Regarding ASP.NET, I'm of the school of thought that database
connections be created at function level; as in, created and destroyed
many many times (if necessary) throughout the page life-cycle.
Just out of interest, is there *any* situation of school of thought
where a single application-level connection to the database would be
better?
Curiously yours,
Ben
On 10/16/07, Mike Andrews <[EMAIL PROTECTED]> wrote:
> This is not the place for a singleton and the singleton is not implemented
> correctly since it doesn't take into account any race conditions that might
> occur with a multi-threaded app such as asp.net. Also you would not want to
> dispose of the connection in the singleton since that defeats the purpose of
> the singleton.
> The connection should be created and destroyed when needed and not kept live
> by using the singleton.
>
>
> On 10/16/07, Abhijit Gadkari <[EMAIL PROTECTED]> wrote:
> >
> > We are writing an ASP.NET application. We have used singleton for
> > instantiating a database connection as explained in the following code
> > sample.
> >
> >
> >
> > Design thought was to use only one instance of MyDb across all the pages
> > in
> > this web application. Is this a correct singleton implementation for
> > Asp.NETweb application for managing database connection? In fact, this
> > code got C –
> > or D in our internal code review. Don't know why? Any idea on how to
> > improve
> > this code to A level.
> >
> >
> >
> > public sealed class AppDbProvider : IDisposable
> >
> > {
> >
> > public static readonly AppDbProvider instance = new
> > AppDbProvider();
> >
> >
> >
> > private readonly MyDb _d = new MyDb(ConfigurationManager
> > .ConnectionStrings["my_connection"].ConnectionString,
> >
> > ConfigurationManager.ConnectionStrings[
> > "my_connection"].ProviderName);
> >
> >
> >
> > public MyDb GetDbConnection()
> >
> > {
> >
> > if (_d != null)
> >
> > return _d;
> >
> > else
> >
> > throw new Exception("Problem with Database Connection in
> > AppDbProvider.");
> >
> > }
> >
> >
> >
> > #region IDisposable Members
> >
> >
> >
> > public void Dispose()
> >
> > {
> >
> > if (_d != null)
> >
> > _d.Dispose();
> >
> >
> >
> > Dispose();
> >
> >
> >
> > }
> >
> >
> >
> > #endregion
> >
> > }
> >
> >
> >
> > Now in code behind file, we have following code
> >
> >
> >
> >
> >
> > public partial class CreatePage
> >
> > {
> >
> > private AmgDb _d;
> >
> >
> >
> > try
> >
> > {
> >
> > _d = AppDbProvider.instance.GetDbConnection();
> >
> > }
> >
> > Catch (Exception exce)
> >
> > {
> >
> > Response.write(exce.message);
> >
> > }
> >
> >
> >
> > }
> >
> >
> >
> > And in the end, in the page unload event we have following cleanup code
> >
> >
> >
> > protected void Page_Unload(object sender, EventArgs e)
> >
> > {
> >
> > if (_d != null)
> >
> > {
> >
> > _d = null;
> >
> > }
> >
> > }
> >
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