WCF Service Base Address vs endpoint address

Question

What's the difference between the following two cases:

Configuration 1:

<service name="WcfService1.Service1" behaviorConfiguration="MyServiceTypeBehaviors">
    <host>
        <baseAddresses>
            <add baseAddress="net.tcp://127.0.0.1:808/" />
        </baseAddresses>
    </host>
    <endpoint address="service"
              binding="netTcpBinding" 
              bindingConfiguration="MainBinding" 
              bindingName="MainBinding" 
              name="DefaultEndpoint" 
              contract="WcfService1.IService1" />
    <endpoint address="mex" 
              binding="mexTcpBinding" 
              contract="IMetadataExchange" />
</service>

Configuration 2:

<service name="WcfService1.Service1" behaviorConfiguration="MyServiceTypeBehaviors">
    <host>
        <baseAddresses>
            <add baseAddress="net.tcp://127.0.0.1:808/service" />
        </baseAddresses>
    </host>
    <endpoint address="net.tcp://127.0.0.1:808/service" 
              binding="netTcpBinding" 
              bindingConfiguration="MainBinding" 
              bindingName="MainBinding" 
              name="DefaultEndpoint" 
              contract="WcfService1.IService1" />
    <endpoint address="mex" 
              binding="mexTcpBinding" 
              contract="IMetadataExchange" />
  </service>

What I understand is In either case base address + endpoint address resolves to same absolute address

But why I get the error on Configuration 2 : "No end point is listening at net.tcp://127.0.0.1:808/
but Configuration 1 runs the service without any errors!!!

Edit 1:

Working Config:

<host>
    <baseAddresses>
        <add baseAddress="net.tcp://127.0.0.1:808/" />
    </baseAddresses>
</host>
<endpoint address="service"
          binding="netTcpBinding" 
          bindingConfiguration="MainBinding" 
          bindingName="MainBinding" 
          name="DefaultEndpoint" 
          contract="WcfService1.IService1" />

Non working Config:

<host>
    <!--
    <baseAddresses>
        <add baseAddress="" />
    </baseAddresses>
    -->
 </host>
 <endpoint address="net.tcp://127.0.0.1:808/service"
           binding="netTcpBinding" 
           bindingConfiguration="MainBinding" 
           bindingName="MainBinding" 
           name="DefaultEndpoint" 
           contract="WcfService1.IService1" />
 <endpoint address="mex" 
           binding="mexTcpBinding" 
           contract="IMetadataExchange" />

In this case, I have removed base address and provided complete service address (with out .svc path) but get a socket time out error. What's wrong in this case? Does the end point address always need the complete address with .svc when base address is not defined? If so, what could be the reason behind?

Solution

baseAddress is just that, the base address for your endpoints (unless specified explicitly). So every <endpoint> will inherit from <baseAddress> (which is why they are usually "" and "mex"). e.g.

<host>
   <baseAddresses>
     <add baseAddress="http://127.0.0.1:1337/" />
   </baseAddresses>
</host>
...
<endpoint address="" contract="MyService.IMyContract" ... />
<endpoint address="mex" contract="IMetadataExchange" ... />

You now have two endpoints:

• http://127.0.0.1:1337/ - service endpoint
• http://127.0.0.1:1337/mex - metadata endpoint

By exempting the <baseAddress> you're requiring the <endpoints> to both be fully qualified (including the mex (which is not)). e.g.

<host>
   <baseAddresses/>
</host>
...
<endpoint address="net.tcp://127.0.0.1:1337/" contract="MyService.IMyContract" ... />
<endpoint address="http://127.0.0.1:1337/mex" contract="IMetadataExchange" ... />

You now have two different endpoints:

• net.tcp://127.0.0.1:1337/ - service endpoint
• http://127.0.0.1:1337/mex - metadata endpoint

Comments

[Simsons]

Thanks ,in my question, in both configuration 1 and 2 , if we append the base address and end point address , the final URI will look like net.tcp://127.0.0.1:808/service .Am I right ? Or , will the base address will look like: net.tcp://127.0.0.1:808/service/net.tcp://127.0.0.1:808/serv‌​ice (appending twice)

[Brad Christie]

Only when an absolute uri is specified does it ignore baseAddress (so, net.tcp://,http://, etc. would be a fully-qualified uri). Otherwise it's essentially appended to the baseAddress (which means your mex, in your second example, becomes net.tcp://127.0.0.1:808/service/mex, but the service remains net.tcp://127.0.0.1:808/service)

[Simsons]

Brad, Edited the question. Just confused , where am I wrong with wcf expectations. If you could have a look on this please