I created a Dotnet api to connect with IRIS database to do some task.
"InterSystems.Data.IRISClient.dll" (NativeAPI) is used in dotnet api to connect IRIS.
I used following code in dotnet to open and close the IRIS connection.

Open Connection
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IRISConnection iRISConnect = new IRISConnection();
IRISCommand command = new IRISCommand();
iRISConnect.ConnectionString = "Server=xxxx.com; Port=1972; Namespace=aaa; Password=yyyy; User ID=xxxxxx;";
IRIS NativeAPI = IRIS.CreateIRIS(iRISConnect);
iRISConnect.Open();

Connection Close
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command.Dispose();
iRISCon