Re: DR201, DR202 and DR203: Programming Language Bindings

I run an open source group (I've mentioned it on here before), we are 
working on a programming language that is an application of XML 
called:

XPL (eXtensible Programming Language)

We do happen to be looking for programmers of all types of different 
languages...so if anyone is interested; then follow the following 
URLs:

http://www.xplatypus.com/ (http://www.vbxml.com/xpl/)
http://www.egroups.com/group/xpl/
http://www.egroups.com/subscribe/xpl/

Michael Lauzon
XPL Group, Founder


> DR201,202 and 205 all relate to programming language bindings.
>
> 	DR 201 states "...There will be straightforward mappings of 
the
> data types used to a wide variety of widely deployed programming
> languages and object systems."
>
> I am concerned that we have some sense of canonical representation
> on the wire that has well understood semantics. It's not clear to
> me that the XP-WG will define language bindings for any particular
> programming languages... indeed I would advocated not. However,
> merely requiring the existence of "straightforward mappings" does
> not necessarily lead to a single mapping for a given programming
> language. I think the important thing is the representation and
> meaning of information on the wire rather than how that same
> information is represented by a particular language binding to a
> given programming language.
>
> 	DR 202 "The XML Protocol will allow applications to include
> custom encodings for data types used for parameters and results in
> RPC messages. Mechanisms for automatically binding data
> represented in RPC messages to native constructs in a programming
> language will not be precluded."
>
> This seems to be a statement of two requirements, one in each
> sentence. The first is a requirement to allow custom encodings for
> parameters and results. Given a need to define define meaning from
> an on the wire point-of-view, I am concerned about the
> interoperability issues that will arise through the 'rampant' use
> of custom encodings - will there be mechanisms that enable the
> initiator of an interaction to determine which (non-default)
> encoding to use in a request message?
>
> I would also be inclined to delete the second sentence of DR 202.
>
> 	DR203 "The XML Protocol will guarantee that RPC messages that
> encode parameters and results using the default encoding for the
> base set of data types will be valid for any conformant binding of
> the RPC conventions. "Valid" in this context means that the
> semantics of the call should remain identical, irrespective of the
> programming language or object system used by the caller or
> receiver."
>
> I share Noah's concern [1] that we define semantics from the
> point-of-view of what is represented on the wire and the need for
> clarity over the difference between 'programming language'
> bindings and 'transport protocol' bindings. On first reading I
> thought that this requirement was oriented around the preservation
> of programming language invocation semantics (in a distributed
> cross language environment) rather than the programming language
> independent semantics of the request and response XP messages. I
> think that this requirement could be re-worded to reflect a wire
> oriented view rather than a PL oriented view.
>
> Regards
>
> Stuart Williams
>
> [1]
> http://lists.w3.org/Archives/Public/xml-dist-app/2000Nov/0051.html

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