[Gvsig_english] [ gvSIG 2.0 extension development ] Howtoimplement and register a new DAL provider
Jorge Piera Llodrá
jpiera at prodevelop.es
Thu Aug 5 20:01:32 CEST 2010
Hi Luca
Have a look to [1]. The method doPostInitialize registers the provider
for the DBF format.
Regards,
Jorge
[1]
https://forge.osor.eu/plugins/scmsvn/viewcvs.php/*checkout*/branches/v2_0_0_prep/libraries/libFMap_dalfile/src/org/gvsig/fmap/dal/store/dbf/DBFLibrary.java?content-type=text%2Fplain&root=gvsig-desktop
El 05/08/2010 16:18, luca bianconi escribió:
> Hi all,
>
> thanks for the big explanation.
> /
> This document explains how you can create a new DataStore using the
> API. In this example it is creating a new DBF. The "DBF provider" has
> to be previously registered with a name or the line
> "serverExplorer.//getAddParameters("DBF")" will send an exception. /
>
> How could I avoid it ? Could you show me how to do ?
>
> Best regards,
>
> Luca
>
>
> 2010/8/4 Jorge Piera Llodrá <jpiera at prodevelop.es
> <mailto:jpiera at prodevelop.es>>
>
> On 08/04/2010 01:31 AM, luca bianconi wrote:
>
> Hi all,
>
> it has past some time since I've started studying gvSIG DAL
> providing system and, even if I've received many useful
> explanations (thanks kind Cèsar!), read longly the
> documentation [1] about it, read other DAL providers code,
> made coding tests, I'm unfortunately still plenty of doubts.
>
> I'd like asking the community some help to understand some
> things (I'm very sorry if some of them could sound very
> trivial to some of you).
>
> First of all, just a curiosity I'd like to ask Spanish
> speaking people :
> I understand the word "almacèn" as "provider", referred in
> documentation as the DAL provider. Is it correct ?
>
>
> I'm not completely agree. An "Almacén" is a "DataStore" that uses
> a provider (DataStoreProvider) to retrieve data from a data source.
>
> The "Almacen o DataStore" is the API of DAL that can be used by a
> data consumer to retrieve data. Providers are a part of the
> Service Provider Interface (SPI) and they register in DAL new
> formats that can be managed using the DAL API.
>
>
>
> If this is correct, and I want to register a new DAL provider
> I guess, after having of course read the whole available (as
> much as I know) documentation [1] on fmap.dal, I should use as
> main reference the chapter "Creación de un nuevo almacén" [2] .
>
>
> This document explains how you can create a new DataStore using
> the API. In this example it is creating a new DBF. The "DBF
> provider" has to be previously registered with a name or the line
> "serverExplorer.getAddParameters("DBF")" will send an exception.
>
>
> I've been suggested to give a glance, as example, at the
> extDwg extension for better understanding how the registration
> of a DAL provider works.
> I see that in this provider, as in other ones, four classes
> are always implemented:
>
> DWGLibrary -> Does it register the provider ? Does it in
> doPostInitialize() method ?
>
>
> Thats right. It registers the DWG provider and the DWG explorer
> that is used to browse by a directory tree for searching DWG's of
> creating new DWG's
>
>
> DWGFilesystemServerProvider, DWGStoreParameters,
> DWGStoreProvider -> How do they work exactly ? What do they do ?
>
>
> DWGFilesystemServerProvider -> It is used to browse by a directory
> tree and search DWG resources. It can be used to get the
> DataStoreParameters that are used to open an existing DWG creating
> a new DataStore or it also can be used to get the
> NewDataStoreParameters that are used to create a new DWG.
>
> DWGStoreParameters -> Defines the parameters that are needed to
> open a DWG
>
> DWGStoreProvider -> This provider is created from a
> DWGStoreParameters and it is able to read (or write) a DWG.
>
>
>
> After having implemented it, how can I register the provider
> with a plugin ?
>
>
> The project xxx.app.extension is the responsible to add a new
> plugin in gvSIG. It will contain the new provider.
>
>
> Which class among those provided by the plugin structure
> should I use ?
>
> These are the classes:
>
> - A xxxManager: is the entry point to the API. Provides the
> main services of the library.
> - A xxxLocator: the responsible to provide access to the
> single Manager instance.
> - A xxxLibrary: initialization and configuration of the library.
> - A xxxService: another interface for the API. You may use it
> or not depending on your library's functionality.
>
> Well, it depends on any project. The Library class is normally
> located in all the projects, but the other classes will be
> contained depending on what are you developing. (e.g. extDWG is a
> DAL provider and it don't need any Manager)
>
> I Hope I clarify you some doubts.
>
> Regards,
> Jorge
>
>
> Thanks a lot for the help,
> Luca
>
>
> [1]
> http://www.gvsig.org/web/projects/gvsig-desktop/docs/devel/org.gvsig.fmap.dal/2.0.0/featurestore
> [2]
> http://www.gvsig.org/web/projects/gvsig-desktop/docs/devel/org.gvsig.fmap.dal/2.0.0/featurestore/consumer-services/creacion-de-un-nuevo-almacen
>
>
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>
> --
> Jorge Piera Llodrá
> gvSIG Development Team
> PRODEVELOP
> Plaza Don Juan de Villarrasa, 14 - 5
> 46001 Valencia
> Tel: +34 963510612
> Fax: +34 963510908
> e-mail:jpiera at prodevelop.es <mailto:jpiera at prodevelop.es>
> http://www.prodevelop.es
> http://www.gvsig.org
>
>
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Jorge Piera Llodrá
Equipo desarrollo gvSIG
PRODEVELOP
Plaza Don Juan de Villarrasa, 14 - 5
46001 Valencia
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