如何创建一个公共客户端类，连接和共享该连接

I'm designing a tool (in .net) which connects to an 3rd party web service API, and once connected creates a single client reference to that API. This single client instance needs to be reused over several other classes which will use the client as a proxy to execute their methods. Once finished, I need to close this single client's connection to the API.I'm designing a tool (in .net) which connects t