We made the Datastore API cache connections and reuse them if a user requested a connection with the same connection params. So when you load layers from a project file they will reuse already-open connections whereever they can.
At least, this is how it's *supposed* to work... it's been a while since I wrote that code, and I don't know if anything changed during the port to OJ. Can someone report on this? P.Rizzi Ag.Mobilità Ambiente wrote: > I can't completely understand what you're saying... > Using the Datastore API you can open several layers from > a single connection... > You can try my PostGIS/Oracle plugin from: > http://sourceforge.net/project/showfiles.php?group_id=118054&package_id=217237 > > But you pointed out something I never realized before, > that inside a project/task file each layer has it's connection > parameter repeated, does it mean that when a project/task is opened > the Datastore API opens a separate connection for each layer??? > I don't know that... > > But the connection dialog lists each connection only once, so there > may be some smart code that "put together" identical connection > opening them only once. > > I'll have to find the time to debug this... > > Anyway something able to "group" layers would be a great thing, > so you can operate on a "group" (or may we call it a theme???) > as a whole (hide/show, refresh, etc.). > > While I'm at it, even if it's not strictly related to this post, > it would be great to be able to save inside a project/task file > also a layer coming from Datastore query, otherwise you to manually > recreate and restyle it every time you run OJ anew. > > Bye > Paolo Rizzi > > > >> -----Messaggio originale----- >> Da: [EMAIL PROTECTED] >> [mailto:[EMAIL PROTECTED] >> conto di Paul >> Austin >> Inviato: martedì 29 maggio 2007 22.16 >> A: jump-pilot-devel@lists.sourceforge.net >> Oggetto: [JPP-Devel] Multiple Layers from the same database connection >> >> >> All, >> >> I've been looking at the existing database and file plugins and the >> com.vividsolutions.jump.io.datasource.DataSource class and from what I >> can tell there is a one to one relationship between a layer and a data >> source. >> >> What I would like to do for some of the file and database based data >> sources is to have the concept of a DataSource that can contain many >> different layers. Within a project you would be able to select which >> layers you wanted to view from that data source. >> >> In the database world this concept would relate to having a connection >> to the data base using a java.sql.Connection. When adding the database >> connection to a project there would be a UI that would list the >> available layers (database tables) and the user could select which >> layers they wish to view. This compares to the current PostGIS plug-in >> where you have to manually enter the connection and table details for >> each layer. >> >> When the project is closed then the "connection" must also be closed. >> >> In the Jump project file the "connection" parameters would be stored >> once, then the data sources used for each layer would reference the >> "connection" and have a different query for each table. >> >> Now if we look at a file based example, I have a file format which is >> basically a zip file that contains one file for each layer along with >> some metadata files. I would like to be able to open the zip file and >> create a layer for each of the layers in the zip file. To do this I >> would extract the file to the temp directory and as required load the >> data from the individual files in the temp directory. Then when you >> close the project the "connection" is closed by deleting the temporary >> files. >> >> Another file based example would be to open a directory of files, >> loading each layer file in that directory, this is basically >> the same as >> the zip file idea but without the temporary files. >> >> In both the file cases once the file is loaded the first time the user >> can select which of the layers to view. >> >> So the question is, does any of the existing functionality in >> JUMP allow >> for multi-layer data sources? If not I'm going to do some prototyping >> for the file format I have and then share this with the group for >> comment to see if it would be useful elsewhere. >> >> After that I have an interest in Oracle connections so would >> need to do >> the same kind of thing there. >> >> One other question, where would I find the code for writing out the >> project .jmp XML files as I'd need to add the "connection" definitions >> to this. >> >> Cheers, >> Paul >> >> -------------------------------------------------------------- >> ----------- >> This SF.net email is sponsored by DB2 Express >> Download DB2 Express C - the FREE version of DB2 express and take >> control of your XML. No limits. Just data. Click to get it now. >> http://sourceforge.net/powerbar/db2/ >> _______________________________________________ >> Jump-pilot-devel mailing list >> Jump-pilot-devel@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel >> >> > > ------------------------------------------------------------------------- > This SF.net email is sponsored by DB2 Express > Download DB2 Express C - the FREE version of DB2 express and take > control of your XML. No limits. Just data. Click to get it now. > http://sourceforge.net/powerbar/db2/ > _______________________________________________ > Jump-pilot-devel mailing list > Jump-pilot-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel > > -- Martin Davis Senior Technical Architect Refractions Research, Inc. (250) 383-3022 ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ Jump-pilot-devel mailing list Jump-pilot-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/jump-pilot-devel
