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Subject: RE: [xri-editors] Xref escaping rules
I think these rules apply to cross-references in general, both general URIs and XRIs. -----Original Message----- From: Wachob, Gabe [mailto:gwachob@visa.com] Sent: Monday, June 30, 2003 12:05 PM To: 'Dave McAlpin'; Wachob, Gabe; 'Drummond Reed'; xri-editors@lists.oasis-open.org Subject: RE: [xri-editors] Xref escaping rules Dave- This seems straightforward and I don't know why it wasn't the first proposal on the table. I can't seem to figure out a problem with it, so +1 unless someone can discover an issue with it. BTW, the way I read it is that this escaping is only neccesary for URIs as xrefs, not XRI values as xrefs... -Gabe > -----Original Message----- > From: Dave McAlpin [mailto:dave.mcalpin@epokinc.com] > Sent: Monday, June 30, 2003 10:08 AM > To: 'Wachob, Gabe'; 'Drummond Reed'; xri-editors@lists.oasis-open.org > Subject: RE: [xri-editors] Xref escaping rules > > > I assumed we would escape iteratively, once for each level of nesting > > 1) Embed http://foo.com?id=21#bar in xri:@foo/baz as a cross-reference > > a) Escape cross-reference to get > http://foo.com%3Fid=21%23bar > > b) Add as cross-reference > xri:@foo/baz/(http://foo.com%3Fid=21%23bar) > > When the cross-reference is extracted, it's unescaped to > > http://foo.com?id=21#bar > > 2) Embed http://foo.com?id=21-%28widget#bar in xri:@foo/baz as a > cross-refrence > > a) Escape the cross-reference to get > http://foo.com%3Fid=21-%2528widget%23bar > > b) Append as cross-reference > xri:@foo/baz/(http://foo.com%3Fid=21-%2528widget%23bar) > > When the cross-reference is extracted, it's unescaped to > > http://foo.com?id=21-%28widget#bar > > 3) A complex nested example. Embed http://foo.com?id=21-%28widget in > xri:+foo.bar.<xref>, which is in turn embedded in > xri://foo.bar/<xref>/baz > > a) First escape the innermost cross-reference to get > http://foo.com%3Fid=21-%2528widget > > b) Add as cross-reference > xri:+foo.bar.(http://foo.com%3Fid=21-%2528widget) > > c) Escape the cross-reference to get > xri:+foo.bar.(http://foo.com%253Fid=21-%252528widget) > > d) Add as cross-reference > xri://foo.bar/(xri:+foo.bar.(http://foo.com%253Fid=21-%252528w > idget)))/baz > > When the XRI is evaluated, the outermost cross-reference is extracted > > xri:+foo.bar.(http://foo.com%253Fid=21-%252528widget)) > > And unescaped to give > > xri:+foo.bar.(http://foo.com%3Fid=21-%2528widget)) > > The next level cross-reference is extracted > > http://foo.com%3Fid=21-%2528widget > > and unescaped to give > > http://foo.com?id=21-%28widget > > Dave > > -----Original Message----- > From: Wachob, Gabe [mailto:gwachob@visa.com] > Sent: Monday, June 30, 2003 9:19 AM > To: 'Drummond Reed'; xri-editors@lists.oasis-open.org > Subject: RE: [xri-editors] Xref escaping rules > > Drummond- > This seems pretty reasonable. > > Have you considered the case where you have two levels of cross > referencing? That is, a cross reference which contains an XRI > value that > itself has a cross reference? > > xri://foo.bar/(+foo.bar.(http://www.foo.com#3ffoo))/baz > > vs > > xri://foo.bar/(+foo.bar.(http://www.foo.com(#3f)foo))/baz > > vs > > xri://foo.bar/(+foo.bar.(http://www.foo.com((#3f))foo))/baz > > I think you need to amend the rules about escaping/unescaping > to account for > nesting.. > > -Gabe > > > > -----Original Message----- > > From: Drummond Reed [mailto:drummond.reed@onename.com] > > Sent: Sunday, June 29, 2003 1:15 PM > > To: xri-editors@lists.oasis-open.org > > Subject: [xri-editors] Xref escaping rules > > > > > > Here's the escaping proposal that I brought up on the last TC call. > > > > The issue is that an XRI or URI is used as a cross-reference > > may contain > > characters that must be escaped in order to conform with 2396. > > Specifically: > > > > * "?" may not appear until the start of the one-and-only > query segment > > allowed by 2396. > > * The same is true with "#" for fragments > > * Lastly, an UNMATCHED opening or closing paren must be > > escaped or else > > the cross-reference will not parse correctly. (Note that > > MATCHED opening > > and closing parens inside do not need escaping because they > represent > > either a second-level nested cross-reference or a parenthetically > > enclosed string in a native URI but either way will not be > ambiguous.) > > > > However we can't use just 2396 escaping rules (i.e., "%xx" > where xx is > > the hex value of the character) for these four characters > > because it if > > the embedded XRI or URI contained those same escape sequences > > natively, > > it would be ambiguous which to unescape and not to unescape when the > > cross-reference is extracted. For example, if a URI already > contained > > the escape sequence %3F (the "?" character) before it was > > turned into a > > cross-reference, how would the parser know NOT to unescape it when > > extracting the cross-reference? > > > > The proposed solution is to apply two special escaping rules to any > > URI/XRI string being embedded as a cross-reference. They must > > be applied > > in the following order: > > > > 1) Parse the string to find any instance of "%3F", "%23", "%28", or > > "%29" and enclose these in parens. Example: "(%3F)". > > 2) Escape any "?", "#", or UNMATCHED paren as per 2396 escaping. > > Example: a URI that contained a query would have the "?" turned into > > %3F. > > > > To extract a cross-reference, apply the same two rules in > > reverse, i.e.: > > > > 1) From the extracted cross-reference, escape any instance of > > %3F, %23, > > %28, or %29 EXCEPT those enclosed in parens. > > 2) For any instance of "%3F", "%23", "%28", or "%29" enclosed > > in parens, > > remove the parens. > > > > Example: > > > > Embed: URI "http://foo.com/?id=21#bar" in XRI "xri:@foo/baz/" > > Result: "xri:@foo/baz/(http://foo.com/%3Fid=21%23bar)" > > > > > > Embed: URI "http://foo.com/?id=21-%28widget#bar" in XRI > > "xri:@foo/baz/" > > Result: "xri:@foo/baz/(http://foo.com/%3Fid=21-(%28)widget%23bar)" > > > > Does this work for everyone? Any other proposals? > > > > =Drummond > > > > > > > > > > > > > --------------------------------------------------------------------- > > To unsubscribe, e-mail: xri-editors-unsubscribe@lists.oasis-open.org > > For additional commands, e-mail: > xri-editors-help@lists.oasis-open.org > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: xri-editors-unsubscribe@lists.oasis-open.org > For additional commands, e-mail: xri-editors-help@lists.oasis-open.org > > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: xri-editors-unsubscribe@lists.oasis-open.org > For additional commands, e-mail: xri-editors-help@lists.oasis-open.org > --------------------------------------------------------------------- To unsubscribe, e-mail: xri-editors-unsubscribe@lists.oasis-open.org For additional commands, e-mail: xri-editors-help@lists.oasis-open.org
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