[Gvsig_english] [ gvSIG 2.0 extension development ] Howtoimplement and register a new DAL provider

Thu Aug 5 22:12:38 CEST 2010

Hi Jorge,

ok, thanks.

I've asked it because I get an error when I execute the code

DataExplorerParameters eparams = manager.createServerExplorerParameters(
"FilesystemExplorer");

as in the doc above [1].
I've thought the reason was the one you've suggested in your last email and
it was related to the fact in that code the Provider was not registered yet.

Thanks for your very precious help,
Cheers,
Luca

[1]
https://gvsig.org/web/projects/gvsig-desktop/docs/devel/org.gvsig.fmap.dal/2.0.0/featurestore/consumer-services/creacion-de-un-nuevo-almacen

2010/8/5 Jorge Piera Llodrá <jpiera at prodevelop.es>

>  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>
>
>>  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.eshttp://www.prodevelop.eshttp://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.eshttp://www.gvsig.org
>
>
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