<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><div>On 08/06/2011, at 8:05 AM, Steve Baskauf wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">
<div bgcolor="#ffffff" text="#000000"><pre wrap="">... I think it's foolish to regard all of these different
resolution mechanisms as distinct "identifiers". There is *ONE* GUID. It
is: A9F435E0-8ED7-46DD-BAB4-EA8E5BF41523. There are ten different ways to
make it actionable. It therefore meets the recommendations of the
applicability statement.</pre>
The problem is that when you create an HTTP URI out of a UUID, you are
creating an identifier whether you think you are or not. </div></blockquote><div><br></div><font class="Apple-style-span" face="Arial">Jumping in again, but perhaps RFC 4122 might help a little here.</font></div><div><font class="Apple-style-span" face="Arial"><br></font></div><div><span class="Apple-style-span" style="font-family: Arial; ">A GUID (or UUID) is a set of 128 bits, 16 octets, 32 hex digits, 5 inches of punched paper tape. However you choose to write or express it, there is indeed "*ONE* GUID".</span></div><div><font class="Apple-style-span" face="Arial"><br></font></div><div><font class="Apple-style-span" face="Arial">A URI is not a GUID. This:</font></div><div><span class="Apple-tab-span" style="white-space:pre"><font class="Apple-style-span" face="Arial"> </font></span><font class="Apple-style-span" face="Arial"><a href="http://example.org/">http://example.org/</a></font><span class="Apple-style-span" style="white-space: pre-wrap; "><font class="Apple-style-span" face="Arial">A9F435E0-8ED7-46DD-BAB4-EA8E5BF41523</font></span></div><div><font class="Apple-style-span" face="Arial"><br></font></div><div><span class="Apple-style-span" style="white-space: pre-wrap; "><font class="Apple-style-span" face="Arial">is a different URI to this</font></span></div><div><span class="Apple-style-span" style="white-space: pre-wrap; "><div style="white-space: normal; "><span class="Apple-style-span" style="white-space: pre-wrap; "><span class="Apple-style-span" style="white-space: normal; "><div><span class="Apple-tab-span" style="white-space: pre; "><font class="Apple-style-span" face="Arial"> </font></span><font class="Apple-style-span" face="Arial"><a href="http://my.organisation.org/">http://my.organisation.org/</a></font><span class="Apple-style-span" style="white-space: pre-wrap; "><font class="Apple-style-span" face="Arial">A9F435E0-8ED7-46DD-BAB4-EA8E5BF41523</font></span></div><div><font class="Apple-style-span" face="Arial"><span class="Apple-style-span" style="white-space: pre-wrap; "><br></span></font></div></span></span></div></span></div><div><font class="Apple-style-span" face="Arial">is a different URI to this:</font></div><div><span class="Apple-tab-span" style="white-space:pre"><font class="Apple-style-span" face="Arial"> </font></span><font class="Apple-style-span" face="Arial"><a href="http://example.org/">http://example.org/</a></font><span class="Apple-style-span" style="white-space: pre-wrap; "><font class="Apple-style-span" face="Arial">A9F435E08ED746DDBAB4EA8E5BF41523</font></span></div><div><span class="Apple-style-span" style="white-space: pre-wrap; "><font class="Apple-style-span" face="Arial"><br></font></span></div><div><span class="Apple-style-span" style="font-family: Arial; white-space: pre-wrap; ">Furthermore, these uris have nothing whatever to do with the guid - apart from the fact that it's obvious to we humans that they do.</span></div><div><span class="Apple-style-span" style="white-space: pre-wrap;"><font class="Apple-style-span" face="Arial"><br></font></span></div><div><span class="Apple-style-span" style="white-space: pre-wrap;"><font class="Apple-style-span" face="Arial">Fortunately, there is a </font></span><span class="Apple-style-span" style="font-family: Arial; white-space: pre-wrap; ">standard for expressing a guid/uuid as a URI, and it is the "uuid" urn namespace, defined in RFC-4122. Thus:</span></div><div><span class="Apple-style-span" style="white-space: pre-wrap;"><font class="Apple-style-span" face="Arial"><br></font></span></div><div><span class="Apple-style-span" style="white-space: pre-wrap;"><span class="Apple-tab-span" style="white-space:pre"><font class="Apple-style-span" face="Arial"> </font></span><font class="Apple-style-span" face="Arial">urn:uuid:</font></span><span class="Apple-style-span" style="white-space: pre-wrap; "><font class="Apple-style-span" face="Arial">A9F435E0-8ED7-46DD-BAB4-EA8E5BF41523</font></span></div><div><span class="Apple-style-span" style="white-space: pre-wrap; "><font class="Apple-style-span" face="Arial"><br></font></span></div><div><span class="Apple-style-span" style="white-space: pre-wrap; "><font class="Apple-style-span" face="Arial">is a URI that - according to a w3c standard - corresponds to the 128-bit guid. This:</font></span></div><div><span class="Apple-style-span" style="white-space: pre-wrap; "><font class="Apple-style-span" face="Arial"><div style="font-family: Helvetica; white-space: normal; "><span class="Apple-style-span" style="white-space: pre-wrap; "><span class="Apple-tab-span" style="white-space: pre; "><font class="Apple-style-span" face="Arial"><br></font></span></span></div><div style="font-family: Helvetica; white-space: normal; "><span class="Apple-style-span" style="white-space: pre-wrap; "><span class="Apple-tab-span" style="white-space: pre; "><font class="Apple-style-span" face="Arial"> </font></span><font class="Apple-style-span" face="Arial">urn:uuid:</font></span><span class="Apple-style-span" style="white-space: pre-wrap; "><font class="Apple-style-span" face="Arial">A9F435E08ED746DDBAB4EA8E5BF41523</font></span></div><div style="font-family: Helvetica; white-space: normal; "><span class="Apple-style-span" style="white-space: pre-wrap; "><font class="Apple-style-span" face="Arial"><br></font></span></div><div style="font-family: Helvetica; white-space: normal; "><span class="Apple-style-span" style="white-space: pre-wrap; "><font class="Apple-style-span" face="Arial">is *not valid* - it doesn't conform to the schema. There is one unique (case insensitive) uuid urn for any guid, and a defined equivalence between them. </font></span><span class="Apple-style-span" style="font-family: Arial; white-space: pre-wrap; ">These are not "cool uris", but guids are inherently uncool so that's to be expected.</span></div><div><span class="Apple-style-span" style="white-space: pre-wrap; "><font class="Apple-style-span" face="Arial"><br></font></span></div></font></span></div><div><span class="Apple-style-span" style="white-space: pre-wrap; "><font class="Apple-style-span" face="Arial">If you want to use GUIDs for identifiers and need equivalent URIs (for use in RDF and the semweb), then urn:uuid:<the guid> might be a good way to go.</font></span></div><div><span class="Apple-style-span" style="white-space: pre-wrap; "><font class="Apple-style-span" face="Arial"><br></font></span></div><div><span class="Apple-style-span" style="font-family: monospace; white-space: pre-wrap; "><br></span></div><p>If you have received this transmission in error please notify us immediately by return e-mail and delete all copies. 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