- From: Farhana Sarker <fs5g09@ecs.soton.ac.uk>
- Date: Tue, 3 Jun 2014 00:28:28 -0400
- To: Dan Brickley <danbri@google.com>
- Cc: W3C Web Schemas Task Force <public-vocabs@w3.org>
Hi Dan, Thank you very much for your kind explanation of these two terms. Your explanation really helps me a lot. Best regards, Farhana On 2 Jun 2014, at 09:40, Dan Brickley wrote: > On 31 May 2014 22:20, Farhana Sarker <fs5g09@ecs.soton.ac.uk> wrote: >> Hi, >> I am Farhana Sarker, student in the University of Southampton. >> I am keen to know the benefit of using schema.org over linked data technology in reusing or interoperability of data or vice versa. >> Could you please help me in this regards? > > There is no rigid line separating "Linked Data" from other > RDF-oriented ways of sharing data. Schema.org can be seen as Linked > Data. But there are differences in emphasis across the community. > > When TimBL originally wrote > http://www.w3.org/designissues/linkeddata.html it was largely a > response to the indirect linking model we'd been using in the FOAF > project. ("This linking system was very successful, forming a growing > social network, and dominating, in 2006, the linked data available on > the web."). Tim was concerned that we (i.e. the FOAF people at the > time) were missing the opportunity to give re-usable real world > entities URL Web identifiers; instead FOAF descriptions tended to > indirectly identify entities, e.g. writing RDF that said "the Person > whose homepage is http://example.com/person123/", rather than giving a > formal URI for that Person (see > http://blog.foaf-project.org/2003/07/identifying-things-in-foaf/ > http://blog.foaf-project.org/2003/07/missing-isnt-broken-data-validation-and-freedom-on-the-semantic-web/ > for the FOAF approaches). So anyway the Linked Data note advocated > for all entities to be given HTTP URLs that pointed at RDF > descriptions. This emphasis ended up becoming a central theme amongst > Linked Data advocates: the idea that real world entities should have > HTTP URLs that give you RDF data when you fetch them. > > At that time, RDFa was also fairly new, although the effort was > underway, http://markbirbeck.com/blog/2004/04/01/xml-europe-2004-rdfxhtml-new-rdf-syntax/ > ... so Linked Data tended to be deployed using distinct > machine-oriented URLs rather than mixed-in with normal HTML content. > > By the time schema.org was created (2011) it was clear that some of > the deployment habits considered "best practice" around Linked Data > were making life hard for publishers, especially those who knew > nothing about RDF. For example, the expectations that every mention of > an entity included an HTTP URL pointing at RDF data; that /-based URLs > redirected, that multiple formats were served using HTTP content > negotiation; that data used several independently managed RDF schemas, > etc. etc. ... > > This 2008-style deployment of RDF as Linked Data has been pretty > successful in various professional settings - e.g cultural heritage, > archives, libraries > (http://www.w3.org/2005/Incubator/lld/XGR-lld-vocabdataset-20111025/), > but was too complex for many mainstream publishers, webmasters and > developers. > > Schema.org makes different tradeoffs, but in the same design space. > Schema.org is an RDF vocabulary, even if we don't shout about the RDF > side of it to publishers. The central emphasis is on ease of adoption > by publishers, even if this introduces more noise into the data. So > for example schema.org has been less emphatic about always > distinguishing URLs for things from URLs for pages about those things. > Those are still important distinctions to make, but we are still > somewhat in the early days of structured data going mainstream - it is > important to make things easy for publishers and introduce complexity > gradually. > > The other "break with tradition" at schema.org is the focus on a > single integrated core vocabulary, rather than an overlapping > patchwork of independent schemas. Again this is motivated by ease of > publisher adoption, and by the importance of getting agreement amongst > high profile consumers. As with entity URLs it is best to consider > this a matter of emphasis rather than a rigid timeless principle. > There are lots of places in schema.org where external schemas could > usefully be combined with the schema.org vocabulary (some discussing > of this is in http://blog.schema.org/2012/05/schemaorg-markup-for-external-lists.html > ). > > And as Peter just mentioned, schema.org's vocabulary is defined using > RDFS a base but with some custom variations. In particular > schema.org's association of properties with types is very informal, > almost wiki-like. This is largely due to the fact that schema.org is > continually growing and evolving while published across millions of > sites, so we have tried to find ways of keeping things loose, so that > new type/property patterns can evolve without too much suprise. > > To cut a long story short, schema.org is another effort in the larger > RDF family. It shares many classic Linked Data concerns but makes > various tradeoffs favouring broad adoption over data purity. > > hope this helps, > > Dan
Received on Tuesday, 3 June 2014 04:28:56 UTC