Hi Jukka,
Very good summary of what a metadata system smust be.
>From my point of view, +1 for all your proposals.
Just one point I don't understand : why would you like to use objects for
metadata keys ? what are the benefits?
BR
Jérôme
On Mon, Mar 10, 2008 at 9:54 AM, Jukka Zitting <[EMAIL PROTECTED]>
wrote:
> Hi,
>
> Last weekend I spent some time thinking about our Metadata class and
> more generally the handling of metadata in Tika. To summarize my
> thoughts, here's a list of things I think are important for metadata
> handling in Tika.
>
> 0) Metadata in Tika is always about the document being parsed.
>
> 1) Metadata should consist of a modifiable set of keys mapped to values.
>
> 2) Metadata keys should be designed to avoid collisions or misspellings.
>
> 3) It should be possible to store non-String metadata, like Locale
> settings, Date instances, thumbnail images, etc.
>
> 4) We should document and enforce a standard set of metadata keys,
> based on Dublin Core and other standards where possible.
>
> 5) It should be easy to extend the set of metadata keys to include
> custom metadata.
>
> 6) All metadata keys (both standard and custom) should be clearly
> documented with the expected value type and recommended usage.
>
> 7) No two distinct metadata keys should be used for the same metadata
> semantics.
>
> 8) The Metadata class should have convenience methods for accessing
> the most commonly used metadata.
>
> The current Metadata class fails somewhat with 2 (there's even a
> SpellCheckedMetadata class) and doesn't support 3 or 8. The constants
> in o.a.tika.metadata interfaces go some way towards 4 and 6, but not
> as far as they could. And we don't do that well on 7.
>
> So in general I think there's much that we could improve on. To
> resolve most of the issues I'd like to modify metadata handling as
> follows:
>
> a) Allow both metadata keys and values to be arbitrary Objects.
>
> b) Instead of String constants as metadata keys, use constant object
> instances like DublinCore.TITLE = new DublinCore("title"). These
> objects should have good hashCode(), equals(), and toString()
> implementations.
>
> c) Use Date instances for date metadata, URI instances for URIs, etc.
> All value objects should preferably have good toString()
> implementations.
>
> d) Use the Dublin Core "identifier" property instead of the current
> RESOURCE_NAME_KEY, and the "format" property instead of CONTENT_TYPE.
>
> e) Add utility methods like set/getIdentifier(), set/getFormat(),
> set/getTitle(), etc. to the Metadata class for accessing the key
> Dublin Core metadata.
>
> WDYT?
>
> BR,
>
> Jukka Zitting
>
--
Jérôme Charron
Directeur Technique @ WebPulse
Tel: +33673716743 - [EMAIL PROTECTED]
http://blog.shopreflex.com/
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http://www.staragora.com/
