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Note: The following is an excerpt from the official IEC catalog. It is provided here as a convenience and is not authoritative. Refer to the original document as the authoritative reference.

IEC 62541-6:2020 specifies the OPC Unified Architecture (OPC UA) mapping between the security model described in IEC 62541-002 OPC Unified Architecture - Part 2: Security Model, the abstract service definitions specified in IEC 62541-004 OPC Unified Architecture - Part 4: Services, the data structures defined in IEC 62541-005 OPC Unified Architecture - Part 5: Information Model and the physical network protocols that can be used to implement the OPC UA specification. This third edition cancels and replaces the second edition published in 2015. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:

a) Encodings:

• added JSON encoding for PubSub (non-reversible);
• added JSON encoding for Client/Server (reversible);
• added support for optional fields in structures;
• added support for Unions.

b) Transport mappings:

• added WebSocket secure connection – WSS;
• added support for reverse connectivity;
• added support for session-less service invocation in HTTPS.

c) Deprecated Transport (missing support on most platforms):

• SOAP/HTTP with WS-SecureConversation (all encodings).

d) Added mapping for JSON Web Token.

e) Added support for Unions to NodeSet Schema.

f) Added batch operations to add/delete nodes to/from NodeSet Schema.

g) Added support for multi-dimensional arrays outside of Variants.

h) Added binary representation for Decimal data types.

i) Added mapping for an OAuth2 Authorization Framework.

See also:

• IEC 62541-001 OPC Unified Architecture - Part 1: Overview and concepts
• IEC 62541-002 OPC Unified Architecture - Part 2: Security Model
• IEC 62541-003 OPC Unified Architecture - Part 3: Address Space Model
• IEC 62541-004 OPC Unified Architecture - Part 4: Services
• IEC 62541-005 OPC Unified Architecture - Part 5: Information Model
• IEC 62541-007 OPC Unified Architecture - Part 7: Profiles
• IEC 62541-008 OPC Unified Architecture - Part 8: Data Access
• IEC 62541-009 OPC Unified Architecture - Part 9: Alarms and Conditions
• IEC 62541-010 OPC Unified Architecture - Part 10: Programs
• IEC 62541-011 OPC Unified Architecture - Part 11: Historical Access
• IEC 62541-012 OPC Unified Architecture - Part 12: Discovery and global
• IEC 62541-013 OPC Unified Architecture - Part 13: Aggregates
• IEC 62541-014 OPC Unified Architecture - Part 14: PubSub
• IEC 62541-100 OPC Unified Architecture - Part 100: Device Interface

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