Transport Protocols

Currently, OPC UA specifications describe the following protocols as its transport protocol:

• OPC UA TCP: a custom binary protocol, usually used for performance-critical environments
• HTTP/SOAP: the standard envelope used on classic Web Services
• HTTPS: usually used for REST Services

All these transport/session protocols are used in conjunction with data encoding techniques such as:

• OPC UA Binary format: used in companion with OPC UA TCP protocol
• XML: used in companion with HTTP/SOAP protocols to expose classic Web Services
• JSON: used in companion with HTTPS to provide a REST service