# jsonpath IETF Working Group September 2021 Interim

Date: 2021-09-17
Time: 9:00 - 11:00 UTC

Chair: Tim Bray
Chair: James Gruessing
Area Director: Francesca Palombini

* [Datatracker](https://datatracker.ietf.org/group/jsonpath/about/)
* [Jabber](xmpp:jsonpath@jabber.ietf.org?join)
* [Minutes](https://codimd.ietf.org/notes-interim-2021-jsonpath-03-jsonpath)

## VC Details
https://meetings.conf.meetecho.com/interim/?short=ae48f1c2-565e-4d19-8605-8fd3e3677a68

## Agenda

### Administrivia

* Note Takers
* Blue Sheets
* Jabber Scribe
* Agenda Bashing

### Discussion of Issues

#### Carsten's slides

Glyn: Nodelist passed as individual nodes to the selector

Stefan: Beyond slide 5:
* in-operator
* existence test

Stefan: Good to restrict the RHS of comparisons to simple \[primitive] values

Tim: runtime...

(We think Greg has been pushing for structured values in comparison)

Meeting consensus seems to be to stick with primitive values for comparisons

cabo: path-to-path comparison

Stefan: first reaction: disallow this

Glyn: Proposal A avoid multiple nodes by limiting the path on the $ side as well, only where they will yield a definite value

Tim: syntactic restriction?
Glyn: single value may be an array, but is not multiple nodes...

Glyn: single value may be structured

Meeting consensus appears to be to limit comp-expr to the equivalent of https://github.com/cburgmer/json-path-comparison/blob/master/proposals/Proposal_A/selector.peg

Stefan: (1) But then there is the in-op
(2) allow existence test -- structured value does exist...
cabo: not spelled out -- only confusingly as "falsy" and "truthy"

See issues #120 and #122

#### #119

11 of 4x implementations do that "right"
Function proposal ("exist()")?

Carsten: stick with exist-expr... use that for existence testing
Use comp-expr to find out whether an existing value is 17, "a", false, null, or true.  (A non-existing value is not equal to any literal.  `@.doesnotexist != 17` is true, as is `@.doesnotexist != false`.)
Discuss: `@.doesnotexist != @.alsodoesnotexist`, note that undefined is not equal to undefined in language X
(True of NaN in most languages, not of undefined in JavaScript .)

For `$.foo == $.bar`, user might expext that to be true if both members are missing.

`$.foo && $.foo == $.bar` could be used for the inverse case.

`$.foo == $.bar || !$.foo && !$.bar` would be needed otherwise.

```
> NaN == NaN
false
> NaN != NaN
true
> NaN < NaN
false
> NaN <= NaN
false
> NaN > NaN
false
> NaN >= NaN
false
```


`$.foo in \[]`
is always false, as is
x` in \[]`
for any x



-> add examples to 3.5.9.1 (filter selector)

#### #70

Tim: leave RE out, as trying to make this consistent will make people unhappy.

James: RE could be for extensions in the future.

Carsten: (iregexp) 
https://www.ietf.org/archive/id/draft-bormann-jsonpath-iregexp-00.html
Implementation: transform this common subset into the RE language at hand (surprisingly easy)

Glyn: One standard spawning another activity; actually quite general not limited to jsonpath

Tim: Once we allow regexp, we have to say what we mean.

Stefan: like to export the RE syntax to another specification

Stefan: What would be an extension point?

Carsten: Provide a well-defined place where extensions can be plugged in

Glyn: E.g., there could be a JSONPath over RE2?

Carsten: Separate issue: Policy for granting extensions

Tim: SGML declaration, had dozens of optional features, nightmare

Tim: Statement I'd like to be able to make: Any (conforming) JSONPath can be processed by any (conforming) JSONPath implementation

Emerging Consensus: If we allow regular expressions, we need to say exactly what they mean.

Options:
(A) No RE.
(B) Full spec of RE included.

James: There may be need for Extension Points for other things than RE.

James: Implementers may want to offer a different RE definition...

(Can't define common subset, but also need transformation...)

Tim: UTF-8 characters in RE should always work, classes more interesting

Consensus on options A or B above.

Actions?
(X) Develop ideas about what could be viable extension point mechanisms
(Y) Examine iregexp



#### #103
List of issues to discuss to be finalised later

### AOB

Do schedule a 112 meeting

Interim?
Not enough time.