Sharing Java developer knowledge, practical articles, and continuous insights into computer engineering.
This article walks through the complete lifecycle of an HTTP API call initiated with Postman, covering DNS resolution, TCP/IP connection, Nginx reverse proxy and load balancing, Spring Boot request handling, service layer processing, JSON serialization, and the final response delivery back to Postman.
This article explains common encryption and signing algorithms—including AES, SM4, RSA2, and SM2—covers key representations in hex and Base64, details digital certificate structures, CSR application, TLS usage scenarios, OpenSSL commands for PEM conversion, and provides Java and JavaScript code examples for secure communication.
This article explains OpenSSL’s origins, its role in encryption on CentOS, common use cases such as web servers and database security, provides step‑by‑step installation and upgrade commands, and demonstrates how to generate RSA, SM2, AES, and SM4 keys via the OpenSSL command line and Java alternatives.
Web containers, such as Tomcat, keep running by continuously listening on network ports with socket servers and thread pools, handling I/O requests; this article explains the role of the main function, servlet lifecycle, Netty’s NIO framework, and why WebFlux‑based gateways outperform traditional Tomcat setups.
This article explains the key performance metrics TPS (transactions per second) and QPS (queries per second), provides formulas for calculating them, and demonstrates practical calculations for multi-node deployments, illustrating how request latency, thread pools, and instance count affect overall system concurrency and throughput.
This guide walks through macOS network configuration on a MacBook Pro M1, covering Wi‑Fi advanced settings, TCP/IP fundamentals such as DHCP, IP addressing and subnet masks, NAT translation, routing tables, DNS servers, proxy types, VPN (L2TP) setup, SSH usage, and Ethernet interface details.
Learn how to use OpenSSH for local, remote, and dynamic port forwarding, including command syntax, practical scenarios, configuration tips, and methods to keep connections alive, enabling secure access to internal services across NAT and firewalls.
This article traces the evolution of remote login from early terminal‑based systems to modern secure protocols, explains the development and key features of SSH, compares it with HTTP, and outlines its main functions such as remote access, file transfer, and port forwarding.
This article explains the fundamentals of hash structures, hash functions, and Java collection implementations such as HashMap, LinkedHashMap, and ConcurrentHashMap, covering their design, collision handling, performance characteristics, and how Redis extends these concepts to a distributed environment.
This article explains the relationships between bits, binary, hexadecimal, bytes and strings, shows how computers store and process data using binary, demonstrates hexadecimal and Base64 encodings, provides conversion tables and examples, and clarifies how UTF‑8 encodes characters.
