[Alpha]{class="badge informative"}

Context and forwarded headers

In a browser, the Web SDK reads the page URL, screen size, time zone, and other details from the page and adds them to each event. A server has no page to read, so the Server SDK adds a smaller set of context data. It also forwards details from the visitor’s request so that the Edge Network can use them.

Implementation details implementation-details

The SDK adds the xdm.implementationDetails object to every event. This object identifies the library that sent the event:

{
  "implementationDetails": {
    "name": "https://ns.adobe.com/experience/alloy-node",
    "version": "0.2.1",
    "environment": "server"
  }
}

The version value matches the installed version of the @adobe/alloy-node package. You can’t turn off this data.

Pass the incoming request request

To add context about the visitor, pass the incoming request to forRequest as the request property:

const visitor = alloy.forRequest({ request: req });

The request value can be any object that has a headers property, including:

If you build a plain object yourself, use lowercase header names, such as { headers: { "user-agent": "..." } }.

Forwarded headers forwarded-headers

When you pass a request, the SDK copies the following headers from it to each request that it sends to the Edge Network. Without these headers, the Edge Network would see your server as the visitor, and its device and location lookups would describe your server instead of the visitor.

The SDK forwards only the headers in this table. It never forwards the visitor’s Cookie, Authorization, or Referer headers.

The Edge Network uses these headers for features such as geolocation and device lookup, when they are enabled on your datastream. If your server runs behind a proxy or load balancer, make sure that it sets X-Forwarded-For or Forwarded to the visitor’s real IP address.

Browsers send only a few low-entropy client hints by default. To receive the others, your server must ask the browser for them with the Accept-CH response header.

Page URL from the Referer header page-url

If the incoming request has a Referer header, the SDK uses its value as xdm.web.webPageDetails.URL. The Referer header contains the address of the page that made the request, so it is accurate only in some cases:

Values that you set in the xdm object take priority over the Referer value. To set the page URL explicitly:

await visitor.sendEvent({
  xdm: {
    eventType: "web.webpagedetails.pageViews",
    web: {
      webPageDetails: {
        URL: `https://www.example.com${req.url}`
      }
    },
    identityMap: {
      Email: [{ id: "visitor@example.com", primary: true }]
    }
  }
});

Data that the SDK doesn’t collect not-collected

The following data that the Web SDK can collect in a browser has no reliable source on a server, so the Server SDK doesn’t add it:

If your application knows any of these values, for example because the browser sent them to your server, add them to the xdm object yourself.