WCF Service app.config

Question

I'm developing a WCF Service and I'm a little confused about where its consuming its configurations.

I have an app.config file in my host application (console application) and in my WCF Service project (came with the template)

In run time I can see that configurations from both files are used.

How does it work? Why does the WCF library project (a dll project) contains an app.config file and what is it's purpose?

I can really use some clarifications about this ...

Update

this is the WCF configuration from my app.config in the host application

<system.serviceModel>

    <!-- services -->
    <services>
        <service name="Services.CalcService">
            <endpoint address="net.tcp://localhost:8412/MyCalcService"
                      binding="netTcpBinding"
                      bindingConfiguration="MyNetTcpBinding"
                      contract="Contracts.ICalc"/>
        </service>
    </services>

    <!-- bindings -->
    <bindings>
        <netTcpBinding>
            <binding name="MyNetTcpBinding"
                     closeTimeout="00:01:00"
                     openTimeout="00:01:00"
                     receiveTimeout="00:10:00"
                     sendTimeout="00:01:00"
                     transactionFlow="false"
                     transferMode="Streamed"
                     transactionProtocol="OleTransactions"
                     hostNameComparisonMode="StrongWildcard"
                     listenBacklog="10"
                     maxBufferPoolSize="524288"
                     maxBufferSize="65536"
                     maxConnections="10"
                     maxReceivedMessageSize="65536">
                <readerQuotas maxDepth="32"
                              maxStringContentLength="8192"
                              maxArrayLength="16384"
                              maxBytesPerRead="4096"
                              maxNameTableCharCount="16384" />
                <reliableSession ordered="true"
                                 inactivityTimeout="00:10:00"
                                 enabled="false" />
                <security mode="Transport">
                    <transport clientCredentialType="Windows" protectionLevel="EncryptAndSign" />
                </security>
            </binding>
        </netTcpBinding>
    </bindings>

</system.serviceModel>

This is my WCF configuration from my WCF service library

  <system.serviceModel>
<services>
  <service name="Services.CalcService">
    <endpoint address="" binding="basicHttpBinding" contract="Contracts.ICalc">
      <identity>
        <dns value="localhost" />
      </identity>
    </endpoint>
    <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" />
    <host>
      <baseAddresses>
        <add baseAddress="http://localhost:8733/Design_Time_Addresses/Services/CalcService/" />
      </baseAddresses>
    </host>
  </service>
</services>
<behaviors>
  <serviceBehaviors>
    <behavior>
      <serviceMetadata httpGetEnabled="True" httpsGetEnabled="True"/>
      <serviceDebug includeExceptionDetailInFaults="False" />
    </behavior>
  </serviceBehaviors>
</behaviors>

Thanks, Omri.

Answer 1

How does it work?

Only the configuration file of the host application is used.

Why does the WCF library project (a dll project) contains an app.config file

If it is in a class library I guess it's the VS template that added it.

what is it's purpose?

It could be used by the WCF Service Host (WcfSvcHost.exe) when you run the WCF service library with F5 in Visual Studio.