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in all the following queries in order to explore the content of the data model below
the IED elements.
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If the Web User has the need to discover the full or partial structure of the hierarchical
data model starting from a specific element (e.g., the IED), he will perform several POST
requests in order to explore the entire data model, starting from the chosen starting ele-
ment of the data model, until the requested data types are found. In order to achieve this,
a particular syntax was defined to be used in these POST requests. This syntax is based on
the same rules described in Section 4.1 for the definition of the name of the data type
identifier; moreover, the syntax contains particular operators aimed to make the explora-
tion of the data model easier.
The following operators were defined to enable the Web User to explore the hierar-
chical IEC 61850 data model. This is not an exhaustive list, as only the most important
operators are described:
1.
getAllIEDs: If the Web User specifies this operator in his request, it will receive a topic
named “IEDs”, whose subscription to the proper Broker enables a JSON description
of the IEDs maintained by the IEC 61850 Server. Considering the data model shown
by Figure 3, the JSON frame shown by Figure 6 will be received through the subscrip-
tion to this topic. Publication of this frame occurs as shown by Figure 5. In this way,
the Web User discovers the value of the attribute name of the IED. This value will be
used in all the following queries in order to explore the content of the data model
below the IED elements.
