Re: [sca-j] NEW ISSUE: Composite Scoped components should be able toimplement Conversational interfaces

This interface is up to the database
implementer to determine.  It does not show through to the client
code.  One way to do this would be for the cursor to maintain positional
state in an optimized form, and use this to access the database across
non-published interfaces.  These interfaces would be stateless.

The principle above would be the same
whether the cursor is collocated with the client or with the database.
 The difference would be how much data is transmitted when the cursor
makes calls to the database.  For a cursor collocated with the client,
it would be desirable to cache more state in the cursor and transmit less
state over each call to the database.

Here's a simple graphic illustrating
the two approaches.

client ------------> cursor ------------> database

        local call    
      remote call

               
             (remotable interface)

client ------------> cursor ------------> database

        remote call    
     local call

               
             (local interface)

    Simon

Simon C. Nash, IBM Distinguished Engineer

Member of the IBM Academy of Technology

Tel. +44-1962-815156  Fax +44-1962-818999

Mike Edwards/UK/IBM@IBMGB

31/03/2008 18:11

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Re: [sca-j] NEW ISSUE: Composite Scoped
components should be able to implement Conversational interfaces

Simon, 

That wasn't the kind of answer I was looking for - whether the link between
those 2 components is local or remote isn't particularly significant, in
my opinion. 

I was asking what the interface looks like. 

Take the case of the cursor collocated with the client.  What kind
of interface does such a component have to have with the (composite scoped)

database service in order for it to work?  Is the interface stateful
- and if so, how? 

For the other case ("the cursor is located with the database"),
then surely the client must have some way of addressing the cursor when
it communicates 

with the composite database component?  What does that mean for the
interface....?  What is the significance of a local reference in this
case, btw? 

Yours,  Mike.

Strategist - Emerging Technologies, SCA & SDO.

Co Chair OASIS SCA Assembly TC.

IBM Hursley Park, Mail Point 146, Winchester, SO21 2JN, Great Britain.

Phone & FAX: +44-1962-818014    Mobile: +44-7802-467431  

Email:   

Simon Nash/UK/IBM@IBMGB

31/03/2008 17:31

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Re: [sca-j] NEW ISSUE: Composite Scoped
components should be able to implement Conversational interfaces

I'd expect it to be a local reference (if the cursor is collocated with
the database), or a remotable reference (if the cursor is collocated with
the client component).  An advantage of this two-component arrangement
is the ability to easily reconfigure between these approaches.

   Simon 

Simon C. Nash, IBM Distinguished Engineer

Member of the IBM Academy of Technology

Tel. +44-1962-815156  Fax +44-1962-818999 

Mike Edwards/UK/IBM@IBMGB

31/03/2008 15:32

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"OASIS Java" <>

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Re: [sca-j] NEW ISSUE: Composite Scoped
components should be able to implement Conversational interfaces

Simon, 

In the solution that you propose below, what would the link between the
conversation-scoped component (cursor) and 

the composite scoped component (database) look like?

Yours,  Mike.

Strategist - Emerging Technologies, SCA & SDO.

Co Chair OASIS SCA Assembly TC.

IBM Hursley Park, Mail Point 146, Winchester, SO21 2JN, Great Britain.

Phone & FAX: +44-1962-818014    Mobile: +44-7802-467431  

Email:   

Simon Nash/UK/IBM@IBMGB

31/03/2008 13:58

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Re: [sca-j] NEW ISSUE: Composite Scoped
components should be able to implement Conversational interfaces

Mike, 

For this use case, and assuming our current resolution to issue 12, isn't
a simple solution to have a conversation-scoped component representing
the cursor and a separate composite-scoped component representing the database?

Given that SCA can handle this so easily, I don't think it would be justified
to reverse the already agreed resolution to issue 12 and add the extra
complexity of defining how conversational interfaces work with non-conversation-scoped
implementations. 

 Simon 

Simon C. Nash, IBM Distinguished Engineer

Member of the IBM Academy of Technology

Tel. +44-1962-815156  Fax +44-1962-818999 

Mike Edwards/UK/IBM@IBMGB

31/03/2008 10:02

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[sca-j] NEW ISSUE: Composite Scoped
components should be able to implement Conversational interfaces

RAISER:  Mike Edwards 

TARGET:  Java Annotations and APIs Specification

DESCRIPTION: 

The resolution of Issue 12 means that a conversational interface can only
be implemented by a conversation scoped component:

http://www.osoa.org/jira/browse/JAVA-12

This restricts an important use case for composite scoped components -
no longer can composite scoped components provide

conversational interfaces. 

One major reason for having composite scoped components is that this covers
the case of components whose implementations

are expensive to initialize.  An example is an in-memory database
component where the loading of the data might take a

substantial amount of time - done order to make subsequent queries and
updates much faster. 

It may well be the case that it is desirable for such a composite scoped
component to be able to offer conversational interfaces

to its clients.  An example is for an in-memory database component
to offer an interface to clients which provides a cursor into

a large set of data and allow a series of requests to be issued using that
cursor.  It seems perverse for SCA to prevent the use

of these scenarios. 

PROPOSAL: 

Permit composite scoped components to implement conversational interfaces.

Yours,  Mike.

Strategist - Emerging Technologies, SCA & SDO.

Co Chair OASIS SCA Assembly TC.

IBM Hursley Park, Mail Point 146, Winchester, SO21 2JN, Great Britain.

Phone & FAX: +44-1962-818014    Mobile: +44-7802-467431  

Email:  

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Unless stated otherwise above:

IBM United Kingdom Limited - Registered in England and Wales with number
741598. 

Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6
3AU 

Unless stated otherwise above:

IBM United Kingdom Limited - Registered in England and Wales with number
741598. 

Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6
3AU 

Unless stated otherwise above:

IBM United Kingdom Limited - Registered in England and Wales with number
741598. 

Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6
3AU 

Unless stated otherwise above:

IBM United Kingdom Limited - Registered in England and Wales with number
741598. 

Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6
3AU 

Unless stated otherwise above:

IBM United Kingdom Limited - Registered in England and Wales with number
741598. 

Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6
3AU