[jira] [Resolved] (JENA-1447) Special case DatasetGraphs

["Andy Seaborne (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/JENA-1447?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Andy Seaborne resolved JENA-1447.
---------------------------------
    Resolution: Fixed

> Special case DatasetGraphs
> --------------------------
>
>                 Key: JENA-1447
>                 URL: https://issues.apache.org/jira/browse/JENA-1447
>             Project: Apache Jena
>          Issue Type: Bug
>          Components: ARQ
>    Affects Versions: Jena 3.5.0
>            Reporter: Andy Seaborne
>            Assignee: Andy Seaborne
>
> Some specialized datasets:
> {{DatasetGraphOne}} - a dataset around a single which becomes the default graph.  This is the converter from graphs to datasets.  A special case is where the graph is GraphView from another dataset. The existing {{DatasetGraphOne}} needs upgrading to map dataset transactions back to the original dataset.
> {{DatasetGraphZero}} - a dataset with no named graph and an always-empty default graph. Convenient to have in place of null pointers.
> {{DatasetGraphSink}} - a dataset that accepts updated but ignores them and so is always empty.
> {{TransactionalNull}} - a transactional to reflect the properties of empty datasets.
> In support of these: 
> {{GraphSink}}, {{GraphZero}}, {{PrefixMappingSink}}, {{PrefixMappingZero}} and {{TransactionHandlerNull}}.
> The graphs do not fully comply with the full {{Graph}} contract:
> * {{GraphZero}} throws {{UnsupportedOperationException}}, not {{AddDeniedException}}/{{DeleteDeniedException}} becaue (1) it is in keeping with {{DatasetGraphZero}} and (2) {{AddDeniedException}} is dynamic - it make be thrown in some situations and not others e.g. permissions.
> * {{GraphSink}} does not contain triples added.
> On naming:
> "DatasetGraphZero" might also be "DatasetGraphNull" but {{/dev/null}} is a sink.



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