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https://issues.apache.org/jira/browse/SIS-73?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Martin Desruisseaux closed SIS-73.
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> Remove the automatic mapping of UUIDs to objects
> ------------------------------------------------
>
> Key: SIS-73
> URL: https://issues.apache.org/jira/browse/SIS-73
> Project: Spatial Information Systems
> Issue Type: Task
> Components: Utilities
> Reporter: Martin Desruisseaux
> Assignee: Martin Desruisseaux
> Priority: Minor
> Fix For: 0.3
>
>
> For every UUID (_Unique Universal Identifier_) assigned to an
> {{IdentifiedObject}}, SIS automatically keeps the association using weak
> references in an internal map. This allow to retrieve the object by UUID if
> the object is still alive in the JVM. The rational was that if UUID are truly
> unique, then there is few risk of ID clash even if we use a system-wide map.
> However this cause a number of risks:
> * The "truly unique" hypothesis may not hold in practice. Consider for
> example the case were the user reloads many times the same ISO 19139
> document. If the document contains an object with {{gco:uuid}} attribute,
> then the same UUID will be assigned many times - admitely to equivalent
> objects, but the user could have edited a previously loaded instance.
> * In order to be truly effective, developers need to provide their own "UUID
> to object" mapping anyway, because the universe of UUIDs is large and the
> developers probably have some database for them. Our own management of "UUID
> assigned in the current JVM" is likely to overlap with the developer's
> database.
> Applying the prudential rule "_in case of doubt, leave it out_", the proposal
> is to remove the automatic "UUIDs to objects" mapping, but keep this JIRA
> task in the archive in order to make easier to find the Subversion revision
> number to revert if this functionality is considered useful in a future SIS
> version.
> As a minor side effect, the {{putIfAbsent}} method from {{WeakValueHashMap}}
> should also be removed. It was added for supporting the feature documented in
> this JIRA task at the cost of slight complication of implementation. Given
> that {{WeakValueHashMap}} is not real concurrent map, we may be better to
> avoid any {{ConcurrentMap}} method.
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