Architecture :: Exception Handling In Multi-tiered Applications?
Apr 27, 2010
Even though I'm trying to implement exception handling in a multi-tiered Windows application, catching and throwing exceptions should be the same for Windows and Web (sans global.asax and web.config custom errors).
I have a webform with a texbox that displays exceptions. So my webform invokes a method in BusinessTier class which then invokes a method in DataTier class. How can I throw my DataTier method exception so it reaches my webform?
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Jun 3, 2010
I devide my website on 3 layers :
DAL(Data Access) - simple extract data from DB using LINQ
BLL(Business Logic) -
cache data and in try/catch block call function from DAL and throw it to UI :
try
{
}
catch (Exception ex)
{
//Log error
throw ex
}
UI (User Interface) - simple working without handling any exception,
So if error occured in BLL i will be redirected to Error.aspx page with message that something wrong.
how and where handle exceptions, or may be exists common patter where handle and how to inform user about errors ? Can anybody share bes practice.
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Jul 2, 2010
i have this application structure:
1. Presentation Layer which calls
2. Business Logic Layer which in turn calls
3. Data Access Layer to do the dealing with the database.
Now i have a Contacts page from where i can add a new contact to the database.So to add a New Contact i fill in all the required details and then call a Add Method (residing in the BLL) from the page, which in turn call a Add Method residing in the DAL.this method in the DAL returns the Current Identity of the record which is then return back to the BLL method and finally delivered on the page.this is fine. but what if a get an exception how do i handle it properly because the method in DAL has a return type of int and i dont want to throw another error!! coz other wise i will have to write try catch in almost all the methods.
//something like this
public int AddMethod(ContactClass contactObj)
{
int result = 0;[code]...
rather i want to show the user a user-friendly message which they can easily understand and in the mean while i will send a mail to myself documenting the Error that just occurred.how can i implement my custom exception classes.
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Aug 3, 2010
I am working on a 3-tier asp.net application. Currently I'm stuck up in a situation where I need to handle a specific type of exception (User Defined) in DAL and Show alert to the user if that exception occurs in DAL.
I tried following things:
1) I raised that exception from the DAL and catch it in BLL and throw a new BLL exception to for that DAL exception and finally catch it in the UI layer to show the alert to the user. I've successfully implement this in my project. But there are some issues in this approach. First of all I feel this is not right way to do this as it may lead to performance related issues. Secondly, the application contains more than 500 pages and classes. so I need to attach additional catch block in every method to catch the BLL exception. which is the last option i'd like to take.
2) in second approach I logged the the DAL exception into a text file. but problem in this approach is that how could the UI layer know that exception has occurred and show the alert to the user. Is there any event in asp.net where i could handle all this activities?
my question is what is the best approach to handle this type of situation? Will Exception handling block help me in this?
I've tried reading many articles on this but i couldn't get an answer for my question? I might not be using right keywords for my search.
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Mar 25, 2011
I created a simple data access layer in the dll and reference it in my web app. How can I point the error to the user that his code in this line has an exception. currently, when i input a nonexisting table it will popup an error "invalid object name table_name" and points the my code throw exception inside my dll. I want it to point out to the user code that uses my function that creates an error.
Line 92: Dim ds As DataSet = DAL.Dal.ExecuteDataset("SELECT * FROM table_nam", "DBConnectionString")
Line 93: GridView1.DataSource = ds.Tables(0)
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Mar 18, 2011
Code:
public static void Test()
{
try
{
OpenConnectionToDatabase(); //Opens a connection to Oracle DB
} catch(Exception e)
{
e.Data.Add("Query:", command.CommandText);
throw e;
}
}
When this code is executed when the Database server is being shutdown and the communication is disrupted, .NET throws the following error: Item has already been added. Key in dictionary: 'Query:' Key being added: 'Query:' at System.Collections.ListDictionaryInternal.Add(Object key, Object value) How can this be?
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Aug 3, 2010
I have a weird situation here. Using VS2010 and the MVC2 application template, I'm trying to set up error handling, but it refuses to work... Even with a simple controller throwing an exception in the index:
[Code]....
And <customErrors mode ="On"></customErrors> in the web.config file, MVC breaks into the code and tells me that "Exception was unhandled by user code". The default Error.aspx (static text only) is located in /Views/Shared, and I've even removed the login partial view from the master page.
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Oct 12, 2010
iam inserting record in three tables in a database, iam using begin trans , commit transaction and rollback,
i want to use throw method, if any value insert wrong, pls correct me, i want to throw the error and
its go to rollback
running = false;
int updaterec = DBmgr.ExecuteNonQuery(CommandType.Text, "update ASArrivedcontainer set billgen ='Y' where billgen ='y' and acontinerid in ("+SelValues+")");
if (updaterec > 0)
{
running = true;
DataSet BillContainerDetails = BillingDetails();
byte[] ContainerDetails = GenerateBill(DBmgr, sContainerIds, rcno,isGeneralRCNo, FetchContainerDetails, ModifyId,ref BillContainerDetails);
DBmgr.CreateParameters(6);
//string otherchargesId = obj.retriveSingleRecord("select top(1) ModifyId from ASOtherCharges");
DBmgr.AddParameters(0, "@InvoiceNo", "1","IN");
DBmgr.AddParameters(1, "@BillDate", DateTime.Now.ToString("yyyy/MM/dd hh:mm:ss tt"), "IN");
DBmgr.AddParameters(2, "@CustomerId", "1", "IN");
DBmgr.AddParameters(3, "@TotalAmount", "10000", "IN");
DBmgr.AddParameters(4, "@OtherChargesId", ModifyId, "IN");
DBmgr.AddParameters(5, "@ContainerDetails", ContainerDetails, "IN");
String BillNo = DBmgr.ExecuteScalar (CommandType.Text, "Insert into BillMaster(InvoiveNo,BillDate,CustomerId,TotalAmount,OtherChargesId,ContainerDetails) values (@InvoiceNo,@BillDate,@CustomerId,@TotalAmount,@OtherChargesId,@ContainerDetails)
Select @@Identity ").ToString();
if (!String.IsNullOrEmpty(BillNo))
{
running = true;
DBmgr.CreateParameters(4);
for (int i = 0; i < BillContainerDetails.Tables[0].Rows.Count; i++)
{
BillContainerDetails.Tables[0].Rows[i]["BillNo"] = BillNo;
DBmgr.AddParameters(0, "@Billno", BillContainerDetails.Tables[0].Rows[i].ItemArray[1].ToString(), "IN");
DBmgr.AddParameters(1, "@rcno", BillContainerDetails.Tables[0].Rows[i].ItemArray[2].ToString(), "IN");
DBmgr.AddParameters(2, "@acontinerid", BillContainerDetails.Tables[0].Rows[i].ItemArray[3].ToString(), "IN");
DBmgr.AddParameters(3, "@bflag", BillContainerDetails.Tables[0].Rows[i].ItemArray[4].ToString(), "IN");
//string value = BillContainerDetails.Tables[0].Rows[i].ItemArray[0].ToString(); ;
// string strsql = "insert into billcontinerdetail(billno,rcno,acontinerid,bflag) values(@billno,@rcno,@acontinerid,@bflag)";
String count = DBmgr.ExecuteScalar(CommandType.Text, "insert into billcontinerdetail(billno,rcno,acontinerid,bflag) values(@billno,@rcno,@acontinerid,@bflag)Select @@Identity").ToString();
if (count > 1)
{
running = true;
}
else
{
}
//running = true ;
//break;
}
DBmgr.CreateParameters(6);
for (int j = 0; j < BillContainerDetails.Tables[1].Rows.Count; j++)
{
DBmgr.AddParameters(0, "@billcontkey", BillContainerDetails.Tables[1].Rows[j].ItemArray[1].ToString(), "IN");
DBmgr.AddParameters(1, "@ratetypcode", BillContainerDetails.Tables[1].Rows[j].ItemArray[2].ToString(), "IN");
DBmgr.AddParameters(2, "@days", BillContainerDetails.Tables[1].Rows[j].ItemArray[3].ToString(), "IN");
DBmgr.AddParameters(3, "@amount", BillContainerDetails.Tables[1].Rows[j].ItemArray[4].ToString(), "IN");
DBmgr.AddParameters(4, "@level", BillContainerDetails.Tables[1].Rows[j].ItemArray[5].ToString(), "IN");
DBmgr.AddParameters(5, "@sflag", BillContainerDetails.Tables[1].Rows[j].ItemArray[6].ToString(), "IN");
// string strsql = "insert into billratedetail(billcontkey,ratetypcode,days,amount,level,sflag)values(@billcontkey,@ratetypcode,@days,@amount,@level,@sflag)";
String count = DBmgr.ExecuteScalar(CommandType.Text, "insert into billratedetail(billcontkey,ratetypcode,days,amount,level,sflag)values(@billcontkey,@ratetypcode,@days,@amount,@level,@sflag)Select @@identity ").ToString()
;
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Feb 26, 2011
A first chance exception of type 'System.Threading.ThreadAbortException' occurred in mscorlib.dll An exception of type 'System.Threading.ThreadAbortException' occurred in mscorlib.dll but was not handled in user code
After banging my head because i could find where the exception came for and global.asax didn't get hit i found that it's from server.transfer and is a known bug. The alternative i read about is server.execute.However if i do this then the next page fires multiple javascript exceptions and a gridview i have is breaking of and the rows appear half at the left page corner and half inside the gridview!!
For now i just put a try catch on the server.transfer although the exception will not affect the application even if i don't use try catch. I also see that the exception is happening again even if i put try catch but with different dll: A first chance exception of type 'System.Threading.ThreadAbortException' occurred in App_Web_benglxq1.dll An exception of type 'System.Threading.ThreadAbortException' occurred in App_Web_benglxq1.dll but was not handled in user code Now what on earth is benglxq1.dll i don't know. What i know is that i'm leaving an exception to run and i don't like that. This is the js error when i use server.transfer btw: Microsoft JScript runtime error: Sys.ArgumentTypeException: Object of type 'Sys._Application' cannot be converted to type 'Sys._Application'.
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Jun 15, 2010
When I do ThreadPool.QueueUserWorkItem, I don't want unhandled exceptions to kill my entire process. So I do something like:
ThreadPool.QueueUserWorkItem(delegate() {
try { FunctionIActuallyWantToCall(); }
catch { HandleException(); }
});
Is this the recommended pattern? It seems like there should be a simpler way to do this. It's in an asp.net-mvc app, if that's relevant.
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Mar 25, 2011
My manager designed a table exactly like this
[Exception]
PK | ExceptionId
ExceptionCode varchar(100)
ExceptionDesc varchar(255)
ExceptionMSG varchar(255)
I'm using ASP.NET Webforms and using stored procedures/ADO.NET for DataAccess. Now he does not want me to hard code validation in stored procedures nor in the code behind, but to catch the constraint exception message and look up the same error message in the database and look for the message that we want to show. I wonder if his design will work or should I explain to him that something is wrong here.
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Dec 21, 2010
I've been all around the net for weeks now trying to figure out the best way to set up a Multi-tenant website (building a web app that multiple companies and their employees will use). As far as a database goes, I am interested in using one database with a copied set of tables for each company. As far as managing the login and security in MVC2 I am lost with the myriad of examples (mostly old and not MVC) that I have seen. So ideally my app would allow a company rep to register their company and then be able to add their own employees to the site. Then all employees could login and be securely associated with their own company's tables (table names would be appended with their AccountID).
I'm not sure if this would be handled using routing or session variables or what the more ideal and up to date methods might be. Like others who have discussed this issue, it seems like this should be a much more fleshed out solution as it is becoming a more common use on the internet. I'm even willing to simplify the database down to one set of tables that stores an AccountID in each row if needed.
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Jul 22, 2010
1) I have a question, many kind of applications / programs offer API's for integration.Is it possible to integrate any kind of application / program with any kind of application with the help of API ?i mean two completely different applications/programs with different database structure can still be integrated with each other with the help of API ?2) Where exactly is the API file stored ? i mean in order to integrate 2 applications i need to create an xml file ? and store it where ? or i have to do some modification in the code of my application in order to work with this api integration ? how it works..please guide me in a right direction....
3) Could anyone explain me how this API thing works ? i have been provided a PDF file by the application company that i need to integrate with my database based web application.now i have to make API connections in my code ? or how ?
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Dec 15, 2010
After many years reading this forum... I didn't found the solution to my actual problem... When I tought... this could be a big problem... I have a web app wich doesn't have try catch blocks in every method... so I need to implement a generic solution to handle exceptions and the most important... show some BO exceptions to user inside a MessageUserControl (ASCX) wich uses AJAX. this is the big problem, I tried many solutions, application_error, a specific log module, page_error... and with all I got to the same problem...
The UpdatePanel, when it got an unhandled exception, it fires the events (application_error, page_error) or even the httpmodule, but I think it call an Response.End, wich stops any action in the page... and this is just I don't want to do... I need to display the message to the client. this is the call to show the message...
[Code]....
My page wich gots an unhandled exception are inside an UpdatePanel, if I remove it, the message shows UP! I'm working on this for 5 long days.
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May 27, 2010
i am having trouble catching errors in an AJAX panel. Even when i throw an exception in the c# code behind the front end completely ignores it. Here is the code i have setup, can anyone see why? I ideally want to show a js alert window on error.
protected void btnX_Click(object sender, EventArgs e)
{
throw new ApplicationException("test");
}
protected void ScriptManager_AsyncPostBackError(object sender, AsyncPostBackErrorEventArgs e)
{
ScriptManager.AsyncPostBackErrorMessage = e.Exception.Message;
}
Markup:
<script type="text/javascript" language="javascript">
Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler);
function EndRequestHandler(sender, e)
{
window.alert(e.get_error().name);
}
</script>
<asp:ScriptManager ID="ScriptManager" runat="server" AllowCustomErrorsRedirect="true" OnAsyncPostBackError="ScriptManager_AsyncPostBackError" />
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