- From: Patrick Stickler <patrick.stickler@nokia.com>
- Date: Fri, 15 Nov 2002 08:17:46 +0300
- To: "Ian Davis" <iand@internetalchemy.org>, www-rdf-interest@w3.org, Patric k Stickler <patrick.stickler@nokia.com>
Ian, The new datatyping facilities in RDF will facilitate what you want to do. What you are dealing with are values, not strings, and even though folks use various lexical representations for dates in the RDF, they are (almost) always denoting the value, not the string. To that end, you will want to use typed literals, which are lexical forms paired with an explicit datatype (e.g. one of the XML schema date/time types), to express your values. Whether you use complete datetime values or break them into complex subgraphs is up to you. In any case, you will still have to parse the lexical forms into system specific value representations to make comparisons. I've been putting together a Java library for working with RDF typed literals, and while very much alpha, it does support xsd:dateTime values. Have a look. Perhaps it will prove useful, at least as an example: http://www-nrc.nokia.com/sw/datatypes.zip Have a look at the Test class for usage examples. Cheers, Patrick [Patrick Stickler, Nokia, +358 40 8019690, patrick.stickler@nokia.com] _____________Original message ____________ Subject: Date Representation Best Practice Sender: ext Ian Davis <iand@internetalchemy.org> Date: Fri, 15 Nov 2002 07:48:43 +0300 Hi all, I'm experimenting with an application that ties people and historical events together and have a question regarding the representation of dates. Currently most RDF applications I have seen use a literal date representation, utilizing one of the various standard date formats. However, this representation requires additional date logic within the RDF application. In order to answer questions such as "In what year did a man first walk on the moon?" the application must first seek the date literal for the event and then parse it to determine the year. I've been looking at representing the dates as resources. This lets me make assertions about each date such as year, month and day. To answer my question above I then ask for the year of the date of the event. I can also assert other relationships with other dates such as before and after which should enable me to find the first man on the moon by finding a moon walk event such that there are no moon walk events before it. Aside from the practical considerations of generating resources for all possible dates, are there any other reasons why one would favour literals over resources? Will the proposals for data typing literals cover date relationships? Ian
Received on Friday, 15 November 2002 01:18:16 UTC