Dchain objects

[patmmccann]

Type of issue

Standardization request

Description

With the adoption of standard bid.meta fields as per #3115 in Prebid 4.0 and their expected enforcement in #6345 with Prebid 5.0, the spec should naturally extend to where to place the demand chain object bidders receive or are required to create.

The IAB DemandChain working spec indicates "The DemandChain object should be included in the BidResponse.seatbid.bid.ext.dchain attribute in OpenRTB 2.5 or later. For OpenRTB 2.4 or prior, the BidResponse.ext.dchain attribute should be used."

Publishers likely prefer to parse complicated demand chain objects themselves over having SSPs return parsed fields into the various existing meta objects, particularly if they are using analytics or security vendors which are able to parse them.

I propose the preferred way to pass the object back is for it to be copied to bid.meta.dchain, with the ssp adding a node as per the spec. Also as per the spec, if the SSP receives a bid with no dchain, it should initiate one eg "dchain" : { "ver": "1.0", "complete" : 0, "nodes" : [ { "asi": "magnite.com", "bsid": "123456789", } ] } either from its adapter code or in its endpoint response. The prebid server adapter bid response should always include a dchain.

A future validation module will likely have options for size validation, dchain validation, meta.advertiserDomains validation, mime type validation etc.

[ChrisHuie]

#6383 merge closes this issue