DNS Web Service Discovery
draft-hallambaker-web-service-discovery-04

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Network Working Group                                 P. M. Hallam-Baker
Internet-Draft                                              27 July 2020
Intended status: Informational                                          
Expires: 28 January 2021

                       DNS Web Service Discovery
               draft-hallambaker-web-service-discovery-04

Abstract

   This document describes a standardized approach to discovering Web
   Service Endpoints from a DNS name.  Services are advertised using the
   DNS SRV and TXT records and the HTTP Well Known Service conventions.

   This document is also available online at
   http://mathmesh.com/Documents/draft-hallambaker-web-service-
   discovery.html.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 28 January 2021.

Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Definitions . . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
     2.2.  Defined Terms . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Service Discovery . . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  Host Identification . . . . . . . . . . . . . . . . . . .   4
       3.1.1.  SRV Host discovery  . . . . . . . . . . . . . . . . .   4
     3.2.  Service Description . . . . . . . . . . . . . . . . . . .   4
       3.2.1.  TXT Service and Host Description  . . . . . . . . . .   4
     3.3.  Service Selection . . . . . . . . . . . . . . . . . . . .   5
     3.4.  Web Service Endpoint Determination  . . . . . . . . . . .   5
     3.5.  DNS Fallback  . . . . . . . . . . . . . . . . . . . . . .   5
     3.6.  Example . . . . . . . . . . . . . . . . . . . . . . . . .   6
   4.  Further Work  . . . . . . . . . . . . . . . . . . . . . . . .   7
     4.1.  Additional Description Keys . . . . . . . . . . . . . . .   8
     4.2.  Service Scaling . . . . . . . . . . . . . . . . . . . . .   8
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
     6.1.  Well-Known URIs . . . . . . . . . . . . . . . . . . . . .   8
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   9
   8.  Informative References  . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   Web services are traditionally identified by means of a URI
   specifying a Web Service Endpoint (WSE).  This is approach is
   unsatisfactory in many situations:

   *  Specification of the Web Service requires the transport and
      presentation protocols to be fixed.

   *  The discovery mechanism does not provide support for load
      balancing or fault tolerance.

   *  The identifiers are unsuited for human interaction.

   The last consideration is a particular concern where an account
   identifier is exposed to the user.  Attempts to 'teach' users to use
   URIs as account identifiers have been predictably unsuccessful.
   Users expect and require accounts to be of the form user@example.com
   and not http://service.example.com/service/user.

   The Web Service discovery process described in this specification
   builds on the approach specified in DNS-Based Service Discovery
   [RFC6763].  This uses DNS SRV records as the basis for service
   discovery and TXT records as the basis for service description.  This

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   approach allows Web Services to make use of the load balancing and
   fault tolerance features of SRV and the service negotiation
   capabilities provided by the service description.