As of PI-SDK 1.1 and with a PI Server version 3.3 or higher, it is possible to configure trust relationships on the server that allow client PI-SDK processes with specific identifying traits to automatically connect to the server as a specific configured PI user. This is particularly valuable for applications that need to run unattended and would need to regain privileged access after a system reboot. Information on configuring these trusts is presented in the PI3 Server documentation.
A PI-SDK application requests a trust by attempting an Open with a connection string that has no UID=xxx phrase, or an empty connection string. Note, calling a Server method or property that requires a call to the server, before Open has been called, results in a default Open call being made with a blank connection string. When invoked this way, Open first tries for a trust connection. If this fails, it attempts to login using the configured default user for this server and a blank password.
If you are installing the PI-SDK to be used by a data-gathering interface, or similar product, you may need to configure a trust on the server to support the intended operation.
The PI-SDK does not support the PI 3.2 Server proxy table that is used by the PI-API. (Note: PI 3.3 upgrades the proxy table to a PI Trust table during the upgrade process.) PI-SDK programs that need to support unattended privileged access on those systems will require an encrypted password or similar mechanism on the client. Such a mechanism is used by the PI-OPC interface.