[logback-dev] ISO8601 format

[Michael Osipov]

> Per LOGBACK-262 [1], logback does not conform to ISO8601 when printing
> %d{ISO8601}. We're in the process of fixing this [2], but we'd like to
> maintain backward compatibility for log parsers that might rely on the
> incorrect format. We have a couple options.
>
>
> OPTION 1. Add a new option for %d that enables the legacy incorrect format.
> Deprecate it, and remove it after several releases. Examples:
>
>   %d{ISO8601_OLD}
>   %d{NOT8601}
>   %d{OLD8601}
>   %d{ISO8601,,old}
>   other?
>
> OPTION 2. Force users to specify a custom date format that matches the
> legacy incorrect format:
>
>   %d{"yyyy-MM-dd HH:mm:ss,SSS"}
>
> Please provide feedback on these options (or a new one) by June 23.

I would go for option one. Here is why:

Make a pattern name HUMAN_ISO8601 to avoid people writing the pattern 
over again like in option two. The NO_T is valid as long as there is a 
mutual agreement among the participating parties. I have access to all 
ISO documents at work and can provide a citation (chapter, verbatim, 
etc.) if needed.

Michael