PRB: Error on .NET client that consumes a Web service through an HTTP proxy server

Symptoms

Note The following .NET Framework Class Library namespace is referenced in this article:

System.Net

When you use a .NET client to consume a Web service through an HTTP proxy server, you may receive the following error message:
The underlying connection was closed: The remote name could not be resolved.

Cause

An HTTP proxy server exists between the Web service and the .NET client, and the proper proxy settings have not been configured.

Resolution

To resolve this problem, supply the proper proxy configuration settings to the .NET client.

More Information

The following are the default settings in the Machine.config file:
<configuration>
<system.net>
<defaultProxy>
<proxy
usesystemdefault = "true"
/>
</defaultProxy>
</system.net>
</configuration>

If the default settings do not automatically detect the proxy server settings, set usessystemdefault to false, and then explicitly designate the proxy server. To designate the proxy server explicitly, use either the Machine.config or Web.config file, or specify the server programmatically.

To specify the proxy server, set the Machine.config or Web.config file settings as follows:
<configuration>
<system.net>
<defaultProxy>
<proxy
usesystemdefault = "false"
proxyaddress="http://proxyserver"
bypassonlocal="true"
/>
</defaultProxy>
</system.net>
</configuration>

To change the settings programmatically by using a WebProxy object, use the following sample code:
Using System.Net;

com.someserver.somewebservice.someclass MyWebServiceClass = new com.someserver.somewebservice.someclass();

IWebProxy proxyObject = new WebProxy("http://myproxyserver:80", true);
MyWebServiceClass.Proxy = proxyObject;

MyWebServiceClass.MyWebMethod();



Proxy servers that require NTLM authentication

To set NTML authentication for the proxy server, use the following sample code:
Using System.Net;

WebProxy myProxy = new WebProxy("http://proxyserver:port",true);
myProxy.Credentials = CredentialCache.DefaultCredentials;
FindServiceSoap myFindService = new FindServiceSoap();
myFindService.Proxy = myProxy;
You can also use system-wide proxy as default. To do this, use the following settings in the configuration file:
<configuration> 
<system.net>
<defaultProxy>
<proxy
proxyaddress = "http://proxyserver:80"
bypassonlocal = "true" />
</defaultProxy>
</system.net>
</configuration>

References

For more information, see the following Microsoft Developer Network (MSDN) Web sites: For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

307220 How to configure an XML Web service client by using the .NET Framework to work with a proxy server

Properties

Article ID: 318140 - Last Review: Jun 18, 2012 - Revision: 1

Microsoft .NET Framework 1.0, Microsoft .NET Framework 1.1, Microsoft ASP.NET 1.0, Microsoft ASP.NET 1.1

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