RE: [wsdm] MUWS - 2.1.2 Message Exchange Patterns

["Dan Foody" <dan@actional.com>]

Hi Sanjeev,

Even with keep-alive, I believe HTTP 1.1 is still a request-response
protocol (the server cannot send unsolicited messages to the client).
So, you can't use an HTTP 1.1 connection for asynchronous traffic.  In
any case, I don't know of any SOAP stacks that could take advantage of
this even if it were allowed behavior.

Cheers.

--
Daniel M. Foody
CTO, Actional Corporation
701 N. Shoreline Blvd. 
Mountain View, CA  94043 

http://www.actional.com


> -----Original Message-----
> From: Sanjeev Kumar [mailto:sakumar@attbi.com] 
> Sent: Wednesday, June 04, 2003 12:45 AM
> To: Geoff Bullen
> Cc: Wsdm (E-mail)
> Subject: Re: [wsdm] MUWS - 2.1.2 Message Exchange Patterns
> 
> 
> 
> Geoff, relevant points wrt co-existence with firewalls. More 
> details below.
> 
> Geoff Bullen wrote:
> > 
> > Hi all,
> > I remember as part of the discussion on this section it was 
> suggested 
> > that if we just specify that we need an asynchronous protocol, then 
> > you can implement the single request/reply concept on top 
> of this... 
> > so therefore you don't need to specify both. It is my 
> belief that we 
> > definitely need to specify a direct request/response 
> protocol.  There 
> > are a number of cases where using firewalls makes it quite 
> difficult 
> > to support asynchronous traffic (messages initiated from both
> > ends) rather than the simpler request/reply - where 
> messages are only 
> > initiated from one end.
> 
> I think, specifically, maintaining a well-known (inbound) 
> port on both sides and the connection being persistent should 
> make things more firewall friendly. If we take the case of 
> MUWS, then the inbound ports used across the firewall on 
> either end are most likely to be 80, and we can be explicit 
> about being able to work over HTTP1.1 and HTTP1.0 w/ 
> Conn:Keep-Alive. There is still the issue of initiation of 
> the connection, which typically should always be done from 
> inside the firewall. But async messages sent over HTTP should 
> not have this problem. [Correct me if my assumption is wrong here.]
> 
> > I am not suggesting we should not support async, but I think you 
> > should be able to create a management solution without it.
> 
> Well, if we are to support async, then we have to address 
> co-existence with firewalls. Given that the transport for WS 
> is HTTP, we will be at the mercy of the idiosychracies (sp?) 
> of this protocol wrt firewall-friendliness regardless of the 
> range of message semantics (sync, async, req-reply) that we address.
> 
> My $0.02!
> Sanjeev K.
> 
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