GPT Pre-Auction Module

• Overview
• Configuration
• How It Works
  • Defining the AdServer name and adslot
  • Defining PbAdSlot and GPID
• Example customPbAdSlot function
• Further Reading

Overview

This module enables bidder targeting and tracking at the ad server ad slot level.

This module is enabled by default if it’s compiled into your PBJS package. It will add the Prebid Ad Slot and GPID along with the matching GAM ad unit name to each ad unit’s first-party data before bid requests are sent to the adapters.

• Prebid.js Adapters - will be able to utilize these values as:
  • AdUnit.ortb2Imp.ext.gpid=”/1111/home-left”
  • AdUnit.ortb2Imp.ext.data.adserver.name=”gam”
  • AdUnit.ortb2Imp.ext.data.adserver.adslot=”/1111/home”
  • AdUnit.ortb2Imp.ext.data.pbadslot=”/1111/home-left”
• Prebid Server Adapters - will see the OpenRTB as:
  • imp[].ext.gpid
  • imp[].ext.data.adserver.name
  • imp[].ext.data.adserver.adslot
  • imp[].ext.data.pbadslot

The Prebid Ad Slot didn’t get broad adoption, so it’s likely that someday we’ll deprecate it in favor of the more standard GPID.

Configuration

Unlike many other modules, the GPT Pre-Auction Module is on by default if it’s compiled into the Prebid.js package.

Optional initialization parameters:

For example:

pbjs.setConfig({
    gptPreAuction: {
	enabled: true, // enabled by default
	useDefaultPreAuction: false,
	customPreAuction: function(adUnit, adServerAdSlot) {
		...
		return "customPbAdSlot";
	},
	customGptSlotMatching: function(gptSlotObj) {
		...
		return true; // or false
	},
	mcmEnabled: true
    }
});

How It Works

When this module is turned on, it uses the BEFORE_REQUEST_BIDS event to insert functionality that:

• loops through each adunit in the auction
• maps the PBJS adunit to the GPT slot using the same algorithm as setTargetingForGPTAsync including customGptSlotMatching

Defining the AdServer name and adslot

If GPT slot matching succeeds:

• it sets the Adunit ortb2Imp.ext.data.adserver.name to ‘gam’
• it copies the resulting GPT slot name to ortb2Imp.ext.data.adserver.adslot

Defining PbAdSlot and GPID

Here’s what the module does to define these values:

1. If AdUnit.ortb2Imp.ext.gpid already exists, use that for GPID.
2. If AdUnit.ortb2Imp.ext.data.pbadslot already exists, use that for PbAdSlot.
3. Otherwise, if a customPreAuction function is specified, run that. If the result isn’t empty, place it in pbAdSlot and GPID.
4. Otherwise, if useDefaultPreAuction is true, run the default logic and place the return value in both pbAdSlot and GPID
   1. If ortb2Imp.ext.data.pbadslot is specified, use that.
   2. If ortb2Imp.ext.gpid is specified, use that.
   3. If GPT isn’t in the page, give up.
   4. Query GPT slots with the adunit.code
   5. If there aren’t any, give up.
   6. If there’s just one, use that slot name as the GPID
   7. If there’s more than on slot with the same name, append the div-id
5. Otherwise, if a customPbAdSlot function is specified and the result is not empty, place it in pbAdSlot and GPID.
6. Otherwise, if the AdUnit.code matched one or more GAM AdSlots, use that for both PbAdSlot and GPID
7. Otherwise use the AdUnit.code for PbAdSlot.

Example customPbAdSlot function

In PBJS 6.5 and later, we recommend using the useDefaultPreAuction flag or the customPreAuction function.

The following customPbAdSlot function will work for many publishers. Assumptions:

• AdUnits have been registered with pbjs.addAdUnits.
• AdUnit.code is either the GPT slot name or the div-id.
• The site has unique (non-random) div-ids.

If either of these isn’t the case, you’ll need to supply your own function.

// Use adunit.ortb2Imp.ext.data.pbadslot if it exists.
// compare adunit.code to find a single matching slot in GPT
// if there is a single slot match, just use that slot name
// finally, there must be multiple slots that match. Define pbadslot as slot#div

pbjs.setConfig({
    gptPreAuction: {
	enabled: true, // enabled by default
	customPbAdSlot: function(adUnitCode, adServerAdSlot) {
		// get adunit object
		au=pbjs.adUnits.filter(au => au.code==adUnitCode);
		if (au.length==0) {
		    return;
		}

		// use pbadslot if supplied
		if (au[0].ort2bImp && au[0].ort2bImp.ext && au[0].ort2bImp.ext.data && au[0].ort2bImp.ext.data.pbadslot) {
		    return au[0].ort2bImp.ext.data.pbadslot;
		}

		// confirm that GPT is set up
		if (!(googletag && googletag.apiReady)) {
		    return;
		}
		// find all GPT slots with this name
		var gptSlots = googletag.pubads().getSlots().filter(function(gpt) {
		    return gpt.getAdUnitPath() == adServerAdSlot;
		});
		if (gptSlots.length==0) {
		    return;  // should never happen
		}
		if (gptSlots.length==1) {
		    return adServerAdSlot;
		}
		// else the adunit code must be div id. append it.
		return adServerAdSlot+"#"+adUnitCode;
	}
  });
};

Further Reading

• Prebid Ad Slot and GPID