3 SYSTEM DESIGN
This section describes the architecture of the
platform-agnostic MLOps framework. It shows, how
the framework can be used to deploy machine learn-
ing models on different platforms, while providing a
consistent interface for data scientists and operators.
3.1 System Architecture
Fig. 1 shows the system architecture. The MLOps
Framework can be deployed on docker-capable de-
vices, which can be a cloud server, a fog node or an
industrial edge device.
The asset, whose data is used for training and later
analyzed, is typically located on the field level. The
edge device is located on this level as well.
The asset can either output its data (examples of
such data is described in Section 4.2) directly to an
MQTT broker or an industrial edge connector can
be used to access the asset data and convert it to a
standardized format which is then forwarded to the
MQTT broker. Each deployment has an MQTT bro-
ker which has to be accessible from the field level, in
order to connect the framework to the asset. MQTT is
chosen as a protocol, as it offers a lightweight and
easy to use messaging system, however, also other
messaging solutions could be chosen.
Once the asset data is pushed to the MQTT bro-
ker it is ingested by the MLOps framework. This
then uses the data for training a machine learning
model or for generating predictions using the trained
model. These predictions might assign classes to data
points, as described in Section 4.2, try to predict fu-
ture anomalies of the asset operation or do any other
kind of analysis a data scientist might come up with.
These predictions can be pushed back to the
MQTT broker, which makes them available on the
field level. For example, to integrate them into the
Siemens Industrial Edge Platform, which offers i.e.
a dashboard for visualizing the data or connectors to
use the data for further controlling of the asset.
The MLOps framework also offers a consistent
view of the system to data scientists and operators on
all levels. Operators can use the web interface to con-
figure the data ingest via MQTT and monitor the sys-
tem’s status. Data scientists can use it to deploy their
machine learning models, packaged as zip files con-
taining the Python sources and the required libraries.
After uploading the model, the data scientists can con-
figure the model’s training, monitor its performance
and manage and monitor the prediction stage.
3.2 Application Architecture
Fig. 2 shows the internal structure of the MLOps
framework. On the left are the assets connected to
the industrial edge platform, which pushes their data
to the MQTT broker. They do this by directly con-
necting to the MQTT broker or using an industrial
edge connector. Industrial edge connectors are part
of the Siemens Industrial Edge Platform and exist for
many commonly used industrial protocols. The con-
nectors interface with the asset and read its data via
the respective protocol, converting the data to a stan-
dardized format
1
and push it to the MQTT broker.
Data in this standardized format can be ingested
directly by the backend-controller service of the
MLOps framework. To directly connect to assets that
push data to the MQTT broker without using an in-
dustrial edge connector, High-Level Drivers (HLD)
are used. These custom modules can be implemented
and added to the MLOps framework. They man-
age data in any arbitrary format the asset provides
and modify it for ingestion by the backend-controller.
The connections can be configured via the web in-
terface of the MLOps framework. Examples of such
High-Level Drivers are the GENICAM HLD, which
enables communication with cameras supporting the
Genicam protocol, or the OPCUA HLD which ac-
cesses data via OPCUA.
The backend-controller is the core of the MLOps
framework. As described above, it handles the data
ingest before the data is stored in an internal database.
Furthermore, the backend-controller handles deploy-
ment, training, monitoring, and management of ma-
chine learning workflows. Workflows can be up-
loaded in a package format in the web interface, mak-
ing them available for use in the MLOps framework.
After uploading the ML workflows, training can be
started via the web interface. For this, data is se-
lected from the previously collected asset data, which
is then sent together with the ML workflow package
to the runtime, which executes the training routine
defined by the workflow on the selected data. The
trained model artifact is then returned to the backend-
controller, and the workflow is ready for use in the
prediction stage. The prediction stage can be initi-
ated via the web interface. In this stage, the backend-
controller sends the ML workflow package and the
trained model artifact to the runtime. The runtime ex-
ecutes the routine defined by the workflow package
for each relevant data point and generates a predic-
tion using the trained model. These predictions are
1
https://github.com/industrial-edge/common-databus
-payload-format/blob/main/docs/payload-format/PayloadF
ormat.md
Platform-Agnostic MLOps on Edge, Fog and Cloud Platforms in Industrial IoT
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