Include a regex for XML Date Time in the next version of the standard.

[OR13]

If we can't agree to relax XML Data Time to the broader category or ISO 8601 date times, we should include a regex that defines the allows string representations, and we should document all known issues with string representations of date times in the spec, so that implementers don't have to guess about "leap seconds" or other time related issues.

[iherman]

The issue was discussed in a meeting on 2021-12-01

• no resolutions were taken

View the transcript

3.3. Include a regex for XML Date Time in the next version of the standard. (issue vc-data-model#846)

See github issue vc-data-model#846.

Brent Zundel: This seems like it's v2.0, anyone disagree?.

[OR13]

Related:

• DHS: Best Practices for Leap Second Event Occurring on 31 December 2016
• leap-second-rattle-internet-theres-plot-kill
• IETF leap-seconds.list
• timeanddate.com
• See also: https://en.wikipedia.org/wiki/Year_2038_problem

Examples should include leap seconds if they are legal, and the regex MUST recognize valid ISO8601 date time strings that include leap seconds.

For example:

{ 
  "issuanceDate": "2016-12-31T23:59:60Z",  // looses leap second
  "expirationDate": "2038-01-19T03:14:08Z" // integer overflow
}

[OR13]

https://github.com/json-schema-org/json-schema-spec/issues/483

[mprorock]

something like (\d{4}-\d{2}-\d{2})[A-Z]+(\d{2}:\d{2}:\d{2}).([0-9+-:]+) ?

[OR13]

possibly useful:

https://github.com/transmute-industries/verifiable-data/blob/43b2dd1f91dc200927bd8c859ece31eae465e4f1/packages/vc.js/src/datetime/datetime.test.ts

https://github.com/transmute-industries/verifiable-data/blob/43b2dd1f91dc200927bd8c859ece31eae465e4f1/packages/vc.js/src/datetime/index.ts

export const RFC_3339 = new RegExp(
  "^([0-9]{4})-([0-9]{2})-([0-9]{2})" +
    "([Tt]([0-9]{2}):([0-9]{2}):([0-9]{2})(.[0-9]+)?)?" +
    "(([Zz]|([+-])([0-9]{2}):([0-9]{2})))?"
);

// Tweaked to allow for leap seconds
export const ISO_8601_FULL = /^([\+-]?\d{4}(?!\d{2}\b))((-?)((0[1-9]|1[0-2])(\3([12]\d|0[1-9]|3[01]))?|W([0-4]\d|5[0-2])(-?[1-7])?|(00[1-9]|0[1-9]\d|[12]\d{2}|3([0-5]\d|6[1-6])))([T]((([01]\d|2[0-3])((:?)[0-5]\d)?|24\:?00)([\.,]\d+(?!:))?)?(\17[0-6]\d([\.,]\d+)?)?([zZ]|([\+-])([01]\d|2[0-3]):?([0-5]\d)?)?)?)?$/;

export const TIME_ZONE_OFFSET_MATCH = /[+-]\d\d:\d\d$/;

[brentzundel]

possible regex from @mprorock:

mprorock spits (\d{4}-\d{2}-\d{2})[A-Z]+(\d{2}:\d{2}:\d{2}).([0-9+-:]+) out of the magic "i hate regex" scratchpad

[mprorock]

and a more brutal, but probably more correct one: ^([0-9]{4}(?!\d{2}\b))((-?)((0[1-9]|1[0-2])(\3([12]\d|0[1-9]|3[01]))?|W([0-4]\d|5[0-2])(-?[1-7])?|(00[1-9]|0[1-9]\d|[12]\d{2}|3([0-5]\d|6[1-6])))([T\s]((([01]\d|2[0-3])((:?)[0-5]\d)?|24\:?00)([\.,]\d+(?!:))?)?(\17[0-5]\d([\.,]\d+)?)?([zZ]|([\+-])([01]\d|2[0-3]):?([0-5]\d)?)?)?)?$

[TallTed]

Of course, we all know that there are multiple flavors of regex in the world, so we have to declare which one is in play here...

[iherman]

The issue was discussed in a meeting on 2022-08-17

• no resolutions were taken

View the transcript

2.3. Include a regex for XML Date Time in the next version of the standard. (issue vc-data-model#846)

See github issue vc-data-model#846.

Orie Steele: found flaws in the v1.0 description of date/times.
… this was fixed in v1.1 DM.
… but need to be clear about which string format is being used.
… so prefer a regex value.

Manu Sporny: we can add this to v2 DM.

Dmitri Zagidulin: +1 to including the RegEx in the spec :) (having had to come up with that same regex for a library...).

Manu Sporny: alternatively we could define an XML schema for date/time and a regex to check if it is correct.

Dmitri Zagidulin: having already implemented this, we will save a lot of time if we add Regex expression to the DMv2.

Gabe Cohen: +1. implementing xsd:dateTime was incredibly painful.

Michael Jones: I added regex to OAuth2 and implementors have found it useful.

Manu Sporny: +1 selfissued, I think that would be fine..

Michael Jones: so I support adding it.

Brent Zundel: we need a volunteer to produce a PR for this? Orie? Dmitry?.

Dmitri Zagidulin: said he would produce the first draft.

[pchampin]

A slightly different, but related question: do we really want the timezone offset to be optional? Strictly speaking, a dateTime without an explicit timezone is ambiguous.

If it is expected that timezone offset are always provided, then the specified datatype should be xsd:dateTimeStamp rather than xsd:dateTime.

[OR13]

https://www.w3.org/TR/xmlschema11-2/#dateTime

• does not support leap seconds.
• 100% compatible with unix timestamps.

[iherman]

The issue was discussed in a meeting on 2023-01-11

• no resolutions were taken

View the transcript

3.2. Include a regex for XML Date Time in the next version of the standard. (issue vc-data-model#846)

See github issue vc-data-model#846.

Brent Zundel: Include date and time for the standard..
… No opposition to this proposal..
… Any volunteers to write this?.

Manu Sporny: Terrified to get this wrong. A bug in the scheme. It's possible that the regx could be incorrect..
… There should be timezone in the date and time. We need regx experts to get it right..

Brent Zundel: Any volunteers?.

Ivan Herman: Do we have a decision to use the XSD date and time?.

Manu Sporny: We have gone through three variants. XML schema 1, regx, ....

Ivan Herman: Not asking about regex. Asking for definition about daytime..

Manu Sporny: We have looked into this. We are looking at XML schema for daytime, but it was wrong..
… You have to specify the timezone..
… Times are hard. :-).
… XML schema must specify timezone..

[iherman]

The issue was discussed in a meeting on 2023-04-04

• no resolutions were taken

View the transcript

1.5. Include a regex for XML Date Time in the next version of the standard. (issue vc-data-model#846)

See github issue vc-data-model#846.

Kristina Yasuda: About regex for XML Date Time..

Manu Sporny: I'll take this one.
… We will provide a regex for XML Date Time that exists in the spec, but we will mandate time zone..
… This has come up in implementations..

Ivan Herman: Manu, didn't we have that in the DID spec?.

Manu Sporny: Not sure if we had a regex for this in DID Core. If we did, it needs to be updated to include the time zone..

[OR13]

If only this came with a regex

https://ijmacd.github.io/rfc3339-iso8601/

[decentralgabe]

Very supportive of this issue. I've had a hard time finding libraries for xsd:dateTime in go. I end up using RFC3339 everywhere which isn't great. A regex would go a long way towards facilitating interoperability.

[msporny]

PR #1183 has been merged to address this issue. Closing.