Fingerpoint

1 Publishing Data

The data a person wishes to share is published to a triple store that exposes a public SPARQL Protocol endpoint. This data must contain at least a foaf:mbox or foaf:mbox_sha1sum predicate, as defined by FOAF.

That is, assuming that the e-mail address the data is to be associated with is [email protected] then at least one of the following two triples must be included in the data:

<WEBID> foaf:mbox <mailto:[email protected]> .
<WEBID> foaf:mbox_sha1sum "9bbb06b3bb947843d3ee37048284926bbebfe8b5" .

2 Discovering the SPARQL Endpoint from an E-mail Address

To locate the SPARQL endpoint from an e-mail address, a convention needs to be applied. The host name of the e-mail address is extracted, and an HTTP request is made for the root URL at that host. In the previous example, the HTTP request would be made to http://example.com/.

Clients hoping to find the SPARQL endpoint(s) associated with that domain should look for HTML <link> elements or HTTP Link headers with a rel attribute with value http://ontologi.es/sparql#fingerpoint. They can then follow those links to the SPARQL endpoints (which may be on a different host) and query the endpoints for the data they were looking for.

An example HTTP Link header that satisfies this requirement is:

Link: <http://example.net/sparql>; rel="http://ontologi.es/sparql#fingerpoint"

3 Querying the SPARQL Endpoint

Once the address of the SPARQL endpoint has been discovered, it can be queried. Consumers should make sure to check for data, not just by mbox, but also by mbox_sha1sum. An example query is:

SELECT DISTINCT ?person
WHERE {
	{ ?person <http://xmlns.com/foaf/0.1/mbox> <mailto:[email protected]> . }
	UNION
	{ ?person <http://xmlns.com/foaf/0.1/mbox_sha1sum> "9bbb06b3bb947843d3ee37048284926bbebfe8b5" . }
}

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