Application-Layer Traffic Optimization (ALTO) Incremental Updates Using Server-Sent Events (SSE)
RFC 8895
Internet Engineering Task Force (IETF) W. Roome
Request for Comments: 8895 Nokia Bell Labs
Category: Standards Track Y. Yang
ISSN: 2070-1721 Yale University
November 2020
Application-Layer Traffic Optimization (ALTO) Incremental Updates Using
Server-Sent Events (SSE)
Abstract
The Application-Layer Traffic Optimization (ALTO) protocol (RFC 7285)
provides network-related information, called network information
resources, to client applications so that clients can make informed
decisions in utilizing network resources. This document presents a
mechanism to allow an ALTO server to push updates to ALTO clients to
achieve two benefits: (1) updates can be incremental, in that if only
a small section of an information resource changes, the ALTO server
can send just the changes and (2) updates can be immediate, in that
the ALTO server can send updates as soon as they are available.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8895.
Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction
2. Terms
2.1. Requirements Language
3. Background
3.1. Incremental Encoding: JSON Merge Patch
3.1.1. JSON Merge Patch Encoding
3.1.2. JSON Merge Patch ALTO Messages
3.2. Incremental Encoding: JSON Patch
3.2.1. JSON Patch Encoding
3.2.2. JSON Patch ALTO Messages
3.3. Multiplexing and Server Push: HTTP/2
3.4. Server Push: Server-Sent Event
4. Overview of Approach and High-Level Protocol Message Flow
4.1. Update Stream Service Message Flow
4.2. Stream Control Service Message Flow
4.3. Service Announcement and Management Message Flow
5. Update Messages: Data Update and Control Update Messages
5.1. Generic ALTO Update Message Structure
5.2. ALTO Data Update Message
5.3. ALTO Control Update Message
6. Update Stream Service
6.1. Media Type
6.2. HTTP Method
6.3. Capabilities
6.4. Uses
6.5. Request: Accept Input Parameters
6.6. Response
6.7. Additional Requirements on Update Stream Service
6.7.1. Event Sequence Requirements
6.7.2. Cross-Stream Consistency Requirements
6.7.3. Multipart Update Requirements
6.8. Keep-Alive Messages
7. Stream Control Service
7.1. URI
7.2. Media Type
7.3. HTTP Method
7.4. IRD Capabilities & Uses
7.5. Request: Accept Input Parameters
7.6. Response
8. Examples
8.1. Example: IRD Announcing Update Stream Services
8.2. Example: Simple Network and Cost Map Updates
8.3. Example: Advanced Network and Cost Map Updates
8.4. Example: Endpoint Property Updates
8.5. Example: Multipart Message Updates
9. Operation and Processing Considerations
9.1. Considerations for Choosing Data Update Messages
9.2. Considerations for Client Processing Data Update Messages
9.3. Considerations for Updates to Filtered Cost Maps
9.4. Considerations for Updates to Ordinal Mode Costs
9.5. Considerations for SSE Text Formatting and Processing
10. Security Considerations
10.1. Update Stream Server: Denial-of-Service Attacks
10.2. ALTO Client: Update Overloading or Instability
10.3. Stream Control: Spoofed Control Requests and Information
Breakdown
11. Requirements on Future ALTO Services to Use This Design
12. IANA Considerations
12.1. application/alto-updatestreamparams+json Media Type
12.2. application/alto-updatestreamcontrol+json Media Type
13. Appendix: Design Decision: Not Allowing Stream Restart
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