[Oslc-pm] Where is Percentage defined

[John Arwe]

That is SO cool!
Sorry, I always get giddy when people just go and do the right thing 
without prompting.  FWIW, in Web standards circles this process is called 
"following your nose" [1].  I'll label each "follow your nose" step FYNn. 
If you just want the punch line, skip to FYN6.  If you want to learn to 
fish for yourself, read on.

If you're starting from prose (human readable text), that's typically a 
harder problem than when you start from machine-readable, simply because 
prose is ambiguous and (most) search engines rely almost exclusively on 
prose and analysis of prose.  If you're in Linked Data, and if the 
vocabularies involved follow best practices, it's incredibly easy once the 
algorithm has been laid out even once; if the vocabularies don't follow LD 
BP's, you're essentially back to the prose case.  Happily for all involved 
here, there's at least one Linked Data example we can use ... and it's 
probably the same one you started from, on [2].  [2] of course is prose, 
but part of its content is two machine-readable versions (RDF/XML and 
Turtle).  Since I know you're more fluent in the former, let's use [3] as 
the starting point.  If you're a coder experienced in HTTP and/or XML, 
many of these steps would happen in your head, but I'm going to more 
explicit to illustrate this process for a more diverse audience.

FYN1: What incredible luck, everything we need from [3] is in the first 
dozen lines or so (nothing up my sleeve, promise!).
The first use I find of percentage is 
<ems:unitOfMeasure rdf:resource="dbp:Percentage"/>

FYN2: The RDF/XML spec tells me that rdf:resource is a reference to a 
resource, and the resource's URI is given by the quoted string.

FYN3: Namespaces in XML spec tells me how to convert from the qualified 
name to a URI, in this case to http://dbpedia.org/resource/Percentage

FYN4: Linked Data best practices (not a spec, I freely admit) tell me that 
URIs should be HTTP (so far so good) and that I should be able to retrieve 
useful information about the resource it identifies (the concept 
"percentage" in this case) by dereferencing the URI.  If this fails, or if 
I don't know about this LD BP, I'm lost and have to treat it as prose.

FYN5: The URI syntax spec tells me how to parse that URI.  One of the most 
important pieces of information is the URI scheme, i.e. HTTP.

FYN6: The HTTP spec describes how one "uses" HTTP URIs; the simplest 
dereference operation that returns data about the resource is GET. 
Browsers are good vehicles for GETting a URI (there are others), but 
especially as you are looking for human-readable information about the 
resource a browser is a great choice.  Paste 
http://dbpedia.org/resource/Percentage into your favorite browser's 
location bar and try it.

FYN7: If your eyes are really fast, or your connection slow, you'll 
observe some "bouncing around" and then a page will render, and the 
location bar will say http://dbpedia.org/page/Percentage (note: /page/ not 
/resource/).  The bouncing around is evidence of the browser being 
redirected (HTTP 3xx status code) from the /resource/ URI (which is the 
identifier of the concept you are interested in) to a human-readable web 
page containing information -about- that resource.  For concrete evidence 
of the redirect happening, you can trace the requests or read the web page 
(third row from the bottom, or search on "redirects").


I did make some assumptions above, the hardest to replicate probably being 
how to find the governing spec(s) at each step.  I happen to know most of 
them because I've wallowed in them for a few years now.  Most people would 
choose some combination of asking someone who already knows (tribal 
knowledge), web search, or "just believing it (FYN) works".  Particularly 
hardy souls and skeptics would just plug away at it until they got through 
everything.  You do need several other specs (Web Architecture, MIME 
types, RDF/XML's MIME type registration document at least) if you want to 
follow the monk's entire path, but everyone so far who has come back down 
from the mountaintop swears there is an unbroken path.


[1] http://www.w3.org/wiki/FollowYourNose
[2] 
http://open-services.net/wiki/performance-monitoring/OSLC-Performance-Monitoring-2.0-Appendix-A:-Samples/#ex1
[3] 
http://open-services.net/wiki/performance-monitoring/OSLC-Performance-Monitoring-2.0-Appendix-A:-Samples/#ex1-rdfxml

Best Regards, John

Voice US 845-435-9470  BluePages
Tivoli OSLC Lead - Show me the Scenario




From:   Janet Andersen/Raleigh/IBM at IBMUS
To:     oslc-pm at open-services.net
Date:   10/17/2012 05:41 PM
Subject:        [Oslc-pm] Where is Percentage defined
Sent by:        "Oslc-Pm" <oslc-pm-bounces at open-services.net>



Where is the dbpedia Percentage class defined in human readable format? 
Julie and  I tried accessing http://dbpedia.org/Percentage, looking at the 
dbpedia Ontology page, accessing 
http://wiki.dbpedia.org/Ontology/Percentage, and performing a Google 
searches but couldn't find a human-readable definition.

Thanks!

Janet S. Andersen
IBM Tivoli Monitoring
Research Triangle Park, NC
Phone:   919-224-1440, T/L 8-687-1440
Internet:  janetand at us.ibm.com
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