Folks,
I tend to sympathise with Anish's view,
with the following motivation:
It is the Assembler of a composite who
makes decisions about the "local channels".
In my opinion, if the Assembler has
a local channel with no binding, then this is a statement of "privacy"
- only local components can produce/consume
events relating to that channel. However, it may be that
the Assembler decides to apply a specific
binding to the Channel, in which case the configuration of that
binding may be specifically designed
to allow events to flow to/from other components that might be using
that binding "directly" (eg
JMS queue).
However, this represents an explicit
decision of the Assembler,
akin to the Assembler choosing to configure
the reference of a component with a binding with a fully
resolved target service address. It
makes the composite less reusable, it makes assumptions about the
"outside world", but it may
well serve the purposes of the Assembler very well.
Yours, Mike
Dr Mike Edwards
Mail Point 146, Hursley
Park
STSM
Winchester, Hants SO21
2JN
SCA & Services
Standards
United Kingdom
Co-Chair OASIS SCA
Assembly TC
IBM Software Group
Phone:
+44-1962 818014
Mobile:
+44-7802-467431 (274097)
e-mail:
From:
Anish Karmarkar <>
To:
OASIS Assembly <>
Date:
01/02/2011 15:08
Subject:
[sca-assembly] Private or local channels
During last week's call Peter and I had a little bit
of back on forth in
the chat regarding private/local channels. I would like to start a
discussion on it on the ML before I file an issue (or not, depending on
the outcome of the discussion).
Peter has pointed out that line 2815 of our spec says:
"Channels within a composite used as an implementation are private
to
the components within that composite. These private channels can only be
the targets for producers existing within the same composite as the
channel. Private channels can only be sources for consumers existing
withing the same composite as the channel. An SCA runtime MAY support
the use of private channels "
Peter's interpretation of this is that composite channels are not
visible to components outside the composite *and* to anyone outside of
the SCA-world. I have a different interpretation of this. I don't think
our spec should talk about what things outside of SCA do or don't do. We
should allow for enough freedom wrt the technology use to implement the
channels. It could be an in-memory channel that is true invisible to
anyone outside the process or a JMS topic, which would have visibility
outside of SCA. We currently allow bindings on a composite channel; that
to me indicates that we intended to allow such variability. If folks
agree with my interpretation, I think we should change the wordings to
replace 'private' with 'local', so as not the give an incorrect impression.
Comments?
-Anish
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