"Application start/stop" events in a WCF service

[Jonny Bergdahl]

I have a WCF service hosted in IIS that accesses a singleton object living
in another thread. This thread is created on the first call, and reused on
subsequent calls, and this works quite well. Problem is that I need to know
when IIS stops or recycles the application so I can call Dispose() on
internal objects. In ASP.NET I would have used Application_End, but this
don't seem to be available for WCF services.

Any ideas?

Regards;
/jb

[Allen Chen [MSFT]]

Hi Jonny,

My name is Allen Chen. It's my pleasure to work with you on this issue.

Quote from Jonny ==================================================

Problem is that I need to know
when IIS stops or recycles the application so I can call Dispose() on
internal objects.

==================================================

To clean up the unmanaged resources we can call the Dispose method in the
destructor method.

For example:

public class Service1 : IService1
{
~Service1()
{
//Clean up the unmanaged resources here
}
public void DoWork()
{
}
}

Any instance of this class is a managed object. Thus it's managed by the
GC. When GC knows there's no reference pointing to this object it will call
its destructor(actually the Finalize method. See
http://msdn.microsoft.com/en-us/library/66x5fx1b.aspx). For more details
please check out:

http://msdn.microsoft.com/en-us/magazine/bb985010.aspx

So we can clean up the unmanaged resources in the destructor.

Please have a try and let me know if you have further questions.

Regards,
Allen Chen
Microsoft Online Support

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[Jonny Bergdahl]

>When GC knows there's no reference pointing to this object it will call

When does this happen? I haven't seen any documentation that describes the
life time of a web service object.

1. Server machine starts, and IIS initializes.
2. A client calls the web service - this instantiates a Service1 instance
3. My code creates a separate thread to host a singleton instance of an
object.
4. A result is sent back to the client (result originates from the singleton
client)
5. Some time elapses
6. Another client calls the web service
7. A result is sent back to the client.

I thought that 2 and 6 above results in that new instances of Service1 is
created, and that 4 and 7 above results in that those instances is released
and reclaimed by the GC. In that case the finalizer is of no use, since the
singleton object would be destroyed at 4 and 7, thus defeating what I need
to accomplish.

Basically, what I need to do is to Dispose of my singleton when IIS shuts
down the application.

Regards;
/jb

[Allen Chen [MSFT]]

Hi Jonny,

Thanks for your clarification. I think there's a misunderstanding in my
previous post. In my previous post I thought you want to clean up some
unmanaged code that the Service1 class uses and it turns out that you want
to clean up a singleton object only once.

If you want to do that in Application_End you can create a global.asax file
in the virtual directory where the WCF resides.
<%@ Application Language="C#" %>

<script runat=server>
protected void Application_End(object src, EventArgs e)
{
//clean up the singleton object here
}
</script>

The behavior should be the same as ASP.NET. Could you test it to see if it
works?

[Jonny Bergdahl]

I thought that global.asa was only supported in ASP.NET application?

Regards;
/jb

"Allen Chen [MSFT]" <v-al...@online.microsoft.com> skrev i meddelandet
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[Allen Chen [MSFT]]

Hi Jonny,

Thanks for your update.

Since the WCF is hosted in IIS the global.asax can also work for it.
Actually, the WCF is running in the same AppDomain of the ASP.NET
application. You can create a new ASP.NET Web Application to test:

1. Add following code in Default.aspx.cs:
protected void Page_Load(object sender, EventArgs e)
{
Response.Write(AppDomain.CurrentDomain.Id);
}
2. Right click the project node on the explorer window, select Add->New
item->WCF service to add a WCF service.
3. Replace the interface in the IService1.cs with:
public interface IService1
{
[OperationContract]
int GetAppDomainID();
}
4. Replace the class Service1 in the Service1.svc.cs with:
public class Service1 : IService1
{
public int GetAppDomainID()
{
return AppDomain.CurrentDomain.Id;
}
}
5. Build the application and publish it on IIS.
6. Close the current project, create another ASP.NET Web Application and
add the previous WCF service as a service reference.
7. Add following code in Default.aspx.cs:
protected void Page_Load(object sender, EventArgs e)
{
Service1Client proxy = new Service1Client();
Response.Write(proxy.GetAppDomainID());
}
8. View the Default.aspx of the first ASP.NET Web Application from IIS.
9. View the Default.aspx of the second ASP.NET Web Application from Visual
Studio.
10. You'll see the same integer on the two pages.
11. Update the Web.config file of the first ASP.NET Web Application (in
C:\Inetpub\wwwroot\YourVirtualDirectoryName) to force calling
Application_End. (You can insert some white spaces) Refresh these two
pages. You may see the integer changed but still it's still same on these
two pages.

Please feel free to ask if you have further questions.

[Jonny Bergdahl]

OK, thanks for the clarification!

Regards;
/jb

"Allen Chen [MSFT]" <v-al...@online.microsoft.com> skrev i meddelandet

news:3LrMgGy...@TK2MSFTNGHUB02.phx.gbl...

[Allen Chen [MSFT]]

Hi Jonny,

You're welcome. Thank you for using our Newsgroup Support Service. Have a
nice day!