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https://issues.apache.org/jira/browse/TIKA-1691?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14645973#comment-14645973
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Nick Burch commented on TIKA-1691:
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Reading the PDF, it looks to me like what our parsers already do. If one file
format has something called Author, another one Creator, another one First
Modified By, another one Created By, another one Email From, the relevant
parsers all map those onto the DublinCore/TikaCoreProperties {{CREATOR}}
metadata property.
If you can point us at an example / use-case where that isn't working / isn't
working enough, that'd help
Otherwise, in the case that Tika parsers are setting
{{TikaCoreProperties.CREATOR}} and your destination use wants a custom
{{author_name}} property for that value instead, I still think that that
mapping needs to happen on the output side (when reading from the metadata
object) and not the input side (monkeying with what gets written into the
metadata object)
> Apache Tika for enabling metadata interoperability
> --------------------------------------------------
>
> Key: TIKA-1691
> URL: https://issues.apache.org/jira/browse/TIKA-1691
> Project: Tika
> Issue Type: New Feature
> Reporter: Giuseppe Totaro
> Assignee: Giuseppe Totaro
> Labels: mapping, metadata
> Attachments: mapping_example.pdf
>
>
> If am not wrong, enabling consistent metadata across file formats is already
> (partially) provided into Tika by relying on {{TikaCoreProperties}} and,
> within the context of Solr, {{ExtractingRequestHandler}} (by defining how to
> map metadata fields in {{solrconfig.xml}}). However, I am working on a new
> component for both schema mapping (to operate on the name of metadata
> properties) and instance transformation (to operate on the value of metadata)
> that consists, essentially, of the following changes:
> * A wrapper of {{Metadata}} object ({{MappedMetadata.java}}) that decorates
> the {{set}} method (currently, line number 367 of {{Metadata.java}}) by
> applying the given mapping functions (via configuration) before setting
> metadata properties.
> * Basic mapping functions ({{BasicMappingUtils.java}}) that are utility
> methods to map a set of metadata to the target schema.
> * A new {{MetadataConfig}} object that, as well as {{TikaConfig}}, may be
> configured via XML file (organized as showed in the following snippet) and
> allows to perform a fine-grained metadata mapping by using Java reflection.
> {code:xml|title=tika-metadata.xml|borderStyle=solid}
> <?xml version="1.0" encoding="UTF-8" standalone="no"?>
> <properties>
> <mappings>
> <mapping type="type/sub-type">
> <relation name="SOURCE_FIELD">
> <target>TARGET_FIELD</target>
> <expression>exclude|include|equivalent|overlap</expression>
> <function name="FUNCTION_NAME">
> <argument>ARGUMENT_VALUE</argument>
> </function>
> <cardinality>
> <source>SOURCE_CARDINALITY</source>
> <target>TARGET_CARDINALITY</target>
> <order>ORDER_NUMBER</order>
> <dependencies>
> <field>FIELD_NAME</field>
> </dependencies>
> </cardinality>
> </relation>
> </mapping>
> ...
> <mapping> <!-- This contains the fallback strategy for unknown metadata
> -->
> <relation>
> ...
> </relation>
> <mapping>
> </mappings>
> </properties>
> {code}
> The theoretical definition of metadata mapping is available in "[A survey of
> techniques for achieving metadata
> interoperability|http://www.researchgate.net/profile/Bernhard_Haslhofer/publication/220566013_A_survey_of_techniques_for_achieving_metadata_interoperability/links/02e7e533e76187c0b8000000.pdf]";.
> This paper shows also some basic examples of metadata mappings.
> Currently, I am still working on some core functionalities, but I have
> already performed some experiments by using a small prototype.
> By the way, I think that we should modify the method {{add}} in order to use
> {{set}} instead of {{metadata.put}} (currently, line number 316 of
> {{Metadata.java}}). This is a trivial change (I could create a new Jira issue
> about that), but it would allow to be coherent with the other implementation
> of {{add}} method and, moreover, the methods of {{Metadata}} could be
> extended more easily.
> I would really appreciate your feedback about this proposal. If you believe
> that it is a good idea, I could provide the code in few days.
> Thanks a lot,
> Giuseppe
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