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Message-ID: <45D21B36.6010601@cs.indiana.edu>
Date: Tue, 13 Feb 2007 15:10:30 -0500
From: Aleksander Slominski <aslom@cs.indiana.edu>
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To: synapse-dev@ws.apache.org
CC: axis-user@ws.apache.org
Subject: Re: asynchronous messaging question
References: <1171361480.4829.11.camel@eskdale.ncl.ac.uk>
 <88f5d710702131155t48291625h42a7657974d31d79@mail.gmail.com>
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Paul Fremantle wrote:
> Michele
>
> We (the Synapse team) have written a pure non-blocking HTTP transport
> for Axis2. Its currently in the Synapse repository, but we will check
> it into the core Axis2 SVN when its stable.
>
> However, I wanted to clear up the asynchronous model. This isn't a
> clear area by any means!
>
> The current Axis2 with Addressing is actually already asynchronous.
> What happens is that if the replyTo address is a real HTTP URL
> (useSeparateListener), then the client will start up a mini HTTP
> server. The service will respond instantly with an HTTP 202 OK
> (accepted message but not yet processed), and the HTTP connection will
> be closed. When the response is ready, the server will open a new
> connection to the client's HTTP server and pass the response over
> that.
>
> The reason we wrote the non-blocking transport is that we wanted to be
> asynchronous even in the case where WS-Addressing ISN'T being used. In
> other words, the client has an open socket to the server, but we
> didn't want to block a thread waiting for the socket.
hi Paul,

but that puts very high burden on server and TCP stack (assuming that
you modified kernel to allow more than usual 1000 socket per process)
and it is not robust in case when client needs to wait for response
longer than few minutes (i have example applications that use WSA to
wait for response for hours or days).

so what is the advantage of not using WSA?


>
> We looked at both Mina and AsyncWeb but AsyncWeb doesn't support a
> client model, so we based our code on the Jakarta HTTPCore project
> which also has NIO support.
>
> BTW Another truly asynchronous protocol we support is SMTP.
SMTP is exactly like WSA+SOAP+HTTP with non-anonymous ReplyTo - and as
history shows that seems to work very well ...

thanks,

alek
>
> Paul
>
> On 2/13/07, Michele Mazzucco <Michele.Mazzucco@ncl.ac.uk> wrote:
>> Hi all,
>>
>> the addressing module allows for asynchronous messaging. However the
>> used transport mechanisms are synchronous (at least tcp and http). Since
>> alternatives exist (e.g. [1, 2]), is there any future plan to take
>> advantage of fully asynchronous computation?
>>
>>
>> Thanks,
>> Michele
>>
>>
>> [1] http://mina.apache.org/index.html
>> [2] http://docs.safehaus.org/display/ASYNCWEB/Home
>>
>>
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>
>


-- 
The best way to predict the future is to invent it - Alan Kay


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