Call web-service's object's method

I have a web-service that returns a custom object, but now I want to call some of the object's methods e.g. to change some of it's values (but also for other needs开发者_开发百科), but how can I do that?

Do I have to set the object up as a web-service or how?

The web-service is created in Java and the client is created in C#

but now I want to call some of the object's methods to change some of it's values, but how can I do that?

This will depend on the protocol you are using but because you mentioned Java service and .NET client I assume SOAP. This is not possible with SOAP. There are no methods in the generated client proxy. It's a POCO. You could modify the properties of this client object and pass it to some server method for processing.