UserAuthenticateHandler handles an incoming request with three query parameters: username, password, and (optional) token.

UserChangPasswordHandler handles an incoming PUT request of url /users/:id/password with three query parameters: newpassword and (optional) token, oldpassword.

UserChangRoleHandler handles an incoming PUT request of url /users/:id/role with two query parameters: role and (optional) token.

UserGETHandler handles an incoming GET request of url /users/:id with one optional query parameter: token.

UserProfileHandler handles an incoming request with one optional query parameter: token.

UserPUTHandler handles an incoming PUT request of url /users/:id with three optional query parameters: token, age, gender.

UserRegisterHandler handles an incoming request with four query parameters: username, password, and (optional) token, role.