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Notification and Subscription for SLP (RFC3082)

IP.com Disclosure Number: IPCOM000005276D
Original Publication Date: 2001-Mar-01
Included in the Prior Art Database: 2001-Aug-20
Document File: 15 page(s) / 33K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

J. Kempf: AUTHOR [+2]

Abstract

The Service Location Protocol (SLP) provides mechanisms whereby service agent clients can advertise and user agent clients can query for services. The design is very much demand-driven, so that user agents only obtain service information when they specifically ask for it. There exists another class of user agent applications, however, that requires notification when a new service appears or disappears. In the RFC 2608 design, these applications are forced to poll the network to catch changes. In this document, we describe a protocol for allowing such clients to be notified when a change occurs, removing the need for polling.

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Network Working Group J. Kempf Request for Comments: 3082 J. Goldschmidt Category: Experimental Sun Microsystems

March 2001

Notification and Subscription for SLP

Status of this Memo

This memo defines an Experimental Protocol for the Internet community. It does not specify an Internet standard of any kind. Discussion and suggestions for improvement are requested. Distribution of this memo is unlimited.

Copyright Notice

Copyright (C) The Internet Society (2001). All Rights Reserved.

Abstract

The Service Location Protocol (SLP) provides mechanisms whereby service agent clients can advertise and user agent clients can query for services. The design is very much demand-driven, so that user agents only obtain service information when they specifically ask for it. There exists another class of user agent applications, however, that requires notification when a new service appears or disappears. In the RFC 2608 design, these applications are forced to poll the network to catch changes. In this document, we describe a protocol for allowing such clients to be notified when a change occurs, removing the need for polling.

1. Introduction

The Service Location Protocol (SLP) [1] provides a mechanism for service agent (SA) clients to advertise network services and for user agent (UA) clients to find them. The mechanism is demand-driven. UAs obtain service information by actively querying for it, and do not obtain any information unless they do so. While this design satisfies the requirements for most applications, there are some applications that require more timely information about the appearance or disappearance in the services of interest.

Ideally, these applications would like to be notified when a new service comes up or when a service disappears. In order to obtain this information with SLP as described in RFC 2608, such applications must poll the network to periodically refresh their local cache of available service advertisements.

Kempf Goldschmidt Experimental [Page 1]

RFC 3082 Notification and Subscription for SLP March 2001

An example of such a client is a desktop GUI that wants to display network service icons as soon as they appear to provide users with an accurate picture of all services available to them.

Because polling is inefficient and wasteful of network and processor resources, we would like to provide these applications a mechanism whereby they can be explicitly notified of changes. In this document, we describe a scalable mechanism allowing UAs to be notified of changes in service availability.

2. Notation Conventions

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [2].

3. Terminology

In this section, we present some additional terminology beyo...