Implementing GenServer Behavior

Welcome back! In the previous lesson, we learned about Erlang's OTP behaviors. One of the most important is the GenServer.

• A GenServer is a generic server that handles requests.
• It manages internal state and processes messages in a sequential manner.
• Think of it as a standardized way to build reliable, fault-tolerant server processes in Erlang.

It's the foundation for many Erlang applications.

To implement a GenServer, you define a module that exports specific callback functions. These functions are called by the gen_server behavior at different stages.

• init/1: Initializes the server's state.
• handle_call/3: Handles synchronous client requests (expects a reply).
• handle_cast/2: Handles asynchronous client requests (fire-and-forget).
• terminate/2: Cleans up when the server stops.
• code_change/3: Handles hot code upgrades.

We'll focus on init, handle_call, and handle_cast in this lesson.