Additional HowTos

[hylkevds]

Two HowTos that would be very useful additions to the documentation would be for the use cases:

• There is an existing HTTP/REST API. How do I make this available using IDS? The chapter "Using IDSCPv2 as a passive (receiving) server component" seems to be in this direction, but how to modify this to REST is not clear.
• There is an existing MQTT server. How do I wrap this in IDS?

[gbrost]

Hi there,

What REST API do you mean? The management API of the Trusted Connector? The existing examples glue also to HTTP.
The examples also include MQTT subscriptions and forward the messages via IDSCP. What is missing?

[hylkevds]

Lets say I have an existing REST service, for example: https://airquality-frost.k8s.ilt-dmz.iosb.fraunhofer.de/v1.1
This service implements the OGC SensorThings API that offers extensive querying capabilities, based on the OASIS OData standard.
I want to make this service available to third parties, using IDS. What steps do I go through to do that?

This example is publicly available, but our real service would, of course, not be. A graphical GUI for this demo service can be found at: https://api4inspire.k8s.ilt-dmz.iosb.fraunhofer.de/servlet/is/127/

In the MQTT example I found (https://industrial-data-space.github.io/trusted-connector-documentation/docs/rest/) the client doesn't actually seem to use MQTT. The client seems to be a REST API that gets data pushed into it using HTTP, not MQTT. In other words, the client is actually a http server.
How do I connect an MQTT client to a MQTT server through IDS?

[gbrost]

Hi there, the example works like this: The client (provider) publishes to a mqtt server. The route picks that up and transmits it to the server (consumer). There it is transferred to a REST endpoint. You can instead publish to MQTT on the server side as well. Drop me a mail if things are unclear, please.

[hylkevds]

So how does the MQTT server on the provider side know which topics have subscribers? Or do all topics need to be pre-determined?
Also still doesn't explain how to connect a REST API like the one I mentioned...

[gbrost]

They need to be predetermined. You could thin about embedding this in the info model, but after all this is the application layer. For "forwarding" REST APIs, you can create a REST interface inside of a Camel route. You will also get the response routed back to you. This is basic Camel then, the IDSCP is just wrapping the payload.