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Figure 4.
Architecture of the proposed IEC 61850 Web Platform.
The term Web User is used in this paper to refer to a generic application running on
a generic device which consumes the services offered by the IEC 61850 Web Platform. It
is constrained neither to be IEC 61850 compliant nor to implement the IEC 61850 commu-
nication stack. The only constraints are the adoption of RESTful-based communication
and the MQTT-based exchange of information.
The RESTful Web Service Interface shown by Figure 4 accepts requests submitted by
a registered and authenticated Web User.
The Middleware module inside the IEC 61850 Web Platform performs all the opera-
tions needed to fulfil each request coming from a Web User. These requests may require
data exchange with the available IEC 61850 Servers; for this reason, the Middleware in-
cludes an IEC 61850 Client used for the access to the IEC 61850 Servers. Communication
between an IEC 61850 Client and IEC 61850 Servers occurs according to the standard IEC
61850 communication protocol and services (i.e., using the IEC 61850 communication
stack) [15]. The Middleware includes a particular module named MQTT Publisher, which
is in charge of publishing information taken from the IEC 61850 Server, through an MQTT
Broker, using the MQTT protocol. The Middleware is made up of a local repository shown
by Figure 4 (i.e., Local SCL Repository), used to store ICD files containing the SCL de-
scription of the data model maintained by each IEC 61850 Server involved in the data
exchanges with Web Users. This description is needed by the IEC 61850 Web Platform to
accomplish the services offered, as explained in the remainder of this section. The use of
this local repository is not mandatory, but it is very useful because it avoids remote que-
ries to the IEC 61850 Server when information about the SCL description of the relevant
data model is needed.
Communication between a Web User and the IEC 61850 Web Platform may be syn-
chronous (based on RESTful web services) or asynchronous (based on MQTT Pub-
lish/Subscribe Pattern), as shown in Figure 4.
The Web User uses synchronous communication to interact with the Web Service
Interface to request one of the services offered by the IEC 61850 Web Platform. POST re-
quests are realized using the JSON format. For each Web User’s request through the REST-
ful Web Service Interface, the IEC 61850 Web Platform will send a relevant response. Each
Web User needing to use the IEC 61850 Web Platform through synchronous communica-
tion must be previously registered (by user credentials in terms of username and pass-
word) and authenticated (through the use of a signed token which is held by the Web
User).
