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OpenRTB SupplyChain object ("Schain") passes information from sellers to intermediaries and buyers designating the chain of upstream organizations involved with a given bid request.[1]

The Schain object contains a minimum of three pieces of information:

  • Complete (e.g., 1)
  • Nodes (an array)
  • Version (e.g., 1.0)

The Schain object can optionally include optional extensions:

  • ext (i.e. optional extensions to this object)

The "Complete" field designates whether the selling organization has a full chain originating the inventory owner with a "1," or reselling inventory that does not identify the publisher inventory owner with a "0".

The Nodes array object contains a minimum of two pieces of information:

  • asi (i.e. domain name of the organization)
  • sid (i.e. the organization ID within a given system)

The Nodes array object may optionally contain:

  • rid (i.e. the request id from inserted by the selling organization)
  • Name (i.e. the selling organization's name)
  • Domain (i.e. the selling organization's domain)
  • hp (i.e. whether the selling organization is passing through inventory or must be paid)
  • ext (i.e. optional extensions to this object)

Schain relies on both ads.txt and sellers.json for understanding signals from both publishers and other selling organizations.


Despite its laudable goal, Schain does not provide full transparency to buyers given the seller's domains are optional fields and thus not easily detected using programmatic means.

Another limitation of this design is that the request identifiers (rid) is issued at the node, rather than the inventory owner level -- thus making it more difficult to compare information from different Schains associated with the same originating bid request.

Another limitation of this design is that it does not enable easy organizational identifiers as they can differ based on which path a given bid request takes and the domain of these organizations is an optional field.

Given these issues the ecosystem is looking into better forms of signaling throughout the distributed advertising supply chain that supports publishers' businesses.

See Also