there is (as far as I know) no plan to add support for transactions to
Internationalisation of feature properties is an interesting use-case.
Reminds me of a gazetteer (and WFS-G).
On 02/03/12 12:08, Sunil Padda wrote:
> Hi Ben,
> Do you know if there is any scope or plan for supporting transactions in
> app-schema? I doubt if it's possible to do this at all. Here is an
> example: Let's say each Feature can have multiple multilingual Names.
> The database would look like this:
> Feature (Feature_id, Shape)
> Name (Name_id, Feature_id, Lang_id, Name)
> Lang (Lang_id, Language)
> Let's say we don't expose Name_id and Lang_id (as they are
> auto-generated). Also, assume Lang table is pre-populated with all
> possible languages, and thus should not be editable. In this case, when
> a WFS addFeature request comes to Geoserver (with Shape, Language(s),
> Name(s)). In this case, we should not be creating a Lang entry. Instead,
> the Lang_id should be figured out using Language, used to create a new
> entry in Name table (of course, taking care that the generated
> Feature_id is added to it). Also, in some cases we need to respect
> unique constraints like there can be only 1 name per language for each
> I doubt if XSLT can handle such use cases. I think an extension where
> these rules can be configured could solve this problem (but this
> configuration can get quite complex, mimicking a database itself).
> Please let me know your thoughts on this.
> On Tuesday 21 February 2012 12:22:06 PM IST, Ben Caradoc-Davies wrote:
>> On 21/02/12 10:40, Sunil Padda wrote:
>>> We want to be able to do both read& write to the underlying database.
>>> As app-schema gives a read-only view of the data, this doesn't suit our
>>> needs. Is there any work in progress for the future to enable
>>> app-schema to support writes? (As I understand, it's not possible. But,
>>> I would like to confirm).
>> Correct. app-schema does not yet support transactions (and in the
>> GeoServer world, it does not support WFS-T).
>> One missing piece is the parsing of complex feature GML into GeoTools
>> objects. There is a third-party implementation based on GeoTools but it
>> has not yet been contributed. Some of my colleagues are currently in
>> communication with the authors. My colleagues aim to get GeoTools
>> consuming complex GML. This would likely be of *great* assistance to you.
>>> I didn't look at the app-schema code yet, but is there any code in
>>> app-schema that we could potentially leverage when building a custom
>>> solution (maybe something like ComplexFeatureType, ComplexFeature,
>>> ComplexFeatureBuilder etc.).
>> Potentially. These are just FeatureTypeImpl and FeatureImpl. There is
>> not yet any builder (Andrea has justifiably complained about this);
>> building complex features is rather tricky as it refers to external
>> schemas and circular relationships between types. Please have a look at
>> the many app-schema unit tests.
>>> One last question. Assuming we somehow build our own custom solution to
>>> create complex features, does GeoServer support reads and writes from
>>> it? If not, are there any other WFS servers that do?
>> Sorry, I don't know.
>> Kind regards,
Ben Caradoc-Davies <Ben.Caradoc-Davies@...>
CSIRO Earth Science and Resource Engineering
Australian Resources Research Centre