I have struggled for the past week not being able to consume a ASMX service exposed through a WCF service app that was created on .Net 4.0 and Entity Framework. The key to make a WCF service consumable by legacy .Net app was to expose the service as an old fashion ASMX, through adding a XmlSerializerFormat attribute while building the ServiceContract interface, as shown in this sample:

[ServiceContract, XmlSerializerFormat]

public interface IService1

{

[OperationContract]

string GetData(int value);

[OperationContract]

CompositeType GetDataUsingDataContract(CompositeType composite);

}

The second key step was to make sure the web.config of the WCF service project would use “basicHttpBinding” and set endpoint address to “basic” type. When I first started out, many cited the reference from MSDN at http://msdn.microsoft.com/en-us/library/ms751433.aspx; I followed the example, and still got the “Underneath connection had been closed” error. Today, I came across another posting at http://social.msdn.microsoft.com/forums/en-US/wcf/thread/1f8c7fe9-784c-4beb-8d0f-060bf8bfc24f and that had liberated me from wondering why this damn thing not working – well, the web.config example in the MSDN article had an empty string in the address field while this social.msdn positing had a “basic” in the enpoint address;  I tried that and it worked this time! Thanks Jay R. Wren who answered a user’s question at social.msdn.com.

Here was the endpoint configuration that worked on my case:

<service name=”WcfService1.Service1″  behaviorConfiguration=”AsmxBehavior”>

<endpoint address=”basic” binding=”basicHttpBinding” contract=”WcfService1.IService1″></endpoint>

The entire web.config file that is in the WCF app project that will generate the ASMX service to be consumed by .Net 1.1 client is as below:

<?xml version=”1.0″?>

<configuration>

<system.web>

<compilation debug=”true” targetFramework=”4.0″ />

</system.web>

<system.serviceModel>

<services>

<service name=”WcfService1.Service1″  behaviorConfiguration=”AsmxBehavior”>

<endpoint address=”basic” binding=”basicHttpBinding” contract=”WcfService1.IService1″></endpoint>

</service>

</services>

<behaviors>

<serviceBehaviors>

<behavior name=”AsmxBehavior”>

<!– To avoid disclosing metadata information, set the value below to false and remove the metadata endpoint above before deployment –>

<serviceMetadata httpGetEnabled=”true”/>

<!– To receive exception details in faults for debugging purposes, set the value below to true.  Set to false before deployment to avoid disclosing exception information –>

<serviceDebug includeExceptionDetailInFaults=”false”/>

</behavior>

</serviceBehaviors>

</behaviors>

<serviceHostingEnvironment multipleSiteBindingsEnabled=”true” />

</system.serviceModel>

<system.webServer>

<modules runAllManagedModulesForAllRequests=”true”/>

</system.webServer>

</configuration>