Glossary
What is SupplyChain object (schain)?
Also called: supply chain object, SupplyChain object, SChain
The SupplyChain object (schain) lists, inside the bid request, every seller that handled the impression, so buyers can trace the path to the publisher.
हिंदी में पढ़ेंThe schain travels in the OpenRTB bid request; in OpenRTB 2.6 it is a core field at source.schain. Its nodes array lists each seller that handled the request, in order, so a buyer can count the hops between the publisher and itself.
Each node has an asi, the ad system’s domain, and a sid, the seller’s account ID there. Both should match the publisher’s ads.txt line and that ad system’s sellers.json. hp flags that the node is in the payment flow, and in version 1.0 it should always be 1. complete: 1 means every seller back to the owner is listed, with the owner’s account first; complete: 0 means some are missing.
Buyers favour short, complete paths they can check, which makes schain part of supply path optimisation. If you run Prebid, note that since Prebid 10 the schain is supplied as first-party data in ortb2.source.ext.schain, and the old schain module is superseded.
Example
A request reaches a DSP through 2 sellers. Node 1: asi ssp-a.example, sid 4521, the publisher's own account. Node 2: asi exchange-b.example, sid 77. With complete: 1, that is 2 hops the buyer can check. If node 1 were missing and complete were 0, the buyer could not trace the path to the owner.
Why it matters to publishers
Incomplete or mismatched chains make your inventory harder to verify, and buyers trim paths they cannot check. Asking each SSP whether it sends a complete schain is a quick health check.