Hi

[Shilpa Nalgonda <sn...@mypublisher.com>]

-----Original Message-----
From: Research labs [mailto:research_labs@yahoo.co.uk]
Sent: Monday, August 02, 2004 5:17 PM
To: Struts Users Mailing List
Subject: Re: DaTASOURCE CREATION AT USER LOGIN TIME...Newbie


Craig,

Thanks a lot.  All points taken.  In the light of what
you and Jim have said, I will re examine my plan of
action

I found out about you in one of my books "Struts in
Action" by Ted Husted et al.  If I may, I would like
to keep this first email from you as some sort of
autograph.

Ola.


 --- Craig McClanahan <cr...@gmail.com> wrote:
> On Mon, 2 Aug 2004 21:23:05 +0100 (BST), Research
> labs
> <re...@yahoo.co.uk> wrote:
> > Jim,
> >
> > Thanks for your response.
> > I want each user to login to the database(MySQL),
> via
> > a JSP.  Once logged in, I want them to use their
> > database username (specified at log in time) for
> > communicating with the database throught their
> > session.  To put it another way, if 4 users are
> > currently logged in (via a JSP etc.), When I query
> the
> > data dictionary of the database, I want their
> names to
> > come up.  At any point in time, I want to be able
> to
> > find out, who is logged in, this is why I do not
> want
> > everyone to log in with the same username and
> password
> > e.g. ola/ola-hardcoded in the Struts config's
> > data-source.
> >
>
> Do you care about finding out who is logged in to
> your *application*,
> or who is logged in to the *database*?  Those can
> easily be made
> separate questions, and in most cases should be
> separate.
>
> > I do not mind using any datasource so long as I
> can
> > achieve my objective.
> >
>
> The <data-source> element in struts-config.xml, like
> using most JNDI
> provided data sources, will not address your need.
> That is because
> they create application wide pools for shared
> connections.
>
> Doing what you want to do, however, will also be
> giving up on the key
> advantage of using a data source in the first place
> -- sharing a small
> number of database connections between multiple
> users.  By definition,
> if you are using per-user logins to the database,
> such connections
> cannot be shared.  That can be problematic for the
> scalability of your
> app, because it will require more database resources
> to be allocated
> than would otherwse be necessary.  Plus, you'll
> likely run into limits
> on how many individual database connections can be
> opened before you'd
> ever run out of capacity in your web server to
> support simultaneous
> users.
>
> If all you care is logins to an application, here's
> a couple of easy
> ways to do that while still sharing database
> connections:
>
> * At login time, write into some table someplace a
> row for the logged in user,
>   and make sure you clean it up when they log out or
> when the session
>   expires.  To see who is logged in, run database
> queries against
>   this table.
>
> * Store some in-memory data structure (perhaps as an
> application scope
>   attribute), and have the login/logout logic add
> and remove entries from
>   this data structure.  To see who is logged in, set
> up a Struts action or
>   something that will go through the data structure
> and list all the logged
>   on users.
>
> If you still really want per-user database logins,
> then give up on the
> idea of using any sort of data source -- it won't
> buy you anything.
> Instead, create a standalone JDBC connection at
> login time, and store
> it in session scope somewhere.  But I would suggest
> you consider the
> disadvantages of such an approach before using it.
>
> > Thanks.
> > Ola.
> >
>
> Craig
>
>
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