• Ad Fraud

Everything You Need To Know About Sellers.json

Team InMobi
5 min read
Posted on April 16, 2019

On April 11, the IAB Tech Lab released two new standards for public review: sellers.json and the OpenRTB SupplyChain object. InMobi has been a key partner in helping to develop these specs, and we are excited for them to be live in this initial instance.

What do these specifications do, and how do they help programmatic advertisers? Keep reading for more information.

What is Sellers.json and How Does It Work?

In short, sellers.json is a file that enables the players of the ecosystem to map back the request to the entities behind that specific opportunity, including the final publisher. Essentially, it’s a file that maintains the mapping between the identifiers and the related entity name along with the relationship type and some additional information.

While ads.txt (To learn more about app-ads.txt, the in-app version of ads.txt, check out this blog post and video) did a great job in publicly disclosing the list of authorized sellers for the demand side to look up, it does not offer any means for the demand-side platform (DSP) to pinpoint the specific publisher behind the ad request (supply side). This is where sellers.json comes in, by allowing the supply-side platform (SSP) to publish such mapping list into its root domain (for example: http://{advertising_system_domain}/sellers.json).

Why is Sellers.json Beneficial?

The goal of sellers.json is to give the buy side (also known as the demand side) and publishers of the advertising ecosystem greater transparency within the larger programmatic and ad tech space. This has long been one of the top concerns around programmatic advertising, and the introduction of sellers.json is a huge step forward in making the programmatic ecosystem much more fair, open, transparent and trustworthy.

This spec mainly aims to combat fraud across the ecosystem. It is also true though that by combating fraud, a brand can have much more confidence on the inventory being bought, so it definitely has an indirect impact into brand safety too. It also gives full transparency into all the intermediaries that participated in the selling of a bid request.

These aren’t the only benefits of sellers.json. It also allows smaller payloads or bid request object sizes, by allowing this information to be directly looked up online as opposed to be supplied with every bid request.

"Sellers.json and SupplyChain object are the natural evolution to help make the ecosystem even more transparent and trustworthy," Sergio Serra, senior product manager, supply and programmatic at InMobi, told The Drum.

What About the OpenRTB SupplyChain Object?

Sellers.json is not the only new spec, as the IAB Tech Lab also released the OpenRTB SupplyChain Object for public comment on the same day. This works in tandem with sellers.json to provide more oversight and transparency on the buy side in the programmatic ecosystem.

Currently, it is possible for the final seller to be identified via the Publisher.name and Publisher.domain attributes in the oRTB request. However, in practice, these properties are wrongly populated or simply omitted by most of the advertising systems. As a result, this also becomes restrictive in the case of resold inventory.

As a consequence, IAB came up with an additional spec - SupplyChain object - which should be included in the BidRequest.Source.ext.schain attribute in OpenRTB 2.5 onwards. For older oRTB versions, the implementer should fall back to BidRequest.ext.schain.

The SupplyChain object is composed primarily of a set of nodes where each node represents a specific entity that participates in the selling of a bid request. Consequently, a complete chain represent all sellers that were paid for an individual bid request. Each node is composed of two required properties:

  • The advertising system identifier (ASI), which is the canonical domain name of the SSP, Exchange, Header Wrapper, etc system that bidders connect to.
  • The Publisher’s account ID (Pub.Id).

How Is This Different from Ads.txt?

In some ways, both ads.txt and app-ads.txt are in the same arena as sellers.json and the OpenRTB SupplyChain object. They’re all from IAB Tech Lab, and are designed to increase transparency and trust in the programmatic space. However, AdExchanger noted that the new specs complement the existing ones and provide additional information that ads.txt was never designed to highlight.

That said, on the app side at least, adoption is taking its own time and there is a long way ahead. Even though app-ads.txt's benefits are undeniable, there is a lot of education that has to be put in place across the ecosystem.

Realistically speaking, DSPs cannot really drive adoption until critical mass is reached. It is a duty of SSPs and exchanges to evangelize and push for it. The demand side will be able to help by mandating app-ads.txt only after a sufficient share of the developers and app publishers have implemented it.

What Are the Next Steps?

IAB has opened the spec to 30-day public comment period, through May 10, 2019. After that deadline, the community will review the feedback from the ecosystem and evaluate whether any further adjustment to the spec is needed.

Post this, the ecosystem is supposed to adopt it. In order to speed up the adoption, it is crucial we get all the possible help from everybody in the chain; for instance, it’s entirely feasible for TAG to mandate this and possibly replace the existing pchain requirement with the SupplyChain object. Specifically, for their CAF program, they require the adoption of pchain (you can refer to oRTB 2.5). Since pchain spec is only available to TAG members, its adoption never really got into the next level of adoption.

Since SupplyChain object is, from some extent, a natural evolution of pchain (it would be best if TAG moved towards it). This would give an enormous boost to SupplyChain object in particular.

As far as next steps are concerned, here’s what Sergio recommends: "It's crucial that everyone in the space evangelize the importance of supply path transparency in the spirit of fair and more reliable advertising and programmatic trading. InMobi will be an early adopter of both sellers.json and SupplyChain object and we hope the rest of the industry will follow."

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