Databases
OpenSensorHub databases are used to persist data from sensor outputs, process outputs, or other nodes via Service Modules.
OpenSensorHub comes pre-packaged with a basic H2 database module, and a System Driver Database, which uses the basic H2 database, but with additional features.
Federated Database
The federated database will always appear at the top of the Databases tab, and contains data from all running databases on the OpenSensorHub node. It features a search bar and the ability to check any system's observations.
If a Sensor Driver, Process Module, or Service Module do not have an associated database, then only the latest observations produced by these modules will be shown in the federated database.
Basic H2 Database
The H2 database module is the most basic module for interfacing between a database file and OpenSensorHub.
Configuration
For an H2 database module to run, a storage path, or path to the database file is required. Once specifying this path, The other default configuration options will be sufficient for most use cases.
The H2 database module wrapped inside the System Driver Database, the configuration of the actual H2 database used by the System Driver Database will appear as it would in an H2 database module.
Usage
The H2 database module can be used as a store that Service Modules can write to, or it can be used to load OpenSensorHub-compatible database files from another node.
System Driver Database
System Driver Databases are used as a means of capturing data from Sensor Drivers or Process Modules for long-term storage. This is different from the standalone H2 database, as it has a mechanism for pulling data directly from sensors or processes without having to edit the Sensor Driver or Process Module configuration.
Configuration
Below, you will see the default configuration of a System Driver Database. There are 3 important parts of the System Driver Database configuration.
| Configuration | Description |
|---|---|
| System UIDs | A list of system UIDs or UID patterns (i.e. urn:osh:sensor:*) to persist. |
| Database Config | H2 database configuration. See previous section. |
| Automatic Purge Policy | A list of policies used to regularly purge data from the database. |
System UIDs
Upon adding system UIDs to your System Driver Database, you will see those systems appear below the System Driver Database configuration. You will also notice that their observations will start being persisted in the table below Database Content. This means that your sensor or process is publishing outputs, and your database is storing those observations.
If you want to add a Sensor System and its subsystems to a System Driver Database, you only need to put the UID of the parent system. This will typically look like urn:osh:system:<parent id>
Click Apply Changes after all module configuration updates!
You may use a UID pattern to specify all UIDs with a certain prefix. For example, urn:osh:sensor:* will add all Sensor Drivers to the System Driver Database.
Database Config
The System Driver Database is built on top of the basic H2 database module. This means that you will need to specify a database file path to use, as well as any other lower-level configuration as needed. Please refer back to the previous section about the basic H2 database module to learn more.
Automatic Purge Policy
Automatic purge policies will instruct the System Driver Database module to purge specified systems from the database routinely.
Here, we can specify a few things
- Which systems are purged via their UIDs or a UID pattern. This is
*by default, which means ALL systems will be purged. - How often these systems are purged from the database (in seconds).
- The maximum age of data to be kept in the database (in seconds).
