Add optional cache-duration attribute to notification message.

[6a6d74]

A WIS Node may indicate that a resource should be cached for a period other than 24-hours. A cache-duration attribute would allow that to be specified for a given resource. In absence of this attribute, the duration should default to 24-hours.

Also see Indicate to Global Caches how long a resource should be cached for.

[tomkralidis]

I am guessing that this (put forth as an ISO 8601 duration) would be best placed in the canonical link, which is what the GC would be locking on for download. For discussion at the next TT-WISMD meeting on 2024-01-30.

[tomkralidis]

TT-WISMD 2024-01-30:

• GC considerations / mechanisms (GC does have the right to not cache)
• should this be in WCMP2 instead?

[kaiwirt]

I am not sure if i remember correctly, but i think at the Washington Meeting it was decided to start with 24h as default and the option to add the possibility for different retention times later, if required.

My question would be: Is there a requirement for different retention times other than 24h?

The WIS2-Guide draft currently says: "A Global Cache shall retain the data and metadata they receive for a minimum period of 24 hours. Requirements relating varying retention times for different types of data may be added later."