RE: [asap] Re: rough draft using ws-addressing

[Keith Swenson <KSwenson@us.fujitsu.com>]

Title: RE: [asap] Re: rough draft using ws-addressing

Thanks John for incorporating the WS-Addressing things.

One of the design goals of ASAP was that an observer has a single address.  The idea is that a by storing a single address, you have everything you need.  "observers" can register to receive events, but this is for a single address for each observer, not a separate address for errors.   WS-Addressing outlines ways to send three addresses, but does not define very well what they are. 

wsa:ReplyTo - this is the address of the observer.  It MUST be included in any message that requires a response (and I think all of our messages require responses).  I think we should simply state that an ASAP compliant implementation MUST include a Reply-To in the header.

wsa:From - This is not well defined.  I would like to state that implementations of ASAP MUST ignore this header, and MUST NOT include it in any message.  In the response header, it is the "ReplyTo" that is required.  Note the subtle distinction: there is is no guarantee that you can send a message to the "From" address, which is why it is more or less useless.

wsa:FaultTo - Similarly, I would like to discourage this optional field.  We specify that errors are included in a response, and they must go back to the source (replyto) address.  The point is that the ASAP pattern has well defined resources, and there is no other well defined resource to which errors might be sent.  ASAP implementation do NOT need to remember this address.  The single ReplyTo address is all that needs to be recorded.  It is possible that for any given particular exchange, FaultTo could be used for that given exchange if there is a message, but there is no real need for this, and it adds complications to the implementations.  I would rather state that an ASAP compliant implementation MUST NOT use this header when sending, so that implementation never need to have the added logic to handle it.

as for the other header fields:

wsa:To - there is discussion over whether this will be required or not.  For ASAP, I feel this should be REQUIRED so that all implementations can count on it being there, incase the transport does not provide complete addressing.  An example is SMTP which has restrictive rules about addressing, but the address in the To field might be longer and include "query parameters" needed to identify the instance.

wsa:Action - this is a fixed value for each of our defined operations.  I don't care too much whether this is required or not.  I think it is completely redundant, because the fist tag within the body is exactly the same thing.  In fact, this value will be the exactly the same as combining the namespace url and the first tag within the body.  We should argue that this is unnecessary and redundant.  But if WS Addressing ends up deciding to make this required, then we should conform.

comments?

Keith D Swenson, < kswenson at us . fujitsu . com >
Fujitsu Software Corporation
1250 E. Arques Avenue, Sunnyvale, CA 94085
(408) 746-6276 mobile: (408) 859-1005

> -----Original Message-----
> From: John Fuller [mailto:jfuller@wernervas.com]
> Sent: Thursday, December 09, 2004 1:46 PM
> To: ASAP
> Subject: [asap] Re: rough draft using ws-addressing
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