd:'update'", user_data, function (err, out) {
            if (err) {
              return respond(null, {ok: false, why: err})
            }
  
            respond(null, out.user)
          })
        }
      })
    }
docs: LOGOUT END default service login trigger