Prebid.js Legacy Native Implementation Guide

• Overview
• 1. Set up your ad server ad slot and HTML div
• 2. Determine where the native template will be defined
• 3. Prebid.js Native AdUnit Overview
  • 3.1. Two ways to define image sizes
  • 3.2 Custom native assets
• 4. Implementing the Native Template
  • 4.1. Implementing AdServer-Defined Template
    • Turn Targeting Keys off in Prebid.js
    • Native Template in AdServer
  • 4.2 Implementing AdUnit-Defined Template
    • Prebid.js AdUnit Setup
    • Native Template in the AdServer
  • 4.3 Implementing the Custom Renderer Scenario
    • Prebid.js AdUnit Setup
    • Native Template in the AdServer
    • The Render JavaScript
• 5. Technical Details
• 6. AdServer Implementation Details
• Further Reading

Overview

A native ad is made up of assets such as a title, description, and image URL that are plugged into a publisher-defined HTML template. The template includes placeholder macros for those assets, and may be styled to match the form of the surrounding page.

At a high level, Prebid.js’ support for native ads works like this:

• The publisher establishes one or more native rendering templates and sets up the ad server.
• The publisher defines which AdUnits are eligible for native ads and the bidders participating in the auction.
• Prebid.js requests native demand from bidder adapters that support the “native” mediatype.
• Native bids are stored in the Prebid.js memory space.
• The call to the ad server is made as usual.
• If the native ad wins, it’s displayed and any trackers are fired.

To determine whether a bidder can supply native demand, check the bidder parameter page.

1. Set up your ad server ad slot and HTML div

Create your ad server in-page implementation as usual. See Setting Up Prebid Native in GAM for instructions for how to do this with Google Ad Manager.

2. Determine where the native template will be defined

There are three options for defining the native template:

• If you want to manage your creative within the ad server (e.g. Google Ad Manager), follow the instructions for AdServer-Defined Template.
• If you’d prefer to manage your creative within the Prebid.js AdUnit, follow the instructions for AdUnit-Defined Template.
• If you’d prefer to manage your creative from a separate piece of JavaScript, follow the instructions for the Custom Renderer.

This table summarizes how the 3 approaches work:

Table 1: Native Implementation Approaches

3. Prebid.js Native AdUnit Overview

The Prebid.js AdUnit needs to defines a native mediatype object to tell bidders which assets are required. This table defines all attributes that could be included in AdUnit.mediatypes.native. Specific examples of the three different scenarios follow.

Table 2: Prebid.js AdUnit Native MediaType Options

Table 3: Native Assets Recognized by Prebid.js

Specific bidders may not support all of the fields listed below or may return differing responses for the assets that are requested.

3.1. Two ways to define image sizes

There are two methods for defining sizes for image-like assets (image and icon). Both are shown below, but the first example (using sizes) is more widely supported by demand partners.

Using mediaTypes.native.image.sizes (or mediaTypes.native.icon.sizes for icons):

mediaTypes: {
    native: {
        image: {
            required: true,
            sizes: [150, 50]
        }
    }
}

Using mediaTypes.native.image.aspect_ratios (or mediaTypes.native.icon.aspect_ratios for icons):

mediaTypes: {
    native: {
        image: {
            required: true,
            aspect_ratios: [{
                min_width: 300,        /* Optional */
                min_height: 200,       /* Optional */
                ratio_width: 2,        /* Required */
                ratio_height: 3,       /* Required */
         }]
        }
    }
}

3.2 Custom native assets

In order to fit special bidder requirements, Prebid.js supports defining assets beyond the standard set. Simply define custom attributes in mediaTypes.native.ext, and they can be retrieved at render time. Other than being under the ext object, custom assets are declared in the same way as the standard ones.

Note: The native-render.js::renderNativeAd() function must be called with requestAllAssets: true.

Bid adapters will declare which custom assets they support in their documentation. It is recommended to prefix the asset name with the bidderCode to avoid collision issues.

mediaTypes {
  native: {
    body: {
      required: true
    },
    ext: {
      bidderA_specialtracking: {    // custom asset
        required: false
      }
  }
}

In the native template, simply access the custom value with the normal Prebid ##macro## format assuming hb_native_ as the prefix. For example:

    <div id="mytemplate">
    ... render a lovely creative ...
    ... refer to ##hb_native_bidderA_specialtracking## when appropriate ...
    </div>

4. Implementing the Native Template

• If you want to manage your creative within the ad server (e.g. Google Ad Manager), follow the instructions for AdServer-Defined Creative.
• If you’d prefer to manage your creative within the Prebid.js AdUnit, follow the instructions for AdUnit-Defined Creative
• If you’d prefer to manage your creative from a separate piece of JavaScript, follow the instructions for the Custom Renderer.

4.1. Implementing AdServer-Defined Template

In this scenario, the body of the native creative template is managed within the ad server and includes special Prebid.js macros.

Turn Targeting Keys off in Prebid.js

When the native AdUnit is defined in the page, declare sendTargetingKeys: false in the native Object. This will prevent Prebid.js from sending all the native-related ad server targeting variables.

Example Native AdUnit:

pbjs.addAdUnits({
    code: slot.code,
    mediaTypes: {
        native: {
	    sendTargetingKeys: false,
            image: {
                required: true,
                sizes: [150, 50]
            },
            title: {
                required: true,
                len: 80
            },
            sponsoredBy: {
                required: true
            },
            clickUrl: {
                required: true
            },
            privacyLink: {
                required: false
            },
            body: {
                required: true
            },
            icon: {
                required: true,
                sizes: [50, 50]
            }
        }
    },
    bids: [{
        ...
    }]
});

Here’s an example native AdUnit using the ‘type’ feature, which implies a number of required and optional attributes.

const adUnits = [{
    code: 'adUnit-code',
    mediaTypes: {
	sendTargetingKeys: false,
        native: {
            type: 'image'
        }
    }
    bids: [{
        ...
    }]
}];

Native Template in AdServer

There are three key aspects of the native template:

1. Build the creative with special Prebid.js macros, e.g. ##hb_native_assetname##. (See the Native Assets table above for an exhaustive list of assets and macros.) Note that macros can be placed in the body (HTML) and/or head (CSS) of the native creative.
2. Load the Prebid.js native rendering code. You may utilize the jsdelivr version of native-render.js or host your own copy. If you use the version hosted on jsdelivr, make sure any necessary ad server permissions are established.
3. Invoke the Prebid.js native rendering function with an object containing the following attributes:
   1. adid - used to identify which Prebid.js creative holds the appropriate native assets
   2. pubUrl - the URL of the page, which is needed for the HTML postmessage call
   3. requestAllAssets - tells the renderer to get all the native assets from Prebid.js rather than having to scan the template to find which specific assets are needed.

Example creative HTML:

<div class="sponsored-post">
  <div class="thumbnail" style="background-image: url(##hb_native_image##);"></div>
  <div class="content">
    <h1><a href="%%CLICK_URL_UNESC%%##hb_native_linkurl##" target="_blank" class="pb-click">##hb_native_title##</a></h1>
    <p>##hb_native_body##</p>
    <div class="attribution">##hb_native_brand##</div>
  </div>
</div>
<script src="https://cdn.jsdelivr.net/npm/prebid-universal-creative@latest/dist/native-render.js"></script>
<script>
    var pbNativeTagData = {};
    pbNativeTagData.pubUrl = "%%PATTERN:url%%";     // GAM specific
    pbNativeTagData.adId = "%%PATTERN:hb_adid%%";   // GAM specific
    // if you're using 'Send All Bids' mode, you should use %%PATTERN:hb_adid_BIDDER%%
    pbNativeTagData.requestAllAssets = true;
    window.pbNativeTag.renderNativeAd(pbNativeTagData);
</script>

When using ‘Send All Bids’ mode you should update pbNativeTagData.adId = "%%PATTERN:hb_adid_BIDDERCODE%%"; for each bidder’s creative

Example CSS:

.sponsored-post {
    background-color: #fffdeb;
    font-family: sans-serif;
    padding: 10px 20px 10px 20px;
}

.content {
    overflow: hidden;
}

.thumbnail {
    width: 120px;
    height: 100px;
    float: left;
    margin: 0 20px 10px 0;
    background-image: url(##native_image##);
    background-size: cover;
}

h1 {
    font-size: 18px;
    margin: 0;
}

a {
    color: #0086b3;
    text-decoration: none;
}

p {
    font-size: 16px;
    color: #444;
    margin: 10px 0 10px 0;
}

.attribution {
    color: #fff;
    font-size: 9px;
    font-weight: bold;
    display: inline-block;
    letter-spacing: 2px;
    background-color: #ffd724;
    border-radius: 2px;
    padding: 4px;
}

4.2 Implementing AdUnit-Defined Template

In this scenario, the body of the native creative template is managed within the Prebid.js AdUnit and includes special Prebid.js macros.

Prebid.js AdUnit Setup

When the Native AdUnit is defined in the page:

• Declare sendTargetingKeys: false in the native Object. This will prevent Prebid.js from sending all the native-related ad server targeting variables.
• Define the adTemplate as an escaped ES5 string using Prebid.js ##macros##. (See the appendix for an exhaustive list of assets and macros.) Note that this approach only affects the HTML body. Any CSS definitions need to be defined in the body of the template or in the AdServer.

Example AdUnit:

var adUnits = [{
      code: 'native-div',
      mediaTypes: {
          native: {
	    sendTargetingKeys: false,
            adTemplate: "<div class=\"sponsored-post\">\r\n  <div class=\"thumbnail\" style=\"background-image: url(##hb_native_image##);\"><\/div>\r\n  <div class=\"content\">\r\n  <h1>\r\n    <a href=\"%%CLICK_URL_UNESC%%##hb_native_linkurl##\" target=\"_blank\" class=\"pb-click\">\r\n  ##hb_native_title##\r\n    <\/a>\r\n   <\/h1>\r\n    <p>##hb_native_body##<\/p>\r\n    \t<div class=\"attribution\">\r\n \t##hb_native_brand##\r\n           \t<\/div>\r\n\t<\/div>\r\n<\/div>",
            title: {
              required: true,
              len: 800
            },
            image: {
              required: true,
              sizes: [989, 742],
            },
            sponsoredBy: {
              required: true
            }
          }
        }
    }
}];

Native Template in the AdServer

Even though the body of the native creative is defined in the AdUnit, an AdServer creative is still needed. There are two key aspects of the native creative in this scenario:

1. Load the Prebid.js native rendering code. You may utilize the jsdelivr version of native-render.js or host your own copy. If you use the version hosted on jsdelivr, make sure any necessary ad server permissions are established.
2. Invoke the Prebid.js native rendering function with an object containing the following attributes:
   1. adid - used to identify which Prebid.js creative holds the appropriate native assets
   2. pubUrl - the URL of the page, which is needed for the HTML postmessage call
   3. requestAllAssets - tells the renderer to get all the native assets from Prebid.js. The rendering function cannot currently scan a template defined in the AdUnit.

Example Creative HTML

<script src="https://cdn.jsdelivr.net/npm/prebid-universal-creative@latest/dist/native-render.js"></script>
<script>
    var pbNativeTagData = {};
    pbNativeTagData.pubUrl = "%%PATTERN:url%%";     // GAM specific
    pbNativeTagData.adId = "%%PATTERN:hb_adid%%";   // GAM specific
    // if you're using 'Send All Bids' mode, you should use %%PATTERN:hb_adid_BIDDER%%
    pbNativeTagData.requestAllAssets = true;
    window.pbNativeTag.renderNativeAd(pbNativeTagData);
</script>

When using ‘Send All Bids’ mode you should update pbNativeTagData.adId = "%%PATTERN:hb_adid_BIDDERCODE%%"; for each bidder’s creative

4.3 Implementing the Custom Renderer Scenario

In this scenario, the body of the native creative is managed from an external JavaScript file.

Prebid.js AdUnit Setup

When the Native AdUnit is defined in the page:

• DeclaresendTargetingKeys: false in the Native Object. This will prevent Prebid.js from sending all the native-related ad server targeting variables.
• Define the rendererUrl as a URL that defines a window.renderAd function in the creative iframe. Any CSS definitions need to be defined in the body (e.g. <style> tags) or in the AdServer creative.

Example AdUnit setup:

var adUnits = [{
      code: 'native-div',
      mediaTypes: {
          native: {
	    sendTargetingKeys: false,
            rendererUrl: "https://files.prebid.org/creatives/nativeRenderFunction.js",
            title: {
              required: true,
              len: 800
            },
            image: {
              required: true,
              sizes: [989, 742],
            },
            sponsoredBy: {
              required: true
            }
          }
        }
    }
}];

Native Template in the AdServer

Even though the body of the native creative is defined in the external JavaScript, an AdServer creative is still needed. There are two key aspects of the native creative in this scenario:

1. Load the Prebid.js native rendering code. You may utilize the jsdelivr version of native-render.js or host your own copy. If you use the version hosted on jsdelivr, make sure any necessary ad server permissions are established.
2. Invoke the Prebid.js native rendering function with an object containing the following attributes:
   1. adid - used to identify which Prebid.js creative holds the appropriate native assets
   2. pubUrl - the URL of the page, which is needed for the HTML postmessage call
   3. requestAllAssets - tells the renderer to get all the native assets from Prebid.js so they can be passed to the render function.

Example creative HTML:

<script src="https://cdn.jsdelivr.net/npm/prebid-universal-creative@latest/dist/native-render.js"></script>
<script>
    var pbNativeTagData = {};
    pbNativeTagData.pubUrl = "%%PATTERN:url%%";    // GAM specific
    pbNativeTagData.adId = "%%PATTERN:hb_adid%%";  // GAM specific
    // if you're using 'Send All Bids' mode, you should use %%PATTERN:hb_adid_BIDDER%%
    pbNativeTagData.requestAllAssets = true;
    window.pbNativeTag.renderNativeAd(pbNativeTagData);
</script>

When using Send All Bids you should update pbNativeTagData.adId = "%%PATTERN:hb_adid_biddercode%%"; for each bidder’s creative

The Render JavaScript

Requirements for a native rendering function:

• It must define a window.renderAd function that will be called by the Prebid Universal Creative
• The renderAd() function is passed an object containing all available native assets and must return a fully resolved and ready-to-display block of HTML that will be appended to the body.

Here’s an example script:

window.renderAd=function(data){
	let template = "<div class=\"sponsored-post\"><div class=\"thumbnail\"><\/div><div class=\"content\"><h1> <a href=\"##hb_native_linkurl##\" target=\"_blank\" class=\"pb-click\">##hb_native_title##<\/a><\/h1><p>##hb_native_body##<\/p> <div class=\"attribution\"> ##hb_native_brand## <\/div> <\/div> <\/div>";
	const map = {
	    title: 'hb_native_title',
	    body: 'hb_native_body',
	    body2: 'hb_native_body2',
	    privacyLink: 'hb_native_privacy',
	    sponsoredBy: 'hb_native_brand',
	    image: 'hb_native_image',
	    icon: 'hb_native_icon',
	    clickUrl: 'hb_native_linkurl',
	    displayUrl: 'hb_native_displayurl',
	    cta: 'hb_native_cta',
	    rating: 'hb_native_rating',
	    address: 'hb_native_address',
	    downloads: 'hb_native_downloads',
	    likes: 'hb_native_likes',
	    phone: 'hb_native_phone',
	    price: 'hb_native_price',
	    salePrice: 'hb_native_saleprice'
	}
	for (var i = 0; i < data.length; i++){
		if (map[data[i].key]) {
			template = template.replace("##"+map[data[i].key]+"##",data[i].value);
		}
	}
	return template;
}

Note that the format of any macros in external render JavaScript is totally up to you. The data object coming in will be keyed according to the Key column in the table in the appendix, e.g. privacyLink and not hb_native_privacy.

5. Technical Details

A few details that may help understand and debug your setup:

1. The system assumes that native creatives will be wrapped in an iframe.
2. The native assets are stored in the Prebid.js memory space as the original asset types, e.g. clickUrl and not hb_native_linkurl.
3. When the window.pbNativeTag.renderNativeAd() function is called, an HTML5 postmessage is made. Prebid.js is listening for this message, and responds with the native assets. Again, the assets are keyed on the original asset type, e.g. clickUrl.
4. If the template was defined in the AdServer, the body of the iframe will be replaced. Otherwise, if the template was defined in the AdUnit or external JavaScript, the body of the iframe will be appended with resolved creative HTML.
5. If the AdServer supports it, CSS styles can be defined in the iframe head. Otherwise, they must be defined in the body of the template, for example with
6. Note that native iframes will be resized to the height of the creative after render.

6. AdServer Implementation Details

There are detailed instructions for setting up native in GAM, but none of the Prebid functionality is specific to GAM. The requirements to use any of these approaches in a different ad server are:

1. Put the creative in an iframe and load native-render.js
2. Invoke the renderNativeAd() function with a hash that includes the following values:
   1. pbNativeTagData.pubUrl = “PAGE URL”;
   2. pbNativeTagData.adId = “PREBID ADID”;
   3. pbNativeTagData.requestAllAssets = true;
3. renderNativeAd() will look for the existence of an “adTemplate” value in the AdUnit. If it finds one, it will resolve ##macros## and append it to the iframe’s body.
4. Otherwise, renderNativeAd() will look for the existence of a “rendererUrl” value in the AdUnit. If it finds one, it loads the script then calls window.renderAd() and appends the results to the iframe’s body.
5. Otherwise renderNativeAd() scans the iframe body and resolves ##macros##.

Further Reading

• Prebid Native Format
• Setting Up Prebid Native in GAM