similarly, and only the attribute kind and the attribute value differ. DataTypeDef is
any XSD datatype [63], and ValueDataType is a value of such type.
Assets may be composed of other assets. In this case, a composite AAS is
constructed, which has a bill of material listing its parts. These assets may be
co-managed within the comprising AAS, or they may be self-managed, that is,
they all have their own AAS. Therefore, complex AAS structures can be built,
which may reflect the physical asset structuring.
The data model and the corresponding data can be serialized (i.e. automatically
transformed to), for example, as extensible markup language (XML), JavaScript
object notation (JSON), resource description framework (RDF), or open platform
communications-unified architecture (OPC-UA). The standard also defines all these
mappings. An AAS can be entirely transported as a so-called AAS extension
(AASX) package. Furthermore, a representational state transfer API (REST-API)
of an AAS is currently being defined and specified by PI4.0. It will be defined as
part 2 of the AAS specification [59], but is work in progress, and intends to
standardize the AAS interfaces.
Another module in the AAS information model is the attribute-based access
control (ABAC) based security model, which protects the AAS, e.g. its RESTAPI. For each subject (role or user), it can be specified which object (submodels
or even properties) the user is allowed or denied to read or to modify using
expressions over attributes of the subject, the object, and the context.
The AAS specification does not provide methods to describe how a physical asset
can be connected with its AAS. Anything is allowed here, hidden to the AAS users.
Therefore, the AAS homogenizes the assets’ diversity in the real world by providing
a standard ecosystem plug.
4.4 Data Sharing Standards
DTs are a mature instrument for data collection and integration that can bridge media
disruptions between distributed systems [64]. A DT forms a central knowledge base
within a company and contributes to enhance business processes [64]. Although the
benefits of DTs are not limited to their use for internal company processes, they are
mainly used to monitor the internal processes. In this context, DTs are a suitable
instrument for sharing data with various stakeholders [65], which companies find it
increasingly important as data represents a strategic resource with economic
value [66].
In principle, the difference between exchange and sharing of data must be
recognized. Exchange of data occurs only in terms of vertical cooperation between
companies, where the optimization of value or supply chains is one of the objectives.
This type of data exchange is common and based on standards developed since the
introduction of electronic data exchange in the 1980s. Data sharing, however,
describes the vertical and horizontal collaboration between companies to achieve
common goals; for example, predictive maintenance through collaborative data
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R. Werner et al.
any XSD datatype [63], and ValueDataType is a value of such type.
Assets may be composed of other assets. In this case, a composite AAS is
constructed, which has a bill of material listing its parts. These assets may be
co-managed within the comprising AAS, or they may be self-managed, that is,
they all have their own AAS. Therefore, complex AAS structures can be built,
which may reflect the physical asset structuring.
The data model and the corresponding data can be serialized (i.e. automatically
transformed to), for example, as extensible markup language (XML), JavaScript
object notation (JSON), resource description framework (RDF), or open platform
communications-unified architecture (OPC-UA). The standard also defines all these
mappings. An AAS can be entirely transported as a so-called AAS extension
(AASX) package. Furthermore, a representational state transfer API (REST-API)
of an AAS is currently being defined and specified by PI4.0. It will be defined as
part 2 of the AAS specification [59], but is work in progress, and intends to
standardize the AAS interfaces.
Another module in the AAS information model is the attribute-based access
control (ABAC) based security model, which protects the AAS, e.g. its RESTAPI. For each subject (role or user), it can be specified which object (submodels
or even properties) the user is allowed or denied to read or to modify using
expressions over attributes of the subject, the object, and the context.
The AAS specification does not provide methods to describe how a physical asset
can be connected with its AAS. Anything is allowed here, hidden to the AAS users.
Therefore, the AAS homogenizes the assets’ diversity in the real world by providing
a standard ecosystem plug.
4.4 Data Sharing Standards
DTs are a mature instrument for data collection and integration that can bridge media
disruptions between distributed systems [64]. A DT forms a central knowledge base
within a company and contributes to enhance business processes [64]. Although the
benefits of DTs are not limited to their use for internal company processes, they are
mainly used to monitor the internal processes. In this context, DTs are a suitable
instrument for sharing data with various stakeholders [65], which companies find it
increasingly important as data represents a strategic resource with economic
value [66].
In principle, the difference between exchange and sharing of data must be
recognized. Exchange of data occurs only in terms of vertical cooperation between
companies, where the optimization of value or supply chains is one of the objectives.
This type of data exchange is common and based on standards developed since the
introduction of electronic data exchange in the 1980s. Data sharing, however,
describes the vertical and horizontal collaboration between companies to achieve
common goals; for example, predictive maintenance through collaborative data
148
R. Werner et al.