Digesting last XDI TC call

[Markus Sabadello <markus.sabadello@xdi.org>]

So we talked about the JSONModel

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

I have been staring now for a pretty long time at some of the examples we came up with:

  =markus+email[1]<$string>/<>/"a@gmail.com"

  =markus+email[2]<$string>/<>/"b@gmail.com"

  =markus+email[3]<$string>/<>/"c@gmail.com"

  =markus+email!:uuid:1234<$string>/<>/"d@gmail.com"

And:

  =markus+email!:uuid:1111<$string>/<>/"1@gmail.com"

  =markus+email!:uuid:2222<$string>/<>/"2@gmail.com"

  =markus+email!:uuid:3333<$string>/<>/"3@gmail.com"

  =markus+email[1]/$ref/=markus+email!:uuid:3333

  =markus+email[2]/$ref/=markus+email!:uuid:2222

  =markus+email[3]/$ref/=markus+email!:uuid:1111

  =markus!(+email)/$ref/ =markus+email!:uuid:1111

And:

 =markus+address!:uuid:123+street[1]<$string>/<>/"..."

 =markus+address!:uuid:123+street[2]<$string>/<>/"..."

 =markus+address!:uuid:123!(+city)<$string>/<>/"..."

 =markus+address!:uuid:123!(+country)<$string>/<>/"..."

 =markus+address!:uuid:456<$string>/<>/"..."

And:

  =sender$msg!:uuid:1234$do/$add/...

  =sender$msg[1]/$ref/=sender$msg!:uuid:1234

I completely understand how they work and what were the steps we took to arrive at this, and I believe I can implement this.

BUT: It all seems very complex to me. :)

I think the biggest turn-offs for me here are:

1. There are two different ways of expressing that something is an instance of something:

1.a. +email!:uuid:1111 is an instance of an +email.

1.b. +email[1] is also an instance of an +email, and in addition it is an ordered element in an array.

1.c. But for example, =!2222!:uuid:1111 is not an instance of =!2222.

2. There are three different ways of expressing that something can have a value:

2.a. +email!:uuid:1111 can have a value, because it is an instance of something that has a + context symbol

2.b. +email[1] can have a value, because it is an instance of something that has a + context symbol

2.c. !(+email) can have a value, because it is a singleton

3. There is no clean syntax for an array/collection/group/set.

If I got this summary wrong, please let me know, but I think it is accurate.

So basically you have to consider both the context symbol, and the brackets, and several special rules, in order to understand what you're dealing with.

I feel this is just so unintuitive, and much more complicated than what we had before in the ContextFunctions proposal.

And while I very much support the idea of 100% map-ability between JSON and XDI (for the purpose of connectors), I don't think it's a great idea to base the XDI graph model itself (and its terminology) on JSON.

So I took a step back and tried to imagine what would work.

I think my favorite thing to do now would be to move back to the general ContextFunctions idea, with a few slight changes:

1. Pattern for root: ( )

2. Pattern for entity: (no pattern)

3. Pattern for attribute: < >

4. Pattern for value: < >

5. Pattern for collection: [ ]

6. Pattern for entity member: ! for unordered, * for ordered

7. Pattern for attribute member: <!> for unordered, <*> for ordered

Using these patterns, here are the same examples as above:

  =markus[+email]<*1><$string>/<>/"a@gmail.com"

  =markus[+email]<*2><$string>/<>/"b@gmail.com"

  =markus[+email]<*3><$string>/<>/"c@gmail.com"

  =markus[+email]<!:uuid:1234><$string>/<>/"d@gmail.com"

And:

  =markus[+email]<!:uuid:1111><$string>/<>/"1@gmail.com"

  =markus[+email]<!:uuid:2222><$string>/<>/"2@gmail.com"

  =markus[+email]<!:uuid:3333><$string>/<>/"3@gmail.com"

  =markus[+email]<*1>/$ref/=markus[+email]<!:uuid:3333>

  =markus[+email]<*2>/$ref/=markus[+email]<!:uuid:2222>

  =markus[+email]<*3>/$ref/=markus[+email]<!:uuid:1111>

  =markus<+email>/$ref/ =markus[+email]<!:uuid:1111>

And:

 =markus[+address]!:uuid:123[+street]<*1><$string>/<>/"..."

 =markus[+address]!:uuid:123[+street]<*2><$string>/<>/"..."

 =markus[+address]!:uuid:123<+city><$string>/<>/"..."

 =markus[+address]!:uuid:123<+country><$string>/<>/"..."

 =markus[+address]<!:uuid:456><$string>/<>/"..."

And:

  =sender[$msg]!:uuid:1234$do/$add/...

  =sender[$msg]*1/$ref/=sender[$msg]!:uuid:1234

I think this supports all the requirements we found and has much cleaner syntax than the JSONModel.

Feedback?

Markus