Prebid.js support for tracking Prebid Server events

[bretg]

Description

Prebid.js support for tracking Prebid Server (PBS) events

PBS has an an orchestrated set of events in place to support the following use cases:

• Mobile app
• Video imps
• AMP
• Programmatic Guaranteed

A document describing this structure is at
https://docs.google.com/document/d/1ry0X4C2EV-R0pMrm1IQk9BstxaT395UCl3KKqTGa5c8/edit

We've determined that several changes are need in Prebid.js to support these scenarios and to better support joining events to their auctions in an offline merge process.

Proposed PBS BidAdapter changes:

on the request:

• set ext.prebid.auctiontimestamp with the auction timestamp. Data type is long integer. Having the timestamp available on both the auction and the event can make the offline join process easier.

on the response:

• The idea discussed in PBJS committee is for pbsBidAdapter to listen to BidsWon events. When it receives an event, it will look up the relevant imp.ext.prebid.event.win and hit the url. The original design here was to use an ad server targeting variable (hb_winurl) that would be invoked by the PUC, but we've found that long ad server targeting variables are sometimes (often?) ignored by GAM, so we had to change the design. Creatives that have server-side cached bids are storing a wurl there, but for regular banner creatives, there's no server-side caching, so keeping this event locally is required.
• remove any hb_winurl and hb_bidid targeting attributes present. PUC no longer looks for hb_winurl. We'll get rid of it from Prebid Server after a transition period, and then we can remove this temporary improvement.
• look for seatbid[].bid[].ext.prebid.bidid and place it in the bidResponse object for use in analytics adapters as 'pbsBidId' in addition to the existing seatBidId. We've found that bidder-generated server-side bid IDs are sometimes (often) not unique enough to support joining events to the auction offline. So PBS is generating a decent bid ID that analytics adapters will be able to use.

events system update

• when an event fires that has the s2s flag, call PrebidServerBid adapter.

videoCache update

• update the 'vasttrack' routine to pass the auction timestamp as 'timestamp'.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[bretg]

This was merged.