Proposed resolution to issue BINDINGS-44

This proposed resolution applies to
JMS binding spec cd01

Notes on this proposal:

I don't propose any new wireFormat or
operationSelector elements other than the jms.default ones.  That
would need to be done via a separate issue with justification required.
 Any additional standardised wireFormat elements would increase the
portability of JMS bindings, so long as they are actually usable in a reasonable
number of real-world scenarios. Two very common cases are likely to be
JMS text message to a single string parameter, and JMS bytes message to
a single byte[] parameter.  Do we think we should push to include
these (wireFormat.text, wireFormat.bytes, or possibly just wireFormat.singleValue)
in the standard?

We could replace the single default
jms wire format by two or three that describe the different cases, which
would then be more specific about what is supported...  wireformat.xml,
wireformat.jmsmessage

We could define explicitly in the wireFormat.jmsdefault
an attribute that defines the jms message type to be used when creating
messages to send, bytes or text.  e.g. <wireFormat.jmsdefault createdType="text
or bytes or dontCare"?> - not currently in the proposed
resolution.  Alternatively we could add a new attribute to the JMS
binding itself that defines the JMS message type of created messages, which
separates it from the wireFormat consideration.

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Move Section 2 down to section 5 and
reword as shown below.

Section 4:

Add the <wireFormat> and <operationSelector>
elements to the pseudo-schema within the <binding.jms> element.

Add a <wireFormat> element within
the <response> element 

Add descriptions of these elements to
the list below the pseudo-schema:

/binding.jms/wireFormat –
identifies the wire format used by requests and responses sent or received
by this binding.

/binding.jms/response/wireFormat
– identifies the wire format used by responses sent or received by this
binding.  This value overrides the wireFormat specifed
at the binding level. 

/binding.jms/operationSelector
– identifies the operation selector used when receiving requests for a
service.  If specified for a reference this provides the default operation
selector for callbacks if not specified via a callback service element.Rename
the nativeOperation attribute to selectedOperation:

/binding.jms/operationProperties/@selectedOperation
– The value generated by the operationSelector that corresponds
to the operation in the service or reference interface identified by the
operationProperties/@name attribute.  If this attribute
is omitted then the value defaults to the value of the operationProperties/@name
attribute.  The value of this attribute MUST be unique across the
containing binding.jms element.Update
description of the property element:

/binding.jms/operationProperties/property
– specifies properties specific to this operation.  These properties
are intended to be used to parameterize the wireFormat identified
for the binding for a particular operation.  The SCA runtime SHOULD
make the operationProperties element corresponding to the
selectedOperation available to the wireFormat implementation.Section
5: rename to "Operation Selectors and Wire Formats"

Insert before section 5.1 (text based
on what was in Section 2):

In general messaging providers deal with message
formats and destinations.  There is not usually a built-in concept
of “operation” that corresponds to that defined in a WSDL portType [WSDL].
 Messages have a format which corresponds in some way to the schema
of an input or output message of an operation in the interface of a service
or reference, however additional information is required in order for an
SCA runtime to know how to identify the operation and understand the format
of messages.

The process of identifying the operation to
be invoked is operation selection; the information that describes
the contents of messages is a wire format.  The binding
element as described in the SCA Assembly specification [ref needed] provides
the means to identify specific operation selection via the operationSelector
element and the format of messages received and to be sent using
the wireFormat element. The JMS binding defines a default
operation selector and wire format and the corresponding operationSelector
and wireFormat elements ; SCA providers may provide
additional such elements.

No standard means is provided for linking
the wireFormat or operationSelector elements
with the runtime components that implement their behaviour.

Section 5.1 "Default Operation Selector",
add the following paragraph:  "The
use of this operation selector can be explicitly specified in a binding.jms
using the <operationSelector.jmsdefault> element; if no operationSelector
element is specified then SCA runtimes MUST use this as the default."

Update the last paragraph: "An
SCA runtime SHOULD provide the means for identifying alternative
operation selectors via additional <operationSelector> elements."

Replace "native operation name"
with "selected operation value" throughout this section.

Section 5.2 "Default Data Binding",
rename to "Default Wire Format" and reword to that effect throughout;
add the following paragraph:

The use of this wire format can be explicitly
specified in a binding.jms using the <wireFormat.jmsdefault> element;
if no wireFormat element is specified then SCA runtimes MUST use this as
the default.

Update the last paragraph: "An
SCA runtime SHOULD provide the means for identifying alternative wire formats
to support any other type of JMS message via additional <wireFormat>
elements."

---------------------------------------------------------------

Simon Holdsworth

STSM, SCA Bindings Architect; Master Inventor; OASIS SCA Bindings TC Chair

MP 211, IBM UK Labs, Hursley Park, Winchester SO21 2JN, UK

Tel +44-1962-815059 (Internal 245059) Fax +44-1962-816898

Internet - 

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