WCF Interop with PHP behind a load balancer

Question

I'm trying to help a customer interop w/ a PHP client but we have a load balancer that is in front of the IIS farm. Because of this when you actually view the .svc?wsdl you get specific server listed inside this WSDL. Then when my customer is trying to generate a client using something like so

$client = new SupplierService();

They get a timeout for a specific server in the farm (not the uri we gave them that points to the load balancer itself)

I have even flatted the WSDL by hand, generated a .net client using svcutil to prove that this WSDL should be enough to get a valid call through the load balancer (and the .net client does work using this flat WSDL generated client)

After I got this working I emailed the client this flat WSDL file to generate a valid php client from it (not the uri that was causing issues) and it just hangs. With no error message or exception to go from ...

Also when I watch the actual message come across using Wireshark the .net and php client SOAP data looks almost identical. yet the .net client works and the php client hangs w/ no error thrown back to the client or logged via .NET

Anything I might have missed here or should be aware of when doing interop w/ WCF behind a load balancer?

Answer 1

In situations where you're balanced behind a balancer like this, if you want have the correct server name emitted in the WSDL you need to actually add the <host> section to your service configuration like so:

<service ...>
    <host>
        <baseAddresses>
            <add baseAddress="http://subdomain.yourexternaldns.com" />
            <add baseAddress="https://subbomain.yourexternaldns.com" />
        </baseAddresses>
    </host>
</service>

You also need to make sure you've configured host headers in IIS for this to work and that your blancer is passing through the host header untouched.

Answer 2

There are a few things you could try:

• Test the php client directly against the service to verify if the load balancer is the problem or not.
• Check the IIS and event logs on the machine running the WCF Service