Privacy Aware GDPR-Conform Low-(Level|Maintence|Data|Impact) PHP (Track|Counter|Logg)er

Counters aim to count how often a page is visited. It is interesting to know how many new users are there. And how many *re-*users are there.

This is usually solved by Cookies or similar technologies. But it has privacy implications and requires the users consent (GDPR).

For simple Web-Applications with no desire to monetize, this is too much trouble.

Lopher uses plain old HTTP-Caching in order to find out if a user was there before.

The App sends a log request to the API. On the first visit the Answer is a simple 200 OK response, with a Last-Modified header. The API increases the counter. On consectuive calls, the Browser sends the If-Modified-Since header. The API responses with 304 Not Modified and may increase a revisit counter.

There can be different log events (index page, about page, click on button) and cycles (once, daily, monthly).

There must be some kind of persistant storage on the server. There are many ways: Log-Files with time-stamps, Session-Storage, Databases. Lopher uses an approach, were statistics are available by looking at the file-system: Each log increases the size of a file by one byte.

• {event}/once/{YYYY}-{MM}/{day}
• {event}/once-revisit/{YYYY}-{MM}/{day}
• {event}/daily/{YYYY}-{MM}/{day}
• {event}/daily-revisit/{YYYY}-{MM}/{day}
• {event}/monthly/{YYYY}-{MM}/{day}
• {event}/monthly-revisit/{YYYY}-{MM}/{day}

By looking at the files size it is for example possible to tell how many first visitors were there at this day.

There are 3 types of cycles:

1. once
2. daily
3. monthly

The content of the files is not just a dummy byte, but a specific value.

1. once: day of month
2. daily: hour of day
3. monthly: day of month