  Background: Modern software systems are commonly built on the top of
frameworks. To accelerate the learning process of features provided by
frameworks, code samples are made available to assist developers. However, we
know little about how code samples are actually developed. Aims: In this paper,
we aim to fill this gap by assessing the characteristics of framework code
samples. We provide insights on how code samples are maintained and used by
developers. Method: We analyze 233 code samples of Android and SpringBoot, and
assess aspects related to their source code, evolution, popularity, and client
usage. Results: We find that most code samples are small and simple, provide a
working environment to the clients, and rely on automated build tools. They
change frequently over time, for example, to adapt to new framework versions.
We also detect that clients commonly fork the code samples, however, they
rarely modify them. Conclusions: We provide a set of lessons learned and
implications to creators and clients of code samples to improve maintenance and
usage activities.
