OPC UA is a series of specifications providing multivendor multiplatform secure reliable information integration interoperability from the embedded world to the cloud. Key parts of OPC UA is about information modeling, and is the foundation providing a complete infrastructure to facilitate other organizations complex data modeling leveraging the OPC UA infrastructure to take advantage of the seamless interoperability.
The modelling capabilities of OPC UA are the fundamental components necessary for semantic interoperability. An increasing number of organizations created standard OPC UA information models for specific domains and/or are currently under development. These OPC UA information models are described in what is known as OPC UA companion specifications.
OPC UA companion standards address use cases and with that increase the applicability and adoption of the OPC UA technology in different verticals.
See https://opcfoundation.org/developer-tools/specifications-unified-architecture for released companion specifications.
The OPC Foundation has been providing support to other consortiums and standard organizations to develop the OPC UA companion specifications via an infrastructure known as joint working groups (JWG).
A “Joint Working Group (JWG)” is a working group formed between an organization (subsequently called “cooperating organization”) and the OPC Foundation. The goal of the JWG is the development of an OPC UA companion standard for use cases defined by the cooperating organization, with a compliance testing strategy to insure compliant implementations of the OPC UA companion standard.
„Joint“ means, that
- Members of both organizations are invited to participate in the working group.
- The cooperation and its purpose are announced to all OPC members and exposed on the OPC Foundation web. Press releases may be issued as agreed by both organizations.
- The companion specification and associated deliverables will follow the layout and rules that the OPC Foundation defines for companion specifications. This will result in consistency for all JWG companion specifications.
- The companion specification will be reviewed by the OPC Technical Advisory Council (TAC) for completeness and will receive the OPC Foundation Logo.
- The released specification will be made available in the download section of the OPC Foundation website.
A “joint companion specification” is not a technology of the OPC Foundation. The OPC Foundation does not guarantee exclusiveness and cannot prove that the use cases of the cooperating organization are fulfilled.
Participation of OPC Foundation members is voluntary. There shall be no expectation that OPC-F provides resources for the JWG.
Criteria for a joint working group
- The OPC Foundation has set some defined rules to enter a cooperation:
The companion specification will not address core OPC UA topics; i.e. it does not compete with the core OPC UA technology.
- The cooperating organization certifies that there is real demand for this model, has resources to develop the companion specification, and can provide a chairman. (The chairman may be a member of the cooperating organization or a corporate OPC Foundation member).
- Any intellectual property rights will be checked by the cooperating organization.
- The joint working group will coordinate with other working groups that work in similar areas or work on overlapping definitions.
Creating a joint working group
- The process starts with a Memorandum of Understanding (MOU) and a charter.
The charter shall be based on the OPC Foundation template.
- The OPC Control Boards (Technical TCB and Marketing MCB) and the OPC Technical Advisory Council (TAC) will review the charter.
- Next, a Kick-Off meeting date is scheduled (2-3 weeks after the review) and announced with a call for experts to OPC-F members.
- The joint working group will use the OPC Foundation template for companion specs.
- During its lifetime, the working group chair shall provide a status update to the OPCF Control Boards (TCB & MCB) 3 times a year and a minimum of one status update to the TAC yearly.
- The OPC Foundation website is used for communication about this joint working group, inclusive of what the collaboration is, who are the contacts, how companies join, roadmap, companies adopting the technology, certification, and more.
- When the companion specification is completed by the working group it has the status of release candidate (RC). The companion specification will be than reviewed by the TAC. The review period will be 2 to 6 weeks depending on the complexity and size of the specification.
Three essential stages of completion
A released specification is a major milestone and for a long time has been everything that was required. However, specifications may have errors or may not be precise enough for interoperable applications. In additions, the demand for stable implementations grows rapidly which requires certification and other tests. Therefore, the OPC Foundation has defined three essential stages of companion work completion:
- Stage: Specification
This is the stage when a companion spec has been released. It means that specification and machine-readable Information Model (NodeSet) have been completed and a proof-of-concept implementation exists. The result has been reviewed by both organizations.
- Stage: Adoption
This stage is reached, when implementations of at least two different vendors exist and have been tested in a PlugFest – for instance an OPC Foundation Interoperability Workshop
- Stage: Certification
Finally, this stage indicates the availability of a test specification and the implementation of test cases and tools that allow products to be certified in an OPC TestLab.
The OPC Foundation website will show the state of work as follows:
- Green: This stage has been completed.
- Yellow: Work for this stage is in progress.
- Grey: No work done so far.
Here is an example where the specification stage is complete and work for achieving adoption is in progress.
Specification Adoption Certification
If interested in such a cooperation please contact either
Stefan Hoppe – firstname.lastname@example.org or
Thomas Burke – email@example.com or
Karl Deiretsbacher – firstname.lastname@example.org