3.2.3 Initialization
The client MUST perform initialization according to the following rules when calling an RPC method:
Either create an RPC binding handle to the server or use an RPC context handle. Details concerning binding handles are as specified in [C706] section 2.3.
Use context handles across multiple calls to server for methods taking METADATA_HANDLE as a parameter.
A context handle SHOULD be reused in multiple invocations when getting or setting information to remote server configuration.
When creating the RPC binding handle, the client MUST specify an ImpersonationLevel value of 2 (Impersonation), as specified in [MS-DCOM].