Re: [Jack-Devel] well-known meta-data

On Tue, Oct 1, 2013 at 1:36 PM, Paul Davis <[hidden]>wrote:

>
>
>
> On Tue, Oct 1, 2013 at 1:22 PM, Lars Luthman <[hidden]> wrote:
>
>> On Tue, 2013-10-01 at 10:07 -0400, Paul Davis wrote:
>> > As the metadata API and jack1 implementation moves along, it would be
>> > useful to define a (small) set of standard names (URIs) for metadata key
>> > names that software (and users) might reasonably anticipate seeing.
>> > "Well-known metadata" or WKM might be a term for it.
>> >
>> > [...]
>> >
>> > I would welcome a discussion on the general design, on these specific
>> WKM
>> > names, and on others that people think may warrant a URI within the
>> > http://jackaudio/metadata space.
>>
>> How many and how large metadata values can the system be expected to
>> handle?
>
>
> There is no API-imposed limit to the size of metadata keys or values.
>

two followups:

  1) they do have to be representable as null-terminated strings. The API
documentation
      provides the example of "image/png;base64", which uses a convention
from CSS
      on how to "encode" an image as a string

  2) although there is no semantics imposed on metadata keys and values, it
is much
      less useful to use it to associate highly structured data with a port
(or client), since
      this then implies the need for some (presumably library-based) code
to parse
      the structure and be able to use it. the real goal of the metadata
API is to be able
      to tag ports (and clients) with small amounts of data that is outside
of the core
      JACK API but nevertheless useful (such as my WKM examples)

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