On Sep 3, 2006, at 12:09 PM, Raymond Feng wrote:
Hi, Jim.
Here's a use case from the EMD spec as I mentioned before. A JCA
binding for SCA probably requires at least the operation-level
DataBinding support.
For JCA, EMD uses "ServiceDescription" to describe an
OutboundService or InboundService (in SCA term, Reference or
Service). Each "ServiceDescription" contains a list of
"FunctionDecription"s to describe the EIS functions. A
"FunctionDescription" has two "DataDescription"s, one for the input
and the other for the output. A "DataDescription" provides
DataBinding information for the EIS data transformation from SDO to
the EIS native format and vice versa.
So is it the case that the issue is not that different operations on
the same service could take completely different data binding types
(e.g. SDO, JAXB, XmlBeans) but that EMD as contributing to an
interface definition may decorate operations with additional
information about the input/output parameters? If this is correct,
the "databinding technology" (e.g. SDO) is the same for all
operations on the contract. There may be additional operation-level
metadata to deal with things such as parameters but that is the
concern of the data binding and IDL technology and not the runtime.
What I want to avoid are situations like a service author being able
to specify completely different databinding technologies within the
same service (or even among parameters on the same operation) since
they are only going to shoot themselves in the foot doing so.
Maybe I'm completely missing the point?
Jim
Thanks,
Raymond
----- Original Message ----- From: "Jim Marino"
<[EMAIL PROTECTED]>
To: <tuscany-dev@ws.apache.org>
Sent: Sunday, September 03, 2006 8:09 AM
Subject: Allow multiple databindings per service contract, was:
SCDL extensions to define data types for parameters and return value
I would like to understand the use cases better for why we need
to support multiple databindings per service contract. Perhaps
they are marginal and could be accommodated by having a component
offer multiple services? If this is the case, I would prefer we
follow Jervis' recommendation and simplify things to one
databinding per service contract. Such use cases could be
important so if anyone has examples, please share them.
Jim
Begin forwarded message:
From: Jim Marino <[EMAIL PROTECTED]>
Date: August 29, 2006 10:08:08 PM PDT
To: tuscany-dev@ws.apache.org
Subject: Re: SCDL extensions to define data types for parameters
and return value
Reply-To: tuscany-dev@ws.apache.org
On Aug 29, 2006, at 1:55 PM, Raymond Feng wrote:
Hi,
I agree with you that only one databinding will be used for the
same interface for most cases.
I have a case that we need at least operation-level
databinding. For SCA reference/service with JCA bindings, we
need databindings to deal with the native EIS data format (for
example, CCI record) at "Interaction" level which usually maps
to an operation in the ServiceContract.
For your reference, there's EMD spec from IBM & BEA @ ftp://
www6.software.ibm.com/software/developer/library/j-emd/
EnterpriseMetadataDiscoverySpecification.pdf nad it talks about
DataBinding for SDO<-->EIS transformations.
Can you explain these use cases further?
Thanks,
Jim
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