[cap-talk] OO interoperation via OCap, presentation level issues

[Kevin Reid]

On May 8, 2008, at 13:47, Jed Donnelley wrote:
> On 5/8/2008 4:30 AM, Kevin Reid wrote:
>> ...
>> Note that VatTP as it is today will be going away when the Pluribus
>> implementation is rewritten in E; the encryption layer is to be
>> replaced with SSL. There will still be a layer on top, to support
>> delimited variable-length messages and PING messages.
>
> Doesn't that "layer on top" also have to distinguish serialized
> capabilities and other parameters with semantic meaning (e.g. strings,
> integers, etc.)?  I ask in case I might be focusing at the wrong  
> point.

No, CapTP handles that part.

Pluribus ~= CapTP . VatTP

VatTP-old = <custom stuff>
VatTP-new = <lighter custom stuff> . SSL

> Do you (Kevin) consider that "layer on top" to be a reasonable place
> for standardization that will allow interoperability between OCap
> languages and OSs?  If not, why not?

The relevant layer is CapTP (but if one is going to standardize, one  
should include the layers below it).

I don't see any serious reasons it shouldn't be usable by other  
languages, other than that it might require more of an 'E emulation  
layer' (to support the serialized objects, especially) than a  
hypothetical designed-for-interop protocol would.

However, such a generic protocol might well end up being less  
powerful than CapTP.

Note that CapTP needs some more design work to make it future-proof /  
capable of working robustly between different versions (specifically  
in definition of what the graph exits are for Data-E serialization,  
and possibly some versioning / 'do you support this' for future  
features); the results of that work may well make it more suitable  
for interop.

-- 
Kevin Reid                            <http://homepage.mac.com/kpreid/>