How do you implement OPC UA for secure data exchange?

OPC UA implementation: architecture design (identify data sources and consumers, define information models), security configuration (authentication: anonymous, username/password, or certificate; encryption: none, basic128, or AES256; select security policy based on risk), endpoint configuration (discovery server, application instance certificates), information modeling (use existing companion specifications or create custom models), address space design (organize nodes logically), historical access configuration (enable historian interfaces), and performance tuning (sampling intervals, queue sizes, keep-alive intervals). Testing: verify connectivity, validate security policy enforcement, load test for expected traffic. Monitor OPC UA server performance and connection status.