On intercepting all Fedx outgoing requests to add custom headers

[fourAnge]

I am using FedX (with RDF4J 5.x) in a server environment. I need to intercept all outgoing SPARQL HTTP requests to external endpoints to add custom headers (for tenant‑ID, auth token, correlation ID, etc.). I know SPARQLRepository offers setAdditionalHttpHeaders(...) when used directly. But with FedX, which manages repositories and sessions internally, is there a supported way (or planned feature) to globally intercept or configure the HTTP clients used by FedX to set custom headers on each request?

[aschwarte10]

Hi @fourAnge

I think the direction would be to use managed repositories (i.e. you have a RepositoryManager with all your individual SPARQLRepositories, and on these SPARQL repositories you define the additional custom headers).

FedX can reference managed repositories from a repository manager.

Maybe you can have a look at one of the unit tests in https://github.com/eclipse-rdf4j/rdf4j/blob/main/tools/federation/src/test/java/org/eclipse/rdf4j/federated/FedXWithLocalRepositoryManagerTest.java which gives a rough idea (in your case would add a configured SPARQLRepository with your custom headers to the repository manager)

[shangeeee]

Hi @aschwarte10

Thanks for your answer.

I ended up using a combination of withRepositoryResolver and withResolvableEndpoint, which are available in the FedXFactory class.

I’ll still take a look at the managed repository approach.

Happy new year !