Register multiple reporters

It's possible for two distinct entities to generate and receive attribution reports for a given set of source events, trigger events, or both. To register multiple reporters, you can rely on redirects, or choose other options, as discussed here.

# Register several triggers using redirects

The following example illustrates the use of redirects to register multiple triggers. In this example, reporter-1.example and reporter-2.example are two distinct entities looking to generate and receive attribution reports.

At source registration time, the following steps take place:

1. reporter-1.example receives a request from the browser.
2. reporter-1.example sends a response that contains the Attribution-Reporting-Register-Source header. It could be a regular response but, in this example, it's a redirect to reporter-2.example because reporter-2.example is another reporter looking to generate and receive attribution reports. Note: If reporter-1 intends to rely completely on reporter-2 as a measurement service, and does not intend to do any measurement themselves, reporter-1.example can omit the Attribution-Reporting-Register-Source header.
3. The browser receives this response. It reads Attribution-Reporting-Register-Source and therefore stores a source event, using reporter-1.example as the reporting origin.
4. Because this request is a redirect, the browser also makes a new request to reporter-2.example.
5. reporter-2.example responds with a regular response that contains the Attribution-Reporting-Register-Source header. The destination value in this header must be identical to the destination value of the Attribution-Reporting-Register-Source header set by reporter-1.example. Otherwise, the source will not be registered.
6. The browser receives this response; it reads Attribution-Reporting-Register-Source and stores a source event, using reporter-2.example as the reporting origin.

# Rely on attributionsrc for source registration

If multiple reporter origins want to register a source on a navigation event, but can't appear in a redirect chain for any reason, you can list multiple sites as attribution sources in attributionsrc as an alternative solution.

At trigger registration time, redirect requests in the same way as for source registration. Source events and trigger events that have been generated by the same origins will be matched.

# Register multiple triggers without redirects

If you need to register multiple attribution triggers without using redirects, you can do so by adding multiple pixel elements on the conversion side (one per trigger).