You have learned in Chapter 5 that there are four types of containers: engine, host, context, and wrapper. You have also built your own simple contexts and wrappers in previous chapters. A context normally has one or more wrappers, in which each wrapper represents a servlet definition. This chapt...

Some contents of a web application are restricted, and only authorized users are allowed to view them, after they supplied the correct user name and password. The servlet technology supports applying security constraint to those contents via the configuration of the deployment descriptor (web.xml...

Catalina supports session management through a component called manager, which is represented by the org.apache.catalina.Manager interface. A manager is always associated with a context. Among others, a manager is responsible for creating, updating, and destroying (invalidating) session objects a...

You have seen a simple loader implementation in the previous chapters, which was used for loading servlet classes. This chapter explains the standard web application loader, or loader for short, in Catalina. A servlet container needs a customized loader and cannot simply use the system's class lo...

A logger is a component for recording messages. In Catalina a logger is associated with a container and is relatively simpler than other components. Tomcat provides various loggers in the org.apache.catalina.logger package. The application that accompanies this chapter can be found in the ex07.py...

Catalina consists of many components. When Catalina is started, these components need to be started as well. When Catalina is stopped, these components must also be given a chance to do a clean-up. For example, when the container is stopped, it must invoke the destroy method of all loaded servlet...

A container is a module that processes the requests for a servlet and populates the response objects for web clients. A container is represented by the org.apache.catalina.Container interface and there are four types of containers: Engine, Host, Context, and Wrapper. This chapter covers Context a...

The connector in Chapter 3 worked fine and could have been perfected to achieve much more. However, it was designed as an educational tool, an introduction to Tomcat 4's default connector. Understanding the connector in Chapter 3 is key to understanding the default connector that comes with Tomca...

As mentioned in Introduction, there are two main modules in Catalina: the connector and the container. In this chapter you will enhance the applications in Chapter 2 by writing a connector that creates better request and response objects. A connector compliant with Servlet 2.3 and 2.4 specificati...

This chapter explains how you can develop your own servlet container by presenting two applications. The first application has been designed to be as simple as possible to make it easy for you to understand how a servlet container works. It then evolves into the second servlet container, which is...

This chapter explains how Java web servers work. A web server is also called a Hypertext Transfer Protocol (HTTP) server because it uses HTTP to communicate with its clients, which are usually web browsers. A Java-based web server uses two important classes: java.net.Socket and java.net.ServerSoc...

Lambda expressions were introduced in Java 8 to allow functional programming in Java. They are a concise way to express functions that can be used as data and provide a more functional approach to programming. Lambda expressions can be used in a variety of ways, from simple expressions to complex...

一. 交易1.1 什么是交易？按照历史趋势：贝壳交换 => 实体货币 => 数据化虚拟货币（轻量化和虚拟化）。一句话：等价交换行为。1.2 交易定义买卖双方对有价值的物品与服务互通有无的行为。关键：双方、有价值、互通有无、物品和服务1.3 交易流程古代：袖内拉手 和 袖内比价。现代：某些交易场景下有专业的手势，比...

起初个人认为是新版本的Obsidian和插件不兼容，于是选择换成旧版本，后来看了一眼Day-Planner更新日志，才发现原来作者基本把插件重做了。

引言本部分整合聊天系统有关的章节，内容主要是介绍关键功能的实现逻辑，建议读者先看看作者的博客项目，切换到不同分支看看各个细节功能如何实现。篇幅有限，这里仅仅记录一些个人学习过程的重点部分。思维导图[链接]项目代码作者的仓库代码地址：[链接]5通信协议设计和自定义编解码实现什么是通信协议？基于TCP通信均...

首先来看一下案例，LifeCycleTestHandlerTest 利用适配器 ChannelInboundHandlerAdapter 重写，重写相关方法。

服务端一上来先构建两个对象NioEventLoopGroup，这两个对象将直接决定Netty启动之后的工作模式，在这个案例中boos和JDK的NIO编程一样负责进行新连接的“轮询”，他会定期检查客户端是否已经准备好可以接入。worker则负责处理boss获取到的连接，当检查连接有数据可以读写的时候就进行数据处理。

《Postgresql 内幕探索》读书笔记 - 第一章：集簇、表空间、元组引言个人建议本章节自己搭建一个Postgresql数据库边实战边阅读更容易理解。思维导图链接：[链接] {代码...} 一、数据库集群的逻辑结构1.1 天然集群PostgreSQL天然集群，多个集群可以组成集簇，有点类似军队的连、团、旅这样的组织规则。对于我们日常学习使...

简介基于慕课网站上的一个一元钱课程《2小时搞定多线程》的 个人笔记。线程的起源我们先来看看网络中关于线程起源的说明，理解线程的来龙去脉对于掌握多线程有一定帮助。此部分内容整理自下面两篇网络博客：# 线程是什么# 线程的起源线程的起源与计算机的发展息息相关。早期的计算机系统是单指令模式，资源利用效率低下...

和 《Netty In Action》 不同，这本书直接从Netty入门程序代码开始引入Netty框架，前半部分教你如何用Netty搭建简易的通讯系统，整体难度比较低，后半部分直接从服务端源码、客户端源码、ChannelPipeline开始介绍，和前半部分割裂较为严重。

与其说是读书笔记，实际上更像是学学英语顺带学学Linux命令。这本书是通过每天挤一点时间边看边学边敲完成的，每天日常翻翻所以顺序和原始博客网站优点不一样。

与其说是读书笔记，实际上更像是学学英语顺带学学Linux命令。这本书是通过每天挤一点时间边看边学边敲完成的，每天日常翻翻所以顺序和原始博客网站不太一样。

2018年9 月 26 日，Oracle 官方宣布 Java 11 正式发布。这个版本中一共包含 17 个 JEP（JDK Enhancement Proposals，JDK 增强提案）。

Kafka 是通过 Scala 和 Java共同编写的语言，之所以选择2.7.2的版本是因为这个版本的Kafka是最后一版本保留ZK的版本。

Awk是一种用于高级文本处理的通用脚本语言，其主要用作报告和分析工具，与大多数其他程序性编程语言不同，Awk是数据驱动的，也就是说需要定义一组针对输入文本要执行的操作，然后其获取输入数据，对其进行转换，然后将结果发送到标准输出。

知识点先说一下重要的知识点：getline;在awk中可以用于控制“循环”。getline;之后，awk会改变对应的NF，NR，FNR和$0等内部变量getline;拿到的是下一行而不是当前行，概念想象为++i操作即可。介绍getline命令改变了awk的运行逻辑，是awk命令不可或缺的一部分。awk本质上就是一个for循环，它每次对输入文件的一行进行处理，...

jq 命令主要是和json文件的操作有关的辅助命令，可以实现对于Json数据的切片，过滤，映射和转换，在功能上毫不逊色于awk、sed、grep等命令。

继 [[【RocketMq】NameServ启动脚本分析（Ver4.9.4）]] 之后又来看看Broker的脚本。总体上来看大差不差，以阅读核心的配置部分调优为主。

最开始的mqnamesrv.sh 脚本获取环境变量的部分看不懂其实没啥影响，大略有个印象即可，当然可以截取部分的命令到Linux运行测试一下就明白了，比如准备环境变量等等，最后一句话比较关键。

本文介绍tldr和Cheat等实用工具的安装和使用，这些工具虽然本身不能替代man、info等命令，但是在很多时候想要快速学习和掌握命令但是忘记常见用法非常有帮助。