Re: [xdi] Collected ABNF ready for review (starting with Joseph & Markus

Subject: Re: [xdi] Collected ABNF ready for review (starting with Joseph & Markus)

On Tue, Mar 17, 2015 at 11:21 AM, Joseph Boyle <planetwork@josephboyle.net> wrote:

I think it shows we’re allowing the ABNF to be very general and generate complex stuff we don’t understand but would have to support - even as we’re using the ABNF to minutely distinguish cases in some other areas.

You can take a relative simple ABNF and use it to generate some pretty wild edge cases, but that doesn't mean you should make the ABNF more complicated. And when you say "we’re using the ABNF to minutely distinguish cases in some other areas", this most recent ABNF eliminated almost all of those. Can you give some examples?

What is the use case for allowing variables to contain definitions? I still don’t understand these well.

Did you miss the TC call where we discussed that? We spent about an hour on it. See the Defined Variables section of the XDI Variables wiki page.

On Mar 10, 2015, at 3:31 AM, Markus Sabadello <markus.sabadello@xdi.org> wrote:
On 03/09/2015 09:06 PM, Joseph Boyle wrote:

Drummond, here are a few initial review questions:

Are definitions as well as variables, collections, and everything else (but inner roots) limited to a single arc?

If so, why not just vertical bar before instead of both before and after?

More generally, it’s a waste to use paired delimiters around single arcs.

Let’s try to construct a maximal nesting example. Is this in fact grammatical and a single arc? Is there any of this nesting that we should rule out either at the syntactic level or higher levels?

{|[(({|[#1]|})({|[#2]|}){|[#3]|}<{|[#4]|}>/({|[#5]|})({|[#6]|}){|[#7]|}<{|[#8]|}>)]|}

Haha I pasted this into my parser just for fun, and it even made it to {|[#4]|} before it gave up with an error!

If we decide this is valid, then it should probably become a unit test for XDI2 !
Why does class have the option of being one of six context symbols followed by nothing, four of which are normally in authorities or instances not classes?

Why can an attribute singleton not be an authority? This seems to be the only difference in content permitted in entities and attributes.

Do you want to use 1*peer and 1*entity? if not, how do we interpret zero cases like () and (/)?
root                    = peer / inner / root-collection / root-definition / root-variable
peer                    = "(" *entity ")"
inner                   = "(" *peer / *entity "/" *entity ")"
root-collection         = "[" peer / inner "]"
root-definition         = "|" peer / inner / root-collection "|"
root-variable           = "{" peer / inner / root-collection / root-definition "}"

entity                  = singleton / collection / definition / variable
singleton               = class / instance / authority
collection              = "[" class "]"
definition              = "|" class / authority / collection "|"
variable                = "{" singleton / collection / definition "}"

attr                    = attr-singleton / attr-collection / attr-definition / attr-variable
attr-singleton          = attr-class / attr-instance
attr-collection         = "[" attr-class "]"
attr-definition         = "|" attr-class / attr-authority / attr-collection "|"
attr-variable           = "{" attr-singleton / attr-collection / attr-definition "}"
attr-class              = "<" class ">"
attr-instance           = "<" instance ">"
attr-authority          = "<" authority ">"
attr-terminal           = attr-class / ( attr-collection attr-instance )

class                   = reserved / unreserved / "$" / "#" / "@" / "*" / "=" / +"
reserved                = "$" 1*xdi-char
unreserved              = "#" id-literal

instance                =  ordered / unordered
ordered                 = "@" [ "!" ] 1*DIGIT
unordered               = "*" [ "!" ] id-literal

authority               = personal / legal
personal                = "=" [ "!" ] id-literal
legal                   = "+" [ "!" ] id-literal

id-literal              = 1*xdi-char / xdi-scheme / xref
xref                    = local / uri
local                   = "(" 1*xdi-char ")"
uri                     = "(" escaped-uri ")"
On Mar 8, 2015, at 5:28 PM, =Drummond Reed <drummond@respectnetwork.com> wrote:

After Friday's very long TC call reviewing the "star shift", "immutability symbol", and "xref" proposals (see https://wiki.oasis-open.org/xdi/StarShift), this weekend I worked on an update to the XDI ABNF that I just uploaded to the ABNF page:

https://wiki.oasis-open.org/xdi/XdiAbnf

I was excited to work on this ABNF because, as I had predicated on Friday, it is significantly more simplified, regular, and elegant than any previous version. (And no longer recursive, which will finally make Joseph happy ;-)

The next step is for Joseph and Markus to review and test it carefully, and for Joseph to attend to some remaining to-dos on the low-level rulesets. There is also one open question about what versions of SHA hashing do we want to support as native XDI schemes. Please feel free to weigh on this thread with your view.

=Drummond

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