Thought Leadership

Dispelling Misconceptions with Sellers.json and Schain

May 18, 2020
By John Clyman

This is the final part of our three-part series on sellers.json and Supply Chain Object. Start here.

Now that you understand sellers.json and schain and how they can be used, let’s take a moment to dispel some potential misperceptions and areas of mystery:

Are all “intermediary” sellers alike; should I just buy inventory on “publisher” sellers to ensure the best supply paths? 

No, it’s not that simple. See part two of this series, Using a Scalpel, Not a Sledgehammer, for explanations and examples.

Can I use sellers.json to deduce inventory sourcing strategies? 

Not really. Sellers.json does tell you which sources an exchange gets inventory from — but it’s just an index that says nothing about the volume or the type of inventory. To use an extreme example, imagine an exchange publishes a sellers.json file that just lists two sellers, one PUBLISHER and one INTERMEDIARY. That doesn’t mean there’s a 50/50 split between direct and indirect inventory for that exchange, since one supplier might be large and another small. This same principle extends to real-world sellers.json files with thousands of supply sources.

Does schain guarantee accuracy and prevent invalid traffic and other types of fraud? 

No, schain provides transparency that is a critical ingredient in fraud detection and prevention. But it’s not a silver bullet, and bad actors can still manipulate it to make their activity harder to detect. That said, the combination of schain, sellers.json, and ads.txt or app-ads.txt can be used to validate aspects of the supply chain from different perspectives, and provides one more tool to look for anomalies that merit further investigation.

Isn’t blockchain the answer to supply chain transparency? 

Blockchain is a general-purpose technology that can be applied in a myriad of ways. While there might be benefit to digitally signing schains and other parts of a bid request to prevent tampering, we haven’t yet seen a reason blockchain needs to be a key part of this effort.

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