The words you'll see

CARP docs use a handful of technical words. Here they are in plain language.

The tools

Note

Flutter and Dart matter if you run the app from source or build your own app. If you only write a protocol, skip to The CARP pieces.

Flutter : A free tool from Google for building phone apps. You write the app once, and it runs on both iPhone and Android. CARP apps are Flutter apps.

Dart : The programming language Flutter apps are written in. If you’ve seen JavaScript, Java or C#, Dart will look familiar.

Package : A ready-made piece of code someone else wrote that you add to your app, like a LEGO brick. Instead of writing step-counting code yourself, you add a package that already does it. Flutter packages are published on pub.dev, a kind of app store for code.

pubspec.yaml : A file in every Flutter app that lists which packages the app uses, like a shopping list. Add a line, run flutter pub get, and the package is downloaded.

The CARP pieces

CAMS (CARP Mobile Sensing) : The main CARP package, carp_mobile_sensing. It’s the engine inside your app that collects the data.

Sampling package : An extra CARP package that teaches CAMS to collect a new kind of data. CAMS already knows steps, screen and battery. Add carp_context_package and it also knows location and weather; add carp_polar_package and it can talk to a Polar heart rate strap.

CAWS (CARP Web Services) : CARP’s own server. It’s where researchers set up studies, invite participants and receive the data.

The study words

Word	Plain meaning	Example
Study protocol	The recipe: what to collect, from which device, and when	“Steps and screen events, all day”
Measure	One thing to collect	Steps
Trigger	When to collect	Right away, every hour, every morning at 8:00
Task	A group of measures that start together	“Background sensing”, “Morning survey”
Device	Where data comes from	The phone, a smartwatch
Deployment	One participant’s copy of the protocol, running on their phone	Anna’s study on Anna’s phone
Measurement	One piece of collected data, with a timestamp	“12 steps at 09:14”
Data endpoint	Where the measurements are saved or sent	On the phone, CAWS, your own server
Informed consent	What the participant reads and signs before the study starts	consent.json
Translation key	A name for a text, looked up in one file per language	study.purpose → “To learn how much people walk”

Tip

If you only remember one sentence: a protocol is a recipe of measures and triggers; the app follows it and produces measurements; the data endpoint decides where they go.

Next: how CARP fits together.