HTTP/2 Server Push Use Cases
draft-bishop-httpbis-push-cases-00

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Last updated 2018-06-29
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HTTPbis                                                        M. Bishop
Internet-Draft                                                    Akamai
Intended status: Informational                             June 28, 2018
Expires: December 30, 2018

                      HTTP/2 Server Push Use Cases
                   draft-bishop-httpbis-push-cases-00

Abstract

   HTTP/2 defines the wire mechanics of Server Push.  Though the
   mechanics of how a pushed resource is delivered are well-specified,
   the use cases that describe which resources can be pushed, in what
   states, and for what purpose are not described in HTTP/2.  As a
   result, support between implementations varies widely.

   This document attempts to enumerate interesting scenarios, in hopes
   that a more concrete taxonomy can assist the community in arriving at
   a standard set of supported scenarios.

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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   This Internet-Draft will expire on December 30, 2018.

Copyright Notice

   Copyright (c) 2018 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

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   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Types of Resources  . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Browser Scenarios . . . . . . . . . . . . . . . . . . . .   3
       2.1.1.  Static DOM contents . . . . . . . . . . . . . . . . .   3
       2.1.2.  Updated DOM contents  . . . . . . . . . . . . . . . .   4
       2.1.3.  Requests made by local script execution . . . . . . .   4
     2.2.  Non-Browser Scenarios . . . . . . . . . . . . . . . . . .   4
       2.2.1.  Subsequent API Requests . . . . . . . . . . . . . . .   4
       2.2.2.  Streaming APIs  . . . . . . . . . . . . . . . . . . .   4
   3.  Types of Pushes . . . . . . . . . . . . . . . . . . . . . . .   5
     3.1.  Pre-Satisfying Requests . . . . . . . . . . . . . . . . .   5
     3.2.  Cache Population  . . . . . . . . . . . . . . . . . . . .   5
     3.3.  Cache Revalidation  . . . . . . . . . . . . . . . . . . .   5
     3.4.  Cache Invalidation  . . . . . . . . . . . . . . . . . . .   6
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   5.  Informative References  . . . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   HTTP is fundamentally a request/response mechanism.  Each request
   specifies some action (often content retrieval) which the user agent
   wishes the server to perform on a resource and return the result of
   the action.

   However, when a response triggers a subsequent request, network and
   processing delays cause this subsequent request not to begin
   immediately.  The client must receive the initial response (0.5 RTT
   network delay), parse it and identify the next request
   (implementation- and page-dependent), then send the request back to
   the server (0.5 RTT network delay) before the server can begin to
   satisfy the request.

   Some mechanisms attempt to reduce the client processing time by
   enumerating important follow-up requests in HTTP headers or at the
   beginning of the response payload.  However, these techniques still
   incur at least 1 RTT of network delay before the server receives the
   subsequent request.  Depending on the distance between client and
   server, this delay might be significant.

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   HTTP/2 defines Server Push, a paradigm in which the server can also
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