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Re: AWWW, 20040816 release, sections 1 and 2

From: Norman Walsh <ndw@nwalsh.com>
Date: Tue, 28 Sep 2004 15:55:53 -0400
To: Graham Klyne <gk@ninebynine.org>
Cc: public-webarch-comments@w3.org
Message-id: <874qli5fsm.fsf@nwalsh.com>
/ Graham Klyne <gk@ninebynine.org> was heard to say:
| General (nits)
| I notice there's some inconsistency about the way that section
| cross-references are presented.  Sometimes they are hyperlinked
| section names, and sometimes they also include section numbers.  For
| people who are reading paper documents, I think that section numbers
| should be included (isn't there an accessibility principle here?).

Fixed. I've added section numbers to all the section cross-references.
Readers may find it overkill...

| I also notice some inconsistency regarding use of URI vs URIs for the
| plural of URI, even between adjacent paragraphs in a section (e.g.
| section 2.3, paras 1 and 2).

Fixed, I believe.

| Section 1.1.1:
| [[
| Readers will benefit from familiarity with the Requests for Comments
| (RFC) series from the IETF, some of which define pieces of the
| architecture discussed in this document.
| ]]
| This isn't very helpful.  The RFC series consists of nearly 4000
| documents, most of which have very little to do with the web.
| Suggest:  drop this para or indicate some specific RFCs.

I agree. And we have a list of the relevant ones in the References.
I dropped it.

| Section 1.1.3, introduction of "Principle"
| I feel this term is being introduced to mean two related but quite
| different things, which I might describe as:
|    principle-as-exhortation: something designers should strive to achieve
| and
|    principle-as-expectation: something that is observed or claimed to occur
| e.g. "separation of concerns" is a case of the former, but "network
| effect" is  the latter.  Given the goal of the AWWW document (which I
| take to be to set out fundamental design choices that make the web
| what it is or is desired to be), I think that it would be appropriate
| for discussion "principles" to focus on the former.  (Principles as
| expectations are subsidiary here, in that they may be used to justify
| the principle design choices; e.g. "network effect" is part of the
| justification for "avoiding URI aliases")
| Maybe it is intended that "Constraints" and "Practices" will cover
| what I call "principle-as-exhortation", and that "Principle" is
| intended to be "principle-as-expectation".  In which case I think the
| description is unclear.

I think our decision about which category a "boxed message" goes in
is a bit arbitrary. A review of
doesn't reveal any obvious pattern.

I'm not sure what to do about this.

| Section 1.1.3, introduction of "Constraint"
| This comes over a bit unfocused;  I think the important statement is
| rather buried in the middle of the paragraph: "Other design choices
| are more fundamental; these are the focus of this document.".  In this
| context, I take this to mean that constraints introduced by this
| document are such fundmeantals.
| Suggest re-working (mainly re-ordering):
| [[
| Constraint
| Constraints are fundamental design choices, imposed to achieve certain
| technical, policy, or other goals, such as accessibility and global
| scope, ease of evolution, re-usability of components, efficiency, and
| dynamic extensibility.  (In the design of the Web, there are also
| lesser design choices, like the names of the p and li elements in
| HTML, the choice of the colon (:) character in URIs, or grouping bits
| into eight-bit units (octets), are somewhat arbitrary; if paragraph
| had been chosen instead of p or asterisk (*) instead of colon, the
| large-scale result would, most likely, have been the same.)
| ]]

This section has already been reworded along similar lines in response
to other comments (Tim Bray's I believe).

| ...
| I think that something like this should be stated clearly toward the
| start of section 2 (either at the end of 2.0, or as the beginning of
| 2.1):
| [[
| URIs are a cornerstone of Web architecture, providing identification
| that is common across the Web.
| ]]
| (This may be obvious to us here, but it's sufficiently fundamental
| that it bears stating (even restarting) very clearly.  It seems to me
| this should be an unmistakable message of AWWW.)

Indeed. Done.

| Section 2.1, 1st para:
| [[
| ... ([URI], currently being revised) ...
| ]]
| I think the "currently being revised" is spurious, transitory and
| should be dropped.

I agree. The cross-referenced References entry makes the point.

| Section 2.1, general:
| I think the key message here doesn't really get stated until the final
| sentence: "... there are substantial costs to creating a new
| identification system that has the same properties as URIs".
| The thrust of the Good Practice here, then, would seem to be that one
| should use URIs rather than other systems of identification:  this
| isn't immediately clear from the Good Practice statement.
| I'd be inclined to *start* this section with the Good Practice statement.

I moved it up, not quite to the start, and moved the "costs" point up
as well. I also removed the "Other resource identification systems may
expand" sentence. Somone else suggested it was unnecessary and with
the "costs" point moved out, I agree. (Anything new may expand the

| Section 2.2, general:
| As far as I can tell, the key message is stated early on in the
| Constraint "URIs identify a single resource" -- I think that is good.
| The section then goes on to expand on this and a number of loosely
| related topics that don't clearly add to this.
| Section 2.2.1 seems to be about the design of specific URI schemes, a
| topic which I think would be better dealt with elsewhere (e.g. in a
| TAG finding or URI-related specification).
| Section 2.2.2 seems to be a further elaboration of the basic
| constraint, and I think should at least be nearby:   as presented, it
| seems to be a distinct matter.   It also seems to relate closely to
| the material in section 2.3.1.
| I don't see the nub of what section 2.2.3 is trying to say, and feel
| it could be elided without any material loss;  if there's a
| fundamental issue here that needs to be stated in this architecture
| document, I think it needs to be stated more clearly.  (I think there
| are allusions here to techniques like "Reference by Description", but
| I think there are just that:  available techniques, not architectural
| constraints.)  If anything, this section seems to be blessing
| techniques like identifying people with their mailto: URIs, which I
| think is contradictory with the previous section and could be a source
| of confusion.

I've tried to clarify 2.2.3. We've rewritten substantially. I
think each of these sections says something useful. I'm not going to
try to do a larger-scale rewrite at this time, though I agree that it
might need one.

| Section, para 3:
| This paragraph gave me a really hard time.  I can only guess at what
| it's trying to say, so it's difficult to offer an alternative.  The
| most problematic clause for me was: "... over a set of URIs with a
| common prefix to one particular owner".

Gone now, I think.

| Section 2.2.2, final para:
| "The section below ..." should be "The section above ...".


| Section 2.3, general:
| I feel there is a lot of duplication here with RFC2396bis [5], which
| has extensive discussion of URI comparison.  This seems like detail
| rather than architectural principle to me, and could reasonably be
| left for that specification to address.
| [5] http://www.ietf.org/internet-drafts/draft-fielding-uri-rfc2396bis-06.txt
|      http://gbiv.com/protocols/uri/rev-2002/rfc2396bis.html
| ...
| Section 2.3, para 2:
| [[
| ... For example, for "http" URIs, the authority component (the part
| after "//" and before the next "/") is defined to be case-insensitive.
| ...
| ]]
| Is this really true or what is intended, for authority components that
| contain usernames and/or passwords?

Indeed. I removed the example and reworded things a bit.

| Section 2.3.1, para 1:
| I don't know what is meant by "(the network neighborhood of the
| measured resource)" in this context.

I've reworded that for clarity. The intent was to say that the network
neighborhood of a resource is the set of resources that link to it.

| Section 2.3.1, general:
| Reading the 1st paragraph of this section, I could get the impression
| that the main reason that URI aliases are not a good thing is because
| they act to depress a resource's Google page ranking.  I think this
| obscures the deeper reason, which I take to be that it damages
| reachability of referring resources (i.e. the 2nd order relatiobships
| mentioned in para 2).
| Suggest:  remove final sentence of 1st paragraph.

Good point.

| Section 2.4.1, 3rd bullet:
| [[
| * One should not expect that general-purpose software will do anything
| useful with URIs of this scheme beyond URI comparison; the network
| effect is lost.
| ]]
| The assertion "the network effect is lost" and/or debatable.  A
| minimal change would be "the network effect is diminished", though I'd
| be more inclined to drop that qualification altogether.

Yes, I don't think it clarifies anything.

| Section 2.5, Good Practice point:
| I found the point, as stated, seemed rather vague (specifically:
| "except as specified by relevant specifications").
| My suggestion would be turn this around to state something like this:
| [[
| The form of URI may indicate how to access a resource, but not about
| the nature of the resource, except insofar as it is constrained by the
| access method.
| ]]

I think the problem is that I could invent and register a scheme that
did allow additional assertions. The data: scheme, for example, allows
me to assert that the resource is the URI.

| Section 2.6, Story:
| I felt the example used in the story here was potentially confusing,
| as elsewhere this document suggests tommorrow's weather is a distinct
| resource and should be identified by a different URI (section 2.3.2).
| Also, the story states that the representation is XHTML, for which the
| representation of the secondary resource indicated by a fragment
| identifier specifically has a representation that is part opf the
| primary resource's representation.
| This is an area where I feel that TimBLs original notes [3] are much
| clearer, albeit somewhat limited to the resource retrieval case.
| [3] http://www.w3.org/DesignIssues/Model.html
| Maybe a better example might be to talk about weather maps (without
| reference to a specific format), for which secondary resources might
| be isobaric vs isothermic vs comic-book sun-and-clouds representations
| (e.g. bit like the map tabs at
| http://www.bbc.co.uk/weather/ukweather/, but using fragment
| identifiers)?

I reworded the example slightly, that may be an improvement, and I
changed the fragment identifier so that it isn't talking about
tomorrow's weather as you point out we suggest elsewhere that each day
gets its own primary resource URI.

| Section 2.7
| I felt that sub-section 2.7.1 didn't really say anything
| architectural, and suggest dropping this, promoting 2.7.1 to be the
| entire content of 2.7.

Hmmm. I agree the sub-sections are unnecessary, but there's a
cross-reference to one of them so simply deleting them would be
disruptive. I'm inclined to leave them for the time being.

| That's all I've time for right now.  I'll try and do some more later.

Thanks for your comments!

                                        Be seeing you,

Norman Walsh <ndw@nwalsh.com> | As a general rule, the most successful
http://nwalsh.com/            | man in life is the man who has the best
                              | information.--Benjamin Disraeli

Received on Tuesday, 28 September 2004 19:56:30 UTC

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