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Subject: RE: [xri] Questions regarding XRI Resoution as client of 2.1 abstract syntax
Drummond, Let's try one more stab at email, and then go to phone. "@" delegates to child authority "ootao" (CID=01). CID=01 delegates to child authority "+home" (CID=01!01). CID=!01!01 delegates to child authority "steve" (cid=01!01!01). Certainly, I can easily set up authorities to do the above. My point is that (if I were to do so) then there is no way to resolve the third child authority. Please correct me where I have strayed. ~ Steve -----Original Message----- From: Drummond Reed [mailto:drummond.reed@cordance.net] Sent: Monday, April 23, 2007 6:33 PM To: 'Steven Churchill'; xri@lists.oasis-open.org Subject: RE: [xri] Questions regarding XRI Resoution as client of 2.1 abstract syntax Steve, you're not missing anything. Think of it this way. What if the delegation you started with was @ootao*(=steve)? And then you asked me how =steve can delegate to *home? My answer would be the same: =steve can't delegate to *home under his own authority -- that local delegation can only be recognized in a cross-reference if @ootao delegates to the whole thing, i.e., @ootao*(=steve*home). However @ootao*(=steve) can delegate directly to @ootao*(=steve)*home because both *(=steve) and *home are local-subsegs. And you can continue that chain of local delegations as long as you want. But Once you delegate to a global-xref, you can't go back to delegating locally in the first namespace, because you've moved to another global namespace. Feel free to give me a call to discuss -- it will be faster than email -- and besides I can roll that into the writeup assignment about the rules for usage of local and global context symbols that I took as an action item at the f2f last week (BTW, minutes of the f2f are underway and should be out shortly). =Drummond Unfortunately =steve can't do that. Only @ootao*(=steve) can control delegation below @ootao*(=steve) -----Original Message----- From: Steven Churchill [mailto:steven.churchill@xdi.org] Sent: Monday, April 23, 2007 5:31 PM To: 'Drummond Reed'; xri@lists.oasis-open.org Subject: RE: [xri] Questions regarding XRI Resoution as client of 2.1 abstract syntax Drummond, My use case is very simple. There are 4 authorities. There is @ which has a child ootao which has a child authority +west which has a child authority *steve. I think you are telling me that there is no way to resolve *steve. What am I missing? ~ Steve -----Original Message----- From: Drummond Reed [mailto:drummond.reed@cordance.net] Sent: Monday, April 23, 2007 5:13 PM To: 'Steven Churchill'; xri@lists.oasis-open.org Subject: RE: [xri] Questions regarding XRI Resoution as client of 2.1 abstract syntax Steve, once you've added a global-xref to an XRI authority segment, you've moved from one global context (the original one established by the first GCS symbol) to another. In this new global context, all local subsegments create different global xrefs. So if you created @ootao+west*steve, in XRI resolution you would get an XRD describing +west*steve from the XRI authority @ootao. This could of course be different from the XRD that @ootao provides for +west. In 2.0, local delegation (to a local-literal or local-xref) was the only option. In 2.1, global delegation (to another global-xref) is a new option. Once you've delegated to a global-xref, the only way to further delegate is via another global-xref. For example, if Steve is =steve or @ootao*steve, the two options for delegation under @ootao+west would be: #1: @ootao+west=steve #2: @ootao+west@ootao*steve Both parse to four top-level subsegments: 1) @ global-literal 2) ootao typeless-literal 3) +west global-xref 4a) =steve global-xref 4b) @ootao*steve global-xref =Drummond -----Original Message----- From: Steven Churchill [mailto:steven.churchill@xdi.org] Sent: Monday, April 23, 2007 4:14 PM To: 'Drummond Reed'; xri@lists.oasis-open.org Subject: RE: [xri] Questions regarding XRI Resoution as client of 2.1 abstract syntax Drummond, this leads me to the following question: Say that I have an authority identified by @ootao+west and that I add an authority into its namespace named *steve. Please show me the XRI that (when passed to a resolver) would end up returning the XRD for *steve. [Remember, the resolver deals with top-level subsegments only.] Thx, ~ Steve -----Original Message----- From: Drummond Reed [mailto:drummond.reed@cordance.net] Sent: Monday, April 23, 2007 3:55 PM To: 'Steven Churchill'; xri@lists.oasis-open.org Subject: RE: [xri] Questions regarding XRI Resoution as client of 2.1 abstract syntax Steve, sorry, my text may not have been clear. The resolver doesn't "do anything different" when it encounters a global-xref vs. a local-xref -- to a resolve they are both just subsegments. What I meant was that a global-xref has a different structure than a local-xref or a local-literal. For example, with the XRI =a*b*(+c)+d*e, the parse tree has 5 top-level subsegments: #1: = global-literal #2: a typeless-literal #3: *b local-literal #4: *(+c) local-xref #5: +d*e global-xref The only thing that distinguishes a global-xref from a local-literal or local-xref is that: a) it starts with a GCS symbol, and b) "inside" it you can have additional local-literal or local-xref subsegments. But from the standpoint of the parser or a local resolver, it's just another subsegment, much as a local-xref has always been just another subsegment even though it has a parsable XRI or IRI inside the parens. =Drummond -----Original Message----- From: Steven Churchill [mailto:steven.churchill@xdi.org] Sent: Monday, April 23, 2007 2:39 PM To: 'Drummond Reed'; xri@lists.oasis-open.org Subject: RE: [xri] Questions regarding XRI Resoution as client of 2.1 abstract syntax [Steve asked] 3. Does the resolver algorithm distinguish between "global" and "local" subsegments. [I would assume the answer is no. The resolver simply walks down the list of top-level subsegment invoking the authority resolution services.] [=Drummond] Yes, the resolver just walks down the list of "top-level" subsegs, but the resolver algorithm DOES distinguish between global-xref and local-xref as shown in the ABNF. A global-xref is the GCS character plus zero or one typeless subseg plus zero or more local subsegs. [Steve] I don't understand. Say the resolver is walking the top-level subsegments. What precisely does it do differently when encountering a global vs local xref? Thx, ~ Steve -----Original Message----- From: Steven Churchill [mailto:steven.churchill@xdi.org] Sent: Sunday, April 22, 2007 8:59 PM To: xri@lists.oasis-open.org Subject: [xri] Questions regarding XRI Resoution as client of 2.1 abstract syntax Drummond, I have some questions regarding the proposed 2.1 abstract syntax and XRI Resolution as client. For the benefit of those on the list who haven't been steeped in XRI Resolution, let me give some context. [Drummond, my questions are below.] The resolver invokes the XRI parser which returns a syntax tree conforming to the abstract syntax. During the "authority resolution" phase, the resolver walks through the top-level subsegments of this tree passing the name of the "next" subsegment to the authority resolution service of the "previous" subsegment, until it gets to then end. In the 2.0 abstract syntax, the subsegments had two types--persistent and reassignable. The notion of persistence is simply a convention for authority resolution services (their registries) as follows: If I pay my registry for a "bang" (persistent) identifier, then my registry should not reassign that identifier to someone else, even if I stop paying my bill. In the proposed 2.1 abstract syntax, the subsegments have seven types. Here are my questions for Drummond: 1. Does the resolver still walk through the top-level subsegments (that is, passing the name of the "next" subsegment to the authority resolution service of the "previous" subsegment) as described above? [I would assume the answer is yes.] [=Drummond] Yes -- but note that global-xrefs are a type of subsegment per your question 3 below. 2. Can authority resolution services now accept 7 types of query? [I would assume the answer is yes.] [=Drummond] Yes. 3. Does the resolver algorithm distinguish between "global" and "local" subsegments. [I would assume the answer is no. The resolver simply walks down the list of top-level subsegment invoking the authority resolution services.] [=Drummond] Yes, the resolver just walks down the list of "top-level" subsegs, but the resolver algorithm DOES distinguish between global-xref and local-xref as shown in the ABNF. A global-xref is the GCS character plus zero or one typeless subseg plus zero or more local subsegs. 4. Are six of the subsegment types reassignable and only one (bang) persistent (as per the definition above)? [=Drummond] No. A GCS character by itself is persistent. Then each subseg inside a global-xref is persistent or not depending on whether it begins with a bang. So a global-xref is persistent if and only if each of its subsegs is persistent. Examples: XRIS WITH PERSISTENT GLOBAL XREFS In #1 and #2, the global-xref beginning with = is persistent. In #3 and #4, the entire XRI is persistent. #1: @example=!1234.5678.a1b2.c3d4 #2: @example=!1234.5678.a1b2.c3d4!55 #3: @!1000.2000.3000.4000=!1234.5678.a1b2.c3d4 #4: @!1000.2000.3000.4000=!1234.5678.a1b2.c3d4!55 NON-PERSISTENT GLOBAL XREFS In all four examples below, the global-xref beginning with = is not persistent, because it does not consist of all persistent subsegments. #5: @example=example.2 #6: @example=!1234.5678.a1b2.c3d4*some.subseg #7: @!1000.2000.3000.4000=example2!55 #8: @!1000.2000.3000.4000=!1234.5678.a1b2.c3d4*some.subseg 5. If the answer to 3 above is "no", then why does the parser care about sticky stars? [=Drummond] See my answer to 3 above.
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