Hi, i would like to suggest classifying engine errors (VdcBllMessages) using these categories: 100-199. entity not found 200-300. missing parameters 300-399. no resources available 400-499. can't perform - user error 500-599. can't perform - server error 600-699. Unauthorized 700-x. Forbidden this way rest api will be able mapping them to HTTP errors e.g any error returned by engine CAN_DO_ACTION 100 < x < 200 will be converted to HTTP 404 with CAN_DO_ACTION message detail - this can be easily done by assigning id to each VdcBllMessages enum member in range of one of mentioned categories. -- Michael Pasternak RedHat, ENG-Virtualization R&D -- Michael Pasternak RedHat, ENG-Virtualization R&D