Guilherme; On 12/2/10 5:58 PM, Guilherme Fernandes wrote:
Hi,
On Thu, Dec 2, 2010 at 4:31 PM, Jason Zurawski <zurawski@internet2.edu <mailto:zurawski@internet2.edu>> wrote:
Hi All;
On 12/2/10 4:16 PM, Aaron Brown wrote: > On the call, I was asked to send some examples of how we've done ordered lists in XML before. Looking through various xml bits, I found a few different ways that we've sorted lists. > > 1) a numerical 'id' element: > > <nmwg-cp:hop id=”0”> > .... > </nmwg-cp:hop> > <nmwg-cp:hop id=”1”> > .... > </nmwg-cp:hop> > <nmwg-cp:hop id=”2”> > .... > </nmwg-cp:hop> > <nmwg-cp:hop id=”3”> > .... > </nmwg-cp:hop> > > 2) explicit 'next' pointers: > > <path> > <hop id="internet2-1"> > .... > <nextHop>esnet-1</nextHop> > </hop> > <hop id="esnet-1"> > .... > <nextHop>bnl-1</nextHop> > </hop> > <hop id="bnl-1"> > .... > </hop> > </path>
As discussed on the call one would need to have a parser that respected 'document order' to ensure the next sequence is correct. Modern XML parsers feature this (e.g. LibXML), but its not a part of the XML standard itself so there is no guarantee you will find it in all implementations.
If an attribute/element 'firstHop' is added to the <path> element above, respecting document order is no longer required:
<path firstHop="internet2-1"> <hop id="internet2-1"> .... <nextHop>esnet-1</nextHop> </hop> .... </path>
You are correct about needing something to denote the head, but I was originally referring to example #3's sequence of values, not #2. 'Document order' (http://www.w3.org/TR/xpath/#dt-document-order) is not something we want to rely on in the first place since availability will vary by library. There needs to be an unambiguous way to determine order. Freek/Jerone: what does RDF do (or would could RDF do) to do the same thing? -jason
Best, Guilherme
Thanks;
-jason
> 3) implicit document ordering (this data corresponds to a traceroute. there would be more 'datum' elements in a real traceroute instance each of which corresponds to a single traceroute probe sent. This was cleaned up to make it easier to read): > > <nmwg:data id="data.AAAFFF.0" metadataIdRef="meta.AAAFFF" xmlns:nmwg="http://ggf.org/ns/nmwg/base/2.0/"> > <traceroute:datum hop="198.129.254.29" numBytes="64" queryNum="1" timeType="unix" timeValue="1282079154" ttl="1" value="0.135" valueUnits="ms"/> > <traceroute:datum hop="134.55.219.10" numBytes="64" queryNum="1" timeType="unix" timeValue="1282079154" ttl="2" value="1.14" valueUnits="ms"/> > <traceroute:datum hop="134.55.217.2" numBytes="64" queryNum="1" timeType="unix" timeValue="1282079154" ttl="3" value="37.212" valueUnits="ms"/> > <traceroute:datum hop="134.55.209.98" numBytes="64" queryNum="1" timeType="unix" timeValue="1282079154" ttl="4" value="1.616" valueUnits="ms"/> > <traceroute:datum hop="134.55.220.49" numBytes="64" queryNum="1" timeType="unix" timeValue="1282079154" ttl="5" value="28.643" valueUnits="ms"/> > <traceroute:datum hop="134.55.209.46" numBytes="64" queryNum="1" timeType="unix" timeValue="1282079154" ttl="6" value="41.773" valueUnits="ms"/> > <traceroute:datum hop="134.55.221.58" numBytes="64" queryNum="1" timeType="unix" timeValue="1282079154" ttl="7" value="52.36" valueUnits="ms"/> > <traceroute:datum hop="134.55.218.101" numBytes="64" queryNum="1" timeType="unix" timeValue="1282079154" ttl="8" value="52.373" valueUnits="ms"/> > <traceroute:datum hop="198.124.252.141" numBytes="64" queryNum="1" timeType="unix" timeValue="1282079154" ttl="9" value="52.311" valueUnits="ms"/> > </nmwg:data> > > Cheers, > Aaron