HTTP Redirects in HTTP Adaptive Streaming
draft-finkelman-httpbis-has-redirecting-00

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Network Working Group                                       O. Finkelman
Internet-Draft                                                     Qwilt
Intended status: Informational                                  A. Begen
Expires: May 8, 2019                                     Networked Media
                                                        November 4, 2018

               HTTP Redirects in HTTP Adaptive Streaming
               draft-finkelman-httpbis-has-redirecting-00

Abstract

   This document motivates the need for clarifications of client
   behavior in cases of HTTP redirect to a content delivery network
   (CDN) when the redirected object contains relative references.  This
   document focuses on HTTP Adaptive Streaming (HAS) use cases, but it
   might be possible to generalize to other use cases.  The goal of this
   document is to present the current status of things and to explore
   potential solutions.

Status of This Memo

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   This Internet-Draft will expire on May 8, 2019.

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Finkelman & Begen          Expires May 8, 2019                  [Page 1]
Internet-Draft  HTTP Redirects in HTTP Adaptive Streaming  November 2018

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Glossary of Terms . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Current State of Things . . . . . . . . . . . . . . . . . . .   3
   4.  Objectives  . . . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Potential Solutions . . . . . . . . . . . . . . . . . . . . .   4
   6.  Examples and Interpretation of the Current RFCs . . . . . . .   5
     6.1.  Example 1: Absolute URI to Manifest . . . . . . . . . . .   6
     6.2.  Example 2: Relative Reference in an Encapsulating Entity    7
     6.3.  Example 3: Relative Reference with Redirect . . . . . . .   8
   7.  Conclusion  . . . . . . . . . . . . . . . . . . . . . . . . .   8
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   11. Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   9
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     12.1.  Normative References . . . . . . . . . . . . . . . . . .   9
     12.2.  Informative References . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   HTTP redirect, commonly using the "302 Found" response code, is
   widely used in Content Delivery Networks (CDN) for HTTP Adaptive
   Streaming (HAS), specifically for HTTP Live Streaming (HLS) [RFC8216]
   and Dynamic Adaptive Streaming over HTTP (DASH) [MPEG-DASH].  Using
   HTTP redirect rather than delegation by CNAME is a more powerful and
   flexible solution.

   At a high level, the required behavior from a HAS client is that
   after getting an HTTP redirect to a playlist address that takes the
   client to a CDN cache, if the playlist contains relative references
   to the media segments, the client should be 'sticky' and request the
   subsequent media segments directly from the cache without the need
   for repeated redirects, which naturally would add undesirable
   latency.  Unfortunately, in some cases, common misinterpretations of
   the RFC lead to wrong behavior of clients, while in other cases, this
   required behavior contradicts the HTTP RFC.  Thus, we are facing
   issues with streaming clients that behave differently under different
   use cases of HTTP redirects when relative references are in use
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