ISSUE-28: Do we need/want multiple POIs in one XML document?


Do we need/want multiple POIs in one XML document?

Raised by:
Matt Womer
Opened on:
Date: Wed May 04 23:02:17 2011

Perhaps it would be better if we just started at the more granular level
of the poi then clarified the use cases for the collections.

I think it's important that an individual poi can have a unique URL
based ID - effectively making this a permalink or similar. This then
relates to the POI/language points in this thread.

However, if we do wrap a collection of poi in a pois tag then we should
think about what else the existing Mobile AR formats also allow in terms
of meta information added at this top level. KML, Layar, etc. This is
kind of similar to the DOM based head/body separation in HTML and is
very useful.

If the collection is designed for responses to Queries then it should
probably at least support pagination related meta data.

If the collection is designed for local serialised storage then
cache/created/modified data would be useful.

Lots of other options here based on the use cases.


Date: Thu May 05 16:37:05 2011

Personly I think we should ignore any concept of colections, at least
for the moment.
It would be very delivery method specific.
We should concentrate on what we are delivering first and then see if
a packaging standard is needed for it.

(Raised by Rob, assigned to Matt)

Date: Mon May 09 17:42:22 2011

The <poi> element in the XML serialization has an "id" attribute. In
XML, attributes named "id" are almost always of type xsd:ID, which has
restrictions on the lexical representation, and on the semantics. If
you do a query over a POI database for "Home" and obtain a result
serialized as XML
<pois><poi id="home" /><poi id="home" />...</pois>
then that would violate the semantic requirement that each id attribute
in the document be unique.

Also, the lexical requirement for ID excludes spaces, numeric first
characters, and a bunch of other things, making this invalid:
<poi id="1. Tom's Place" />

The suggestion I made was to use a name attribute instead, so you are
free to define your own syntax and semantics for it. Then you can use
name for the machine-readable name and label for the L10N label, and use
this terminology consistently in the data definition and all serializations.

However, if you're looking to make the id be unique in the document,
then using URIs as you suggest makes sense. I saw some hints of that
with "#" in some of the examples. I'd suggest taking a look at the
CURIE working draft which defines a straightforward way of dealing with
the URI prefix problem. (Briefly, it shows how to declare prefix
definitions so you can say "eq:" is "" and
then you can define your poi attribute to by a URI.)

While on this topic you might take a look at RDFa, which defines a set
of attributes you can place on some other XML (or HTML) for adding in
attributes such as "about", which might be good for this purpose instead
of "id" or "name". (RDFa has some measure of adoption on the web, being
used in Google Site Maps and other such places.)
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Related emails:
  1. ISSUE-28 (poi-collections-wrapper): Do we need/want multiple POIs in one XML document? [Core FPWD] (from on 2011-05-11)

Related notes:

See also ISSUE-35

Matt Womer, 11 May 2011, 21:08:39

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