Sensor and Process Modules
Sensors and processes are at the core of OpenSensorHub's ability to deploy and use inputs and outputs of physical and non-physical sensors, systems, processes, etc.
Sensor Drivers and SensorML Processes both utilize SensorML and SWE Common Data Modeling to describe systems, features of interest, data streams, commands, controls, and more.
Sensors
OpenSensorHub uses Sensor Drivers to act as a bridge between a physical sensor (or non-physical stream of data) and OpenSensorHub's inner workings.
Sensor Drivers allow us to do the following
- Persist data via OpenSensorHub's database engine for long term storage
- Serve sensor data or actuator inputs via OGC API - Connected Systems
- This acts as an easy-to-use interface to create client applications to visualize sensor data
- Connect sensor output streams or actuator inputs to be used in SensorML process chains
- Capture sensor data to push to other OpenSensorHub nodes via OSH client modules
- Group sensor outputs and metadata via Sensor Systems
Selecting a Sensor Driver
The easiest way to deploy Sensor Drivers is to use the Admin UI. The Admin UI is available by default on all OpenSensorHub nodes at
{protocol}://{host}:{port}/sensorhub/admin
On a local OpenSensorHub node, this will typically be
http://localhost:8181/sensorhub/admin
OpenSensorHub nodes are password protected.
The default Admin UI credentials: username: admin password: admin
On the Admin UI, if you right-click the space under the Sensors tab, and select Add New Module, you can add a new Sensor Driver from a list of all Sensor Drivers that have been included in your OpenSensorHub build.
In this example, I'll select and show the outputs of a simulated weather sensor.
This specific driver can be found in osh-addons/sensors/simulated/sensorhub-driver-fakeweather which is pre-packaged in
osh-node-dev-template.
Or, you can add it to your own node by pulling the latest osh-addons repository.
Please see the quickstart guide on Build Configuration
Configuring Sensor Drivers
After you've selected a Sensor Driver, you'll see a panel to configure this driver. The driver will also appear under the Sensors tab with the LOADED state.
Here you can edit information required for describing your driver such as a name, description, unique ID, as well as an actual SensorML description of the sensor, if applicable.
Almost all Sensor Drivers will include important configuration options for establishing a connection to the sensor, configuring parameters, describing the sensor's location, etc. Make sure that you provide accurate and up-to-date configuration to ensure a connection is made to your sensor.
Once you are happy with the Sensor Driver's configuration, select Apply Changes at the top-right of the panel, and your Sensor Driver will initialize with the provided configuration.
Module Actions
For any OpenSensorHub module, you can control its state in the Admin UI by right-clicking the module on the sidebar, and selecting an action.
| Action | Usage/Purpose |
|---|---|
| Start | Starts the selected module. For Sensor Drivers, this will start the data stream of sensor outputs from the sensor to OSH's internal event bus. |
| Stop | Stops the selected module. For Sensor Drivers, this will close the connection to the sensor, and stop the sensor from publishing data to OSH. |
| Force Init | Re-initializes the module, setting it to INITIALIZED state. Typically, you use this to clear up issues that prevented the module from starting under its previous conditions. |
| Remove Module | Completely removes the module from OpenSensorHub. Persisted data will not be removed when performing this action. Please see Databases. |
| Add New Module | Allows you to add a new module of the type for whichever sidebar tab you are in. (Sensors, Databases, Processes, etc.) |
Sensor Driver's Outputs
To check that your Sensor Driver is publishing outputs, you can check under the Outputs section that appears under the Sensor Driver's configuration, once initialized.
You may also check the Federated Database under the Databases tab, to check that your Sensor Driver is publishing its latest outputs to the OpenSensorHub State Database.
Sensor Driver's Commands
Some Sensor Drivers will have Control Streams in addition to their output Data Streams. These Control Streams act as an interface for sending commands to a sensor or actuator.
If your Sensor Driver has Control Streams, you will see a user interface for sending commands under a Sensor Driver's Outputs section.
Sensor Systems
OpenSensorHub has a built-in Sensor module that acts as a parent to a group of Sensor Drivers and/or Processing Modules. This can be useful for deployments where multiple Sensor Drivers and/or Processing Modules must be linked to a common parent.
We will walk through setting up a basic Sensor System.
A Sensor System is configured like all other OpenSensorHub modules. While it is necessary to provide a unique ID, you may optionally provide additional descriptive information such as the Sensor System's location, orientation, and SensorML description.
Once configured, you may add Sensor Drivers and Process Modules under a Sensor System by right-clicking the Sensor System and selecting Add Submodule.
A Sensor System's children can be configured as if they were standalone modules. Below, you can see a Sensor System with 2 simulated weather Sensor Drivers.
Submodules may not be started unless the parent Sensor System is started. Also, if submodules have autoStart enabled, then they will start once the parent Sensor System is started.
Processing
SensorML Stream Processing
SensorML Stream Processing can be used to connect sensor outputs/commands, and other processes' outputs/commands. This allows for complex calculations and automations to be done on the fly.
Currently, OpenSensorHub comes pre-packaged with a SensorML Stream Process module, accessible under the Processing tab.
In order to run this processing module, you will need to provide a SensorML Process Description, which should be provided in a .xml or .json file.
Please review the Developer Documentation for developing processes and describing their execution with a SensorML Process Description.
For the sake of this example, I will load a preconfigured simulated weather process which you can find at
/osh-node-dev-template/include/osh-addons/processing/sensorhub-process-fakeweather
This Gradle module provides you with a test class that will print a process description to your console in XML and JSON. After putting this process description in a file and loading it into the SensorML Stream Process module, we can see a stream of the process' outputs, similar to a Sensor Driver.
