3.IO

Comparing blocking streams, selector-based non-blocking channels, and asynchronous completion APIs without oversimplifying their OS mappings.

A thread-per-connection blocking server, its simplicity, and the need for bounded resources and modern virtual-thread context.

Java asynchronous channel APIs, completion handlers/futures, and the distinction between API-level asynchrony and OS implementation details.

Java blocking I/O semantics and when a simple blocking programming model remains appropriate.

ByteBuffer position, limit, capacity, flip/clear/compact, and heap versus direct buffers.

A selector/event-loop server architecture and the separation of I/O readiness from application work.

A completion-driven server design using asynchronous accept/read/write operations and explicit connection state.

Byte streams, character streams, buffering, decorators, and explicit charset boundaries in Java I/O.

Java NIO channel abstractions, partial reads/writes, scattering/gathering, and channel lifecycle.

Choosing text/binary serialization by schema evolution, compatibility, size, CPU, tooling, and security.

Reading and writing files with stream APIs, buffering, resource cleanup, and when NIO Files is simpler.

High-level Java filesystem operations and important caveats around atomicity, metadata, and large files.

Heartbeat design for detecting stale connections and distinguishing liveness from end-to-end health.

A blocking server architecture, thread-per-connection trade-offs, and bounded concurrency requirements.

Buffers, channels, selectors, readiness-based multiplexing, and the scope of Java NIO.

Length-prefix, delimiter, and fixed-size framing for converting a TCP byte stream into application messages.

Path composition, normalization, absolute/real paths, and filesystem-safe comparisons.

Designing a Java non-blocking server with Selector, per-connection state, partial I/O, and backpressure.