From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-0.3 required=5.0 tests=BAYES_00,
	REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4
Path: 
 eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!mx02.eternal-september.org!feeder.eternal-september.org!aioe.org!.POSTED!not-for-mail
From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: ANN: Simple components v.4.3 released
Date: Sun, 23 Nov 2014 17:33:08 +0100
Organization: cbb software GmbH
Message-ID: <11qdtipniibky$.153zsecim7qpq.dlg@40tude.net>
References: <1shoxw3taj1h0$.3uygcqi194a8.dlg@40tude.net>
 <d5a2d07a-0e9a-4764-a755-9ed6e6109563@googlegroups.com>
Reply-To: mailbox@dmitry-kazakov.de
NNTP-Posting-Host: wfRpp7ltpEWhI2na6kgpfA.user.speranza.aioe.org
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
X-Complaints-To: abuse@aioe.org
User-Agent: 40tude_Dialog/2.0.15.1
X-Notice: Filtered by postfilter v. 0.8.2
Xref: news.eternal-september.org comp.lang.ada:23663
Date: 2014-11-23T17:33:08+01:00
List-Id: <comp.lang.ada>

On Sun, 23 Nov 2014 07:39:38 -0800 (PST), David Botton wrote:

>> - WebSockets integrated into the HTTP server. Both half-duplex and
>> full-duplex operating modes are supported.
> 
> Is half duplex mode part of the Websocket standard or just an
> implementation method in your code?

WebSocket is full-duplex in the sense that it allows full-duplex exchange.
AFAIK that was one of the reasons to introduce it, because HTTP is
half-duplex. But it is up to the server and the client to decide if they
actually do.

> What would be the advantages or
> reasons for choosing one mode over the other?

The advantage of a half-duplex exchange is that the server need not to
start an extra task or tasks. Therefore the server need not to protect its
state from concurrent access, since only one task can access it at the
time.

Being half-duplex is a property of the higher-level protocol and ultimately
of the application.

If the application is an echo server, the server only responds to the
client. This can be handled in the half-duplex mode.

If the application is a game when the server sends messages to the client
on real-time events then it must be full-duplex. E.g. a Tetris-game
implementation will use a full-duplex exchange.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de