Changes between Version 21 and Version 22 of ComposedMetadataRecords

Timestamp:

Aug 31, 2009, 9:57:28 PM (15 years ago)

Author:

simonp

Comment:

--

ComposedMetadataRecords

@@ -21 +21 @@
 === Links ===
  * '''Subtemplates''': Metadata fragments are equivalent to subtemplates (which were only partially implemented in !GeoNetwork). Subtemplates appear to have been an extension of the template concept in !GeoNetwork. Templates are complete metadata records with some elements filled in. A user can clone such a record for use in the editor as a template. At this stage all connection between the template and the cloned record is broken ie. changes to the template are not visible in the cloned record and vice versa. Subtemplates (as they were partially implemented in !GeoNetwork) took the template concept down to the level of individual elements in the metadata record. So for example, contact information could be saved as a subtemplate and then reused when editing different elements. The implementation of subtemplates didn't make clear whether the link between a subtemplate and the record it had been added to was maintained. This proposal intends to implement subtemplates as fragments of metadata harvested from an external database - the link between a metadata record and a fragment will be maintained ie. changes in the fragment will be visible in the record.  
- * '''Composed, Componentized and Relational Metadata''': The idea of composed or componentized metadata and the term itself, appears to be common to many discussions on the net and in the literature. Another term with similar concepts is "relational" metadata (!LISASoft metadata report). Although there has been discussion in and around these topics and even some implementation of fragments in !GeoNetwork as subtemplates, this proposal appears to be the first to suggest the mechanisms for implementing these concepts in !GeoNetwork using fragments harvested from a database with a WFS interface. 
+ * '''Composed, Componentized and Relational Metadata''': The idea of composed or componentized metadata and the term itself, appears to be common to many discussions on the net and in the literature. Another term with similar concepts but more heavily focused on reuse/normalization/removal of redundancy (as used for relational databases) is "relational" metadata (eg. LISASoft metadata report). Although there has been discussion in and around these topics and even some implementation of fragments in !GeoNetwork as subtemplates, this proposal appears to be the first to suggest the mechanisms for implementing these concepts in !GeoNetwork using fragments harvested from a database with a WFS interface. 
 
 === Voting History ===
@@ -37 +37 @@
  * WFS fragment harvester - this is a harvester that accepts (along with the usual harvester parameters) a WFS GetFeature query, a template 
 
- * XLink resolver and cache
-
+ * XLink resolver and cache - the geocat.ch sandbox uses and is developing an XLink resolver and cache mechanism. The implementation in the BlueNetMEST sandbox uses the same cache mechanism (based on Apache JCS) but has modified the resolver links
+ 
 Future work would add:
 
@@ -55 +55 @@
 Effects on export (eg. MEF): Composed metadata records exported as MEF files would normally have their XLinks resolved before export. If there was a requirement for composed metadata records to be exported with unresolved XLinks then an option could be added to the MEF export service to prevent XLink resolution before export.
 
-XLinks and metadata records composed from xlink'd fragments can be made optional through the use of a system configuration option.
+XLinks and metadata records composed from xlink'd fragments can be made optional through the use of a system configuration option. This has been implemented in the BlueNetMEST sandbox.
 
 == Risks ==
+
+Some XLink concepts are open to a number of interpretations eg. the notion of a relative URL with fragment identifier such as: 
+
+<gmd:temporalExtent xlink:href="#temporalExtent">
+
+would (I think) be interpreted as a link to a fragment within the same document. From discussions with the deegree developers (who have an advanced xlink implementation in their WFS), it appears that some organisations are interpreting such a link as being a fragment in any document within the local database. (reference required)
 
 == Participants ==