Question

Simple issue. I m working on a proof-of-concept for an application with additional database connection, so I will create a WCF service to wrap around the database. Multi-user environments will get this service installed on a centralized server with a client application on their local system. These users will automatically have to deal with firewall issues, so this is acceptable.

But the single-user environments will have the service and client application running on a single system. The service host doesn t have a definite shape right now, but it s likely that it will be hosted within the application itself or as a Windows service.

Unfortunately, the client application is a WIN32 Delphi application which needs a simple way to access the service. Preferably, the single-user version should use the same technique to access the server as the multi-user version, which means that it behaves like a SOAP client, with a WSDL imported and converted to Delphi code.

Still not a problem, but I have to consider possible problems that we can encounter in this setup, with the most important issue: possible firewall that closed the connection port.

So, does anyone know about any firewall problems that can occur in this single-user environment?

Answer 1

You haven t mentioned which WCF channel you re using- I ll assume basicHttpBinding. Generally, if your local service is bound to 127.0.0.1 using self-hosting, and the on-box client accesses it that way, you should be fine. No firewalls I m aware of will screw with your loopback adapter. If you bind the service to the machine s IP though, you may subject yourself to firewall fun.

If you have WCF 3.5 available on the client on both ends (sorry, I don t know anything about Delphi), have a go with netNamedPipeBinding.

Answer 2

You didn t mention which version of Delphi you use but I once had hard time making Delphi 2005 import a WCF service with basicHttpBinding. As the WSDL is split among many pages, the SOAP import wizard in Delphi wasn t capable of understanding it. I finally ended up writing an ASMX wrapper around the WCF service for Delphi clients.

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