lophper

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

The Problem

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.

The Solution

Disitinguishing (Re-)Visitors

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).

Counter-Storage

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