Re: using MapViewer from PL/SQL vs Java

From: Frank van Bortel <>
Date: Thu, 01 Nov 2007 19:58:07 +0100
Message-ID: <fgd7jq$i38$>

Lukas wrote:
> Hi group!
> The MapViewer User's Guide has this to say about using MapViewer from
> "The usage model for the SDO_MVCLIENT package is almost identical to
> that of
> MapViewer JavaBean-based API" etc etc .. "For usage and reference
> information about specific functions or procedures, see the
> description of the associated JavaBean-Based API. methods and
> interfaces in Chapter 4"
> If I don't misunderstand the basic concept, in a Java Web App (using
> the MapViewer Bean) you create a MapViewer object for each HTTP-user-
> session, like so:
> MapViewer mv = new MapViewer("
> omserver");
> ... which you would then store in the user's session object, so that
> the MapViewer Bean conveniently holds the map's state on the user's
> behalf.
> To do the equivalent in PL/SQL, the User's Guide suggests:
> "connect scott/tiger
> call sdo_mvclient.createmapviewerclient(
> '') ;
> The preceding example creates, in the current session, a unique
> MapViewer client
> handle to the MapViewer service URL"
> Does "current session" refer to the HTTP-user-session? While I've used
> PL/SQL before, I've not used the PL/SQL Web Toolkit. Is the session
> handling implicit here (and invisible?) or should the sdo_mvclient be
> subsequently stored in the PL/SQL equivalent of a (J2EE) HttpSession
> object?
> YT
PL/SQL Web toolkit does nothing more than generate (badly formatted) HTML-code. Should be pushed to the web, using a Database Access Descriptor (DAD) on the Oracle Application Server. Having said that (there's some stuff on my blog), http sessions are stateless: you click in your browser, connection is made to the webserver, passed on to the database, processes, passed back to the web server (throught the DAD), and your browser renders the page - no more connections.
The Oracle web server has some tricks to prevent sessions to the database being opened and closed all the time. Maybe that is meant here?
If not - you must maintain your own state (cookies).

( doesn't the mapviewer maintain state? What happens after htp.p(sdo_mvclient.createmapviewerclient( '' ));

Frank van Bortel

Top-posting is one way to shut me up...
Received on Thu Nov 01 2007 - 19:58:07 CET

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