ASP.Net Response.Close issue

c# asp.net .net visual-studio-2008 iis-7

10,040

Solution 1

The following from the MSDN website might be useful here:

This method terminates the connection to the client in an abrupt manner and is not intended for normal HTTP request processing. The method sends a reset packet to the client, which can cause response data that is buffered on the server, the client, or somewhere in between to be dropped.

You might use this method in response to an attack by a malicious HTTP client. However, typically you should call CompleteRequest instead if you want to jump ahead to the EndRequest event and send a response to the client.

Solution 2

You should not normally use the Response.Close method in "normal" ASP.NET processing.

All of your data that is written to a HttpResponse "stream" is buffered before being sent to the client browser. The Response.Close method will abruptly terminate the HTTP connection and you may lose data that you have previously Response.Written inadvertently.

If you really want to programmatically "force" the end of a response stream, you should use either: Response.Flush(); followed by Response.End();

The Response.Flush method call ensures that all data that you may have written to the response stream is "flushed" to the client, and Response.End ensures all currently buffered data is correctly sent to client, and also raises the EndRequest event, which you may want to handle.

You can also use the HttpApplication's CompleteRequest() method.

The MSDN documentation states it best:

This method terminates the connection to the client in an abrupt manner and is not intended for normal HTTP request processing. The method sends a reset packet to the client, which can cause response data that is buffered on the server, the client, or somewhere in between to be dropped.

You might use this method in response to an attack by a malicious HTTP client. However, typically you should call CompleteRequest() instead if you want to jump ahead to the EndRequest event and send a response to the client.

Solution 3

In my experience there is no reason to call Response.Close(); within the code example you've provided, just remove it.

In the pages lifecycle after the Page_Load is fired, there are a number of other methods that will be called that will close your responses for you.

Read here for the Page Lifecycle

Solution 4

.NET is a very flexible network it will let you do anything you could before .NET. (and more obviously). But the most wonderfull thing is that .NET will take care of verything it can take care of for you.

That means if you create and empty web page and run it in your browser you don't have to do anything else to make it work.

Sometimes however you might find yourself in a situation where you need to do something extraordinary and you will be thankfull for the existance of functions like Reponse.Close()

In your case you're not doing such a thing so there's no need for any special function calling.

Besides that Response.Write() is what we used to use back in the days...Are you still thinking in the classic ASP mode maybe?

Suggestion: Don't use Response.Write()

But put a label in your web page and use:

this.Label1.Text = "Hello world";

Addtional comment:

The purpose of ASP.Net in particular is to send web pages to a browser, collect any posted data, process it, interact with the server OS and so on.

So you might, in my opinion, assume that some care has been taken in 1) serving pages fast and 2) making sure nothing goes wrong when the user follows the guide lines on how to program .Net web pages.

There's no need to implement ALL Page event handlers. Understand the framework, understand what each page event does and learn when to implement which event.

If you're only going to show data from a database you don't even need event handlers. Read about the Data Controls (Data sources, GridView, ListView, Repeater, etc).

Assume that if you do nothing, the framework will do it for you. (IF you do nothing at all, nothing happens, that's by design)

Cheers.

Solution 5

To answer question 1:

You should call Response.Close() when your need to terminate the connection - that is, nothing else needs to be sent to the client at all. This does not include what you have posted, since the rest of the page needs to be processed and sent to the client. Normally you would call it when returning data that is not a page from an aspx page (for example a pdf file, an image etc...).

To answer question 2:

You should not call Response.Close() in your Page_Load event handler - it will mean that the rest of the page lifecycle will not run properly.

From MSDN (HttpResponse.Close method):

This method terminates the connection to the client in an abrupt manner and is not intended for normal HTTP request processing. The method sends a reset packet to the client, which can cause response data that is buffered on the server, the client, or somewhere in between to be dropped.

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10,040

Author by

George2

Updated on August 12, 2022

Comments

George2 over 1 year
I am using ASP.Net + .Net 3.5 + VSTS 2008 + IIS 7.0 + C# to develop a web application. I find when debugging in VSTS 2008, if I call Response.Close() method in page_load (please refer to code below), there will be error (from IE when accessing the page) like can not connect to server.

My question is,
1. Normally when should we call Response.Close()? Or no need to call (rely on ASP.Net framework to automatically close)?
BTW: my previous understanding is developer should always call Response.Close when processing is completed at server side and all data has been written to client using Response.Write. Am I correct?

2 Why I met with such error in my code? What is the root cause?
```
    protected void Page_Load(object sender, EventArgs e)
    {
        Response.Write("Hello World! ");
        Response.Close();
    }
```
George2 almost 14 years

You mean in all situations, no need to call Response.Close? If so, why ASP.Net expose such a method?
George2 almost 14 years

If do not call Response.Close(), how to tell client request has been completed and all response has been generated? IE does not need such info?
Chase Florell almost 14 years

I'm making this statement with the confounds of his code example
George2 almost 14 years

What do you mean "in the off case"? I am confused about what means off cae? Could you show me a sample please?
George2 almost 14 years

"confounds of his code example" -- confounds you mean what? :-)
George2 almost 14 years

"there are a number of other methods that will be called that will close your responses for you." -- you mean in all situations, no need to call Response.Close? If so, why ASP.Net expose such a method?
George2 almost 14 years

Do you mean in any situations, we do not need to call Response.Close? If so, why ASP.Net expose such a method?
George2 almost 14 years

Do you mean in any situations, we do not need to call Response.Close? If so, why ASP.Net expose such a method?
Oded almost 14 years

@George2 - In most situations you do not need to use it. It is there for the rare situations that you do need it.
Erv Walter almost 14 years

"You might use this method in response to an attack by a malicious HTTP client."
Andy almost 14 years

Certainly not in normal use. See second paragraph from MSDN for a possible usage.
George2 almost 14 years

Thank you Oded! I think we just need to implement all the phase/event handlers documented in the link about life cycle document you mentioned, and ASP.Net underlying framework will close connection automatically for us, correct? My previous confusion is if we do not close Response, are there any leaks?
Oded almost 14 years

@George2 - You do not need to implement them. These are extension points of the framework and are supposed to be used when needed. As for the closing of the Response object - that will normally get handled in the unload event of the page.
George2 almost 14 years

Thanks CraigTP! I think we just need to implement all the phase/event handlers documented in the link about life cycle document (msdn.microsoft.com/en-us/library/ms178472.aspx), and ASP.Net underlying framework will close connection automatically for us, correct? My previous confusion is (1) if we do not close Response, are there any leaks? (2) if we do not close, response data may be buffered at server and not send to client browser immediately in a timely fashion. Any comments?
George2 almost 14 years

Thanks rockinthesixstring! I think we just need to implement all the phase/event handlers documented in the link about life cycle document (msdn.microsoft.com/en-us/library/ms178472.aspx), and ASP.Net underlying framework will close connection automatically for us, correct? My previous confusion is (1) if we do not close Response, are there any leaks? (2) if we do not close, response data may be buffered at server and not send to client browser immediately in a timely fashion. Any comments?
George2 almost 14 years

Thanks Jeroen! I think we just need to implement all the phase/event handlers documented in the link about life cycle document (msdn.microsoft.com/en-us/library/ms178472.aspx), and ASP.Net underlying framework will close connection automatically for us, correct? My previous confusion is (1) if we do not close Response, are there any leaks? (2) if we do not close, response data may be buffered at server and not send to client browser immediately in a timely fashion. Any comments?
George2 almost 14 years

Another confusion is, if we do not close, response data may be buffered at server and not send to client browser immediately in a timely fashion. Any comments?
George2 almost 14 years

Thanks Andy! I think we just need to implement all the phase/event handlers documented in the link about life cycle document (msdn.microsoft.com/en-us/library/ms178472.aspx), like page_load method, and ASP.Net underlying framework will close connection automatically for us, correct? My previous confusion is (1) if we do not close Response, are there any leaks? (2) if we do not close, response data may be buffered at server and not send to client browser immediately in a timely fashion. Any comments?
Oded almost 14 years

@George2 - this is the kind of worry you need to have once you have problems, not before. The buffered data will be sent to the client as soon as the page has finished processing.
Andy almost 14 years

No this will not cause leaks, and no issue with speed of response. In fact if you call Request.Close() the browser will not receive the "Hello World" that you are clearly intending at all.
George2 almost 14 years

Thanks Andy! So for our developers, we just need to implement all the necessary phase/event handlers which matters to our specific application, as documented in the link about life cycle document (msdn.microsoft.com/en-us/library/ms178472.aspx), like page_load method, and ASP.Net framework will handle sending response back to client automatically for us (means we do not need to control when to send data and when to close underlying http connection), correct?
George2 almost 14 years

Thanks Jeroen! So for our developers, we just need to implement all the necessary phase/event handlers which matters to our specific application, as documented in the link about life cycle document (msdn.microsoft.com/en-us/library/ms178472.aspx), like page_load method, and ASP.Net framework will handle sending response back to client automatically for us (means we do not need to control when to send data and when to close underlying http connection), correct?
Andy almost 14 years

Yes just put your code in page_load or the appropriate event handler and don't call Request.Close()
George2 almost 14 years

(1) And no leak if I do not call Response.Close? (2) So for our developers, we just need to implement all the necessary phase/event handlers which matters to our specific application, as documented in the link about life cycle document (msdn.microsoft.com/en-us/library/ms178472.aspx), like page_load method, and ASP.Net framework will handle sending response back to client automatically for us (means we do not need to control when to send data and when to close underlying http connection), correct?
Jeroen almost 14 years

Correct. In fact calling Response.Close() interrupts the page's life cycle. .Net will try to send the page to the browser after the Render event so if you already closed the connection, bad things will happen.
DMpal Jain almost 14 years

@George2 - Yes, the ASP.NET framework will close the HttpResponse's connection for you and ensure that all of it's buffers are "flushed" when doing so. There should not be any leaks at all. I have manually written data to the HttpResponse stream (using Response.Write) many times without explicitly closing the connection (using Response.End or other method calls) and the underlying ASP.NET framework has always correctly flushed it's buffers and sent the entire buffered response stream to the client browser correctly.
yu yang Jian over 5 years

the comment here says Response.Flush still get error : stackoverflow.com/a/1907766/4573839