The public standard specification of OCA is the AES70 standard, published by the Audio Engineering Society, or AES. AES70 is an open, license-free specification that may be freely used at no cost.
The current version of the standard is AES70-2024.
The AES70-2024 Standards Suite
The standards in the AES70-2024 suite are as follows:
| Standard | Contents | Download Link |
|---|---|---|
| AES70-1-2024 | Overall architecture of AES70 and mechanisms of AES70. Also known as OCF. | AES70-1-2024: AES standard for Audio applications of networks - Open Control Architecture - Part 1: Framework |
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| AES70-2-2024 | Object-oriented class structure that defines the functional repertoire (connection management, control, and monitoring) of AES70. Also known as OCC. | AES70-2-2024: AES standard for Audio applications of networks - Open Control Architecture - Part 2: Class structure |
| AES70-2-2024 Annex A |
Formal specification of AES70 class structure in Unified Modeling Language (UML). Available in Enterprise Architect format (.EAP file extension) or XMI format (.XMI file extension). See Unified Modeling Language below. |
www.aes.org/standards/models/AES70-2-2024-AnnexB.eap
or www.aes.org/standards/models/AES70-2-2024-AnnexB.xmi |
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| AES70-3-2024 | Specification of OCP.1, a compact binary protocol for AES70 that runs over IP networks. Defines variants for using TCP, TCP/SSL, UDP, or WebSocket transport protocols. | AES70-3-2024: AES standard for Audio applications of networks - Open Control Architecture - Part 3: Protocol for TCP/IP Networks |
| AES70-3-2024 Annex B |
Formal specification of OCP.1 in Unified Modeling Language (UML). Available in Enterprise Architect format (.EAP file extension) or XMI format (.XMI file extension). See Unified Modeling Language below. |
www.aes.org/standards/models/AES70-3-2024-AnnexB.eap
or www.aes.org/standards/models/AES70-3-2024-AnnexB.xmi |
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| AES70-22-2024 | "Adaptation" standard that specifies how to use AES70 for managing connections of the Milan AVB media transport protocol. | AES70-22-2024: AES standard for audio applications of networks - Open Control Architecture - Part 22: Using AES70 to manage Milan media transport |
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Unified Modeling Language (UML)
AES70-2 Annex A and AES70-3 Annex B are Unified Modeling Language (UML) specifications. AES70-2 Annex A is particularly important, as it contains the entire specification of the AES70 Class Structure.
The UML files are in two forms:
- *.eap files are master files from a UML tool named Enterprise Architect from Sparx Systems. The usual version of the tool costs approximately US$245 (as of April 2025), but Sparx Systems offers a free viewer. There is also a 30-day free trial version of the full package. Both of these products are available from the Sparx Systems download page here.
- *.xmi files are master files in XMI 2.1, a standard format for representation of UML information. XML stands for "XML Metadata Interchange". XMI files can be opened by most UML editors, including free ones. See this Wikipedia article for more information on the XMI standard.