Updated proposal for BINDINGS-96

[Simon Holdsworth <simon_holdsworth@uk.ibm.com>]

As per my other note and the discussion
on yesterday's call, I'm restating the proposal for resolution of issue
BINDINGS-96.

Overview:

Currently the spec says that request/response
operations which expect callbacks use JMSReplyTo for the response, and
scaCallbackDestination for the callback.  One-way operations which
expect callbacks use scaCallbackDestination for the callback and MAY also
use JMSReplyTo in case the target application doesn't understand scaCallbackDestination.
    There was some agreement that this flexibility is somewhat
confusing and asymetrical.  So the proposal is to simplify this behaviour
to leave request/response as-is, and change oneway so that JMSReplyTo is
always used (and not scaCallbackDestination).  This can be summarised
as:

• unidirectional oneway - don't set JMSReplyTo/ignore it
• unidirectional request/response - set JMSReplyTo/use it for responses
• bidirectional oneway - set JMSReplyTo/use it for callbacks
• bidirectional request/response - set JMSReplyTo and scaCallbackDestination/use JMSReplyTo for responses, scaCallbackDestination for callbacks.

Detail:

In order to resolve BINDINGS-96 in this
manner the updates would be as follows:

BJM60002 would need to be updated to
apply only to unidirectional services:

For an SCA service with a JMS binding
>> and unidirectional interface <<, when a request message
is received as part of a one-way MEP, the SCA runtime MUST ignore the JMSReplyTo
destination header in the JMS message, and not raise an error [BJM60002].

The words in section 6.4 would need
to be updated from:

Messages that correspond to one-way
or request/response operations on a bidirectional interface use either
the scaCallbackDestination user property or the JMSReplyTo destination,
or both, to identify the destination to which messages are to be sent when
operations are invoked on the callback interface.  

to:

Messages that correspond to one-way
or request/response operations on a bidirectional interface use either
the scaCallbackDestination user property (for request/reply) or the JMSReplyTo
destination (for one-way) to identify the destination to which messages
are to be sent when operations are invoked on the callback interface. 

BJM60011 needs to be specific to request/reply:

For an SCA reference with a JMS binding
and a bidirectional interface, when a request message is sent >>
as part of a request/response MEP << the SCA runtime MUST set the
destination to which callback messages are to be sent as the value of the
scaCallbackDestination user property in the message it creates [BJM60011].

BJM60012 needs changing to only apply
to one-way and not mention scaCallbackDestination, so change:

For an SCA reference with a JMS binding
and bidirectional interface, when a request message is sent the SCA runtime
MAY set the JMSReplyTo destination to the same value as the scaCallbackDestination
user property [BJM60012]. 

to

For an SCA reference with a JMS binding
and bidirectional interface, when a request message is sent as part of
a one-way MEP the SCA runtime MUST set the destination to which callback
messages are to be sent as the JMSReplyTo destination in the message it
creates [BJM60012]. 

In section 6.4.2 the definition needs
rewording from:

An SCA service with a callback interface
can invoke operations on that callback interface by sending messages to
the destination identified by the scaCallbackDestination user property
in a message that it has received, the JMSReplyTo destination of a one-way
message that it has received, or the destination identified by the service's
callback reference JMS binding. 
For an SCA service with a JMS binding,
the callback destination is identified as follows, in order of priority:
•        The
scaCallbackDestination identified by an earlier request, if not null;
•        the
JMSReplyTo destination identified by an earlier one-way request, if not
null;
•        the
request destination of the service’s callback reference JMS binding, if
specified

To:

An SCA service with a callback interface
can invoke operations on that callback interface by sending messages to
the destination identified by the scaCallbackDestination user property,
the JMSReplyTo destination or the destination identified by the service's
callback reference JMS binding. 
For an SCA service with a JMS binding,
the callback destination is identified as follows, in order of priority:
•        The
scaCallbackDestination identified by an earlier request/response operation,
if not null;
•        the
JMSReplyTo destination identified by an earlier one-way operation, if not
null;
•        the
request destination of the service’s callback reference JMS binding, if
specified




Simon Holdsworth
STSM, SCA Bindings Architect; Master Inventor; OASIS SCA Bindings TC Chair,
AT&T and Boeing Lab Advocate
MP 211, IBM UK Labs, Hursley Park, Winchester SO21 2JN, UK
Tel +44-1962-815059 (Internal 245059) Fax +44-1962-816898
Internet - Simon_Holdsworth@uk.ibm.com

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