[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
Tef: +34 963510612
Fax: +34 963510908
e-mail: jpiera at prodevelop.es
http://www.prodevelop.es
http://www.gvsig.org

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