Page 126 - DCAP312_WEB_TECHNOLOGIES_II

Web Technologies-II

Notes By default, the section looks like this when you create a Web application.
<customErrors mode= “Remote Only” />
This will show a generic page to users. To redirect it to one of your own pages, you would
change it to this:
<customErrors mode= “On” defaultRedirect= “error.htm” />
Now all errors that occur will be brought to the error.htm page.
To handle specific errors, and redirect to the error page for everything else you can specify the
error code you want specially handled like so:
<customErrors mode= “On” defaultRedirect= “error.htm”>
<error statusCode= “500” redirect= “error500.aspx?code=500”/>
<error statusCode= “404” redirect= “filenotfound.aspx”/>
<error statusCode= “403” redirect= “authorizationfailed.aspx”/>
</customErrors>
There is a problem here with this solution. Once the redirect is done, your error information is
no longer available on the redirected page. This is because IIS (via the .net framework) performs
a plain old GET request to the error page and does not do a “Server. Transfer” likes the built-in
IIS error handling does.
The only information available to you at this time is the URL that caused this error to be raised.
This is located on the query string as“aspxerrorpath”: http://localhost/ErrorHandling/error500.
aspx?aspxerrorpath=/ErrorHandling/WebForm1.aspx. The only places this information is
available is the two methods described above.
Another interesting point about the above customErrors element is that you can specify different
error pages for different subdirectories.
For this example, let us say you have a directory named “Customers” off of your root directory
that contains a branding specific for logged in customers but is not in its own application. As
such you want to define a different set of pages for errors. Please note that these pages specified
in the “redirect” attribute are relative to the “Customers” subdirectory and not the root path of
your site. It also included a security rule which says only MYDOMAIN\Customers can access
these files. You can define rules for these errors in the web.config file:
<Configuration>
<system.web>
</system.web>
<!-- Configuration for the “Customers” subdirectory.
-->
<location path= “Customers”>
<system.web>
<customErrors mode= “On” defaultRedirect= “error.htm”>
<error statusCode= “500” redirect= “CustomerError500.
aspx”/>
<error statusCode= “401”
redirect= “CustomerAccessDenied.aspx”/>
<error statusCode= “404”
redirect= “CustomerPageNotFound.htm”/>
<error statusCode= “403” redirect= “noaccessallowed.
htm”/>
</customErrors>
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