DNS Web Service Discovery
draft-hallambaker-web-service-discovery-05
Network Working Group P. M. Hallam-Baker
Internet-Draft 13 January 2021
Intended status: Informational
Expires: 17 July 2021
DNS Web Service Discovery
draft-hallambaker-web-service-discovery-05
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
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 17 July 2021.
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Copyright (c) 2021 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
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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.
One difficulty that is frequently encountered in attempting to make
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