posixfs should map dublin core extended attributes to the XML namespace

[butonic]

When I set dublin core extended attributes on my files I want to see them in the web UI.

Posixfs and the webdav layer should map the extended attribute namespace user.dublincore.* to xmlns:dc="http://purl.org/dc/elements/1.1/".

The default 15 terms defined in https://www.dublincore.org/specifications/dublin-core/dcmi-terms/ dublin core has an official XML namespace xmlns:dc="http://purl.org/dc/elements/1.1/" as per https://www.dublincore.org/specifications/dublin-core/dc-xml-guidelines/ and https://www.dublincore.org/specifications/dublin-core/dc-xml/, eg:

  <dc:title>
    UKOLN
  </dc:title>
  <dc:description>
    UKOLN is a national focus of expertise in digital information
    management. It provides policy, research and awareness services
    to the UK library, information and cultural heritage communities.
    UKOLN is based at the University of Bath.
  </dc:description>
  <dc:publisher>
    UKOLN, University of Bath
  </dc:publisher>
  <dc:identifier>
    http://www.ukoln.ac.uk/
  </dc:identifier>

The extended attributes representation is defined in https://www.freedesktop.org/wiki/CommonExtendedAttributes/

    user.dublincore.title
    user.dublincore.creator See also user.xdg.creator
    user.dublincore.subject
    user.dublincore.description
    user.dublincore.publisher
    user.dublincore.contributor
    user.dublincore.date
    user.dublincore.type
    user.dublincore.format
    user.dublincore.identifier
    user.dublincore.source
    user.dublincore.language See also user.xdg.language
    user.dublincore.relation
    user.dublincore.coverage
    user.dublincore.rights

[aduffeck]

@butonic the user.oc.md. prefix has been used in the past already though, also for the decomposed driver. Are you sure that we want to have different behavior for posix?

[kulmann]

I don't really understand what this issue is about. What kind of metadata in the web ui are you talking about? 😅

[butonic]

I rewrote the issue to be about dublin core only.

There are more extended attributes in https://www.freedesktop.org/wiki/CommonExtendedAttributes/ that are interesting:

Proposed metadata attributes

Extended attributes are especially useful when they add information that is not present in the in the actual file. Depending on the file origin, an application can add metadata that is not present and/or can not be specified by the file or its format. For example file downloaded from a web server can be tagged with the url, which can be convenient if its source has to be determined in the future. Likewise, an email attachment can when saved be tagged with the message-id of the email. This will make it possible to trace the original message.

These attributes are currently proposed

• user.xdg.comment: A comment specified by the user. This comment could be displayed by file managers
• user.xdg.origin.url: Set on a file downloaded from a url. Its value should equal the url it was downloaded from.
• user.xdg.origin.email.subject: Set on an email attachment when saved to disk. It should get its value from the originating message's "Subject" header
• user.xdg.origin.email.from: Set on an email attachment when saved to disk. It should get its value from the originating messsage's "From" header. For example '"John Doe" <jdoe@example.com>', or 'jdoe@example.com'
• user.xdg.origin.email.message-id: Set on an email attachment when saved to disk. It should get its value from the originating message's "Message-Id" header.
• user.xdg.language: Language of the intellectual content of the resource. The value should follow the syntax described in RFC 3066 in conjunction with ISO 639 language codes. When a file is downloaded using HTTP, the value of the Content-Language HTTP header can if present be copied into this attribute. See also the Language element in Dublin core.
• user.xdg.creator: Reserved but not yet defined. The string "user" has a different meaning in ROX Contact Manager (creating application) compared with Dublin core (creating person/entity).
• user.xdg.publisher: Name of the creating application. See also the Publisher element in Dublin core.

[...]

Proposed control attributes

Extended attributes could also act as flags for backup programs, indexing programs and similar, to control their behaviour. Below is an initial proposal for start of discussion, to alter the default behaviour. They are inspired by html attributes to control web crawling.

• user.xdg.robots.index: On a file: "true" to index, "false" to not index. On a directory: "true" to traverse the into the directory for indexing, "false" for not traversing into it.
• user.xdg.robots.backup: On a file: "true" to index, "false" to not backup. On a directory: "true" to traverse the into the directory for backup, "false" for not traversing into it.

Interesting, but certainly nothing for now and I don't see a way for a generic mapping of extended attributes if there is no corresponding XML namespace.

The only part that could be added is a dublin core mapping ... which can remain with a junior job label IMO. I'll update the title.