RE: Clarification on HPACK dynamic table size increases?

Mike Bishop <Michael.Bishop@microsoft.com> Thu, 12 March 2015 23:52 UTC

Return-Path: <ietf-http-wg-request+bounce-httpbisa-archive-bis2juki=lists.ietf.org@listhub.w3.org>
X-Original-To: ietfarch-httpbisa-archive-bis2Juki@ietfa.amsl.com
Delivered-To: ietfarch-httpbisa-archive-bis2Juki@ietfa.amsl.com
Received: from localhost (ietfa.amsl.com [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id C84021A8850 for <ietfarch-httpbisa-archive-bis2Juki@ietfa.amsl.com>; Thu, 12 Mar 2015 16:52:32 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -6.912
X-Spam-Level:
X-Spam-Status: No, score=-6.912 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_HI=-5, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001, T_RP_MATCHES_RCVD=-0.01] autolearn=ham
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id xvaannfYp_nV for <ietfarch-httpbisa-archive-bis2Juki@ietfa.amsl.com>; Thu, 12 Mar 2015 16:52:31 -0700 (PDT)
Received: from frink.w3.org (frink.w3.org [128.30.52.56]) (using TLSv1.2 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id B7B611A884B for <httpbisa-archive-bis2Juki@lists.ietf.org>; Thu, 12 Mar 2015 16:52:31 -0700 (PDT)
Received: from lists by frink.w3.org with local (Exim 4.80) (envelope-from <ietf-http-wg-request@listhub.w3.org>) id 1YWCre-00054W-6s for ietf-http-wg-dist@listhub.w3.org; Thu, 12 Mar 2015 23:50:06 +0000
Resent-Date: Thu, 12 Mar 2015 23:50:06 +0000
Resent-Message-Id: <E1YWCre-00054W-6s@frink.w3.org>
Received: from maggie.w3.org ([128.30.52.39]) by frink.w3.org with esmtp (Exim 4.80) (envelope-from <Michael.Bishop@microsoft.com>) id 1YWCrX-0003Xo-5a for ietf-http-wg@listhub.w3.org; Thu, 12 Mar 2015 23:49:59 +0000
Received: from mail-bl2on0134.outbound.protection.outlook.com ([65.55.169.134] helo=na01-bl2-obe.outbound.protection.outlook.com) by maggie.w3.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.72) (envelope-from <Michael.Bishop@microsoft.com>) id 1YWCrS-0002bE-6F for ietf-http-wg@w3.org; Thu, 12 Mar 2015 23:49:59 +0000
Received: from BL2PR03MB129.namprd03.prod.outlook.com (10.255.230.20) by BL2PR03MB164.namprd03.prod.outlook.com (10.255.230.148) with Microsoft SMTP Server (TLS) id 15.1.106.15; Thu, 12 Mar 2015 23:49:27 +0000
Received: from BL2PR03MB132.namprd03.prod.outlook.com (10.255.230.24) by BL2PR03MB129.namprd03.prod.outlook.com (10.255.230.20) with Microsoft SMTP Server (TLS) id 15.1.106.15; Thu, 12 Mar 2015 23:49:26 +0000
Received: from BL2PR03MB132.namprd03.prod.outlook.com ([169.254.9.181]) by BL2PR03MB132.namprd03.prod.outlook.com ([169.254.9.181]) with mapi id 15.01.0106.007; Thu, 12 Mar 2015 23:49:27 +0000
From: Mike Bishop <Michael.Bishop@microsoft.com>
To: Daurnimator <quae@daurnimator.com>, "ietf-http-wg@w3.org" <ietf-http-wg@w3.org>
Thread-Topic: Clarification on HPACK dynamic table size increases?
Thread-Index: AQHQXRgSak+bgP3ueUGgkdlk9YSeX50Zg5KQ
Date: Thu, 12 Mar 2015 23:49:26 +0000
Message-ID: <BL2PR03MB13254980CFB31A76C197F9C87060@BL2PR03MB132.namprd03.prod.outlook.com>
References: <CAEnbY+fx3YSvpsEefP9u9=KXh2QaF=m+QdTXVzB8KKK91nacGA@mail.gmail.com>
In-Reply-To: <CAEnbY+fx3YSvpsEefP9u9=KXh2QaF=m+QdTXVzB8KKK91nacGA@mail.gmail.com>
Accept-Language: en-US
Content-Language: en-US
X-MS-Has-Attach:
X-MS-TNEF-Correlator:
x-originating-ip: [2001:4898:80e8:ed31::3]
authentication-results: daurnimator.com; dkim=none (message not signed) header.d=none;
x-microsoft-antispam: UriScan:; BCL:0; PCL:0; RULEID:; SRVR:BL2PR03MB129; UriScan:; BCL:0; PCL:0; RULEID:; SRVR:BL2PR03MB164;
x-forefront-antispam-report: BMV:1; SFV:NSPM; SFS:(10019020)(6009001)(13464003)(377454003)(46102003)(74316001)(19580395003)(19580405001)(122556002)(2950100001)(2900100001)(102836002)(92566002)(2501003)(77156002)(62966003)(40100003)(106116001)(107886001)(99286002)(54356999)(76176999)(50986999)(76576001)(2656002)(87936001)(33656002)(86612001)(86362001)(3826002); DIR:OUT; SFP:1102; SCL:1; SRVR:BL2PR03MB129; H:BL2PR03MB132.namprd03.prod.outlook.com; FPR:; SPF:None; MLV:sfv; LANG:en;
x-microsoft-antispam-prvs: <BL2PR03MB1299937EF422CFE32749E7E87060@BL2PR03MB129.namprd03.prod.outlook.com>
x-exchange-antispam-report-test: UriScan:;
x-exchange-antispam-report-cfa-test: BCL:0; PCL:0; RULEID:(601004)(5002009)(5005006); SRVR:BL2PR03MB129; BCL:0; PCL:0; RULEID:; SRVR:BL2PR03MB129;
x-forefront-prvs: 05134F8B4F
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: base64
MIME-Version: 1.0
X-MS-Exchange-CrossTenant-originalarrivaltime: 12 Mar 2015 23:49:26.9345 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL2PR03MB129
X-OriginatorOrg: microsoft.onmicrosoft.com
Received-SPF: pass client-ip=65.55.169.134; envelope-from=Michael.Bishop@microsoft.com; helo=na01-bl2-obe.outbound.protection.outlook.com
X-W3C-Hub-Spam-Status: No, score=-3.1
X-W3C-Hub-Spam-Report: AWL=-3.137, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001
X-W3C-Scan-Sig: maggie.w3.org 1YWCrS-0002bE-6F fff2ad0e893334ad6ef537083f705b94
X-Original-To: ietf-http-wg@w3.org
Subject: RE: Clarification on HPACK dynamic table size increases?
Archived-At: <http://www.w3.org/mid/BL2PR03MB13254980CFB31A76C197F9C87060@BL2PR03MB132.namprd03.prod.outlook.com>
Resent-From: ietf-http-wg@w3.org
X-Mailing-List: <ietf-http-wg@w3.org> archive/latest/28947
X-Loop: ietf-http-wg@w3.org
Resent-Sender: ietf-http-wg-request@w3.org
Precedence: list
List-Id: <ietf-http-wg.w3.org>
List-Help: <http://www.w3.org/Mail/>
List-Post: <mailto:ietf-http-wg@w3.org>
List-Unsubscribe: <mailto:ietf-http-wg-request@w3.org?subject=unsubscribe>

6.3 isn't saying that the value can only be reduced.  There is a maximum that the decompressor has said it's willing to allow the compressor, and the compressor is allowed to choose any value <= what the decompressor allows it.  The wording there could be cleaner, since there's a maximum table size, and a maximum value *for* the maximum table size.  :-(

-----Original Message-----
From: Daurnimator [mailto:quae@daurnimator.com] 
Sent: Thursday, March 12, 2015 3:53 PM
To: ietf-http-wg@w3.org
Subject: Clarification on HPACK dynamic table size increases?

I'm working on implementing HPACK, wanted clarification on whether the dynamic table can grow:

>From 4.2
> This mechanism can be used to completely clear entries from the dynamic table by setting a maximum size of 0, which can subsequently be restored.

However, 6.3 has a MUST that the table may only be reduced in size:
> The new maximum size MUST be lower than or equal to the last value of the maximum size of the dynamic table.


Regards,
Daurn.