This article explains the PHP mb_substr() function, detailing its multibyte‑safe substring behavior, parameter list (str, start, length, encoding), return value, and provides a clear example showing how to extract the first two characters from a Chinese string.
This article details JD Daojia's order system architecture, tracing its evolution from a monolithic design to a micro‑service, multi‑cluster setup with Redis, MySQL, and Elasticsearch, and explains the high‑availability, disaster‑recovery, capacity‑planning, and alerting techniques that keep billions of orders running smoothly.
This article explains how to seamlessly replace Spring Boot's default Logback logging framework with alternatives like Log4j2 by leveraging the SLF4J facade, covering version requirements, dependency management, configuration files, and detailed XML examples for various log levels.
This article explains how aggregated QR payment codes unify WeChat and Alipay transactions by detecting the client via User-Agent, using JSAPI instead of Native payments, and outlines static, dynamic, and UnionPay QR workflows with practical code examples.
The article compares PHP and .NET, highlighting their performance, rapid development cycles, strong community support, rich libraries, security features, and cross‑platform capabilities, explaining why they are the preferred backend stacks for businesses building modern web applications.
This article explains what cache avalanche, cache breakdown, and cache penetration are, why they threaten database stability, and presents practical solutions such as mutex locking, pre‑warming, double‑cache, timed updates, empty‑value caching, Bloom filters, as well as common cache patterns like Cache‑Aside, Read/Write‑Through, and Write‑Behind.
This article explains how to automatically renew JWT tokens in a front‑end/back‑end separated system by storing tokens in a cache, checking them in a filter, and refreshing them when expired, thereby preventing frequent logins and preserving form data.
This article explains the PHP substr_count() function, detailing its syntax, parameter meanings, return value, and provides multiple code examples demonstrating how to count substring occurrences with optional offset and length arguments.
This article explains why DingTalk workflow is chosen, outlines its advantages and limitations, and provides a detailed, code‑driven tutorial on how to quickly integrate and launch a custom approval process using DingTalk's open platform APIs.
This article explains why retry mechanisms are essential for unstable network requests, introduces the Tenacity library, and provides clear, step‑by‑step Python examples covering basic retries, stop conditions, conditional retries, exception re‑raising, and callback handling.
This article examines cache‑database dual‑write consistency challenges, explains the Cache Aside pattern, outlines basic and complex inconsistency scenarios, and proposes a queue‑based solution with operational tips for maintaining data integrity under high concurrency.
This article explains PHP's count_chars() function, detailing its purpose of counting character occurrences in a string, describing the string and mode parameters, enumerating the five possible return modes, and providing a complete PHP example that demonstrates how to output character frequencies.
This article explains RabbitMQ’s AMQP fundamentals, exchange types, reliability mechanisms such as confirms and returns, consumer flow control, idempotency, dead‑letter handling, and for various high‑availability deployment models including mirrored clusters and federation.
The PHP substr_count() function counts the number of non‑overlapping occurrences of a substring within a string, optionally starting from a given offset and limiting the search length, and the article explains its signature, parameters, return value, and provides practical code examples.
This tutorial walks through the fundamentals of Nginx, explains its main features, details version choices, outlines the directory layout, and provides complete step‑by‑step commands for installing and configuring Nginx on both Windows and CentOS Linux environments.
The article explains PHP's str_repeat function, which repeats a given string a specified number of times, details its parameters, return value, usage constraints, and provides a sample code snippet demonstrating its output.
The article analyzes common coupling problems in microservice architectures and presents practical decoupling techniques—including asynchronous messaging, event‑driven design, local caching, data landing, and CQRS—while also offering refactoring guidelines for tightly coupled services.
This article explains the PHP str_pad function, detailing its syntax, parameter meanings, return value, and provides multiple code examples demonstrating right, left, and both-side padding with custom strings.
The article analyzes a production incident where a Dubbo thread pool exhausted its threads due to CompletableFuture#join blocking, explains how the custom business thread pool caused mutual waiting, and presents a solution that isolates asynchronous tasks into a separate pool to restore service stability.
This article explains Nginx’s highly modular architecture, its multi‑process and asynchronous non‑blocking request handling, the event‑driven model, and the master/worker design, providing a comprehensive foundation for developers who want to understand or explore Nginx’s source code.
A high‑traffic Java backend service suddenly suffered seconds‑long response times, prompting a systematic investigation that traced the issue from unexpected QPS spikes through database checks, local call delays, CPU load, and frequent ParNew GC, ultimately revealing oversized responses and memory pressure as the root cause.
The article explains PHP's chown() function, detailing its purpose, syntax, parameters, return values, and provides a complete example with code and expected output for changing a file's owner on a server.
This guide explains every common way to pass parameters in MyBatis—including single values, multiple arguments via indexes, @Param, Map, POJO, List, and array—showing mapper signatures, XML mappings, and sample code to help interview preparation and real‑world development.
This article walks through building a two‑level caching system in Java, starting with a generic cache interface, implementing a local Guava cache, then adding a Redis distributed cache, and finally combining them with versioned keys to achieve timely expiration and seamless cache switching.
This article details the architecture, protocol design, permission control, reliability mechanisms, and scaling strategies of a long‑connection gateway built with OpenResty, Kafka, and Redis, illustrating how to share persistent connections across multiple business services while ensuring high performance and fault tolerance.
The article explains PHP’s chgrp function, which changes a file’s group ownership, outlines its syntax, required parameters, permission restrictions, return values, and provides a complete PHP example demonstrating how to modify a file’s group and display the result.
This article details a four‑layer cloud‑native system architecture that separates presentation, communication, service, and data layers, leveraging Spring Cloud microservices, Alibaba Cloud networking, multiple databases, JWT authentication, ELK logging, and HTTP DNS to achieve scalability, reliability, and optimal user experience across web, app, and IoT platforms.
Learn how to configure Nginx’s three health‑check methods—TCP, HTTP, and custom—by understanding each parameter such as interval, fall, rise, timeout, and type, and see a complete upstream example that ensures timely detection of unhealthy service nodes.
This article reviews Java WebSocket options—including the Java EE specification, SockJS, Socket.IO, and reactive stream implementations—detailing their advantages, drawbacks, and performance characteristics, and provides benchmark data to help developers choose the most suitable solution for their backend communication needs.
The PHP chmod function changes a file's permission mode by specifying the file path and an octal mode value, returning true on success and false on failure, with detailed parameter descriptions and multiple code examples illustrating correct and incorrect usage.
Learn how Spring stores bean metadata, the structure of BeanDefinition, naming conventions, alias configuration, and various bean instantiation methods—including constructors, static and instance factory methods—while also discovering how to determine a bean's runtime type using BeanFactory.getType.
This article details the design and implementation of 58.com’s intelligent voice robot backend, covering its four‑layer architecture, SIP/SDP/RTP protocols, connection setup, multi‑turn voice interaction flow, DTMF handling, common troubleshooting issues, algorithm service modularization, SIP scheduling optimizations, and Java thread‑pool system tuning.
This article explains how MyBatis dynamic SQL tags such as if, choose, trim, foreach, and bind can be used to build flexible SELECT, INSERT, UPDATE, and DELETE statements, showing code examples, test cases, and best‑practice tips for handling optional parameters and batch operations in Java backend development.
The article explains PHP's getcwd() function, detailing its purpose, syntax, return values, edge‑case behavior on Unix systems, and provides a complete example demonstrating how to echo the current directory before and after changing it.
This article walks through the evolution of an online supermarket from a simple monolithic web application to a fully decomposed microservice architecture, highlighting the challenges of scaling, the need for monitoring, tracing, service discovery, fault tolerance, and the eventual adoption of a service mesh.
This article explains the PHP chdir() function, its syntax, parameters, return values, and provides a practical example showing how to change the current working directory and verify the change using getcwd().
The article explains how distributed cache‑aside patterns work, why deleting stale cache entries is often preferable to updating them, analyzes basic and complex cache‑database inconsistency scenarios, and proposes a JVM‑queue‑driven, single‑threaded update mechanism with practical considerations for high‑concurrency environments.
This article details CTrip's journey from its early .Net‑based ESB architecture through a self‑developed Java microservice framework to the current CDubbo platform, covering registration, monitoring, dynamic configuration, protocol compatibility, performance gains, extensibility, and future Service Mesh integration.
This tutorial walks through setting up a four‑node Kafka cluster—including Zookeeper installation, broker configuration, service startup, replication settings, fault handling, and leader election—using Linux commands and detailed code snippets to help readers build a production‑ready streaming platform.
This article explains the PHP is_dir() function, describing its purpose to check whether a given filename refers to an existing directory, detailing its parameter, return values, and providing example code snippets demonstrating true and false outcomes for various path inputs.
This article explains what MyBatis TypeHandler is, how to configure the environment, create custom handlers, register them via Spring Boot or XML, and details the internal execution flow for converting parameters and results between Java and JDBC types.
This article walks through creating, configuring, testing, and deploying a Spring Boot application on Alibaba Cloud's Development Platform, covering both online and local development modes, CI/CD pipelines, environment management, and practical tips for smoother serverless workflows.
The PHP rmdir() function removes an empty directory with proper permissions, returning TRUE on success or FALSE on failure, and the article explains its parameters, return values, and provides cross‑platform code examples for safely deleting directories.
This article explains how to use Spring's event‑driven mechanism to decouple business operations such as saving a product and sending notifications, showing step‑by‑step code for custom events, publishing, asynchronous listeners, and custom thread‑pool configuration to improve resilience and maintainability.
This article explains the PHP mkdir() function, detailing its signature, parameter meanings, default mode, recursive option, return values, and provides two practical code examples demonstrating simple directory creation and nested directory creation with error handling.
This guide walks through creating a Django‑based monitoring system that collects CPU, memory, and process metrics from MySQL, defines models, runs migrations, implements views that format data for Highcharts, builds HTML templates with interactive charts, configures URLs, and runs the server to display real‑time performance dashboards.
This article explains, from source‑code analysis, why MyBatis mapper methods cannot be overloaded, shows the resulting BeanCreationException, walks through the MyBatis‑SpringBoot auto‑configuration that builds SqlSessionFactory, and demonstrates how to trace a mapper method to the exact SQL statement defined in the XML mapping file.
This article explains why idempotency is essential, presents simple database‑based and concurrency‑safe implementations, and then details a generic, annotation‑driven idempotent framework with multi‑level storage, code examples, and deployment guidelines for Java backend services.
This article explains PHP's preg_match_all function, detailing its purpose, parameters, return values, and providing multiple code examples that demonstrate how to extract phone numbers, capture HTML tags, and use named subpatterns with regular expressions.
This article explains the PHP preg_match() function, its parameters, return values, and optional flags, and provides four practical code examples demonstrating simple pattern matching, word‑boundary searches, URL host extraction, and named‑capture groups for extracting data.
The article explains three common Redis cache problems—avalanche, penetration, and stampede—detailing their causes, impacts on system stability, and practical mitigation techniques such as random expiration, Bloom filters, mutex locks, and rate limiting, accompanied by code examples.
This guide explains why Java 11 is worth adopting, lists its major language and API enhancements over Java 8—including var type inference, improved collections, stream and HTTP client APIs—and provides detailed solutions for common migration issues such as missing JAXB modules and container‑aware JVM behavior.
Umajs is a lightweight Node.js web framework written in TypeScript that offers rich built‑in decorators, IOC, AOP, a flexible plugin system, and a unified Result API, enabling developers to build high‑performance, maintainable backend services with minimal boilerplate.
The team built a log‑based replay framework that pulls and cleans old gateway logs, samples requests, concurrently replays them against both old and new gateways, automatically compares JSON responses with configurable ignore rules, retries failures, and uses matching response distributions to safely verify and migrate thousands of APIs.
This guide walks through building a Java SMS verification service, covering code generation, API integration, session handling, and a reusable HTTP utility with full source examples, including Maven dependency setup, configuration file preparation, and step‑by‑step execution.
This article explains PHP's preg_filter() function, its equivalence to preg_replace(), details each parameter, usage notes, and provides a complete example with code and output to illustrate how it performs regex search-and-replace returning only matched results.
This article explains the concept of AOP, its typical use cases, the underlying mechanisms of Spring AOP (JDK dynamic proxy and CGLIB), the relationship with AspectJ, and provides a complete XML‑free code example that demonstrates aspects, pointcuts, join points and advice.
This article explains how to design a high‑performance, billion‑user feed stream system, covering product definition, data modeling, storage choices, synchronization modes, metadata handling, commenting, likes, search, sorting, deletion, updates, and practical architecture examples for different feed‑type applications.
This article explains how to set up the environment, identify key MyBatis components such as SqlSession, Executor, StatementHandler, ParameterHandler, TypeHandler, and ResultSetHandler, and strategically place breakpoints to effectively read and understand MyBatis 3.5 source code within a Spring Boot 2.3.3 application.
Xianyu’s new attribute completion system combines MetaQ messaging, AI image recognition, and offline option configuration to auto‑populate key product details, incentivize sellers, and iteratively refine attributes via sales metrics, boosting structured coverage by 30%, cutting verification time 70%, and raising UV‑CTR around three percent.
This article presents the background, core features, system architecture, internal mechanisms, and practical extensions of ZZSCHEDULE, a distributed task scheduling platform built on the open‑source XXL‑JOB framework, detailing its design goals, HA strategies, task dependency handling, and deployment experiences at Zhuanzhuan.
This article explains the technical solutions for unified multi‑account login in web applications, covering early‑stage username/password and mobile verification flows, detailed process steps, OAuth2.0 third‑party integration, and comprehensive database schema design for local and third‑party user authentication.
This article explains the PHP preg_split() function, its signature, parameters, return values, and provides multiple code examples demonstrating how to split strings using regular expressions, control split limits, and apply flags such as PREG_SPLIT_NO_EMPTY and PREG_SPLIT_OFFSET_CAPTURE.
This article explains the concept of caching, why database caching with Redis is needed for MySQL, the consistency challenges it introduces, and compares four practical solutions—TTL, write‑through, message‑queue, and binlog replication—offering guidance on selecting the appropriate approach for different latency and reliability requirements.
This article explains PHP's str_word_count() function, detailing how it counts words in a string, the optional format and charlist parameters, the possible return types (integer or array), and provides multiple code examples demonstrating different usage scenarios.
This guide shows how to externalize fixed settings like file upload paths in a SpringBoot backend by defining them in application.yml, creating a @ConfigurationProperties‑annotated config class with matching fields, and accessing the values via static methods or bean injection.
The article explains PHP's str_split() function, which converts a string into an array of characters or fixed‑length chunks, details its parameters and return behavior, and provides example code with output, including demonstrating how split_length affects the result.
This article introduces a self‑implemented Swagger UI built on think‑vuele, explains its architecture and dependencies, provides step‑by‑step usage instructions and Maven integration, and details performance optimizations such as API summary loading, mock data generation, and customizable request headers.
This article explains PHP's chunk_split() function, detailing its purpose of dividing a string into fixed-size pieces, describing its parameters (body, chunklen, end), return value, and providing a practical example that formats base64‑encoded data according to RFC 2045.
This guide walks through essential Elasticsearch operations, covering cluster health checks, creating and querying indices, managing settings, templates, aliases, index shrink, split, rollover, and detailed mapping definitions, providing practical code examples for each step.
An extensive compilation of regular expressions covering numeric, character, email, URL, phone, ID, password, date, IP, and other validation patterns, complete with examples and explanations, providing developers a ready reference for implementing robust input validation across various programming contexts.
This article explains how the PHP implode() function joins the values of a one‑dimensional array into a single string, describes its parameters and return value, and provides clear code examples demonstrating typical usage and edge cases.
This article compares three real‑time data delivery techniques—long/short polling, Server‑Sent Events, and WebSockets—explaining their mechanisms, advantages, drawbacks, and providing sample client‑server implementations to help developers select the most suitable approach for a dashboard that streams GitHub/Twitter activity.
This article explains the fundamentals of cookies and sessions, provides a detailed analysis of the koa-session source code, demonstrates how to configure and use koa-session with in‑memory, Redis, and MySQL stores, and summarizes security considerations and performance trade‑offs.
This article provides a detailed overview of common Spring Boot annotations, their purposes, usage examples, and related code snippets, helping developers understand how to configure and build RESTful Java applications efficiently.
The DTLE 3.20.08.0 release introduces Nomad integration, code optimizations, reduced memory usage, improved Kafka performance, enhanced logging, bug fixes, and management updates such as Consul‑based clustering and HCL job specifications, with quick‑start instructions for RPM, Docker, and documentation links.
This article explains how HashMap stores data using hash functions, illustrates hash collisions and chain addressing, and demonstrates why overriding hashCode and equals in custom key classes is essential for correct retrieval, using Java code examples and interview insights.
This tutorial walks you through registering a QQ Connect application, adding the required Maven dependency, creating the login page, implementing the Spring Boot controller and AuthComment utility class, configuring Freemarker, and handling the OAuth flow to achieve seamless QQ authentication in a Java backend.
This article explains MyBatis result mapping techniques—including alias mapping, camel‑case automatic mapping, explicit resultMap definitions, and advanced one‑to‑one and one‑to‑many associations—providing code examples, configuration details, and performance considerations such as the N+1 query problem.
This article explains the three primary ways to launch a Spring Boot application—running a class with a main method, using the java -jar command, and leveraging the spring-boot-maven-plugin—along with code examples, configuration details, and Maven command options.
This guide explains why Dubbo introduced application‑level service discovery, how it differs from interface‑level registration, and provides step‑by‑step instructions—including Docker‑based Zookeeper setup, source code configuration, and code examples—to enable and test the new feature in Dubbo 2.7.5.
This article explains how to tune Java ThreadPoolExecutor parameters—including corePoolSize, maxPoolSize, keepAliveTime, and queue length—for both CPU‑bound and IO‑bound workloads, offering practical formulas, example calculations, and a step‑by‑step adjustment workflow.
The article analyzes a real‑world incident where duplicate order IDs were generated under high concurrency, demonstrates the shortcomings of the original Java implementation, and presents a thread‑safe redesign using AtomicInteger, Java 8 date‑time API and container IP suffix to guarantee unique identifiers across parallel requests and clustered instances.
The article explains, through interview excerpts, why many game studios avoid microservice architectures for their real‑time servers, highlighting latency‑sensitive communication, stateful processing, and the overhead of distributed networking that conflict with the performance demands of modern multiplayer games.
This article explains the PHP fgetcsv() function, its parameters, return values, and provides a complete example showing how to open a CSV file, read each line as an array of fields, and process the data in a backend script.
The article explains PHP's ltrim() function, its syntax, parameters, default characters removed, and provides example code demonstrating how to strip whitespace or custom characters from the start of a string, including removing ASCII control characters.
This article explains the fundamentals of backend architecture, covering Maven's settings.xml, front‑back separation, various types of locks (thread, process, distributed), detailed Redis‑based and Zookeeper‑based distributed lock implementations with code examples, session handling in distributed systems, and key Spring‑Redis caching annotations.
This article explains the PHP rtrim() function, describing how it removes trailing whitespace or specified characters from a string, detailing its parameters and return value, and providing multiple code examples that demonstrate typical usage and edge‑case handling.
This article explains the PHP ltrim() function, its parameters, default character list, return value, and provides multiple code examples demonstrating how to trim whitespace, custom characters, and ASCII control characters from the beginning of strings.
The article details how a SaaS application's intermittent slowdown was traced to a Log4j logger lock contention issue, discovered via thread dumps and an online analysis tool, and resolved by migrating from the unmaintained Log4j 1.x to Log4j2.
This article demonstrates how to use JsonPath's built‑in functions such as $.ss.min(), $.ss.max(), $.ss.avg(), $.ss.stddev(), $.ss.length() and $.ss.sum() to compute minimum, maximum, average, standard deviation, length and sum of JSON array elements, providing Java code examples and expected console output.
This article provides a comprehensive guide to Spring Validation, covering basic usage, dependency setup, requestBody and requestParam validation, group and nested validation, collection checks, custom constraints, programmatic validation, fail‑fast configuration, and the underlying implementation mechanisms within Spring MVC and Hibernate Validator.
This article explains PHP's trim() function, detailing how it removes leading and trailing whitespace or custom characters, describes its parameters and return value, and provides multiple code examples demonstrating default usage, custom character lists, and applying trim via array_walk.
This article dives deep into Spring's transaction infrastructure, explaining how @EnableTransactionManagement activates transaction support, detailing the roles of key configuration classes, core interceptors, transaction attribute resolution, propagation behaviors, and the commit‑and‑rollback processes that power reliable data operations in Spring and Spring Boot applications.
This article explains the core concepts and architecture of an e‑commerce product center, covering SPU, SKU, sales and non‑sales attributes, pricing models, inventory control, scheduled on/off‑shelf operations, and optimization techniques for querying product data.
This article explains PHP's mb_http_input() function, detailing how it detects the character encoding of HTTP input, the meaning of its optional type parameter, possible return values, and notes on its practical usage.
This article explains the internal mechanics of Java Stream’s pipeline, covering how operations are recorded as stages, how intermediate and terminal operations are composed via the Sink interface, and why the implementation achieves lazy evaluation and efficient parallel execution.
This article explains how the PHP mb_send_mail() function works as a wrapper for mail(), detailing its parameters, return values, and providing a complete example that demonstrates sending Japanese‑encoded email bodies, subjects, and headers with proper MIME settings.
Spring Boot 2.3.3 has been released, offering initial support for JDK 15, a Maven parent pom snippet, 67 bug fixes and enhancements—including HTTP/2 improvements, configuration fixes, and numerous dependency upgrades—along with updated documentation and a link to the full release notes.
This article explains how Java's CompletableFuture and CompletionStage APIs enable asynchronous programming without external libraries, providing detailed explanations and 20 code examples that cover creation, chaining, combining, exception handling, cancellation, and execution with custom executors.
