ASP.NET Common Error Page Best Practises - asp.net

Question

I am working on an ASP.NET web application. I am implementing the logging framework for the entire application.
web application has around 7-8 pages and is a simple CRUD operations web application.
Its an Azure hosted application. Following is the approach i am following for logging and exception handling.
1) Added Try...Catch blocks in the Data Access Layer, and Click events.
2) Upon catching errors, I am propagating the exceptions upto the Globabl.asax leve, and in Application_Error event logging the error into Event Logs and Trace Logs.
3) After this in the Global.asax file I am Redirecting to an Error Page to show a User Friendly Message and link to the failed page.
4) Just wanted to know whether is it a good approach to do this.
Thanks Friends.

Answer 1

Are you actually handling exceptions on the DAL (ie, logging, trying to fix it, etc)? If not, then the try catch serves no purpose other than spinning cycles. The same is true for the click events, but it is not a bad practice to handle errors on the UI, even if you are not truly doing anything with them, as you will divert the user from the ugly error page to your own friendly message.
A single error page works fine, if you truly cannot handle the exception thrown. The upside is time to market, as you write precious little code to avoid showing the user an ugly message. The downside is the user misses context. I am not really up on the one size fits all exception handler, except as a backup (have an error I did not envision that got past my first line handler).
There is a variation of the common error page, if you are handling based on HTTP statuses and that is to use config.
Another pattern is to set up your own base page and have it work as an error handler. You can then set aside a container to fill when an error occurs. This approach works nicely for adding context, as the user still sees part of the page he was on, but you have given an error message, so he knows things have failed. I have seent this pattern used with a user control that is added to the container when an error occurs, but this is a bit more invovled, as you have to set up a table of codes and proper messages to show (which can be buggy in and of itself).

Answer 2

Why not using ASP.NET custom error pages ? You can specify each error page for each status code or you can specify a default redirect.
You can configure this in the web config and you are all set.
<customErrors defaultRedirect="GenericError.htm" mode="On">
<error statusCode="404" redirect="notfound.htm"/>
</customErrors>
You can configure it for showing the custom error pages to all users or only to remote users etc..
http://aspnetresources.com/articles/CustomErrorPages
I totally agree that you should log all errors in your catch block and write it to a log.

Answer 3

It sounds like you're kind of reinventing the wheel here. ASP.NET already includes things to help you achieve the desired result. Unless you need handling logic to cleanup after the errors, I wouldn't use try catch blocks. Have a look at the ASP.NET Health Monitoring Overview for logging errors. As far as presenting a custom error page see How to create custom error reporting pages in ASP.NET by using Visual C# .NET.

Answer 4

I think, You need not to use Exception Handling. Suppose You have a Presentation Layer and a Business Logic Layer/DataAccess Layer.
Upon facing the error in say Business Logic, it will move directly to Glogal.asax.cs file under Application_Error Event without going back to the calling function. Here you can log the error message like below....
HttpContext.Current.Server.GetLastError().InnerException.StackTrace
HttpContext.Current.Server.GetLastError().InnerException.Message
HttpContext.Current.Server.GetLastError().InnerException.Source
HttpContext.Current.Server.GetLastError().InnerException.TargetSite.DeclaringType.FullName
HttpContext.Current.Server.GetLastError().InnerException.TargetSite.DeclaringType.Name
HttpContext.Current.Server.GetLastError().InnerException.TargetSite.DeclaringType.Namespace
Now in the Web Config you can write code to redirect the user on some default page like below.
<customErrors defaultRedirect="ErrorPage.htm" mode="On">
<error statusCode="404" redirect="ErrorPageNotFound.htm"/>
</customErrors>