Re: [sca-assembly] Private or local channels

From
Mike Edwards <>
Date
2011-02-02T11:25:57+00:00
ID
Thread
Re: [sca-assembly] Private or local channels
Danny,

Can you explain in which way anyone
would be "treating one of the levels as special"?

I simply don't understand your comment.

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:
Danny van der Rijn <>

To:
Mike Edwards/UK/IBM@IBMGB

Cc:
OASIS Assembly <>

Date:
01/02/2011 19:16

Subject:
Re: [sca-assembly] Private or local
channels

I have to disagree again with your point of view, Mike.
 In a recursive decomposition model, you don't want to be counting
one one of the levels (the Assembler) to be special.  

On 2/1/2011 7:59 AM, Mike Edwards wrote: 

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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Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6
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