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
X-Google-Thread: 103376,ff1f0403676a2300
X-Google-NewGroupId: yes
X-Google-Attributes: gida07f3367d7,domainid0,public,usenet
X-Google-Language: ENGLISH,ASCII-7-bit
Received: by 10.180.103.197 with SMTP id fy5mr1565024wib.1.1344888197113;
        Mon, 13 Aug 2012 13:03:17 -0700 (PDT)
Path: 
 n2ni114448226win.0!nntp.google.com!goblin3!goblin2!goblin.stu.neva.ru!aioe.org!.POSTED!not-for-mail
From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Ada Networking (General/Design)
Date: Mon, 13 Aug 2012 22:03:16 +0200
Organization: cbb software GmbH
Message-ID: <19sij6rw9nhaa.164mz6sr816wk.dlg@40tude.net>
References: <1gfytw9o9pem2.1xvhednlaotb3$.dlg@40tude.net>
 <k0bjh2$kg$1@speranza.aioe.org>
Reply-To: mailbox@dmitry-kazakov.de
NNTP-Posting-Host: 9A8bJrx4NhDLcSmbrb6AdA.user.speranza.aioe.org
Mime-Version: 1.0
X-Complaints-To: abuse@aioe.org
User-Agent: 40tude_Dialog/2.0.15.1
X-Notice: Filtered by postfilter v. 0.8.2
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Date: 2012-08-13T22:03:16+02:00
List-Id: <comp.lang.ada>

On Mon, 13 Aug 2012 19:11:30 +0000 (UTC), tmoran@acm.org wrote:

>>>> If Ada provided higher level socket library with an integrated support of
>>>> protected objects and tasks...
>>>   What do you mean?
>>
>>The most difficult and unavoidable part about socket programming is
>>tasking. We need reader and writer tasks or else socket-select-driven
>>co-routines. The reader and writer parts have to communicate each other in
>>some intricate way because it is two tasks but one protocol state machine,
>>or one task and many state machines in the case of socket select. There is
>>the issue of blocking socket I/O non-abortable by Ada means. All this
> 
> The Claw.Sockets package has a simple Socket_Type with
>   procedure Open(Socket     : in out Socket_Type;  -- or Server_Type
>                  Domain_Name: in     String;  -- or Network_Address_Type
>                  Port       : in     Port_Type;
>                  Timeout    : in     Duration := 30.0);
> and Text_IO style Get/Put for Strings, Input/Output for streams, etc.
> It also has a non-blocking Async_Socket_Type with overridable
> When_Connect, When_Readable, etc routines, but I find using blocking
> sockets with tasks whose structure encodes the state machine is much
> simpler.  All the blocking socket routines allow a timeout parameter,

In an Ada friendly way they should be entry calls, with the semantics of
canceling the request when a timed entry call gets timed out. That is when
the socket is blocking:

    select
        Socket.Receive (Packet);
    or delay 10.0;  -- Failed to read
    or terminate; -- Yes I know, it is illegal to have terminate + delay
    end select;

Or maybe other way round, they should be "entry points" to which socket I/O
could call to.

For non-blocking I/O there should be a way to have a pseudo-task ran by the
events on the socket, rather than scheduled.

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