Domain-Based Application Service Location Using SRV RRs and the Dynamic Delegation Discovery Service (DDDS)
RFC 3958

Network Working Group                                          L. Daigle
Request for Comments: 3958                                     A. Newton
Category: Standards Track                                 VeriSign, Inc.
                                                            January 2005

    Domain-Based Application Service Location Using SRV RRs and the
              Dynamic Delegation Discovery Service (DDDS)

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   This memo defines a generalized mechanism for application service
   naming that allows service location without relying on rigid domain
   naming conventions (so-called name hacks).  The proposal defines a
   Dynamic Delegation Discovery System (DDDS) Application to map domain
   name, application service name, and application protocol dynamically
   to target server and port.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.  Straightforward-NAPTR (S-NAPTR) Specification  . . . . . . . .  3
       2.1.  Key Terms. . . . . . . . . . . . . . . . . . . . . . . .  3
       2.2.  S-NAPTR DDDS Application Usage . . . . . . . . . . . . .  4
             2.2.1.  Ordering and Preference. . . . . . . . . . . . .  4
             2.2.2.  Matching and Non-matching NAPTR Records. . . . .  4
             2.2.3.  Terminal and Non-terminal NAPTR Records. . . . .  5
             2.2.4.  S-NAPTR and Successive Resolution. . . . . . . .  5
             2.2.5.  Clients Supporting Multiple Protocols. . . . . .  6
   3.  Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . .  6
       3.1.  Guidelines for Application Protocol Developers . . . . .  6
             3.1.1.  Registration of Application Service and
                     Protocol Tags. . . . . . . . . . . . . . . . . .  7
             3.1.2.  Definition of Conditions for Retry/Failure . . .  7
             3.1.3.  Server Identification and Handshake  . . . . . .  8
       3.2.  Guidelines for Domain Administrators . . . . . . . . . .  8

Daigle & Newton             Standards Track                     [Page 1]
RFC 3958                          DDDS                      January 2005

       3.3.  Guidelines for Client Software Writers . . . . . . . . .  8
   4.  Illustrations  . . . . . . . . . . . . . . . . . . . . . . . .  9
       4.1.  Use Cases  . . . . . . . . . . . . . . . . . . . . . . .  9
       4.2.  Service Discovery within a Domain  . . . . . . . . . . .  9
       4.3.  Multiple Protocols . . . . . . . . . . . . . . . . . . . 10
       4.4.  Remote Hosting . . . . . . . . . . . . . . . . . . . . . 11
       4.5.  Sets of NAPTR RRs  . . . . . . . . . . . . . . . . . . . 12
       4.6.  Sample Sequence Diagram  . . . . . . . . . . . . . . . . 13
   5.  Motivation and Discussion  . . . . . . . . . . . . . . . . . . 14
       5.1.  So Why Not Just SRV Records? . . . . . . . . . . . . . . 15
       5.2.  So Why Not Just NAPTR Records? . . . . . . . . . . . . . 15
   6.  Formal Definition of <Application Service Location>
       Application of DDDS  . . . . . . . . . . . . . . . . . . . . . 16
       6.1.  Application-Unique String  . . . . . . . . . . . . . . . 16
       6.2.  First Well-Known Rule  . . . . . . . . . . . . . . . . . 16
       6.3.  Expected Output  . . . . . . . . . . . . . . . . . . . . 16
       6.4.  Flags  . . . . . . . . . . . . . . . . . . . . . . . . . 16
       6.5.  Service Parameters . . . . . . . . . . . . . . . . . . . 17
             6.5.1.  Application Services . . . . . . . . . . . . . . 17
             6.5.2.  Application Protocols  . . . . . . . . . . . . . 17
       6.6.  Valid Rules  . . . . . . . . . . . . . . . . . . . . . . 17
       6.7.  Valid Databases  . . . . . . . . . . . . . . . . . . . . 18
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 18
       7.1.  Application Service Tag IANA Registry  . . . . . . . . . 18
       7.2.  Application Protocol Tag IANA Registry . . . . . . . . . 18
       7.3.  Registration Process . . . . . . . . . . . . . . . . . . 19
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 19
   9.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 20
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
       10.1. Normative References . . . . . . . . . . . . . . . . . . 21
       10.2. Informative References . . . . . . . . . . . . . . . . . 21