Service Modules
Service modules in OpenSensorHub are typically used to expose resources via a standard method of communication. OpenSensorHub exposes resources most commonly through a REST API, or via streaming protocols such as MQTT, etc.
The default Service Modules packaged in an OpenSensorHub node are Connected Systems API Service, SOS Service, and SPS Service.
While SOS Service and SPS Service are mostly deprecated, the Connected Systems API Service is the newest and most up-to-date common Service Module.
The Connected Systems API Service Module allows an OpenSensorHub node to expose its resources on a configurable endpoint via OGC API - Connected Systems.
You can learn more about OGC API - Connected Systems here or refer to the OSH Connect documentation for building OpenSensorHub clients using OGC API - Connected Systems.
This guide will cover basic configuration of only the Connected Systems API Service Module, but you will find that most service modules have similar configuration.
Connected Systems API Service
The Connected Systems API Service exposes a REST API which conforms to OGC API - Connected Systems.
By default, this API is hosted at /sensorhub/api, but this can be configured in the Connected Systems API Service Module.
Below are highlighted configuration sections that may be useful in configuring the Connected Systems API Service
Using a Database
By default, the Connected Systems API Service will not be attached to any specific database, but will use OpenSensorHub's default state database.
If clients try to POST resources to your OpenSensorHub node via the Connected Systems API, you will likely see these resources appear in the Federated Database (if systems/datastreams/observations),
but they will not persist upon shutting down the node.
In order to persist resources that are inserted via the Connected Systems API, you must attach a database to this Service Module through the configuration (Database ID field). The attached database can be a simple H2 Historical Obs Database. As long as the database is running, resources will be persisted.
Exposed Resources
The Exposed Resources configuration enables filtering of what resources are accessible through this service.
By default, Exposed Resources uses no filtering, which means that ALL resources in the Federated Database will be accessible through the Connected Systems API Service.
This configuration allows us to filter by resources in a certain database, or through the use of different OpenSensorHub filters. You may provide a filter to only expose certain Systems, Data Streams, Observations, Features, etc.
Below shows a tree containing different filters editable in the web interface.
Security
The Security configuration features two key options.
The first option is to enable access control, which allows the use of granular permissions that are configurable in the Users security module under the Security tab.
The second option is to require authentication for this service. If this is enabled, clients may only connect to your service if authenticated via OpenSensorHub's security module. This just means that clients sending requests to your Connected Systems API service will need to include user authentication in request headers.
API Web Interface
OpenSensorHub has an easy-to-navigate web interface for its Connected Systems API Service. If you go to the endpoint at which the Connected Systems API is being served, you are greeted with a web interface which allows you to explore resources on the node, namely Systems, Data Streams, Observations, Sampling Features, etc.
If you would like to learn more about how to understand and use the Connected Systems API, please refer to the OSH Connect documentation, as well as the OGC API - Connected Systems website.
Clicking any of the hyperlinks under the Available Resources section will take you to the associated collection of resources, conformant to the OGC API - Connected Systems specification.
Below is an example of the /sensorhub/api/systems web interface.
Other Service Modules
Feel free to check out the Service Modules available in OpenSensorHub's collection of module addons (osh-addons).
You will find addons for serving data via OGC SensorThings API, OGC API - Moving Features, MQTT Services, and more.