CookieMapping

原文阅读


This guide explains how the Cookie Matching Service enables you to
make more effective bidding choices.

The Cookie Matching Service enables a buyer to associate two types of
cookies:

  1. One that identifies a user within the buyer domain.

  2. A doubleclick.net cookie that identifies a Google user.
    (We share a buyer-specific encrypted user ID for buyers to match on.)

With an RTB application, the buyer can bid on impressions where the user has
a specific Google User ID, and can use information associated with that ID as
criteria in a bid for an ad impression. Google can host the match table that
correlates the data from the two domains. Having Google host the table may be
simpler, with reduced latency and easier upgrades.



Background


A browser cookie is typically set by the party that owns the domain to which
the cookie belongs. The cookie identifies a user within that domain. The
security model of the browser restricts one party from reading the cookie set
by another party, even if both parties would otherwise agree to such an
exchange.

The buyer typically identifies users with cookies that belong to the domain
of a third-party ad network. The buyer can associate the cookies with other
user information in a database.

For itself, Google identifies users with cookies that belong to the
doubleclick.net domain under which Google serves ads. For buyers,
Google identifies users using a buyer-specific Google User ID consisting of an
encrypted version of the doubleclick.net cookie, derived from but
not equal to that cookie. Google passes the user ID to the buyer (raw
DoubleClick cookies are never sent).

When receiving a particular Google User ID for the first time, the buyer has
no knowledge about the user associated with the ID other than what the bid
request reveals. The buyer can match the Google User ID with a buyer cookie, and
subsequently consider user information associated with the buyer cookie in
making decisions about users identified by the Google User ID. This can be
useful in remarketing
campaigns, and in refining targeting or bidding for impressions in real time
bidding.

The Cookie Matching Service provides the information that a buyer network
needs to maintain an association between the buyer cookie and the Google user
ID, in the form of a match table. Additionally, the buyer can forward data to
Google for storage and later use in bid requests.

Benefits of hosted match tables


Buyers who choose to have Google host their match tables stand to gain the
following benefits:

  • Lower infrastructure investment

  • Mapping the Google User ID to a useful form does not require a table
    lookup

  • During pretargeting, there is the option to filter on whether or not a
    cookie match exists, which can reduce unwanted bid requests

How cookie matching works


To build an association in the match table, the buyer must serve a tag
provided by Google, called the match tag. The match tag can be served
with the buyer's ads, or it can be placed on its web properties outside of ads.
It is structured as follows:

<img src="http://cm.g.doubleclick.net/pixel?google_nid=1234&google_cm" />

Here 1234 would be replaced by the buyer identifier supplied by
Google.

The buyer should only serve this tag if the buyer does not already have a
match for this user (or if that entry is stale).

Upon receiving the request for the tag from the user's browser, Google
issues a 302 redirect to the buyer. This 302 redirect
includes the Google User ID and a version number in the URL, and the buyer
cookie in the request headers. The buyer supplies the base URL, and Google appends
URL parameters.(Google收到请求以后，会进行302跳转，302请求中包含gid,请求Header中包含购买方Cookie,该302请求URL由购买方提供,Google会在该URL后追加参数)

For example, the buyer could supply this base URL:

http://ad.network.com/pixel

Google could then redirect to a URL like this:

http://ad.network.com/pixel?google_gid=dGhpcyBpcyBhbiBleGFtGxl&google_cver=1

The Google User ID passed through the google_gid parameter is
an unpadded URL-safe
standard base64-encoded
string. We recommend storing the exact string returned by the Cookie Matching
Service in the match table.


The google_cver parameter indicates a numeric version number
for the Google User ID. Google may infrequently change the cookie obfuscation
scheme, at which point the google_cver value will be increased.

The buyer receives this redirect, which includes the buyer cookie in the
request headers, and updates the match table with the association between this
buyer cookie and the Google User ID. The buyer must then serve a 1x1 invisible
image pixel to the user's browser, or return a 204 No
Content response.

Entries are added to the match table at the rate at which match tags are
served to unique users.

This process is illustrated by the diagram below. Each request or response
is represented by an arrow, and the data items that accompany the request or
response are listed in parentheses.

You can opt to set extra URL parameters on the request and these are passed to your server in the redirect:

<img src="http://cm.g.doubleclick.net/pixel?google_nid=1234&google_cm&extra1=xx&extra2=yy" />

All parameters that do not start with the google_ prefix are
copied over into the redirect URL. The order in which the parameters are passed
to the Cookie Matching service is not important. Similarly, the order in which
extra parameters are passed in the redirect URL is not guaranteed.

http://ad.network.com/pixel?google_gid=dGhpcyBpcyBhbiBleGFtGxl&google_cver=1&extra1=xx&extra2=yy

You can use these parameters to pass additional information about the
impression. Extra parameters should be no longer than one kilobyte.

It is also possible to make https rather than
http requests to the cookie matching service. In this case the
protocol of the redirect URL is likewise https rather than
http.

Example scenarios


How would cookie matching look to a typical web user, and what's happening
behind the scenes? Let's take a look at two scenarios.
Scenario 1: Cleared cookies

Jane clears her cache of all cookies. She then visits the homepage of ExampleNews.com.

Here's what happens:

  1. ExampleNews.com renders, and calls ads from Google (DFP).

  2. Because the ad unit is eligible for dynamic allocation, Ad Exchange sends
    bid requests to FinestDSP (among other DSPs).

  3. FinestDSP processes the bid request in its bid engine, and sends its bid
    response to Ad Exchange

  4. FinestDSP wins the auction, and sends an ad with a match tag (pixel) to Ad
    Exchange.

  5. Ad Exchange serves FinestDSP's ad and match tag to Jane, and also sets
    Jane's DoubleClick cookie.

  6. The match tag calls Google's Cookie Match Service.

  7. The Cookie Match Service reads Jane's DoubleClick cookie, and sends a
    redirect to FinestDSP with google_user_id set.

  8. The browser loads FinestDSP's URL.

  9. FinestDSP generates a cookie, which it stores against Jane's
    google_user_id in its match table.

  10. FinestDSP drops its cookie in Jane's browser and responds to the redirect
    with an invisible 1x1 pixel.


Scenario 2: Buyer and DoubleClick cookies

A week after Scenario 1, Jane visits ExampleNews.com again. Now that Jane
has both buyer and DoubleClick cookies on her machine, let's see how matching
works.

  1. The web page renders, executing the HTML code's call to Google for ads.

  2. During the ad auction, Ad Exchange sends a bid request to an
    RTB buyer, FinestDSP, giving that buyer the option of bidding on the
    impression.

  3. The buyer receives the bid request with impression information and the
    google_user_id.

  4. FinestDSP looks up the google_user_id in its match table to
    find the cookie created a week earlier (in Scenario 1).

  5. Based on the information associated with its cookie, FinestDSP decides to
    bid on the impression, and wins the auction.

  6. Jane might see an ad tailored to her or her interests, again based on
    information that FinestDSP possesses.


This section explains how buyers can use the Cookie Matching Service.

Before you can use the Cookie Matching Service, you must have:

  • An Ad Exchange account

  • A real-time bidder up and running

Next, you must provide Google with your redirect URL. This is the URL to
which the Cookie Matching Service should redirect the request for your match
tag. This request comes from the user's browser, as described in
How cookie matching works above.

You can provide Google with the redirect URL through your Ad Exchange
account representative. Or, if you have access to the Ad Exchange Buyer REST
API, you can set the URL using one of the methods for updating an
Accounts
resource.

Serve cookie match tag


You must have the ability to place the Google-supplied match pixel tag on
the user's browser. You may choose to place this pixel along with served ads,
or on web properties under your control.

Serve pixels


Your servers must recognize the redirect URL, and serve a 1x1 empty pixel to
the user's browser in a timely fashion. While processing incoming requests to
the redirect URL, your servers should also parse the URL to extract the Google
User ID and error codes, and update the match table.

Handle errors


The Cookie Matching Service communicates errors in the
google_error special URL parameter in the redirect. The value of
this parameter is numeric and identifies the particular error that occurred.
You should still respond with a 1x1 empty pixel if the google_error
URL parameter is present. If you receive an error, you may show a match tag
for the related buyer cookie again.

To do cookie matching without using the Cookie Matching Service, embed the
google_user_id field in the BidRequest. This way,
the google_user_id can be extracted from the BidRequest
and not from the redirect URL to which the Cookie Matching Service inserts
the google_user_id. By avoiding redirects, you also reduce the
likelihood of the cookie match request timing out, as from the user navigating
away from the page for example.

Pixel matching


In cookie matching, the buyer that wins the auction for an impression can
associate a cookie with a Google User ID. In another component of Google's
cookie matching code, called pixel matching, Google algorithmically selects an
additional buyer whose cookie can be matched with the Google User ID. Google
then places a match tag onto the impression, and includes the chosen buyer's
URL in the match tag.

This sets the stage for the following interaction:

  1. When the page loads in the user's browser, the match tag generates a pixel
    request to the buyer.

    • If you are the chosen buyer:

      1. You receive your own cookie along with the Google User ID, enabling
        you to associate the two in your match table.

      2. You must redirect the request back to Google.

  2. The chosen buyer responds with a redirect.

  3. Google receives the redirect and stores the match between user and buyer.

  4. Google serves the pixel to the browser.

Pixel matching does not operate on the properties of publishers who opt out
of the additional match.

How it works

Google places the match tag on the page, which combines a buyer-supplied URL
with the Google User ID (the google_gid parameter) and a new
google_push parameter. The match tag is structured as follows:

<img src="http://ad.network.com/pixel?google_gid=abcdef&google_cver=1&google_push=<push_data>" />

The match tag causes the buyer to receive a request for the pixel (see item
1 in the diagram below). Upon receiving the request, the buyer
must redirect to a URL structured as follows:

http://cm.g.doubleclick.net/pixel?google_nid=1234&google_push=<push_data>

This URL is similar to the one used in buyer-initiated cookie matching,
except that the google_push parameter replaces the
google_cm parameter. The <push_data> value
passed in the redirect must be identical to the value provided by Google in the
match tag. The buyer also has the option of adding parameters such as
google_ula or google_hm.


The reply that the buyer sends to the browser is depicted by item 2 in the
diagram below, and the redirect that the browser then sends to Google is
depicted by item 3.

Upon receiving the redirect, Google returns an invisible pixel (item 4 in
the diagram). Google then logs that a match has been created for the user.
Google also handles any other requested operations, such as storing hosted data
or adding the user to a user list. Google waits 14 days, until the user-buyer
match has expired, before introducing the match again.

In the diagram below, each request or response is represented by an arrow,
and the data items that accompany the request or response are listed in
parentheses.


Restrictions


This section describes the restrictions that Google has put in place to
protect user privacy and ensure a pleasant user experience.

Respects user privacy

The Cookie Matching Service respects user privacy by adhering to the
following principles:

  • Google does not accept any user information provided by the buyer (such
    as the cookie, user demographics, etc.)

  • Google prohibits multiple buyers from joining their match tables.

  • The Cookie Matching Service does not expose Google's DoubleClick cookie.

  • The purpose of the match table is to allow buyers to use the
    information they own about the user in transacting with Google. The use of the
    Cookie Matching Service for the purpose of data harvesting is strictly prohibited
    by the Ad Exchange contract and policies.

Bidders are expected to support the above principles, and to safeguard user
privacy in their implementations.

Cap frequency


You, as the buyer, are responsible for frequency capping the Cookie
Matching Service so that it is not used for users who already have a fresh
entry in the match table. You should not serve the Cookie Matching tag unless
the match table does not have an entry for the user in question, or the entry
is stale. After 14 days, you may consider the Match entry expired, and refresh
it.

Google does not enforce frequency capping at serving time. However, it does
periodically monitor that you are respecting the frequency capping policy, and
reserves the right to interrupt the free service in case of violation.

Respond to all pixel match requests


If you sign up to use the Pixel Matching service you are expected to respond
to all Pixel Match requests. This allows us to monitor various policies of how
you are using this service. If your response rate drops below a 90% response
rate we will throttle the number of Pixel Match requests we send to your
account.

Use HTTPS when responding to HTTPS pixel match requests


When responding to a Pixel Match request sent to you over HTTPS, you are
required to redirect to the Cookie Matching Service over HTTPS. Redirections
sent over HTTP will cause the user to receive mixed-content warnings. If you
redirect HTTPS requests to us over HTTP more often than once every 2 minutes,
we will throttle the number of Pixel Match requests we send to your
account.

Please note that there are no requirements concerning which protocol to use
for Pixel Match requests sent over HTTP. It is therefore acceptable to respond
to all requests over HTTPS.

Adhere to maximum request rate


When you sign up for the Cookie Matching Service, Google provides a maximum
request rate. Google monitors your transactions to ensure that you adhere to
this request rate.

API specifications

Match tag

The match tag must contain the buyer ID (passed through the
google_nid parameter), as well as the Cookie Matching Service URL.
The protocol may be either http or https. The
following are examples of valid match tag URLs:

http://cm.g.doubleclick.net/pixel?google_nid=my_nid https://cm.g.doubleclick.net/pixel?google_nid=my_nid

Google reserves all URL parameters for the Cookie Matching Service that
start with the prefix google_ for future API expansion. Any other
URL parameters added to the match tag pass into the redirect URL
uninterpreted.

The Cookie Matching service supports several operations:

  • Perform cookie matching -- the basic cookie matching operation described
    above.

  • Add the user to a user list -- adds the user to a user list, avoiding the
    need for a separate tag.

  • Set cookie if missing -- normally the Cookie Matching Service does not
    set a doubleclick.net cookie on the user's browser if one is not already
    present. When this option is set, the Cookie Matching Service sets the
    doubleclick.net cookie.

These operations are supported through the following URL parameters:

ParameterDescription
google_nidNetwork ID. This is a buyer ID. Here, "network" refers to the
typical buyer, an ad network. This ID can be retrieved through the
Buyer REST API Accounts resource's

cookieMatchingNid field.
google_cmPerform cookie matching. The value the parameter is ignored
and may be omitted.
google_scSets the cookie if one is not present. The value of the parameter is
ignored and may be omitted. Omitting the parameter results in an error if no
doubleclick cookie is present.
google_no_scDoes not set the cookie if one is not present. The value of the
parameter is ignored and may be omitted.
google_ulaAdds to the user list. The value is in the format
userlistid[,timestamp]

  • userlistid: a single numerical user list ID.

  • timestamp: an optional timestamp in POSIX format,
    indicates when the user has been added to the user list.

This URL parameter may be repeated to add the user to multiple lists.


All other parameters that start with the google_ prefix are
ignored by the Cookie Matching service and are not passed through to the
redirect URL. Parameters that do not begin with the google_ prefix
are added to the redirect URL together with the response google_
parameters.

The order of parameters is not important. See the Examples section for illustrations of valid and invalid
URLs.

Redirect URL


All URL parameters starting with the prefix google_ are
reserved for future API expansion.

The redirect URL is built from several parts:
  • The protocol, http or https, as determined
    by the protocol with which the match tag was called.

  • The base redirect URL supplied by you to Google (including any hard-coded
    URL parameters).

  • Response google_ parameters (depending on the request
    google_ parameters supplied by you in the match tag).

  • Extra URL parameters sent in the match tag that do not start with the
    google_ prefix.
The following google_ response parameters are defined:


ParameterDescription
google_errorOverall request error. No operations have been performed and no
other google_ response parameters will be set. Error codes are
integral values. Possible values are:

  • 1 - User has a Google cookie, but has opted out of any
    tracking using this cookie.

  • 2 - No valid operations specified. e.g., a no-op
    request was received.

  • 3 - User does not have a Google cookie. Google will not
    set the cookie via the Cookie Matching Service.

  • 4 - Conflicting operations specified. You are not
    allowed to specify both the google_push and google_cm
    flags on the same request since they have conflicting purposes.

  • 5 - An invalid google_push parameter was
    passed in a redirect to a Google server as part of a
    Pixel Matching Service request. Your redirect must
    set google_push to the same value passed to you in the initial
    pixel request.

google_gidGoogle User ID. Set if google_cm is specified in the request and the request was successful.
google_cverCookie version. Set if google_cm is specified in the request and the request was successful.
google_ulaStatus of user list add operation, repeated if multiple
google_ula were specified in the request. The format is:
<userlistid>,<status code>

Ex: google_ula=1234567890,0

The google_ula operation can return any of the following status codes:

  • 0 - No error. The user has been added to the user list.

  • 2 - Permission denied. You don't have permission to add users to the given user list.

  • 5 - Bad user list ID. The supplied user list ID is invalid.

  • 6 - Closed attribute ID. The supplied user list ID is closed.

  • 10 - Internal error. The Cookie Matching service
    has encountered an internal error; you can try re-matching the user again.

Hosted match table


You can choose to have Google host your match table. This may improve
reporting of table size and match rates, and reduce the amount of
infrastructure you need to support.

A Google-hosted match table offers a mechanism whereby data which you pass
to Google for storage is later passed back to you in bid requests. Typically,
when you have placed a match tag for a user whom you have identified with your
own internal cookie ID, you include that cookie ID in the cookie match request
that you send to Google. Google hosts the data you sent, and includes it in
subsequent bid requests for impressions viewed by the same user. This enables
you to:
  • Skip the step of storing the mapping between the Google User ID and your
    cookie space.

  • Opt to receive a bid request only when the user is one for whom you have
    a match table entry.
The google_hm parameter serves as a container for data that you
pass to Google in the cookie match request. When Google responds with the
302 redirect, the google_hm parameter may be present
with an error code.

When Google needs to pass the data back to you, it does so in the
hosted_match_data field of the bid request. See the
realtime-bidding-proto
file for a description of the hosted_match_data field.

google_hm as a cookie match request parameter
google_hmContains data which the buyer wants Google to store in the hosted match
table. The value is a URL-safe base64 string (padding optional).
google_hm as a redirect parameter
google_hmOnly appears if the attempt to write data to the hosted match table
fails. When that happens, its value is one of the following status codes:

  • 1 - Forbidden: The customer is not yet whitelisted to write hosted match table entries.

  • 2 - Decode error: The parameter value could not be decoded.

  • 3 - Payload too long: The parameter value decoded into more than 24 bytes of data.

  • 4 - Internal error: There was an internal error storing the data.

  • 5 - Throttled: This write was not processed due to throttling.

google_hm with an explicit redirect URL
google_hmBase64-encoded user ID.
google_redirThe encoded URL of where the buyer wants Google to send a
302 redirect. This allows Ad Exchange to be placed at the
front in a chained call to partners.


Example:

http://cm.g.doubleclick.net/pixel?google_nid=<my_nid> \ &google_hm=<user_id_base64>&google_redir=<encoded_URL>

You can now optionally configure your URLs with one or more macros in the
form of either %%GOOGLE_GID%% or %%GOOGLE_GID_PAIR%%. The %%GOOGLE_GID%% will
be substituted for the google_gid value directly, while the
%%GOOGLE_GID_PAIR%% will be substituted with a google_gid=value.

The supported macros are:

MacroExpands to
GOOGLE_GID<google user id>
GOOGLE_GID_PAIR&google_gid=<google user id>
GOOGLE_CVER<cookie version number>
GOOGLE_CVER_PAIR&cver=<cookie version number>
GOOGLE_ERROR<error id>
GOOGLE_ERROR_PAIR&google_error=<error id>
GOOGLE_PUSH<pixel match data>
GOOGLE_PUSH_PAIR&google_push=<pixel match data>
GOOGLE_ALL_PARAMSgoogle_gid=<google user id>&cver=<cookie version number>&google_error=<error id>

Examples

Simple request

The simplest form of a Cookie Match request is one with no extra parameters.
The match tag URL in this case would be:
  • http://cm.g.doubleclick.net/pixel?google_nid=ad_network_xyz&google_cm
Assuming your configured redirect URL is:
  • http://ad.network.com/pixel?id=
An example of a successful response is:
  • http://ad.network.com/pixel?id=&google_gid=dGhpcyBpcyBhbiBleGFtGxl&google_cver=1
If the user does not have a doubleclick.net cookie, the response is:
  • http://ad.network.com/pixel?id=&google_error=3
In the case where the user has a doubleclick.net cookie, but has opted out
from behavioral targeting, the error code would be 1.

Extra parameters in match tag

If you use extra parameters in the match tag that do not begin with
google_, they are passed on to your server. For example, let's
take the two extra parameters p1=v1 and p2=v2.

The match tag URL in this case is:
  • http://cm.g.doubleclick.net/pixel?google_nid=ad_network_xyz&google_cm&p1=v1&p2=v2
An example of a successful response is:
  • http://ad.network.com/pixel?id=&p1=v1&p2=v2&google_gid=dGhpcyBpcyBhbiBleGFtGxl&google_cver=1

An error response would add the extra parameters in a similar way, while
reporting the error as in the first example.

Extra parameters in configured redirect URL

Suppose your configured URL is:
  • http://ad.network.com/pixel?id=&p1=v1&p2=v2
And you use the simple version of the match tag URL:
  • http://cm.g.doubleclick.net/pixel?google_nid=ad_network_xyz&google_cm
An example of a successful response is:
  • http://ad.network.com/pixel?id=&p1=v1&p2=v2&google_gid=dGhpcyBpcyBhbiBleGFtGxl&google_cver=1

google_ parameters


If you pass an extra parameter in the match tag URL or in your configured
redirect URL which begins with google_, the parameter is not
passed in the redirect to your server.

For instance, if you use the following two match tag URLs with the simple
configured redirect URL:
  • http://cm.g.doubleclick.net/pixel?google_nid=ad_network_xyz&google_cm&google_p1=v1&p2=v2
An example of a successful response is:
  • http://ad.network.com/pixel?id=&p2=v2&google_gid=dGhpcyBpcyBhbiBleGFtGxl&google_cver=1
Note that the google_p1 parameter is not passed in the redirect
to your server.

google_ula

Assuming your configured redirect URL is:
  • http://ad.network.com/pixel?id=
And you use the following match tag URL:
  • http://cm.g.doubleclick.net/pixel?google_nid=ad_network_xyz&google_ula=12345
Upon success the user is redirected to
  • http://ad.network.com/pixel?id=&google_ula=12345,0
If there is an overall error (e.g., the user has no doubleclick.net cookie),
the redirect URL is:
  • http://ad.network.com/pixel?id=&google_error=3
You can also specify a timestamp:
  • http://cm.g.doubleclick.net/pixel?google_nid=ad_network_xyz&google_ula=12345,7654321
The redirect URL upon success would be the same.

The redirect URL in case of error is similar, but the status code would be
different. Suppose you don't have permission to add users to user list
12345, the redirect URL would be:
  • http://ad.network.com/pixel?id=&google_ula=12345,2
You can also specify multiple lists using multiple google_ula request
parameters. Note that you can specify a timestamp on each independently:
  • http://cm.g.doubleclick.net/pixel?google_nid=ad_network_xyz&google_ula=12345,7654321&google_ula=45678
The status of each operation is reported separately in the redirect URL:
  • http://ad.network.com/pixel?id=&google_ula=12345,2&google_ula=45678,0
Here the user has been added to the list 45678, but there was a
permission error for list 12345.

You can combine the google_ula and google_cm
request parameters to perform cookie matching and add the user to a user list
in a single request:
  • http://ad.network.com/pixel?id=&google_ula=12345&google_cm
The redirect URL is:
  • http://ad.network.com/pixel?id=&google_gid=dGhpcyBpcyBhbiBleGFtGxl&google_cver=1&google_ula=12345,0

google_sc and google_no_sc

google_sc

The google_sc request parameter causes the Cookie Matching
service to set the doubleclick.net cookie if the user does not currently have
it set.

google_no_sc

The google_no_sc request parameter prevents the Cookie
Matching service from setting the doubleclick.net cookie if the user does not
currently have it set. The default behavior is to set the cookie.
These parameters do not otherwise modify the result of the request. The
Cookie Matching Service may not always succeed in setting the cookie if, for
example, the user has disallowed cookies generally or the doubleclick.net
cookie in particular.

If the Cookie Matching service needs to set a cookie, it verifies that
the user's browser has accepted the cookie by issuing a self-redirect with
the Set-Cookie header. If the user's browser does not send the
cookie in the self-redirect, it is classified as not accepting the
doubleclick.net cookie and the redirect to you contains
google_error=3.

Assuming your configured redirect URL is:
  • http://ad.network.com/pixel?id=
And you use the following match tag URL:
  • http://cm.g.doubleclick.net/pixel?google_nid=ad_network_xyz&google_ula=12345
If the user does not have the doubleclick.net cookie, and you used
google_no_sc, the redirect URL is:
  • http://ad.network.com/pixel?id=&google_error=3
If instead, you specify the google_cm request parameter and the
cookie is successfully set, then the redirect URL is:
  • http://ad.network.com/pixel?id=&google_gid=dGhpcyBpcyBhbiBleGFtGxl&google_cver=1

If the cookie cannot be set, the redirect URL is identical to the regular error redirect URL:
  • http://ad.network.com/pixel?id=&google_error=3

Hosted match table

Successful write
Values to use in the example:
  • for the google_hm parameter, Cookie number 1!
    encoded in URL-safe base64 as Q29va2llIG51bWJlciAxIQ==

  • for the configured redirect URL, http://cookie-monster.com/pixel?id=

The Cookie Match Request is:
  • http://cm.g.doubleclick.net/pixel?google_nid=cookie-monster&google_hm=Q29va2llIG51bWJlciAxIQ%3D%3D
The 302 redirect is:
  • http://cookie-monster.com/pixel?id=
Because the google_hm parameter has been set with the encoded
value Cookie number 1!, subsequent bid requests for
impressions viewed by the same user contain that value in the
hosted_match_data field:

BidRequest <
...
hosted_match_data: "Cookie number 1!"
>

Here's what happens:

  • Because google_cm was not set in the request, google_gid is not in the response.

  • Because the hosted write was successful, google_hm is not in the response.

  • Because the write was successful, the hosted data becomes available in subsequent bid requests.
Decode error
For this example, assume that the configured redirect URL is:
  • http://cookie-monster.com/pixel?id=
The Cookie Match Request is:
  • http://cm.g.doubleclick.net/pixel?google_nid=cookie-monster&google_hm=chocolate_chunk!
Note that the buyer has added the google_hm parameter but has
neglected to encode its value, and instead attempted to set the parameter with
the unencoded value chocolate_chunk!.

The 302 redirect is:
  • http://cookie-monster.com/pixel?id=&google_hm=2
Here's what happens:
  • Because google_cm was not set in the request, google_gid is not in the response.

  • The Cookie Matching Service tries to decode the value of the
    google_hm parameter as URL-safe base64, but
    chocolate_chunk! cannot be successfully decoded as base64, and
    this causes the hosted write to fail.

  • Because the hosted write fails, google_hm appears in the
    response with error code 2—a decode error.

  • Since the write was unsuccessful, no new hosted match data becomes
    available in bid requests (although old data is still sent).
No-cookie error
For a variety of reasons, not every user has a doubleclick.net
cookie at any given time.

For this example, assume that there is no doubleclick.net
cookie in the user's browser. We'll also assume that the configured redirect
URL is:
  • http://cookie-monster.com/pixel?id=
The Cookie Match Request is:
  • http://cm.g.doubleclick.net/pixel?google_nid=cookie-monster&google_hm=chocolate_chunk!
Note that the buyer has added the google_hm parameter but has
neglected to encode its value, and instead attempted to set the parameter with
the unencoded value chocolate_chunk!.

The 302 redirect is:
  • http://cookie-monster.com/pixel?id=&google_error=3
Here's what happens:
  • The lack of a cookie causes the overall request to fail, so
    google_error is set in the response.

  • Although the buyer set the google_hm with an unencoded
    value, which would fail when the Cookie Matching Service tried to decode it,
    there is no attempt to decode google_hm because the failure of the
    overall request is a higher-level error that takes precedence. Therefore
    google_hm is not set with a decode error in the response.

  • Since the write was unsuccessful, no new hosted match data becomes
    available in bid requests (although old data is still sent).
Putting it all together
Values to use in the example:
  • for the google_hm parameter, Cookie number 1!
    encoded in base64 as Q29va2llIG51bWJlciAxIQ==

  • for the google_ula parameter, the value 12345

  • for the configured redirect URL, http://cookie-monster.com/pixel?id=

  • for the extra parameter my_extra_param, no value

  • for the extra parameter my_other_extra_param, value 7
The Cookie Match Request is:
  • http://cm.g.doubleclick.net/pixel?
    google_nid=cookie-monster&google_cm&google_hm=Q29va2llIG51bWJlciAxIQ%3D%3D
    &google_ula=12345&my_extra_param=&my_other_extra_param=7
The 302 redirect is:
  • http://cookie-monster.com/pixel?
    id=&my_extra_parameter=&my_other_extra_param=7
    &google_gid=ABCDETC&google_cver=1&google_ula=12345,0
Here's what happens:

  • The extra parameters pass through first untouched.

  • The google_ula parameter contains the status of the userlist
    add attempt (0: OK).

  • Because the hosted match table write was successful, the hosted match
    data becomes available in subsequent bid requests.

  • Because the google_hm parameter has been set with the
    encoded value Cookie number 1!, subsequent bid
    requests for impressions viewed by the same user contain that value in the
    hosted_match_data field:

BidRequest <
...
hosted_match_data: "Cookie number 1!"
>

Cookie matching macros

Without macros
Typically the user supplies Google with a base cookie matching URL to which
cookie matching parameters are appended. For example, this URL is passed to be
stored as rtb-keys:
  • http://user.buyer.com/cookies?x=0&y=1
This is appended with parameters when calling it:
  • http://user.buyer/cookies?
    x=0&y=1&google_push=456&google_gid=1&google_cver=1
With macros
If the buyer needs the parameters in a specific order, they could provide
the following for rtb-keys:
  • http://user.buyer.com/cookies?
    w=0%%GOOGLE_PUSH_PAIR%%&x=1%%GOOGLE_GID_PAIR
    &y=2%%GOOGLE_CVER_PAIR%%&z=3%%GOOGLE_ERROR_PAIR%%
Google would expand the macro and append the rest of the parameters:
  • http://user.buyer.com/cookies?
    w=0&google_push=456&x=1&google_gid=1&y=2&google_cver=1&z=3
Note that, because the _PAIR style macro was used, the macro
expansion also included the parameter name. The following URL would produce the
same result:
  • http://user.buyer.com/cookies?
    w=0&google_push=%%GOOGLE_PUSH%%&x=1&google_gid=%%GOOGLE_GID%%&y=2
    &google_cver=%%GOOGLE_CVER%%&z=3%%GOOGLE_ERROR_PAIR%%

时间：