GeoServer : GSIP 64 - Keyword Vocabularies and Languages
This page last changed on Oct 06, 2011 by jdeolive.
Supporting vocabulary and language attributes for keywords with OGC services.
Under Discussion, In Progress, Completed, Rejected, Deferred
Many OGC services allow keywords to contain additional attributes. WMS 1.3 allows a keyword to have a vocabulary. The OWS schema allows for a keyword to specify a language. This proposal expands on current GeoServer keyword support in support of this.
For the quick version see the current patch
Currently keywords are implemented as a single string. For instance consider the ServiceInfo interface:
Similarly so does ResourceInfo. The idea is to change this from a string to a domain object named KeywordInfo that can model the additional information:
The ServiceInfo and ResourceInfo interfaces/classes will be changed to contain list of KeywordInfo rather than list of String. See backwardscompatibility for details on how this affects the serialized representation.
The keyword editor is extended to allow for setting language and vocabulary from the UI.
And the capabilities transformers are updated to output the values.
Changing the keyword class leads to a different representation produced by xstream and hence changes the data directory format. However, with some XStream trickery this can be done in a 100% backward compatible way. Currently keyword persistence looks like the following:
The idea is to serialize KeywordInfo (via a custom XStreamPersister binding) as a simple string of the format:
As an example:
In this way we don't change the structure of the serialized format, and hence don't introduce any data directory incompatibilities. There is however the forward compatibile issue that if someone adds keywords (with one of the new attributes) with a new version, saves them, and then reverts to an older geoserver the keyword strings will contain the full serialized versions.
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