1、Shared service_BPR

cobbler常见问题http://@@http_server@@/cblr/links/CentOS-6.4-x86_64cobbler cblr/svc四、配置⽂件cobbler有许多的配置⽂件，但是只有少部分基本功能需要修改。

Settings FileModules ConfigurationCobbler最主要的 setting file就是/etc/cobbler/settings。

Cobbler2.4.0开始引⼊动态修改模式（Dynamic Settings），我们只需启动这⼀模式，便不⽤再⼿动修改这个⽂件了。

该⽂件是YAML格式的，如果直接修改setting⽂件，则必须重启 cobbler服务才会⽣效，但如果是通过CLI命令或者是Web GUI进⾏修改的话，改动会⽴即⽣效，⽆需重启服务。

五、常见问题1、cobblerd校验错误：cobblerd does not appear to be running/accessible解决⽅法：service cobblerd startservice httpd start2、重启httpd错误：Starting httpd: Syntax error on line 10 of /etc/httpd/conf.d/cobbler.conf:Invalid command 'WSGIScriptAliasMatch', perhaps misspelled or defined by a module not included in the server configuration解决⽅法：vi /etc/httpd/conf.d/wsgi.conf#LoadModule wsgi_module modules/mod_wsgi.so 去掉#号，使之成为：LoadModule wsgi_module modules/mod_wsgi.so。

managed_shared_memory工作原理managed_shared_memory 是一个内存分配器，允许多个进程在共享内存中动态分配和管理对象。

它提供了一个容器类 managed_shared_memory 来存储和操作对象，使得多个进程可以通过共享内存进行数据交换和共享。

1.创建共享内存：首先，需要调用 create_or_open 函数，以创建或打开一个共享内存对象。

每个进程都可以通过这个函数来获取一个指向共享内存的唯一标识符。

2.分配和释放内存：在共享内存中，可以使用标准的内存分配方式来动态分配和释放内存。

managed_shared_memory 对象提供了 alloc 和 dealloc 函数来完成这些操作。

通过 alloc 函数，可以在共享内存中分配指定大小的内存空间，并返回一个指向该内存空间的指针。

该空间可以存储任意类型的对象。

通过 dealloc 函数，可以释放先前分配的内存空间，并在共享内存中回收这些空间。

管理共享内存对象的最后一个进程负责调用 dealloc函数来释放共享内存。

3.构造和析构对象：在共享内存中，可以调用对象的构造函数和析构函数来创建和销毁对象。

这是通过使用共享内存的分配器来实现的。

通过使用分配器，可以在共享内存中创建对象，并在不同的进程之间共享这些对象。

例如，可以使用共享内存在多个进程中创建一个共享数组，这样所有进程都可以访问和修改这个数组。

4.同步和互斥：在多进程环境中，共享内存的访问需要进行同步和互斥操作，以防止数据的不一致性和竞争条件。

此外，还可以使用条件变量来实现进程之间的通信和同步。

条件变量允许进程在满足特定条件之前等待，并在条件满足后唤醒等待的进程。

总的来说，managed_shared_memory 提供了一种方便的方式来实现多个进程之间的数据共享和交换。

它通过使用共享内存、内存分配、对象构造和析构、同步和互斥机制等核心功能来实现多进程之间的数据共享。

rosservice serviceproxy使用例子-回复ServiceProxy是ROS中的一个重要工具，用于在ROS节点之间进行服务调用。

本文将介绍ServiceProxy的使用方法，并以一个实际的例子来说明其具体应用。

一、什么是ServiceProxy？在ROS中，ServiceProxy是一个客户端工具，用于调用运行在其他节点上的服务。

它可以像调用本地函数一样调用远程节点中的服务，并接收返回结果。

ServiceProxy的工作原理很简单，它首先连接到指定的服务，然后发送请求，并等待服务节点的响应。

一旦收到响应，ServiceProxy将返回结果给调用者。

二、ServiceProxy的使用步骤1. 导入ServiceProxy类首先，在Python脚本中导入ServiceProxy类。

ServiceProxy类通常来自于rospy库。

pythonimport rospyfrom rospy import ServiceProxy2. 初始化ROS节点在使用ServiceProxy之前，需要先初始化ROS节点，以便与ROS系统建立通信。

pythonrospy.init_node('service_proxy_node')3. 创建ServiceProxy对象使用导入的ServiceProxy类创建一个ServiceProxy对象，并传入要调用的服务名称和服务类型。

pythonservice_proxy = ServiceProxy('service_name', ServiceType)这里，'service_name'是要调用的服务的名称，ServiceType是该服务的类型。

4. 调用服务通过ServiceProxy对象的调用方法，可以调用远程服务。

pythonresponse = service_proxy(request)在调用方法中，request是要发送给服务的请求参数，而response则是服务的返回结果。

managed_shared_memory工作原理1. 创建共享内存区域：首先，使用managed_shared_memory类创建一个共享内存区域。

可以指定一个名称和一些初始参数来描述这个共享内存区域。

这些参数包括共享内存区域的大小、权限等。

2. 分配共享内存：在共享内存区域中分配一些共享对象的内存空间。

可以使用placement new运算符来在共享内存中构造对象。

3.共享内存中的对象使用：将共享内存分配给多个进程使用。

进程可以使用共享内存中的对象，读取或修改它们的成员变量，调用它们的成员函数等。

4.同步机制：由于多个进程同时访问共享内存区域，为了防止数据冲突和保护共享资源，需要使用一些同步机制。

C++标准库提供了一些同步原语，如互斥锁、信号量等。

在访问共享内存时，进程需要通过这些同步原语来保证数据的一致性和正确性。

5. 对象销毁和内存释放：当进程不再需要使用共享内存中的对象时，需要显式地销毁这些对象并释放内存。

这可以通过调用对象的析构函数和使用placement delete运算符来实现。

当所有的对象都被销毁后，共享内存区域也可以被销毁和释放。

1. 跨平台支持：managed_shared_memory可以在不同操作系统上使用，如Windows、Linux等。

这使得它具有很好的可移植性和兼容性。

2. 空间效率高：managed_shared_memory使用虚拟内存技术，可以灵活地将共享内存映射到进程的地址空间。

这样可以最大程度地减小内存的使用。

3. 线程安全：managed_shared_memory提供了一些同步机制，如互斥锁、信号量等，可以保证多个进程对共享内存的并发访问的正确性和一致性。

4. 支持动态管理：managed_shared_memory允许在运行时动态地创建、销毁和调整共享内存区域的大小。

这为程序的设计和扩展提供了更大的灵活性。

总结起来，managed_shared_memory是通过虚拟内存技术来实现进程间共享内存的一种机制。

k8s 中service暴露端口,外部可以访问的原理-回复Kubernetes (K8s) 是一种开源的容器编排和管理平台，广泛用于应用程序的部署和管理。

在K8s中，Service是一种用于暴露应用程序由Pod组成的逻辑集合的对象。

通过Service，可以实现将应用程序暴露给集群内部和外部访问的需求。

那么，在K8s中，Service是如何暴露端口并允许外部访问的呢？本文将详细介绍K8s中Service暴露端口的原理。

1. Service是什么在K8s中，Service是一种抽象，用于将一组由Pod组成的逻辑集合公开为一个单一的DNS名称。

这样，其他应用程序或用户可以通过这个DNS 名称来访问Service所代表的所有Pod。

Service充当了一组Pod的负载均衡器，它将请求分发给后端的Pod。

这种抽象隐藏了底层Pod的细节，使得应用程序无需考虑具体的Pod IP地址和端口，从而实现了在K8s集群内动态地访问后端应用程序。

2. Service类型在K8s中，有三种类型的Service，分别为ClusterIP、NodePort和LoadBalancer。

- ClusterIP：默认类型，该类型的Service只会在集群内部进行通信，即只能被集群内的其他应用程序访问，无法从集群外部访问。

- NodePort：该类型的Service会在每个节点上监听一个端口，并通过该端口将外部流量转发到Service所代表的Pod。

这样，可以通过集群节点的IP地址和相应的端口来访问Service。

- LoadBalancer：该类型的Service会根据云厂商提供的负载均衡器来将请求分发给Service所代表的Pod。

这样，不仅可以通过集群节点的IP 地址和端口访问Service，还可以通过云负载均衡器提供的外部IP地址来访问Service。

3. Service暴露端口的原理# ClusterIP类型的Service对于ClusterIP类型的Service，它默认只能在集群内部访问，无法从集群外部访问。

android共享内存(ShareMemory）的实现Android 几种进程通信方式跨进程通信要求把方法调用及其数据分解至操作系统可以识别的程度，并将其从本地进程和地址空间传输至远程进程和地址空间，然后在远程进程中重新组装并执行该调用。

然后，返回值将沿相反方向传输回来。

Android 为我们提供了以下几种进程通信机制（供开发者使用的进程通信 API）对应的文章链接如下：•文件•AIDL （基于 Binder）•Binder•Messenger （基于 Binder）•ContentProvider （基于 Binder）•Socket在上述通信机制的基础上，我们只需集中精力定义和实现 RPC 编程接口即可。

如何选择这几种通信方式这里再对比总结一下：•只有允许不同应用的客户端用 IPC 方式调用远程方法，并且想要在服务中处理多线程时，才有必要使用 AIDL•如果需要调用远程方法，但不需要处理并发 IPC，就应该通过实现一个Binder 创建接口•如果您想执行 IPC，但只是传递数据，不涉及方法调用，也不需要高并发，就使用 Messenger 来实现接口•如果需要处理一对多的进程间数据共享（主要是数据的 CRUD），就使用ContentProvider•如果要实现一对多的并发实时通信，就使用 Socketimage.pngIPC分析：android IPC的核心方式是binder，但是android binder的传输限制1M(被很多进程共享)，在较大数据交换一般通过文件，但是效率很低，因此介绍下新的内存共享方式： ShareMemory具体实现：通过binder把MemoryFile的ParcelFileDescriptor 传到Service；在服务端通过ParcelFileDescriptor 读取共享内存数据；•客户端 LocalClient.java 通过MemoryFile获取ParcelFileDescriptor，通过Binder把ParcelFileDescriptor(int类型)传递到服务端•服务端 RemoteService 获取到ParcelFileDescriptor 之后，有两种方式第一种：通过FileInputStream 读取ParcelFileDescriptor 的FD，此种方式的问题在于，每次读取之后FD的游标都在文件最后(也就是说第二次读取结果是不低的，必须重置FD的游标) 第二种：就是通过反射，直接ParcelFileDescriptor构建MemoryFile，然后读取，此种方式问题在于26和27实现的不同，代码如下：Android P（9.0）反射限制: 上述反射的方式在android P上被限制(android 9.0禁止通过放射调用系统的的非公开方法)，此路不同(If they cut off one head, two more shall take it's place... Hail Hydra.)，还有千万条路•ShareMemory android O(8.0)之后增加新的共享内存方式，SharedMemory.java 此类继承Parcelable，可以作为IPC通讯传输的数据；•ClassLoader 多态：此方式并非真正的多态，而是根据ClassLoader类的加载顺序，在应用中构建一个和系统类同样包名的类(方法也同名，可以不做实现)，编译时使用的应用中的类，运行时加载的是系统中的类，从而实现伪多态；GitHub:ShareMemory优点：binder 限制（binder的android上的限制1M，而且是被多个进程共享的）; binder 在android进程中经过一次内存copy，内存共享通过mmap，0次copy效率更高；。

android sharedmemory用法全文共四篇示例，供读者参考第一篇示例：Android SharedMemory是一种用于在多个进程之间共享数据的机制。

它允许不同应用程序之间共享大块内存，这对于需要高性能数据交换的应用程序非常有用，比如多媒体应用程序或游戏。

在Android系统中，每个进程都有自己的独立地址空间，因此默认情况下进程之间不能直接共享内存。

但是Android SharedMemory 提供了一种方法让不同进程之间可以共享内存块。

这种共享内存块创建的共享内存区域可以由不同进程映射到自己的地址空间中，从而实现数据共享。

SharedMemory的用法非常简单，首先需要创建一个SharedMemory对象，然后使用该对象创建一个共享内存区域，并将数据写入其中。

接着，其他进程可以通过SharedMemory对象来访问共享内存区域，即可以将这个内存区域映射到自己的地址空间，并读取其中的数据。

在Android中，可以使用SharedMemory API来实现SharedMemory的功能。

下面是一个基本的SharedMemory用法示例：1. 创建SharedMemory对象SharedMemory sharedMemory =SharedMemory.create("shared_memory_name", 1024);这行代码创建了一个名为"shared_memory_name"，大小为1024字节的共享内存区域。

2. 写入数据这段代码将"Hello, SharedMemory!"这个字符串写入了共享内存区域中。

3. 读取数据SharedMemory sharedMemory =SharedMemory.create("shared_memory_name", 1024);ByteBuffer byteBuffer = sharedMemory.mapReadOnly();byte[] data = new byte[1024];byteBuffer.get(data);通过上面的示例，我们可以看到SharedMemory的基本用法。

一、什么是rpcserviceclientRPC（Remote Procedure Call）是一种远程过程调用的技术，允许客户端程序调用服务器上的程序而不需要了解底层的网络细节。

rpcserviceclient是一个用于访问远程过程调用服务的客户端工具，它提供了方便的接口和方法来与远程服务器进行通信，并调用其提供的服务。

二、 rpcserviceclient使用方法1. 导入依赖在使用rpcserviceclient之前，需要在项目中导入相应的依赖。

通常情况下，可以通过Maven或者Gradle等工具来管理依赖，并在项目的配置文件中添加rpcserviceclient所需的依赖项。

2. 创建rpcserviceclient实例在项目中，可以通过以下方式来创建rpcserviceclient的实例：```RPCServiceClient rpcClient = new RPCServiceClient();```通过这个实例，可以实现与远程服务器的连接并进行通信。

3. 设置服务器位置区域和端口在创建rpcserviceclient实例之后，需要通过以下方法来设置要访问的服务器的位置区域和端口号：```rpcClient.setServerAddress("127.0.0.1");rpcClient.setServerPort(8080);```这里需要根据实际情况设置服务器的位置区域和端口号。

4. 创建请求参数在调用远程服务时，通常需要传递一些参数给服务器。

可以通过以下方法创建请求参数：```RPCRequest request = new RPCRequest();request.setMethod("add");request.setParams(new Object[]{1, 2});```这里设置了要调用的方法名和参数。

5. 发送请求创建好请求参数之后，就可以通过rpcserviceclient来发送请求，并获取服务器返回的结果：```RPCResponse response = rpcClient.sendRequest(request);```通过这个response对象，可以获取服务器返回的结果，并进行后续处理。

品管处专业词汇表8D 8 Discipline 处理问题手法AQL Acceptable Quality Level 可接受质量水平ASL Approved Supplier List 合格供应商清单AVL Approved Vendor List 合格供应商清单CA Corrective Action 纠正措施CIFIR Combined Initial Field Incident RateCIP Continuous Improvement Process 持续改进过程CLCA Closed Loop Corrective Action 闭环纠正措施CSD Customer Service DeliveryDOA Dead On Assembly 生产线出现的不良件DOE 试验设计DPHU Defects Per Hundred Units 故障率（百分之几）DPPM Defective Parts Per Million 故障率（百万分之几）ECN Engineering Change Notice 工程变更通知ECO Engineering Change Order 工程变更指令EMR Electromechanical Repair 电动机械修复ERP Enterprise Resource Plan 企业资源规划ESG Enterprise Systems GroupFA Failure Analysis 错误分析FAI First Article Inspection 首件确认FCS First Customer ShipFIFO Front In Front Out 先进先出原则FMEA Failure Model Effectiveness Analysis 失效模式与影响分析FQC Final Quality Control 成品检验FTA Failure Tree Analyze 故障树分析GR&R Gage Repeatability & ReproducibilityGSQE Global Supplier Quality Engineer 全球供应商质量工程师IFIR Initial Field Incident RateIQA Incoming Quality Assurance 来料检验IQC Incoming Quality Control 进料品质管制(人员)IPQC In Process Quality Control 制程中的品质管制(人员)JIT Just In Time 准时生产JQE Joint Quality Engineer 联合质量工程师LOB Line of Business 业务线LRR Line Reject Rate 在线淘汰率MQE Manufacturing Quality Engineer 制程质量工程师MRB Material Review Board 材料对照表MTBF Mean Time Between Failures 平均无故障间隔时间MWD Missing, Wrong, Damaged 少的、错的、坏的N/A Not Applicable 不适用NFF No Fault FoundNG No Good 不行，不合格NTF No Trouble Found 问题不复现OBA Out of Box AuditOCM Operational Commodity ManagerOQC Output Quality Control 最终出货品质管制(人员)<针对将出厂的产品> ORT Ongoing Reliability Test 出货可靠性实验OTFTF On Time First Time FixPoka Yoke 防差错设计PDCA Plan, Do, Check, Action 戴明质量环（计划，执行，检查，总结）PDM Product Data Management 产品数据管理PG Product GroupPM Preventive Maintenance 预防保持PMP Product Management Plan 制程管理计划PPID Piece Part Identification 部件鉴定PrP Phase Review ProcessPSG Personal Systems GroupQC Quality Control 质量控制QE Quality Engineer 品质工程人员(质量工程师)QEI Quality Evaluation Index 质量评价指数QIT Quality Improvement Team 品质改善小组QMP Quality Management Plan 质量管理计划QPA Quality Process Audit 质量过程审核QSA Quality Systems Audit 质量体系审核QTY Quantity 数量RFQ Request For QuoteRMA Reject Material Analyzing 不合格物料分析RMT Reduce Manufacturing Time 缩短生产工时RSM Response Surface Method 响应曲面方法RSQE Regional Supplier Quality Engineer 区域供应商质量工程师RTS Ready To ShipRTV Return To Vender 退回供应商SCM Server Chain Management 供应链管理SCM Strategic Commodity ManagerSCT Strategic Commodity TeamSIP Specification In Process 制程检验规范SOSA Supplier Online Scorecard ApplicationSPC Statistical Process Controls 统计过程控制SPEC Specification 规格SQE Supplier Quality Engineer 供应商质量控制SQS Supplier Quality Standard 供应商质量标准STR Shared Technology Resource groupsTQM Total Quality Management 全面质量管理TTR Technology Transition RoadmapsUAI Use As IsVIFIR Verified Initial Field Incident RateVLRR Verified Line Reject RateWIP Work In Process信息化管理术语简介BPR──Busine ss Process Reengineering业务流程优化CRM──Custermor Relationship Management客户关系管理EIP──Enterprise Information Portal 企业信息门户EDI──Electronic Data Interchange 电子数据交换，电子商务ERP──Enterprise Resource Planning 企业资源计划系统HRM──Human Resource Management 人力资源管理KM──Knowledge Management 知识管理MIS――Management Information System 管理信息系统MRP──Material Requirement Planning 物料需求计划MRP II──Manufacturing Resource Planning 制造资源计划OA──Office Automation 办公自动化SCM──Supply Chain Management 供应链管理。

android vpnservice 原理Android的VPN服务（VPNService）是Android提供的一个内置框架，它允许开发者创建自己的VPN连接，实现安全的远程访问和通信。

在本文中，我们将一步一步地解释Android VPN服务的原理。

1. 什么是VPN？VPN（虚拟专用网络）是一种安全的通信方式，它使用加密和认证机制来保护用户的网络连接。

它通过在公共网络上创建加密的隧道，使用户能够安全地访问私人网络。

VPN可以用于保护隐私、绕过地理限制以及远程访问等场景。

2. VPNService类Android的VPNService类是用于实现VPN连接的关键类。

开发者可以继承这个类，并重写一些关键的方法来自定义VPN连接的行为。

首先，我们需要创建一个继承自VPNService的类。

在这个类中，我们需要实现以下几个方法：- onCreate()：在这个方法中，我们可以进行一些初始化操作，比如创建网络连接和配置参数。

- onStartCommand()：在这个方法中，我们可以处理启动服务的操作，比如建立VPN连接。

- onRevoke()：在这个方法中，我们可以处理VPN连接被取消的情况。

- onDestroy()：在这个方法中，我们可以进行一些资源释放的操作。

3. VPN连接的建立在VPNService类中，我们需要重写onStartCommand()方法来建立VPN连接。

在这个方法中，我们需要创建一个文件描述符（FileDescriptor）来实际建立VPN 连接。

首先，我们需要创建一个TunnelInterface（隧道接口），通过系统提供的VpnService.Builder类来获取一个ParcelFileDescriptor对象。

然后，我们可以使用这个文件描述符来创建网络连接。

在这个过程中，我们可以设置一些连接参数，比如IP地址、DNS服务器和路由表等。

一旦连接建立成功，我们就可以开始处理输入和输出流的数据，实现加密和解密的功能。

开始介绍之前，先看一下本例的界面：Android远程Service调用简介：远程Service调用，是Android系统为了提供进程间通信而提供的轻量级实现方式，这种方式采用一种称为远程进程调用技术来实现，英文名全称是Remote Procedure Call，即RPC。

RPC简介：远程进程调用是指在一个进程里，调用另外一个进程里的服务。

Android通过接口定义语言来生成两个进程间的访问代码。

接口定义语言（Android Interface Definition Language，即AIDL）是Android系统的一种接口描述语言，Android编译器可以将AIDL文件编译成一段JA V A代码，生成相对的接口。

下面来详细介绍下如何通过RPC机制来达到远程进程调用的目的和步骤。

第一，我们要先弄清楚这是怎么样的一个流程。

用通俗点语言来说，打个例子：比如公司A提供A服务，并且这种服务是对外开放的，也就是其他公司或者个人都可以通过某种方式来使用这种服务，公司B想要使用A公司的A服务，就以通过公司A编制的一种形式来使用它。

用图来表示就是：公司B通过公司A的某种形式来使用公司A提供的服务A现在，我们可以说，进程B可以通过进程A提供的某种形式来使用进程A的服务A。

这个过程就是RPC。

了解基本概念之后，我们可以开始进行RPC的实现步骤。

下面我们分点来说明实现RPC 的步骤。

第一、创建AIDL文件。

这个文件和普通的JA V A文件差不多，只不过后缀名是.aidl。

这个文件相当于一个接口，里面要声明一些你想对外提供服务的方法，也就是你要对外暴露的方法。

注意，这个文件里，除了JA V A基本类型和String,List,Map和Charquene类型不需要引入相应的包外，其他的都要引入包。

例如我们创建一个IPerson.aidl文件，里面只声明了一个方法display():package com.test.service;interface IPersonaidl {String display();//该接口里面所有的方法都应该是你想对外暴露的}第二、创建完AIDL文件后，刷新项目，会发现在gen目录对应的目录下会生成一个IPerson.java接口文件，打开该文件，会发现你在aidl文件里面定义的display()方法，不过没有实现。

流程再造理论在财务共享中的作用下载温馨提示:该文档是我店铺精心编制而成，希望大家下载以后，能够帮助大家解决实际的问题。

文档下载后可定制随意修改，请根据实际需要进行相应的调整和使用，谢谢!并且，本店铺为大家提供各种各样类型的实用资料，如教育随笔、日记赏析、句子摘抄、古诗大全、经典美文、话题作文、工作总结、词语解析、文案摘录、其他资料等等，如想了解不同资料格式和写法，敬请关注!Download tips: This document is carefully compiled by theeditor.I hope that after you download them,they can help yousolve practical problems. The document can be customized andmodified after downloading,please adjust and use it according toactual needs, thank you!In addition, our shop provides you with various types ofpractical materials,such as educational essays, diaryappreciation,sentence excerpts,ancient poems,classic articles,topic composition,work summary,word parsing,copy excerpts,other materials and so on,want to know different data formats andwriting methods,please pay attention!流程再造理论在财务共享中的重要性在当今的商业环境中，流程再造理论已逐渐成为推动企业效率提升和优化运营的关键工具。

表达对朋友的思念英语作文全文共3篇示例，供读者参考篇1Missing My Best FriendI never imagined how much I would miss having Sam by my side after he moved away last summer. We had been inseparable best friends since we were little kids growing up on the same street. Now with him living across the country, there's aSam-shaped hole in my life that nothing else can quite fill.We did absolutely everything together - going to the same schools, being on all the same sports teams, riding our bikes around the neighborhood, video gaming for endless hours, you name it. My earliest memories are of the two of us causing mischief and getting into trouble, with our parents laughing and shaking their heads at our latest shenanigans. We were infamous partners in crime, a dynamic duo.I remember one time when we were about 8 years old, we got it into our crazy minds that we wanted to go exploring in the woods behind Sam's house. This was strictly forbidden by our parents who worried about us getting lost or hurting ourselvesout there. But like the rebellious little troublemakers we were, we snuck off into the forest one afternoon without telling anyone.At first it was an exhilarating adventure trekking through the trees and brush. But after what felt like hours of wandering, we became hopelessly lost and terrified. We started crying and calling out for help until thankfully Sam's dad found us and carried us home, scolding us the whole way but also relieved we were safe. That didn't stop us from getting grounded for what seemed like an eternity at the time! Adventures like that were just par for the course with me and Sam.As we got older, we still remained joined at the hip through our high school years. We tried out for the same teams, went to all the same parties, and spent countless Study Hall periods goofing off instead of doing work. We had so many amazing memories - celebrating championships, going to prom, pulling endless pranks, and getting into hilarious mishaps along the way.I'll never forget this one time after winning the championship game for our high school basketball team senior year. Sam and I were such adrenaline junkies caught up in the thrill of victory. Without even thinking it through, we made an impulsive decision to climb up the scaffolding on theconstruction site next to the gym to keep celebrating at the top. Because you know, what could go wrong with that brilliant idea?Next thing we knew, we were being apprehended and handcuffed by the police at 2 am for trespassing. I still have that mugshot photo framed in my room, his goofy smile plastered on his face as usual. We had to do community service to clear the charges, but we're still proud of pulling one of the most iconic senior pranks our high school had ever seen.That's just the kind of dynamic Sam and I had - always down for the next adrenaline rush, constantly chasing that endorphin high together through stupid stunts.Looking back now as a college freshman, I realize just how much I taken for granted having him as my partner through all the dumb ideas and incredible experiences we lived. Don't get me wrong, I've made some great new friends here at university. But that bond I had with Sam , that complete trust and willingness to follow each other off any cliff, that's something truly rare and special. We always just got each other on such a deep level after knowing one another literally our entire lives.My friends here are cool and everything, but they'll never quite understand the depth of my connection with Sam. They didn't grow up having backyardcamp-outs in the treehouse webuilt with our dads, or trading disgustingly aged snacks we had stashed away in our childhood hidey-holes years ago. Without Sam here, it feels like a huge part of my past and present is simply missing.Some of my favorite nights in recent memory were just the two of us hanging out, playing video games and swapping stories all night long like we were 10-year-old kids again instead of heading off to college soon. We'd laugh about reliving our childhood memories until our sides hurt and stomachs were sore. It felt like we were the only two people on the planet whopolitely understood the jokes and references we were making.But those all-night bro bonding sessions are no more with Sam being thousands of miles away now. Instead, our communication is limited to pathetically infrequent texts, Snapchats, and gaming sessions when our schedules miraculously sync up. Technology is great and all for keeping that connection somewhat alive, but it just doesn't compare to actually being in each other's presence and presence. Everyfirst thing I still reflexively think to tell Sam whenever something interesting happens in my life... only to remember with a pang that he's not right there by my side to regale with it anymore.Sam was the first real best friend I ever made, and I always took for granted that he would be by my side forever as we navigated life together. I think I convincedmyself somewhere inalong the way that we'd be a modern-day version of two lovable old men still causing hilarious hijinks in our twilight years.Now with this extended stint of separation facing us for the foreseeable future. I feel like I'm mourning the loss of that imagined life-long partnership in real time, at least for now. Who knows whatwill happen as life' unpredictability unfolds, but I'm terrified that our friendship will slowly disintegrate into infrequent text NEAR catching up for old time's sake. That bonds willfade and inside jokes forgotten as we become shady acquaintances instead of bonded-for-life comrades.The tight vest that prison hoursharges we had is slowly unraveling with this distance creating an ever-expanding gap between us. I wonder if one day I'll be looking at Sam as more of a long-lost friend from the past, rather than an active present in my life. That would be one of my biggest regrets to let such an incredibly special platonic relationship wither away into obsolescence.For now, I have to cherish the memories Sam I created overapx two decades of unbridled chaos and laughter that wecaused. No matter how much physical distance separates us, those coveted moments of brotherhood he andare comparewarped together for eternity. I have to keep reminding myself that while we may not be able to share the same experiences side-by-side for a while, our connection runs far too deep to let something as trivial as miles between us toworry shatter it.Our friendship was forged over rites of passage starting from those carefree childhood days of perpetual make-believe andure adventure-seeking. It blossomed through thecringe-worthy awkwardness of puberty, adolescence and all its growth that helps tw o people figure outAct how the title character. And ultimately it was solidified by the unpredictable rollercoaster of crazy high school yearsean andtestrun shared each other. Those bonds don't just disintegrate from being apart temporarily, right?So while I miss Sam's presence more than I could everaguearding words, I chpathmaintaining our connection meanseverything tomiforgettable codin. Imightn'tbacks,t pubeArtbehavior link but I'lloops havove goonthose useiter memories oftwidity was built on. Andh lake him, tered inserversbridgedmss chaos and laughter that builtis legendary broath us oveearmed. NoI need to stay eagerly await the next time hs philosophers andand I can cause some equallyeban gives us our youth link mischief, because you knowbpr0t0 itnships will happen eventually. For now, it's keeping the faith that ourlastmiles, ...between tweeplicati0nrecognizes Sam andme as bestfriends forever. And no partition, however washall preventdynamic duo from causing infinitely more insanity in the time we still have left.篇2Missing My Best FriendI never imagined how much I would miss Samantha after she moved away last summer. We had been inseparable best friends since kindergarten, living just two blocks apart. We walked to school together every morning, spent evenings at each other's houses, and summers were one long sleepover adventure. Samantha was basically a sister to me.When her dad got a new job across the country, I was devastated that she would be leaving. The weeks leading up to her departure were a blur of tears, reminiscing about all ourfavorite memories, and making promises to visit each other. I don't think either of us truly grasped how different things would be.That first day of 6th grade without Sam was one of the loneliest of my life. I kept looking over at the empty desk beside me expecting her bright smile and a friendly wave. The walk home alone was agonizing. Her house that I had practically lived at now had a "For Sale" sign out front, mocking me. I tried calling but just ended up crying into the phone.In the days and weeks after, everything reminded me of Samantha. I missed her goofy jokes and contagious laughter filling the halls between classes. I missed her supporting me from the sidelines at soccer games. I missed our yearly traditions like dressing up as humorous duo costumes for Halloween. Without her there, it all felt empty.At first we sent constant text updates about the tiny details of our days, but it's just not the same as experiencing it together.I realized I took for granted all the little moments - making comedy show commentaries under our breath, previewing new cafeteria food creations, or just zoning out during class lectures by passing silly doodles back and forth.As the months passed, things still didn't feel right without my best friend around. I struggled making new friends, haunted by this void where Sam used to be. Other kids seemed to pick up on my loneliness and insecurity, avoiding the sad girl. It was a vicious cycle of isolation.Phone calls and video chats helped slightly, but there's something deeply unsatisfying about long-distance conversation. You can't truly share experiences virtually. I wanted a reassuring hug after a rough day, not just a flat "That's terrible, I'm so sorry" over pixels. I wanted to share a celebratory high-five for accomplishments, not type "Congrats!" with a emoji.While Samantha seemed to be adapting and finding her way in her new town, making new friends at her new school, I felt left behind. The jealousy added another complicated layer to my sadness at her leaving. I didn't want to resent her happiness without me, but I couldn't help missing how it used to be.I busied myself with schoolwork, sports, and other extracurriculars to distract from the Samantha-sized hole in my life. But nothing could fill that void of such a deep, lasting friendship. I started doubting if we would ever really pick up where we left off if she visited over breaks. What if the magical bond that made us so close was fading by the day?Last month, Sam did come to visit for her birthday during spring break. It started off awkward, like we were both overthinking our interactions, afraid of shattering old memories. But after a few deep breaths and some tentative jokes that landed well, we fell back into our old rapport. The laughter and inside jokes flowed effortlessly again. Her presence went from haunting to healing.It was gut-wrenching when she left again, of course. But I felt a rekindled sense of hope that our friendship could survive the test of distance and change. The ache is still there, don't get me wrong. I miss my best friend every single day. But I now have faith that our bond is strong enough to pick up easily whenever we're reunited.Samantha's departure taught me the intense value offace-to-face friendship. Digital connections can never replace the intimacy of shared experiences and quality time together. It also showed me the resilience of our bond - no matter the miles, no matter the months apart, when we're together it's like no time passed at all. We shape each other's lives so fundamentally.While I desperately wish I could hit rewind and keep Sam by my side always, I've gained perspective on the rarity of such an enduring friendship. Out of everyone I've ever met, she saw meat my worst and best, knew all my embarrassing quirks, made more inside jokes than I could count, and wholeheartedly accepted the real me. How many people are lucky enough to have that?So I'll continue counting the days until summer, when Sam visits for an entire glorious month. I'll text her daily dumb tweets to maintain our comedian connection. And I'll soak in every second we're reunited to bank more priceless memories to replay in my head during those inevitable lonely days ahead. Because that's what you do for your life confidante, your partner in crime, your very best friend in the world.篇3Missing My Best FriendAs I sit here alone in my bedroom, I can't help but feel a deep sense of longing and nostalgia. It's been nearly a year since I last saw my best friend, Jessica, and the distance between us has never felt greater. We used to be inseparable, sharing secrets, laughing until our sides hurt, and making memories that I'll cherish forever. But now, with her family having moved across the country, our once unbreakable bond has been tested by the cruel hands of fate.I remember the day she told me the news like it was yesterday. We were lounging in her backyard, basking in the warm summer sun, when she broke the silence with a trembling voice. "My dad got a new job offer," she said, her eyes already brimming with tears. "We're moving to California at the end of the summer." Those words hit me like a ton of bricks, and for a moment, I couldn't breathe. California might as well have been on the other side of the world.In the weeks that followed, we tried our best to make the most of the time we had left together. We went on adventures, explored every nook and cranny of our small town, and stayed up late into the night, talking and laughing as if there was no tomorrow. But as the dreaded moving day drew nearer, a heavy cloud of sadness loomed over us, threatening to burst at any moment.The morning of her departure was one of the hardest days of my life. We clung to each other, tears streaming down our faces, promising to stay in touch and visit as often as possible. But as her family's car pulled away, taking her further and further from me, I felt a piece of my heart being ripped away.In the months that followed, we tried our best to maintain our friendship through texts, calls, and video chats. But as thedays turned into weeks, and the weeks into months, the once constant communication became sporadic and strained. We were both busy with new schools, new friends, and new lives, and the distance between us seemed to grow wider with each passing day.Sometimes, I'll catch myself reminiscing about the good old days, when we were just a couple of carefree kids, blissfully unaware of the challenges that lay ahead. I'll remember the time we tried to build a treehouse in her backyard, only to have it come crashing down around us. Or the time we snuck out past curfew to go stargazing, lying on the grass and dreaming about our future adventures.But as much as I cherish those memories, they also serve as a painful reminder of what I've lost. I miss the way we could communicate with just a glance, the way we finished each other's sentences, and the way we always seemed to be on the same wavelength. I miss the comfort of having someone who truly understood me, flaws and all, and accepted me for who I was.Of course, I've made new friends since Jessica's departure, and they've been an incredible source of support and companionship. But there's something about that childhood bond, forged in the fires of shared experiences and unwaveringloyalty, that can never be replicated. Jessica was more than just a friend; she was my partner in crime, my confidante, and my sister in all but blood.As the days turn into weeks, and the weeks into months, I hold onto the hope that our paths will cross again someday. Maybe we'll reunite at a high school reunion, or perhaps our lives will take us to the same city, allowing us to pick up where we left off. Or maybe, just maybe, the universe will conspire to bring us back together in some unexpected way, reminding us of the unbreakable bond that exists between two kindred spirits.Until then, I'll continue to cherish the memories we made and the lessons we learned together. I'll carry her with me wherever I go, a constant reminder of the power of true friendship and the unbreakable bonds that transcend time and distance. And when the world feels like a lonely, overwhelming place, I'll close my eyes and remember the sound of her laughter, the warmth of her embrace, and the unwavering love and loyalty that only a true best friend can provide.。

vipserver工作原理1. 什么是vipserver在计算机和网络领域，vipserver通常指的是Virtual IP Server，即虚拟IP服务器。

它是一种网络架构，通过虚拟IP技术实现服务器的负载均衡、高可用性和故障切换等功能。

本文将深入探讨vipserver 的工作原理，以及它在网络中的应用。

1.1 虚拟IP技术虚拟IP技术是vipserver实现其功能的关键。

通过虚拟IP，多个服务器可以共享同一个IP地址，实现负载均衡和高可用性。

1.2 服务器集群vipserver通常与服务器集群结合使用，集群中的多台服务器共同对外提供服务。

vipserver负责分发流量和管理这些服务器，以提高整体性能和稳定性。

2. 负载均衡vipserver的一个主要功能是实现负载均衡，即将客户端请求均匀地分发到服务器集群中的各个节点，避免单一节点负载过重。

2.1 请求分发算法vipserver使用不同的算法来分发请求，常见的算法包括轮询、加权轮询、最小连接数等。

这些算法根据服务器的性能和负载情况动态调整流量分发。

2.2 会话保持在某些应用场景中，需要确保用户的请求能够持续地发送到同一服务器，以保持会话状态。

vipserver通过会话保持技术实现这一目标，确保用户体验的连续性。

3. 高可用性和故障切换vipserver通过监控服务器的状态，实现高可用性和故障切换。

当某个服务器发生故障或不可用时，vipserver会自动将流量重新分发到其他正常工作的服务器上。

3.1 健康检查vipserver通过定期的健康检查来监测服务器的状态，包括网络连通性、负载情况等。

一旦发现故障，它会及时做出调整。

3.2 无缝切换在服务器发生故障时，vipserver能够实现无缝切换，确保用户感知不到服务的中断。

这一特性对于保障服务的连续性至关重要。

4. 内容缓存与加速vipserver还可以通过内容缓存和加速技术，提升用户访问网站时的响应速度和性能。

serviceentry 工作原理
ServiceEntry是Istio中的一个组件，它用于定义服务入口的规则和配置。

ServiceEntry可以用来描述集群内或集群外的服务入口，包括外部服务、云服务、虚拟机、物理主机等。

ServiceEntry的工作原理如下：
1. 用户在Istio中创建一个ServiceEntry对象，该对象包含了服务的名称、IP地址、端口等信息。

2. 当有服务流量需要到达指定的服务时，Istio的数据平面（Envoy代理）会根据ServiceEntry中定义的规则进行流量路由。

3. 如果ServiceEntry中定义了集群内的服务入口，Envoy代理会使用集群内部的负载均衡机制将流量路由到对应的服务实例。

4. 如果ServiceEntry中定义了集群外的服务入口，Envoy代理会将流量转发到外部服务的IP地址和端口。

5. 在流量转发过程中，Envoy代理还会执行一些其他的操作，比如流量控制、安全认证等。

ServiceEntry是Istio中的一个重要组件，它通过定义服务入口的规则和配置，实现了对服务流量的路由和转发。

Package‘rcoder’October6,2023Type PackageTitle Lightweight Data Structure for Recoding Categorical Data withoutFactorsVersion0.3.0Description A data structure and toolkit for documenting and recodingcategorical data that can be shared in other statistical software.License MIT+file LICENSEEncoding UTF-8Depends R(>=3.5)Imports rlang,glue,dplyrSuggests testthat(>=2.1.0),tidyfast,magrittrRoxygenNote7.2.1URL https:///nyuglobalties/rcoderBugReports https:///nyuglobalties/rcoder/issuesNeedsCompilation noAuthor Patrick Anker[aut,cre](<https:///0000-0003-2302-0445>), Global TIES for Children[cph](https:///ihdsc/global-ties)Maintainer Patrick Anker<***************>Repository CRANDate/Publication2023-10-0608:30:05UTCR topics documented:assign_coding (2)as_coding_list (3)code (3)coding (4)coding_to_haven_labels (5)coding_to_odk (5)12assign_coding eval_coding (6)is_empty_coding (7)link_codings (7)make_recode_query (8)matches_coding (9)missing_codes (10)odk_to_coding (10)recode_vec (11)Index13 assign_coding Adds a coding as an attribute to a vectorDescriptionStores a coding at the"rcoder.coding"attribute of a vectorUsageassign_coding(vec,.coding,.bpr=TRUE)Argumentsvec A vector.coding A‘coding‘object.bpr Also overwrite the"bpr.coding"attribute with the character representation of ‘.coding‘.Used for interop with blueprintr variable decorations.ValueThe vector with its"rcoder.coding"attribute set to‘.coding‘See Also[recode_vec()]Examplescdng<-coding(code("Yes",3),code("Maybe",2),code("No",1))vec<-sample(1:3,50,replace=TRUE)assign_coding(vec,cdng)as_coding_list3 as_coding_list Evaluate a collection of codings from a character vectorDescriptionEvaluate a collection of codings from a character vectorUsageas_coding_list(x)Argumentsx A character vectorValueA list of codingsExampleschar_vec<-c("coding(code( Yes ,1),code( No ,0))","")as_coding_list(char_vec)code Encode a label to a value with other metadataDescriptionThe most fundamental components of a‘code‘object are the‘label‘and‘value‘elements.A‘code‘object is essentially a key-value tuple that has some extra metadata.Usagecode(label,value,description=label,links_from=label,missing=FALSE,...)4codingArgumentslabel A short label for a value in a vectorvalue The raw value found in the respective vectordescription A longer-form label for the value,if extra context for that label is neededlinks_from A reference to another‘code‘in another‘coding‘object for recoding purposes.missing Whether this‘code‘represents a missing response...Any extra metadataValueA‘code‘object that contains the key-value map of label to valueExamplescode("Yes",1)code("No",0)code("No response",-88,description="Participant ignored question when prompted",missing=TRUE)code("Missing",NA,links_from=c("Refused","Absent"))coding Catalog the categorical data representation in a vectorDescriptionA‘coding‘object holds a list of‘code‘s that map vector values to human readable labels.An abstraction of factors,this data structure is designed to be portable and not directly attached to the underlying data.Moreover,‘coding‘objects can be"linked"for recoding and data lineage purposes.An"empty coding"is used to represent data that has no categorical interpretation.Usagecoding(...,.label=NULL)empty_coding()Arguments...A collection of‘code‘objects.label A label for this coding,available for interoperabilityValueA‘coding‘object that contains each‘code‘inputcoding_to_haven_labels5Examplescoding(code("Yes",1),code("No",0),code("Not applicable",NA))empty_coding()coding_to_haven_labelsConvert coding to‘haven‘-compatible labelsDescriptionConverts a‘coding‘object into a named vector to be used in the‘labels‘parameter for‘haven::labelled()‘. Usagecoding_to_haven_labels(coding)Argumentscoding A coding objectValueA named vector representation of the codingExamplescdng<-coding(code("Yes",1),code("No",0))coding_to_haven_labels(cdng)coding_to_odk Convert a coding object to ODK XLSForm choicesDescriptionODK XLSForms link the categorical codings to a variable type name in the’survey’sheet.The codings are specified in the’choices’sheet which has a‘list_name‘column that holds the variable type names.Each row that has that name will be associated with that categorical type coding.This function converts‘coding‘objects into tables that can be inserted into that’choices’sheet.The categorical type is specified with the coding‘.label‘.Usagecoding_to_odk(coding)Argumentscoding A coding object6eval_coding ValueA data.frame or tibble that can be included in an XLSForm’choices’sheetSee Also[odk_to_coding()]Examplescdng<-coding(code("Yes",1),code("No",0),.label="yesno")coding_to_odk(cdng)eval_coding Evaluates a coding expression in a safe environmentDescriptionTo prevent requiring attaching the‘rcoder‘package,this function takes in an unevaluated expression –assumed to be a‘coding()‘call–and evaluates the expression with_only_‘coding‘and‘code‘provided to guard against rogue code.Usageeval_coding(expr)Argumentsexpr An expressionValueAn evaluated‘coding‘objectExampleseval_coding( coding(code("Yes",1),code("No",0)) )is_empty_coding7 is_empty_coding Is an object the empty coding?DescriptionIs an object the empty coding?Usageis_empty_coding(x)Argumentsx An objectValueTRUE/FALSE if the object is identical to‘empty_coding()‘Examplesis_empty_coding(empty_coding())is_empty_coding(coding())is_empty_coding(coding(code("Yes",1),code("No",0)))link_codings Link a coding from others for recodingDescriptionCoding objects can be linked together to create mappings from one or more codings to another.This creates a‘data.frame‘that outlines how the codings are linked,to be used in‘make_recode_query()‘.Usagelink_codings(to,...,.to_suffix="to",.drop_unused=FALSE)Argumentsto A coding to be linked to...Codings to be linked from.to_suffix A suffix signifying which columns in the output‘data.frame‘came from‘to‘.drop_unused Logicalflag to drop any codes in‘...‘that have no counterparts in‘to‘8make_recode_queryValueA‘linked_coding_df‘with all necessary information for a recoding queryExampleswave1<-coding(code("Yes",1),code("No",2),code("Refused",-88,missing=TRUE))wave2<-coding(code("Yes","y"),code("No","n"),code("Missing",".",missing=TRUE))link_codings(to=coding(code("Yes",1),code("No",0),code("Missing",NA,links_from=c("Refused","Missing"))),wave1,wave2)make_recode_query Make a recoding call from linked codingsDescriptionThis creates a function that accepts a vector and recodes it from the information provided in a ‘linked_coding_df‘.Usually this is intended for package authors who want to operate at the re-coding relational table level(e.g.mapping multiple codings to one).Most end users should use [recode_vec()]instead.Usagemake_recode_query(linked_codings,from=1,to_suffix="to",...)Argumentslinked_codings A‘linked_coding_df‘from A character or integer that selects the correct original coding.Defaults to1,the first linked coding.to_suffix The suffix used to signify which columns refer to values to which the vector will be recoded...Any other parameters passed onto the recoding function selectormatches_coding9ValueA function with single argument when applied to an input vector will recode the vector appropriatelyExamplescdng_old<-coding(code("Yes",1),code("No",2))cdng_new<-coding(code("Yes",1),code("No",0))recode_func<-make_recode_query(link_codings(cdng_new,cdng_old))vec<-sample(1:2,20,replace=TRUE)recode_func(vec)matches_coding Checks if vector’s content adheres to a codingDescriptionPerforms to check to see if the set of vector values are equal to or a subset of a coding’s values. Usagematches_coding(vec,coding,ignore_empty=TRUE)verify_matches_coding(vec,coding,ignore_empty=TRUE)Argumentsvec A vectorcoding A‘coding‘objectignore_empty Logicalflag to skip check if coding is emptyValueTRUE/FALSEFunctions•verify_matches_coding():Rather than returning TRUE/FALSE,this function halts execu-tion if‘matches_coding()‘returns FALSE.Examplesvec1<-sample(1:2,10,replace=TRUE)vec2<-sample(0:1,10,replace=TRUE)cdng<-coding(code("Yes",1),code("No",0))matches_coding(vec1,cdng)matches_coding(vec2,cdng)10odk_to_coding missing_codes Get missing codes from a codingDescriptionTakes a coding a returns a new coding with all codes that represent a missing value.Usagemissing_codes(coding)Argumentscoding a codingValueA coding that contains all missing codes.If no codes are found,returns‘empty_coding()‘Examplesmissing_codes(coding(code("Yes",1),code("No",0),code("Missing",NA)))missing_codes(coding(code("Yes",1),code("No",0)))odk_to_coding Convert ODK choices to a codingDescriptionODK XLSForms link the categorical codings to a variable type name in the’survey’sheet.The codings are specified in the’choices’sheet which has a‘list_name‘column that holds the variable type names.Each row that has that name will be associated with that categorical type coding.This function converts subsets of the choices sheet into individual’coding’objects.Usageodk_to_coding(choice_table)Argumentschoice_table A data.frame slice of the"choices"table from an XLSFormValueA‘coding‘object that corresponds to the choices’sliceSee Also[coding_to_odk()]Exampleschoice_excerpt<-data.frame(list_name=rep("yesno",2),name=c("Yes","No"),label=c(1,0))odk_to_coding(choice_excerpt)recode_vec Recode a vectorDescriptionA simple interface to recoding a vector based on the coding linking mechanism.If the vector hasthe"rcoder.coding"attribute,then the coding object stored in that attribute will be used by default. Usagerecode_vec(vec,to,from=NULL,.embed=TRUE,.bpr=TRUE)Argumentsvec A vectorto A coding object to which the vector will be recodedfrom A coding object that describes the current coding of the vector.Defaults to the "rcoder.coding"attribute value,if it exists,_or_the"bpr.coding"value(fromblueprintr).If neither are found,‘from‘stays‘NULL‘and the function errors..embed If‘TRUE‘,‘from‘will be stored in the"rcoder.coding"attribute.bpr If‘TRUE‘,adds the_character_representation of the coding to the"bpr.coding"ed for interop with blueprintr variable decorationsValueThe recoded vectorSee Also[assign_coding()]Examples#Using an explicit fromvec<-sample(1:3,50,replace=TRUE)cdng_old<-coding(code("Yes",3),code("Maybe",2),code("No",1)) cdng_new<-coding(code("Yes",2),code("Maybe",1),code("No",0)) recode_vec(vec,to=cdng_new,from=cdng_old)#Using an implicit from with assign_coding()vec<-sample(1:3,50,replace=TRUE)vec<-assign_coding(vec,cdng_old)recode_vec(vec,cdng_new)Indexas_coding_list,3assign_coding,2code,3coding,4coding_to_haven_labels,5coding_to_odk,5empty_coding(coding),4eval_coding,6is_empty_coding,7link_codings,7make_recode_query,8matches_coding,9missing_codes,10odk_to_coding,10recode_vec,11verify_matches_coding(matches_coding),913。

k8s的serviceip实现原理Kubernetes（K8s）的Service IP实现原理主要基于iptables或ipvs。

在这里，我们将详细介绍iptables方式。

首先，K8s会在集群的每一个节点上运行一个叫kube-proxy的Pod。

这个Pod负责监听api-server中的Service、EndPoint和Node类型的资源变化事件。

当Service资源发生变化时，kube-proxy会获取Service的配置信息，包括其选择器和端口号等。

然后，kube-proxy会根据Service的配置信息，操作本机的iptables来创建Service IP。

具体来说，kube-proxy会在iptables中添加一些规则，将目标地址为Service IP的数据包转发到后端Pod的IP上。

这些规则通常包括DNAT（目标地址转换）规则和转发规则。

DNAT规则的作用是将数据包的目标地址从Service IP改写为后端Pod的IP。

这样，数据包就能被正确地路由到后端Pod上。

转发规则的作用是将数据包从iptables转发到后端Pod上。

这些规则通常使用iptables的PREROUTING和POSTROUTING链来实现。

当数据包到达节点时，iptables会根据DNAT规则将数据包的目标地址改写为后端Pod 的IP。

然后，数据包会被转发到后端Pod上。

当数据包从后端Pod返回时，iptables会根据转发规则将数据包的目标地址重新改写为Service IP，并将数据包发送回原始客户端。

需要注意的是，Service IP只是转发记录里的一个虚拟地址，只有在K8s集群内部才有效。

对于集群外部的节点或其他系统来说，是无法直接访问Service IP的。

此外，Service IP的分配和管理由K8s的控制器负责，默认情况下会从Service网段（默认为10.96.0.0/16）中分配。

总的来说，K8s的Service IP实现原理主要基于iptables的转发和地址转换功能。

在Kubernetes 中，Service 是一种抽象，用于将一组Pod 暴露为一个网络服务。

Service 的External Traffic Policy 是一个重要的配置选项，它决定了外部流量（来自Service 外部的请求）如何路由到后端的Pod。

在Kubernetes 中，External Traffic Policy 可以有两个值：Cluster 和Local。

让我们深入探讨这两个选项以及它们的影响。

### Cluster 外部流量策略：当Service 的External Traffic Policy 设置为Cluster 时，这意味着Service 将接受来自集群外部的所有流量，并将其均匀分配到Service 的所有可用后端Pod。

这样的配置适用于那些不关心请求的源IP 地址的应用场景，因为它会导致请求的源IP 地址被Network Address Translation（NAT）。

**特点和优势：**1. **均衡负载：** 集群外部的请求将会被均匀地分发到Service 的所有后端Pod，确保负载均衡。

2. **适用性广泛：** 适用于那些不依赖于请求源IP 地址的应用，例如大多数Web 服务。

**适用场景：**- Web 应用：对于不依赖于源IP 地址的应用，如基于HTTP/HTTPS 的Web 服务，Cluster 外部流量策略是一个简单有效的选择。

### Local 外部流量策略：当Service 的External Traffic Policy 设置为Local 时，Service 会尝试将来自集群外部的请求路由到与请求IP 地址最接近的节点上的Pod。

这意味着，Service 将尽可能地将流量引导到与请求IP 地址最近的节点上，以减少流量在集群内部的传输。

**特点和优势：**1. **降低跨节点通信：** Local 外部流量策略可以减少节点之间的流量，降低了集群内部的通信开销。

k8s 聚合apiserver工作机制？答：Kubernetes（k8s）中的聚合apiserver工作机制如下：聚合apiserver允许用户扩展Kubernetes API，而无需修改Kubernetes核心代码或运行自己的API服务器。

它提供了一个可扩展的、一致的、和安全的方式来将自定义API 资源和服务集成到Kubernetes集群中。

聚合apiserver通过以下步骤工作：1. 注册API服务：聚合apiserver在Kubernetes API 中注册自己作为一个API服务。

这可以通过创建一个自定义资源定义（CustomResourceDefinition，CRD）来完成，该定义描述了自定义API资源的类型和版本。

2. 配置代理：一旦API服务被注册，Kubernetes API 服务器将配置一个代理，将请求路由到聚合apiserver。

这确保了聚合apiserver可以接收到与标准Kubernetes API 相同的请求。

3. 认证和授权：聚合apiserver使用Kubernetes的认证和授权机制来验证和授权API请求。

这确保了只有经过身份验证和授权的用户才能访问自定义API资源。

4. 处理请求：当请求到达聚合apiserver时，它将根据请求的路径和方法调用相应的处理程序。

处理程序负责处理请求，并与后端系统（如自定义控制器或服务）进行交互以执行所需的操作。

5. 返回响应：处理程序将生成一个响应，并将其发送回Kubernetes API服务器。

API服务器将响应转发给原始请求的发起方。

通过这种机制，聚合apiserver使开发人员能够轻松地将自定义API资源和服务集成到Kubernetes集群中，同时保持与标准Kubernetes API的一致性和安全性。