How to build a Generic Webservice/WCF service that any type of client in the world can communicate

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Hi all,
Right now I am developing a WCF service that has to be capable to communicate with any Type of client.
I am actually stressing 'any Type of client' right now in our project before sending a complex class(array of class/object) they are serializing the entire array of object and sending to the client.
Basically we have method and having only one parameter of type string.
so every time we serialize a complex class and send/receive data through simple types(string).
But I had worked with java(client) with .net web service and viceversa and we have used the following piece of code to communicate/exchange the complex types and it worked fine. And from java side they have used literl protocol for data exchange.
Initially we struggled a lot for exchanging the complex types across different platforms.
<SoapRpcService()> _
<ToolboxItem(False)> _
Public Class AsdWebService
In the same way is there any possibility to just configure the protocols wrt to different types of client in WCF. I am actually new to WCF.
I am actually thinking in a way like tomorrow, suppose a new type of language has evolved and they need to consume the WCF(service). I have to just add another node and the data exchange should be done according to the protocol provided by microsoft.
smth like this. Smth like <SoapRpcnewprotocol()> and it should be configurable through web.cong
We are calling this as a platform approach.
Please guide me what to do exactly.
Thanks