Network deduplication with last view/event logic (LEC) – Daisycon Advertiser FAQ

Last Event Counts, or LEC, helps advertisers use recent Daisycon event data in their own deduplication setup. It is especially useful when post view attribution is enabled, because a banner view does not set an advertiser-side cookie, click ID, or network flag by itself.

What is LEC?

LEC stands for Last Event Counts. It is a client-side Daisycon endpoint that can return recent Daisycon event data for a specific campaign and the visitor’s device or browser.

The endpoint can be used by advertisers to support deduplication logic. For example, an advertiser can trigger the endpoint on the visitor’s client and use the response to set or update an advertiser-side deduplication cookie.

When should LEC be used?

LEC is mainly used when post view attribution should be included in advertiser-side deduplication.

The campaign uses post view attribution
The advertiser uses deduplication between multiple affiliate networks
The advertiser’s current setup depends on click cookies, click IDs, or network flags
The advertiser wants to set its own deduplication cookie based on recent Daisycon event data

Why LEC is needed for post view attribution

Daisycon post view attribution is cookieless. When a user views a Daisycon banner, the view can be registered through the banner material request, but no advertiser-side cookie or network flag is set automatically.

This means a strict click-based deduplication setup may not recognize recent Daisycon activity when the user later visits the advertiser website directly. LEC helps solve this by making recent Daisycon event data available on the visitor’s client.

The LEC endpoint

The endpoint has the following structure:

https://<tracking_domain>/js/lec/?ci=<program_id>

<tracking_domain> is the Daisycon tracking domain used for the campaign
<program_id> is the Daisycon campaign or program ID

The LEC endpoint returns JavaScript, not JSON. It should be loaded as a script on the visitor’s client. The response is made available through window.__dc_response.

Example response when a view is found

var __dc_response = {
    "status": "G",
    "status_description": "Matching event found",
    "view": {
        "timestamp": 1790000000,
        "iso_date": "2026-01-01T10:00:00+02:00",
        "media_id": 67890
    }
}

Example response when no view is found

var __dc_response = {
    "status": "V",
    "status_description": "No matching event found"
}

How LEC works

A typical LEC-based deduplication flow works like this:

A user sees a Daisycon banner on a publisher website
The banner is loaded from Daisycon servers
Daisycon registers the banner material request as view data
The user later visits the advertiser website directly
The advertiser triggers the LEC endpoint on the visitor’s client
The LEC endpoint returns recent Daisycon event data for the campaign and device or browser, if available
The advertiser uses the response to set or update its own deduplication cookie or attribution marker
The user completes a conversion
The advertiser’s deduplication setup allows Daisycon tracking to fire because recent Daisycon activity was detected
Daisycon receives the conversion and checks for a valid click first
If no valid click is available, Daisycon can evaluate the registered view for attribution

Example script: load LEC and store recent Daisycon activity

The example below loads the LEC endpoint, reads the response and stores a cookie when a matching Daisycon event is found.

This example is simplified and should be adapted to the advertiser’s website, tag management setup and deduplication rules.

<script>
(function () {
  var trackingDomain = 'https://[matching_domain]';
  var programId = '12345';

  var cookieName = 'daisycon_recent_event';
  var cookieMaxAgeSeconds = 5 * 24 * 60 * 60; // maximum view attribution window

  function setCookie(name, value, maxAgeSeconds) {
    document.cookie =
      name + '=' + encodeURIComponent(value) +
      '; Max-Age=' + maxAgeSeconds +
      '; Path=/' +
      '; SameSite=Lax' +
      '; Secure';
  }

  function handleLecResponse(response) {
    if (!response || !response.status) {
      return;
    }

    if (response.status === 'G' && response.view) {
      var cookieValue = JSON.stringify({
        source: 'daisycon',
        type: 'post_view',
        program_id: programId,
        media_id: response.view.media_id,
        view_timestamp: response.view.timestamp,
        view_iso_date: response.view.iso_date
      });

      setCookie(cookieName, cookieValue, cookieMaxAgeSeconds);

      window.dataLayer = window.dataLayer || [];
      window.dataLayer.push({
        event: 'daisycon_recent_event_detected',
        daisycon_event_type: 'post_view',
        daisycon_program_id: programId,
        daisycon_media_id: response.view.media_id,
        daisycon_view_timestamp: response.view.timestamp,
        daisycon_view_iso_date: response.view.iso_date
      });

      return;
    }

    if (response.status === 'V') {
      window.dataLayer = window.dataLayer || [];
      window.dataLayer.push({
        event: 'daisycon_recent_event_not_found',
        daisycon_program_id: programId
      });
    }
  }

  function loadLec() {
    window.__dc_response = undefined;

    var script = document.createElement('script');
    script.async = true;
    script.src = trackingDomain + '/js/lec/?ci=' + encodeURIComponent(programId);

    script.onload = function () {
      handleLecResponse(window.__dc_response);

      if (script.parentNode) {
        script.parentNode.removeChild(script);
      }

      window.__dc_response = undefined;
    };

    script.onerror = function () {
      window.dataLayer = window.dataLayer || [];
      window.dataLayer.push({
        event: 'daisycon_lec_error',
        daisycon_program_id: programId
      });
    };

    document.head.appendChild(script);
  }

  loadLec();
})();
</script>

Example script: read the stored LEC result on conversion

On the conversion page, the advertiser can read the stored LEC result and use it in their tag logic. The example below pushes the result to the data layer, so a tag management system such as Google Tag Manager can decide whether Daisycon tracking should fire.

<script>
(function () {
  var cookieName = 'daisycon_recent_event';

  function getCookie(name) {
    var cookies = document.cookie ? document.cookie.split(';') : [];

    for (var i = 0; i < cookies.length; i++) {
      var cookie = cookies[i].trim();

      if (cookie.indexOf(name + '=') === 0) {
        return decodeURIComponent(cookie.substring(name.length + 1));
      }
    }

    return null;
  }

  var recentEvent = getCookie(cookieName);

  window.dataLayer = window.dataLayer || [];
  window.dataLayer.push({
    event: 'daisycon_conversion_deduplication',
    daisycon_recent_event: recentEvent ? 'found' : 'not_found'
  });
})();
</script>

Example conversion logic

The advertiser can use the stored LEC result to decide whether Daisycon tracking should be considered on the conversion page.

If recent Daisycon event data is found, the advertiser can allow the Daisycon conversion pixel to fire
If no recent Daisycon event data is found, the advertiser can apply the agreed fallback rule
When Daisycon receives the conversion, Daisycon still checks for a valid click first
If no valid click is available, Daisycon can evaluate the registered view for attribution

LEC does not decide final attribution by itself. It only helps the advertiser include recent Daisycon event data in their own deduplication setup.

Google Tag Manager example

The following simplified version can be used as a starting point for a Custom HTML tag in Google Tag Manager. It only pushes the result to the data layer. Cookie handling and tag firing logic can then be managed separately in GTM.

<script>
(function () {
  var trackingDomain = 'https://[matching_domain].com';
  var programId = '12345';

  window.__dc_response = undefined;

  var script = document.createElement('script');
  script.async = true;
  script.src = trackingDomain + '/js/lec/?ci=' + encodeURIComponent(programId);

  script.onload = function () {
    window.dataLayer = window.dataLayer || [];

    if (window.__dc_response && window.__dc_response.status === 'G' && window.__dc_response.view) {
      window.dataLayer.push({
        event: 'daisycon_recent_event_detected',
        daisycon_event_type: 'post_view',
        daisycon_program_id: programId,
        daisycon_media_id: window.__dc_response.view.media_id,
        daisycon_view_timestamp: window.__dc_response.view.timestamp,
        daisycon_view_iso_date: window.__dc_response.view.iso_date
      });
    } else {
      window.dataLayer.push({
        event: 'daisycon_recent_event_not_found',
        daisycon_program_id: programId
      });
    }

    if (script.parentNode) {
      script.parentNode.removeChild(script);
    }

    window.__dc_response = undefined;
  };

  document.head.appendChild(script);
})();
</script>

Example scenarios

Scenario 1: recent Daisycon view found

The user previously viewed a Daisycon-hosted banner
The advertiser triggers LEC on the visitor’s client
LEC returns status: "G"
The advertiser stores a recent Daisycon event marker
The user converts
The advertiser allows Daisycon tracking to be considered

Scenario 2: no recent Daisycon view found

The advertiser triggers LEC on the visitor’s client
LEC returns status: "V"
No recent Daisycon event marker is stored
The advertiser applies the agreed fallback rule

Scenario 3: recent Daisycon click exists

The user previously clicked a Daisycon affiliate link
The user later converts
Daisycon checks for a valid click first
If the click is valid, click attribution has priority over view attribution

Relation to LCC

LEC is related to LCC, but it solves a different problem. LCC stores the latest click source. LEC makes recent Daisycon event data available on the visitor’s client, which is useful when post view attribution should be included in deduplication.

Use LCC for click-based deduplication. Use LEC when recent Daisycon post view event data should also be considered.

Important limitations

This example is meant to explain the concept. It is not a standard Daisycon script and should not be copied without review.

LEC is not a reporting API
LEC does not provide full view or impression statistics
LEC only checks recent Daisycon event data for the selected campaign and local device or browser
LEC does not replace the Daisycon conversion pixel
LEC does not decide final attribution by itself
Daisycon still checks for a valid click first when the conversion is received

Testing checklist

Load a Daisycon-hosted banner and confirm that a recent event can be found through LEC
Test a situation where no recent Daisycon event exists and confirm that status: "V" is handled correctly
Check whether the advertiser-side cookie or marker is set only when expected
Confirm that the Daisycon conversion pixel only fires according to the agreed deduplication rules
Test the fallback rule when no recent Daisycon event is available

Conclusion

LEC makes recent Daisycon event data available on the visitor’s client. It is mainly used to support deduplication when post view attribution is enabled. It can help advertisers set their own deduplication cookie or attribution marker, but it should not be used as a reporting API or impression statistics endpoint.