Connectivity Framework Annex B: Assessment Template: OPC-UA
B. 6.4 Functional Viewpoint B. 6.4.1 Core Framework Layer Functions
Data Resource Model
( Section 4.1.1)
ID & Addressing( Section 4.1.2)
Data Type System( Section 4.1.3)
Data Resource Lifecycle( CRUD)( Section 4.1.4)
State Management( Section 4.1.5)
Publish-Subscribe( Section 4.1.6)
Request-Reply( Section 4.1.7)
Discovery( Section 4.1.8)
Exception Handling( Section 4.1.9)
Data Quality of Service( QoS)( Section 4.1.10)
Does it provide a data resource model? Summarize the salient aspects.
OPC-UA resources are called nodes. They can be individually addressed using a NodeId. Nodes contain data-elements, operations and references to other nodes.
Does it provide a way to identifying and addressing data objects? Summarize the identification and addressing scheme.
OPC-UA nodes have a unique identifier within a server, called the NodeId.
Addressing a node also requires addressing the OPC-UA server using its network IP address and port, plus the NodeId. Does it provide a data type system? Summarize the salient aspects.
OPC-UA defines a full data type system. Data-variables within nodes can be of simple or complex( structured) data types.
Does it provide a means of managing a data object’ s lifecycle? Summarize the salient aspects.
There is no pre-defined resource lifecycle in OPC-UA. However, applications can define their own lifecycles and operations to control the resources.
Does it provide a means to manage the recent history of data objects? Summarize the salient aspects.
The variables within each node constitute the state of the Node.
Each OPC-UA server manages its own state that is accessible via Query and Browsing services. They cache the last value of every variable they contain. Those can be queried using the Query service.
There is also a full set of historical data access services defined.
Does it provide a means to publish and subscribe the state of data objects? Summarize the salient aspects.
Plans are underway to include publish-subscribe data exchange. Prototypes are already in field-test.
Does it provide a means to request the state of data objects? Summarize the salient aspects.
Yes, this is the core primary communication pattern in OPC-UA. Does it provide a means to discover the data objects? Summarize the salient aspects.
OPC-UA servers can implement a discovery service allowing client applications to discover the nodes they contain.
An OPC-UA server may provide a global registration and discovery service, allowing discovery of all the OPC-UA servers in a system.
Does it provide a means to handle exceptions when quality of service or connectivity violations happen? Summarize the salient aspects.
Exceptions are supported and communicated via events and alarms.
Does it support data QoS? Summarize the scope and coverage. Highlight the salient aspects.
OPC-UA offers limited quality of service options beyond the ability to specify an update frequency for the monitored data. There are many QoS features built into the services of OPC-UA. The services are purpose built to provide appropriate QoS.
IIC: PUB: G5: V1.0: PB: 20170228- 76-