Google Git
Sign in
apache / servicecomb-website / refs/heads/asf-site / . / content / cn / docs / distributed-transaction-of-services-2 / index.html
blob: e20133c79c6cb75e730515d4edd0f3513a48ff63 [file] [log] [blame]
<!doctype html>
<!--
Minimal Mistakes Jekyll Theme 4.4.1 by Michael Rose
Copyright 2017 Michael Rose - mademistakes.com | @mmistakes
Free for personal and commercial use under the MIT license
https://github.com/mmistakes/minimal-mistakes/blob/master/LICENSE.txt
-->
<html lang="cn" class="no-js">
<head>
<meta charset="utf-8">
<!-- begin SEO -->
<title>基于服务的分布式事务(下篇) - Apache ServiceComb</title>
<meta name="description" content="在本文中我们先从分布式事务场景入手，采用交互图的方式，向大家介绍分布式Saga以及TCC分布式事务协调协议交互，最后结合ServiceComb Pack所提供的示例向大家介绍如何编写Saga以及TCC的应用代码。">
<meta name="author" content="Willem Jiang">
<meta property="og:locale" content="cn">
<meta property="og:site_name" content="Apache ServiceComb">
<meta property="og:title" content="基于服务的分布式事务(下篇)">
<link rel="canonical" href="https://github.com/pages/apache/incubator-servicecomb-website/cn/docs/distributed-transaction-of-services-2/">
<meta property="og:url" content="https://github.com/pages/apache/incubator-servicecomb-website/cn/docs/distributed-transaction-of-services-2/">
<meta property="og:description" content="在本文中我们先从分布式事务场景入手，采用交互图的方式，向大家介绍分布式Saga以及TCC分布式事务协调协议交互，最后结合ServiceComb Pack所提供的示例向大家介绍如何编写Saga以及TCC的应用代码。">
<meta name="twitter:site" content="@ServiceComb">
<meta name="twitter:title" content="基于服务的分布式事务(下篇)">
<meta name="twitter:description" content="在本文中我们先从分布式事务场景入手，采用交互图的方式，向大家介绍分布式Saga以及TCC分布式事务协调协议交互，最后结合ServiceComb Pack所提供的示例向大家介绍如何编写Saga以及TCC的应用代码。">
<meta name="twitter:url" content="">
<meta name="twitter:card" content="summary">
<meta name="twitter:creator" content="@willemjiang">
<meta property="og:type" content="article">
<meta property="article:published_time" content="2019-01-10T00:00:00+08:00">
<script type="application/ld+json">
{
"@context" : "http://schema.org",
"@type" : "Person",
"name" : "Apache ServiceComb",
"url" : "https://github.com/pages/apache/incubator-servicecomb-website",
"sameAs" : null
}
</script>
<meta name="google-site-verification" content="HvJjNd7vvJ-yjSTHlBiIWEYxp_Hrz-PYEY5Idz9LRcA" />
<!-- end SEO -->
<link href="/feed.xml" type="application/atom+xml" rel="alternate" title="Apache ServiceComb Feed">
<!-- http://t.co/dKP3o1e -->
<meta name="HandheldFriendly" content="True">
<meta name="MobileOptimized" content="320">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<script>
document.documentElement.className = document.documentElement.className.replace(/\bno-js\b/g, '') + ' js ';
</script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/clipboard.js/1.7.1/clipboard.min.js"></script>
<script src="/assets/vendor/prism/prism.js"></script>
<script type="text/javascript" async
src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config=TeX-MML-AM_CHTML">
</script>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/css/bootstrap.min.css" integrity="sha384-/Y6pD6FV/Vv2HJnA6t+vslU6fwYXjCFtcEpHbNJ0lyAFsXTsjBbfaDjzALeQsN6M" crossorigin="anonymous">
<script src="https://www.apachecon.com/event-images/snippet.js"></script>
<script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.11.0/umd/popper.min.js" integrity="sha384-b/U6ypiBEHpOf/4+1nzFpr53nxSS+GLCkfwBdFNTxtclqqenISfwAzpKaMNFNmj4" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/js/bootstrap.min.js" integrity="sha384-h0AbiXch4ZDo7tp9hKZ4TsHbi047NrKGLO3SEJAg45jXxnGIfYzk4Si90RDIqNm1" crossorigin="anonymous"></script>
<!-- For all browsers -->
<link rel="stylesheet" href="/assets/css/main.css">
<link rel="stylesheet" href="/assets/vendor/prism/prism.css">
<!--[if lte IE 9]>
<style>
/* old IE unsupported flexbox fixes */
.greedy-nav .site-title {
padding-right: 3em;
}
.greedy-nav button {
position: absolute;
top: 0;
right: 0;
height: 100%;
}
</style>
<![endif]-->
<meta http-equiv="cleartype" content="on">
<!-- start custom head snippets -->
<!-- insert favicons. use http://realfavicongenerator.net/ -->
<link href="https://fonts.loli.net/css?family=Roboto:400,500,700|Source+Code+Pro" rel="stylesheet">
<script src="/assets/js/custom.js"></script>
<!-- end custom head snippets -->
</head>
<body class="layout--single">
<!--[if lt IE 9]>
<div class="notice--danger align-center" style="margin: 0;">You are using an <strong>outdated</strong> browser. Please <a href="http://browsehappy.com/">upgrade your browser</a> to improve your experience.</div>
<![endif]-->
<div class="masthead" onmouseleave="$('#childrenShow').css('display', 'none')">
<div class="masthead__inner-wrap">
<div class="masthead__menu">
<nav id="site-nav" class="greedy-nav">
<a class="site-title active" href="/cn"><img src="https://www.apache.org/img/servicecomb.png"></a>
<ul class="visible-links">
<li class="masthead__menu-item" onmouseenter="$('#childrenShow').css('display', 'none')">
<a href="/cn/">首页</a>
</li>
<li class="masthead__menu-item" onmouseenter="$('#childrenShow').css('display', 'none')">
<a href="/cn/developers/">项目</a>
</li>
<li class="def-nav-li" onmouseenter="$('#childrenShow').css('display', 'block')">
<a href="/cn/docs/users/">文档</a>
<ul id="childrenShow" class="def-children-show-cn" onmouseleave="$('#childrenShow').css('display', 'none')">
<li><a href="/cn/docs/getting-started/" class="">入门指南</a></li>
<li><a href="/cn/docs/users/" class="">用户手册</a></li>
<li><a href="/cn/slides/" class="">大咖视频</a></li>
<li><a href="/cn/faqs/" class="">常见问题</a></li>
</ul>
</li>
<li class="masthead__menu-item" onmouseenter="$('#childrenShow').css('display', 'none')">
<a href="/cn/year-archive/">博文</a>
</li>
<li class="masthead__menu-item" onmouseenter="$('#childrenShow').css('display', 'none')">
<a href="/cn/release/">下载</a>
</li>
</ul>
<button><div class="navicon"></div></button>
<ul class="hidden-links hidden"></ul>
<div class="nav-lang">
<a href=/docs/distributed-transaction-of-services-2/>English</a>
</div>
</nav>
</div>
</div>
</div>
<div id="main" role="main">
<div class="sidebar sticky">
<div class="back-to-home"><a href="/cn/">首页</a> > 基于服务的分布式事务(下篇)</div>
<div itemscope itemtype="http://schema.org/Person">
<div class="author__content">
<h3 class="author__name" itemprop="name">Willem Jiang</h3>
<p class="author__bio" itemprop="description">
Apache member, open source addict.
</p>
</div>
<div class="author__urls-wrapper">
<button class="btn btn--inverse">关注</button>
<ul class="author__urls social-icons">
<li>
<a href="http://willemjiang.github.io" itemprop="url">
<i class="fa fa-fw fa-chain" aria-hidden="true"></i> 网站
</a>
</li>
<li>
<a href="mailto:willemjiang@gmail.com">
<meta itemprop="email" content="willemjiang@gmail.com" />
<i class="fa fa-fw fa-envelope-square" aria-hidden="true"></i> 电子邮箱
</a>
</li>
<li>
<a href="https://twitter.com/willemjiang" itemprop="sameAs">
<i class="fa fa-fw fa-twitter-square" aria-hidden="true"></i> Twitter
</a>
</li>
<!--
<li>
<a href="http://link-to-whatever-social-network.com/user/" itemprop="sameAs">
<i class="fa fa-fw" aria-hidden="true"></i> Custom Social Profile Link
</a>
</li>
-->
</ul>
</div>
</div>
</div>
<article class="page" itemscope itemtype="http://schema.org/CreativeWork">
<meta itemprop="headline" content="基于服务的分布式事务(下篇)">
<meta itemprop="description" content="在本文中我们先从分布式事务场景入手，采用交互图的方式，向大家介绍分布式Saga以及TCC分布式事务协调协议交互，最后结合ServiceComb Pack所提供的示例向大家介绍如何编写Saga以及TCC的应用代码。">
<meta itemprop="datePublished" content="January 10, 2019">
<meta itemprop="dateModified" content="January 10, 2019">
<div class="page__inner-wrap">
<header>
<h1 class="page__title" itemprop="headline">基于服务的分布式事务(下篇)
</h1>
<p class="page__meta"><i class="fa fa-clock-o" aria-hidden="true"></i>
2 分钟 阅读
</p>
</header>
<section class="page__content" itemprop="text">
<h3 id="分布式事务协调场景介绍">分布式事务协调场景介绍</h3>
<p>在基于服务的分布式事务上篇中， 我们举了了一个业务场景，就是一个初始服务创建了一个分布式事务，在这个分布式事务包含了两个参与服务的本地事务，这两个本地事务由初始服务通过调用两个参与事务的服务方式组合在一起。根据分布式事务一致性的要求，这两个本地事务要么同时成功，要么同时失败。 由于这两个参与事务的服务并不知道对方的存在，当一个参与服务调用（Invocation A）成功而另外一个参与服务调用（Invocation B）失败，我们就需要分布式事务协调器的进行相关的补偿，保证分布式事务的一致性。</p>
<p><img src="/assets/images/dts2/image2-DT-introduction.png" alt="" /></p>
<h3 id="分布式saga">分布式Saga</h3>
<p><a href="https://github.com/apache/servicecomb-pack">ServiceComb Pack</a>目默认采⽤用的是名为Saga分布式事务协调方案。<a href="https://www.cs.cornell.edu/andru/cs711/2002fa/reading/sagas.pdf">Sagas</a>这个概念来源于三十多年前的一篇数据库论文，一个Saga事务是一个有多个短时事务组成的长时的事务。 在分布式事务场景下，我们把一个Saga分布式事务看做是一个由多个本地事务组成的事务，每个本地事务都有一个与之对应的补偿事务。在Saga事务的执行过程中，如果出现某一步执行出现异常的，Saga事务会被终止，同时会调用之前执行成功的事务对应的补偿事务完成相关的恢复操作，这样保证Saga相关的本地事务要么同时成功，要么通过执行补偿恢复成为Saga执行之前的状态。</p>
<p><img src="/assets/images/dts2/image2-saga-introduction.png" alt="" /></p>
<p><a href="https://github.com/apache/servicecomb-pack">ServiceComb Pack</a> 在实现分布式Saga协调协议的过程中需要追踪分布式事务的执行情况。首先介绍一下正常流程下分布式事务执行流程是如何记录下来的 ，下图的红线部分是Omega端与Alpha端交互序列图，蓝色部分原有服务直接的调用。在分布式事务初始阶段由初始服务的Omega将<strong>SagaStarted</strong>事件到Alpha进行进行分布式事务备案。当有新的服务参与到这个分布式事务中，参与服务的Omega会在本地事务执行前发送<strong>TxStarted</strong>到Alpha端； 并在本地事务执行成功之后将<strong>TxEnded</strong>事件发送到Alpha。如果分布式事务正常结束，初始服务Omega会直接发送<strong>SagaEnded</strong>事件到Alpha结束整个分布式事务。</p>
<p><img src="/assets/images/dts2/image2-saga-sq1.png" alt="" /></p>
<p>参与分布式事务的服务在执行本地事务出现异常，如下图所示Transaction B执行出现错误。这个时候参与服务B会向Alpha发送一个<strong>TxAborted</strong>的事件，Alpha收到这个事件后会将整个Saga事务挂起，终止Saga事务的继续执行。如果这个时候还有其他的Omega向Alpha发送挂载在这个Saga事务下的<strong>TxStarted</strong>事件的话，Alpha会直接发送拒绝应答消息通知Omega这个Saga事务已经出现异常，Omega收到应答之后会抛出异常拒绝执行新的本地事务。由于初始服务在调用参与服务B的过程中，通过服务B的应答消息也知道了服务调用失败的消息，初始服务也会发生<strong>SagaAborted</strong>事件至Alpha来关闭整个Saga事件。虽然在<strong>TxAborted</strong>存在的情况下，<strong>SagaAborted</strong>事件看上去有点多余，但是为了应对诸如初始服务无法调用参与服务B的情况下（这个时候Alpha没有收到<strong>TxAborted</strong>事件），设置<strong>SagaAborted</strong>事件还是非常有必要的。</p>
<p><img src="/assets/images/dts2/image2-saga-exception.png" alt="" /></p>
<p>现在Alpha可以通过查询<strong>TxEnded</strong>事件可以获取到需要进行补偿恢复的服务信息，Alpha会向相关的服务实例Omega发送<strong>TxCompensated</strong>事件，由Omega调用服务实例补偿方法进行相关的恢复操作。为了恢复本地事务执行上下文，ServiceComb Pack会将<strong>TxStarted</strong>传递过来的方法参数列表信息放入<strong>TxCompensated</strong>消息中传递给Omega，除此之外ServiceComb Pack 还会将<a href="[OmegaContext](https://github.com/apache/servicecomb-packblob/master/omega/omega-context/src/main/java/org/apache/servicecomb/saga/omega/context/OmegaContext.java)">OmegaContext</a>的全局事务ID和本地事务ID设置成本地事务执行时的状态。用户可以在应用代码可以通过获取这些ID在分布式缓存或者数据库中检索获取自定义的上下文环境。</p>
<p><img src="/assets/images/dts2/image2-saga-exception2.png" alt="" /></p>
<p>除了要考虑异常情况，我们还需要考虑事务执行超时的处理的问题（为了简化场景，这里我们不考虑由于网络连接中断导致的事务异常或者结束消息丢包的情况）。目前我们可以在saga事务以及本地事务设置执行超时时间，Alpha上的事件扫描器会定时查找Started事件在设定的超时时间内是否有对应的Aborted或者Ended事件，如果没有，Alpha事件扫描器则会生成对应的Aborted时间触发相关的补偿操作。</p>
<p>当整个saga事务执行超时，Alpha事件扫描器会在后台数据库中添加<strong>SagaAborted</strong>事件终止整个Saga事务，并且调用Omega注册的恢复函数进行相关的恢复操作。</p>
<p><img src="/assets/images/dts2/image2-saga-timeout-2.png" alt="" /></p>
<p>下图展示的是在本地事务执行超时的情况下，Alpha事件扫描器会识别出Transaction B 执行超时，同时会发生<strong>TxAborted</strong>事件终止整个Saga 事务，调用相关的恢复方法进行恢复。由于Alpha无法确认对应的本地事务的执行情况，Alpha会采用向Omega发送<strong>TxCompensated</strong>的方式强制恢复事务，即使这时参与的服务B的本地事务已经执行成功了，Alpha还是会调用参与服务B的Omega来执行相关的恢复操作。</p>
<p><img src="/assets/images/dts2/image2-saga-timeout.png" alt="" /></p>
<h3 id="编写saga应用代码">编写Saga应用代码</h3>
<p>在文章开头我们给大家介绍了一个典型的分布式事务业务场景，其中涉及到一个初始服务，以及两个参与服务。 为了方便大家理解，我们将以<a href="https://github.com/apache/servicecomb-pack/tree/master/demo/saga-spring-demo">ServiceComb Pack Spring Demo</a>为例介绍如何使用Saga实现分布式事务。这里预订服务(Booking) 相当于之前提到的分布式事务初始服务，对外提供一个租车(Car)和酒店(Hotel)聚合服务，在<a href="https://github.com/apache/servicecomb-pack/blob/master/demo/saga-spring-demo/booking/src/main/java/org/apache/servicecomb/pack/demo/booking/BookingController.java">BookingController</a> 中使用Spring提供的<a href="https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/client/RestTemplate.html">RestTemplate</a> 向租车和酒店服务转发请求。租车和酒店服务分别作为Saga事务参与方参与整个事务。预订服务，租车和酒店服务都是基于<a href="https://spring.io/projects/spring-boot">Spring-Boot</a>编写独立进程应用，应用代码通过<a href="https://github.com/apache/servicecomb-pack/blob/master/omega/omega-spring-starter/src/main/java/org/apache/servicecomb/pack/omega/spring/EnableOmega.java">@EnableOmega</a>加载Omega相关的<a href="https://github.com/apache/servicecomb-pack/blob/master/demo/saga-spring-demo/booking/src/main/resources/application.yaml">配置</a>，同时需要在Spring的配置文件中配置与Alpha服务相关的信息。</p>
<div class="language-java highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="kn">import</span> <span class="nn">org.apache.servicecomb.pack.omega.spring.EnableOmega</span><span class="o">;</span>
<span class="kn">import</span> <span class="nn">org.springframework.boot.SpringApplication</span><span class="o">;</span>
<span class="kn">import</span> <span class="nn">org.springframework.boot.autoconfigure.SpringBootApplication</span><span class="o">;</span>
<span class="nd">@SpringBootApplication</span>
<span class="nd">@EnableOmega</span>
<span class="kd">public</span> <span class="kd">class</span> <span class="nc">Application</span> <span class="o">{</span>
<span class="kd">public</span> <span class="kd">static</span> <span class="kt">void</span> <span class="nf">main</span><span class="o">(</span><span class="nc">String</span><span class="o">[]</span> <span class="n">args</span><span class="o">)</span> <span class="o">{</span>
<span class="nc">SpringApplication</span><span class="o">.</span><span class="na">run</span><span class="o">(</span><span class="nc">Application</span><span class="o">.</span><span class="na">class</span><span class="o">,</span> <span class="n">args</span><span class="o">);</span>
<span class="o">}</span>
<span class="o">}</span>
</code></pre></div></div>
<p>在应用代码中需要描述出Saga事务的边界，我们可以在BookingController的 order方法上标准@SagaStart；</p>
<div class="language-java highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="kn">import</span> <span class="nn">org.apache.servicecomb.pack.omega.context.annotations.SagaStart</span><span class="o">;</span>
<span class="nd">@SagaStart</span>
<span class="nd">@PostMapping</span><span class="o">(</span><span class="s">"/booking/{name}/{rooms}/{cars}"</span><span class="o">)</span>
<span class="kd">public</span> <span class="nc">String</span> <span class="nf">order</span><span class="o">(</span><span class="nd">@PathVariable</span> <span class="nc">String</span> <span class="n">name</span><span class="o">,</span> <span class="nd">@PathVariable</span> <span class="nc">Integer</span> <span class="n">rooms</span><span class="o">,</span> <span class="nd">@PathVariable</span> <span class="nc">Integer</span> <span class="n">cars</span><span class="o">)</span> <span class="o">{</span>
<span class="c1">// Calling the car service</span>
<span class="n">template</span><span class="o">.</span><span class="na">postForEntity</span><span class="o">(</span>
<span class="n">carServiceUrl</span> <span class="o">+</span> <span class="s">"/order/{name}/{cars}"</span><span class="o">,</span>
<span class="kc">null</span><span class="o">,</span> <span class="nc">String</span><span class="o">.</span><span class="na">class</span><span class="o">,</span> <span class="n">name</span><span class="o">,</span> <span class="n">cars</span><span class="o">);</span>
<span class="c1">// Calling the hotel service</span>
<span class="n">template</span><span class="o">.</span><span class="na">postForEntity</span><span class="o">(</span>
<span class="n">hotelServiceUrl</span> <span class="o">+</span> <span class="s">"/order/{name}/{rooms}"</span><span class="o">,</span>
<span class="kc">null</span><span class="o">,</span> <span class="nc">String</span><span class="o">.</span><span class="na">class</span><span class="o">,</span> <span class="n">name</span><span class="o">,</span> <span class="n">rooms</span><span class="o">);</span>
<span class="k">return</span> <span class="n">name</span> <span class="o">+</span> <span class="s">" booking "</span> <span class="o">+</span> <span class="n">rooms</span> <span class="o">+</span> <span class="s">" rooms and "</span> <span class="o">+</span> <span class="n">cars</span> <span class="o">+</span> <span class="s">" cars OK"</span><span class="o">;</span>
<span class="o">}</span>
</code></pre></div></div>
<p>本地事务是通过@Compensable来标识， 并且在Compensable的compensationMethod属性中描述补偿方法。 注意补偿方法和本地事务方法的参数必须一致，否则Omega在系统启动进行参数检查的时候报找不到恢复方法的错误。</p>
<div class="language-java highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="kn">import</span> <span class="nn">org.apache.servicecomb.pack.omega.transaction.annotations.Compensable</span><span class="o">;</span>
<span class="nd">@Compensable</span><span class="o">(</span><span class="n">compensationMethod</span> <span class="o">=</span> <span class="s">"cancel"</span><span class="o">)</span>
<span class="kt">void</span> <span class="nf">order</span><span class="o">(</span><span class="nc">CarBooking</span> <span class="n">booking</span><span class="o">)</span> <span class="o">{</span>
<span class="n">booking</span><span class="o">.</span><span class="na">confirm</span><span class="o">();</span>
<span class="n">bookings</span><span class="o">.</span><span class="na">put</span><span class="o">(</span><span class="n">booking</span><span class="o">.</span><span class="na">getId</span><span class="o">(),</span> <span class="n">booking</span><span class="o">);</span>
<span class="o">}</span>
<span class="kt">void</span> <span class="nf">cancel</span><span class="o">(</span><span class="nc">CarBooking</span> <span class="n">booking</span><span class="o">)</span> <span class="o">{</span>
<span class="nc">Integer</span> <span class="n">id</span> <span class="o">=</span> <span class="n">booking</span><span class="o">.</span><span class="na">getId</span><span class="o">();</span>
<span class="k">if</span> <span class="o">(</span><span class="n">bookings</span><span class="o">.</span><span class="na">containsKey</span><span class="o">(</span><span class="n">id</span><span class="o">))</span> <span class="o">{</span>
<span class="n">bookings</span><span class="o">.</span><span class="na">get</span><span class="o">(</span><span class="n">id</span><span class="o">).</span><span class="na">cancel</span><span class="o">();</span>
<span class="o">}</span>
<span class="o">}</span>
</code></pre></div></div>
<h3 id="tcc实现">TCC实现</h3>
<p><a href="https://github.com/apache/servicecomb-pack">ServiceComb Pack</a> 还提供了一个名为TCC（Try-Cancel/Confirm实现)分布式事务协调实现。TCC借助两阶段提交协议提供了一种比较完美的恢复方式。在TCC方式下，cancel补偿显然是在第二阶段需要执行业务逻辑来取消第一阶段产生的后果。try是在第一阶段执行相关的业务操作，完成相关业务资源的占用，例如预先分配票务资源，或者检查并刷新用户账户信用额度。 在取消阶段释放相关的业务资源，例如释放预先分配的票务资源或者恢复之前占用的用户信用额度。 那我们为什么还要加入确认操作呢？这需要从业务资源的使用生命周期来入手。在try过程中，我们只是占用的业务资源，相关的执行操作只是出于待定状态，只有在确认操作执行完毕之后，业务资源才能真正被确认。</p>
<p>在下图展示了正常的TCC调用流程，就是参与服务A，B分别在尝试方法中完成相关业务资源的预先分配，然后在提交阶段完成业务资源的确认操作。在实现层面和前面提到的Saga实现一样，我们需要协调器在分布式事务执行完成时向各个参与服务发送执行确认消息，由服务实例执行确认操作。</p>
<p><img src="/assets/images/dts2/image-tcc-confirm.png" alt="" /></p>
<p>如果参与服务在执行try方法出现错误，事务协调器Alpha会终止整个TCC分布式事务，同时事务协调器会向注册成功的参与服务发送取消消息，由服务实例执行取消操作。 假如这时还有其他的服务想参与到这个分布式事务的话， 事务协调器会以这个分布式事务已经失败为由，向参与的服务发送失败的应答消息。</p>
<p><img src="/assets/images/dts2/image-tcc-cancel.png" alt="" /></p>
<p>在ServiceComb Pack中，在为了实现上面描述的TCC业务述求，需要初始服务在分布式事务开始时向Alpha协调器发送<strong>TccStarted</strong>事件，Alpha协调器在接收到<strong>TccStarted</strong>事件之后，会创建相关事务追踪资源跟踪这个TCC事务整个生命周期。当在参与服务调用try方法前发送<strong>ParticipationStarted</strong>事件来声明与TCC相关本地事务。Alpha协调器会根据TCC事务当前的状态决定是否允许后续的参与服务参加到TCC事务中。 如果参与的TCC事务没有终止，Alpha协调器会回复确认消息，参与服务会继续执行相关的try方法调用；如果TCC事务已经出错终止了，Alpha协调器会回复终止消息，参与服务所在的Omega将抛出异常，直接终止try方法调用。如果参与服务调用try方法成功，则会向Alpha发送<strong>ParticipationEnded</strong>事件，因为这个事件发送之后Omega端不需要做任何操作，为了提高系统效率，Omega采用异步方式通知Alpha协调器。当初始服务执行完TCCStart所标注的方法之后， 初始服务所在的Omega会向Alpha协调器发送<strong>TccEnded</strong>事件，Alpha协调器在接收到这个事件之后会查询与本次TCC调用相关的<strong>ParticipationStarted</strong>事件识别相关的参与服务实例，然后通过向这些服务实例所对应的Omega发送<strong>Coordinated</strong>事件，由Omega调用相关的确认方法，完成本地事务提交工作。</p>
<p><img src="/assets/images/dts2/image2-Tcc-confirm.png" alt="" /></p>
<p>当TCC调用执行过程中出现异常，初始服务所在的Omega会向Alpha协调器发送<strong>TccEnded</strong>事件来终止当前的TCC事务。Alpha协调器则会根据其记录的TCC分布式事务的参与情况，向相关服务的Omega发送<strong>Coordinated</strong>事件，由Omega调用相关的取消方法。</p>
<p><img src="/assets/images/dts2/image2-Tcc-cancel.png" alt="" /></p>
<p>如果参与服务在执行try方法出错了，那Alpha协调器会收到一条标注try方法执行状态的<strong>ParticipationEnded</strong>事件，Alpha协调器会给自己发送一个包含Aborted信息的<strong>TccEnded</strong>事件来关闭正在执行的TCC事务，同时触发Omega相关恢复操作的调用。</p>
<p><img src="/assets/images/dts2/image2-Tcc-exception.png" alt="" /></p>
<p>下面介绍参与服务本地事务执行超时的处理的设计， 对于参与服务的try方法来说，Alpha协调器可以通过是否接收到<strong>ParticipationEnded</strong>事件判断参与服务try方法是否执行超时。 如果在超时时间内没有收到<strong>ParticipationEnded</strong>事件，Alpha事件扫描器会向数据库添加<strong>TccEnded</strong>信息，触发和之前描述一样的事务错误处理流程，关闭分布式事务以及调用Omega进行相关恢复的操作。</p>
<p><img src="/assets/images/dts2/image2-Tcc-timeout.png" alt="" /></p>
<p>同理当TCC分布式事务执行超时（Alpha在一定时间内没有收到TccEnded事件）， Alpha事件扫描器会发送<strong>TccEnded</strong>终止整个TCC事务，触发与上面相同的恢复操作。</p>
<p><img src="/assets/images/dts2/image2-Tcc-timeout-2.png" alt="" /></p>
<h3 id="编写tcc应用代码">编写TCC应用代码</h3>
<p>下⾯面我们会结合ServiceComb中的<a href="https://github.com/apache/servicecomb-pack/tree/master/demo/tcc-spring-demo">TCC示例</a>，向大家介绍如何编写与TCC应用代码。这个示例以我们常见的电商场景为例，用户通过Ordering应用进行下单，Odering会调用Inventory以及Payment两个服务进行相关的业务操作。和之前Saga的示例一样，我们可以通过@EnableOmega的方式在这几个应用中注入Omega。</p>
<div class="language-java highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="kn">import</span> <span class="nn">org.apache.servicecomb.pack.omega.spring.EnableOmega</span><span class="o">;</span>
<span class="kn">import</span> <span class="nn">org.springframework.boot.SpringApplication</span><span class="o">;</span>
<span class="kn">import</span> <span class="nn">org.springframework.boot.autoconfigure.SpringBootApplication</span><span class="o">;</span>
<span class="nd">@SpringBootApplication</span>
<span class="nd">@EnableOmega</span>
<span class="kd">public</span> <span class="kd">class</span> <span class="nc">TccOrderingApplication</span> <span class="o">{</span>
<span class="kd">public</span> <span class="kd">static</span> <span class="kt">void</span> <span class="nf">main</span><span class="o">(</span><span class="nc">String</span><span class="o">[]</span> <span class="n">args</span><span class="o">)</span> <span class="o">{</span>
<span class="nc">SpringApplication</span><span class="o">.</span><span class="na">run</span><span class="o">(</span><span class="nc">TccOrderingApplication</span><span class="o">.</span><span class="na">class</span><span class="o">,</span> <span class="n">args</span><span class="o">);</span>
<span class="o">}</span>
<span class="o">}</span>
</code></pre></div></div>
<p>接下来我们需要在OrderingController中通过加入@TccStart来定义这个TCC分布式事务的范围，这个分布式事务的范围就是order方法，order方法会调用Inventory的order服务接口，以及Payment的pay服务接口。</p>
<div class="language-java highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="kn">import</span> <span class="nn">org.apache.servicecomb.pack.omega.context.annotations.TccStart</span><span class="o">;</span>
<span class="nd">@TccStart</span>
<span class="nd">@PostMapping</span><span class="o">(</span><span class="s">"/order/{userName}/{productName}/{productUnit}/{unitPrice}"</span><span class="o">)</span>
<span class="nd">@ResponseBody</span>
<span class="kd">public</span> <span class="nc">String</span> <span class="nf">order</span><span class="o">(</span>
<span class="nd">@PathVariable</span> <span class="nc">String</span> <span class="n">userName</span><span class="o">,</span>
<span class="nd">@PathVariable</span> <span class="nc">String</span> <span class="n">productName</span><span class="o">,</span> <span class="nd">@PathVariable</span> <span class="nc">Integer</span> <span class="n">productUnit</span><span class="o">,</span> <span class="nd">@PathVariable</span> <span class="nc">Integer</span> <span class="n">unitPrice</span><span class="o">)</span> <span class="o">{</span>
<span class="c1">// Calling the inventory service</span>
<span class="n">restTemplate</span><span class="o">.</span><span class="na">postForEntity</span><span class="o">(</span>
<span class="n">inventoryServiceUrl</span> <span class="o">+</span> <span class="s">"/order/{userName}/{productName}/{productUnit}"</span><span class="o">,</span>
<span class="kc">null</span><span class="o">,</span> <span class="nc">String</span><span class="o">.</span><span class="na">class</span><span class="o">,</span> <span class="n">userName</span><span class="o">,</span> <span class="n">productName</span><span class="o">,</span> <span class="n">productUnit</span><span class="o">);</span>
<span class="kt">int</span> <span class="n">amount</span> <span class="o">=</span> <span class="n">productUnit</span> <span class="o">*</span> <span class="n">unitPrice</span><span class="o">;</span>
<span class="c1">// Calling the payment service</span>
<span class="n">restTemplate</span><span class="o">.</span><span class="na">postForEntity</span><span class="o">(</span><span class="n">paymentServiceUrl</span> <span class="o">+</span> <span class="s">"/pay/{userName}/{amount}"</span><span class="o">,</span>
<span class="kc">null</span><span class="o">,</span> <span class="nc">String</span><span class="o">.</span><span class="na">class</span><span class="o">,</span> <span class="n">userName</span><span class="o">,</span> <span class="n">amount</span><span class="o">);</span>
<span class="k">return</span> <span class="n">userName</span> <span class="o">+</span> <span class="s">" ordering "</span> <span class="o">+</span> <span class="n">productName</span> <span class="o">+</span> <span class="s">" with "</span> <span class="o">+</span> <span class="n">productUnit</span> <span class="o">+</span> <span class="s">" OK"</span><span class="o">;</span>
<span class="o">}</span>
</code></pre></div></div>
<p>Inventory会在try阶段先进行库存的扣减，在分布式业务执行成功之后进行设置库存订单状态；如果业务执行失败，Inventory服务会执行恢复操作。通过定义@Participate，ServiceComb Omega可以标注相关try方法，同时通过confirmMethod 以及cancelMethod定义相关确认以及取消方法名。 这里需要注意的是这里提到的confirm，cancel方法的参数必须和try方法的相同。</p>
<div class="language-java highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="kn">import</span> <span class="nn">org.apache.servicecomb.pack.omega.transaction.annotations.Participate</span><span class="o">;</span>
<span class="kn">import</span> <span class="nn">org.springframework.transaction.annotation.Transactional</span><span class="o">;</span>
<span class="nd">@Participate</span><span class="o">(</span><span class="n">confirmMethod</span> <span class="o">=</span> <span class="s">"confirm"</span><span class="o">,</span> <span class="n">cancelMethod</span> <span class="o">=</span> <span class="s">"cancel"</span><span class="o">)</span>
<span class="nd">@Transactional</span>
<span class="kd">public</span> <span class="kt">void</span> <span class="nf">pay</span><span class="o">(</span><span class="nc">Payment</span> <span class="n">payment</span><span class="o">)</span> <span class="o">{</span>
<span class="nc">Account</span> <span class="n">account</span> <span class="o">=</span> <span class="n">getAccount</span><span class="o">(</span><span class="n">payment</span><span class="o">);</span>
<span class="k">if</span> <span class="o">(</span><span class="n">account</span><span class="o">.</span><span class="na">getCredit</span><span class="o">()</span> <span class="o">&gt;=</span> <span class="n">payment</span><span class="o">.</span><span class="na">getAmount</span><span class="o">())</span> <span class="o">{</span>
<span class="n">account</span><span class="o">.</span><span class="na">setCredit</span><span class="o">(</span><span class="n">account</span><span class="o">.</span><span class="na">getCredit</span><span class="o">()</span> <span class="o">-</span> <span class="n">payment</span><span class="o">.</span><span class="na">getAmount</span><span class="o">());</span>
<span class="n">accountDao</span><span class="o">.</span><span class="na">saveAndFlush</span><span class="o">(</span><span class="n">account</span><span class="o">);</span>
<span class="n">payments</span><span class="o">.</span><span class="na">put</span><span class="o">(</span><span class="n">payment</span><span class="o">.</span><span class="na">getId</span><span class="o">(),</span> <span class="n">payment</span><span class="o">);</span>
<span class="o">}</span> <span class="k">else</span> <span class="o">{</span>
<span class="k">throw</span> <span class="k">new</span> <span class="nf">IllegalArgumentException</span><span class="o">(</span><span class="s">"Insufficient funds!"</span><span class="o">);</span>
<span class="o">}</span>
<span class="o">}</span>
<span class="nd">@Transactional</span>
<span class="nc">Account</span> <span class="nf">getAccount</span><span class="o">(</span><span class="nc">Payment</span> <span class="n">payment</span><span class="o">)</span> <span class="o">{</span>
<span class="nc">Account</span> <span class="n">account</span> <span class="o">=</span> <span class="n">accountDao</span><span class="o">.</span><span class="na">findByUserName</span><span class="o">(</span><span class="n">payment</span><span class="o">.</span><span class="na">getUserName</span><span class="o">());</span>
<span class="k">if</span> <span class="o">(</span><span class="nc">Objects</span><span class="o">.</span><span class="na">isNull</span><span class="o">(</span><span class="n">account</span><span class="o">))</span> <span class="o">{</span>
<span class="k">throw</span> <span class="k">new</span> <span class="nf">IllegalArgumentException</span><span class="o">(</span><span class="s">"Cannot find the account!"</span><span class="o">);</span>
<span class="o">}</span>
<span class="k">return</span> <span class="n">account</span><span class="o">;</span>
<span class="o">}</span>
<span class="nd">@Transactional</span>
<span class="kd">public</span> <span class="kt">void</span> <span class="nf">confirm</span><span class="o">(</span><span class="nc">Payment</span> <span class="n">payment</span><span class="o">)</span> <span class="o">{</span>
<span class="nc">Account</span> <span class="n">account</span> <span class="o">=</span> <span class="n">getAccount</span><span class="o">(</span><span class="n">payment</span><span class="o">);</span>
<span class="n">payment</span><span class="o">.</span><span class="na">setConfirmed</span><span class="o">(</span><span class="kc">true</span><span class="o">);</span>
<span class="n">payment</span><span class="o">.</span><span class="na">setCancelled</span><span class="o">(</span><span class="kc">false</span><span class="o">);</span>
<span class="n">account</span><span class="o">.</span><span class="na">setBalance</span><span class="o">(</span><span class="n">account</span><span class="o">.</span><span class="na">getBalance</span><span class="o">()</span> <span class="o">-</span> <span class="n">payment</span><span class="o">.</span><span class="na">getAmount</span><span class="o">());</span>
<span class="n">payment</span><span class="o">.</span><span class="na">setBalance</span><span class="o">(</span><span class="n">account</span><span class="o">.</span><span class="na">getBalance</span><span class="o">());</span>
<span class="n">accountDao</span><span class="o">.</span><span class="na">saveAndFlush</span><span class="o">(</span><span class="n">account</span><span class="o">);</span>
<span class="o">}</span>
<span class="nd">@Transactional</span>
<span class="kd">public</span> <span class="kt">void</span> <span class="nf">cancel</span><span class="o">(</span><span class="nc">Payment</span> <span class="n">payment</span><span class="o">)</span> <span class="o">{</span>
<span class="nc">Account</span> <span class="n">account</span> <span class="o">=</span> <span class="n">getAccount</span><span class="o">(</span><span class="n">payment</span><span class="o">);</span>
<span class="n">account</span><span class="o">.</span><span class="na">setCredit</span><span class="o">(</span><span class="n">account</span><span class="o">.</span><span class="na">getCredit</span><span class="o">()</span> <span class="o">+</span> <span class="n">payment</span><span class="o">.</span><span class="na">getAmount</span><span class="o">());</span>
<span class="n">accountDao</span><span class="o">.</span><span class="na">saveAndFlush</span><span class="o">(</span><span class="n">account</span><span class="o">);</span>
<span class="n">payment</span><span class="o">.</span><span class="na">setBalance</span><span class="o">(</span><span class="n">account</span><span class="o">.</span><span class="na">getBalance</span><span class="o">());</span>
<span class="n">payment</span><span class="o">.</span><span class="na">setConfirmed</span><span class="o">(</span><span class="kc">false</span><span class="o">);</span>
<span class="n">payment</span><span class="o">.</span><span class="na">setCancelled</span><span class="o">(</span><span class="kc">true</span><span class="o">);</span>
<span class="o">}</span>
</code></pre></div></div>
<p>Payment会在try阶段先验证用户账户的信用值，在确认阶段执行扣减用户账户余额的操作，在恢复阶段恢复信用值。</p>
<div class="language-java highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="kn">import</span> <span class="nn">org.apache.servicecomb.pack.omega.transaction.annotations.Participate</span><span class="o">;</span>
<span class="kn">import</span> <span class="nn">org.springframework.transaction.annotation.Transactional</span><span class="o">;</span>
<span class="nd">@Participate</span><span class="o">(</span><span class="n">confirmMethod</span> <span class="o">=</span> <span class="s">"confirm"</span><span class="o">,</span> <span class="n">cancelMethod</span> <span class="o">=</span> <span class="s">"cancel"</span><span class="o">)</span>
<span class="nd">@Transactional</span>
<span class="kd">public</span> <span class="kt">void</span> <span class="nf">reserve</span><span class="o">(</span><span class="nc">ProductOrder</span> <span class="n">order</span><span class="o">)</span> <span class="o">{</span>
<span class="nc">Product</span> <span class="n">product</span> <span class="o">=</span> <span class="n">getProduct</span><span class="o">(</span><span class="n">order</span><span class="o">.</span><span class="na">getProductName</span><span class="o">());</span>
<span class="k">if</span> <span class="o">(</span><span class="n">product</span><span class="o">.</span><span class="na">getInStock</span><span class="o">()</span> <span class="o">&gt;=</span> <span class="n">order</span><span class="o">.</span><span class="na">getUnits</span><span class="o">())</span> <span class="o">{</span>
<span class="n">product</span><span class="o">.</span><span class="na">setInStock</span><span class="o">(</span><span class="n">product</span><span class="o">.</span><span class="na">getInStock</span><span class="o">()</span> <span class="o">-</span> <span class="n">order</span><span class="o">.</span><span class="na">getUnits</span><span class="o">());</span>
<span class="n">productDao</span><span class="o">.</span><span class="na">saveAndFlush</span><span class="o">(</span><span class="n">product</span><span class="o">);</span>
<span class="n">orders</span><span class="o">.</span><span class="na">put</span><span class="o">(</span><span class="n">order</span><span class="o">.</span><span class="na">getId</span><span class="o">(),</span> <span class="n">order</span><span class="o">);</span>
<span class="o">}</span> <span class="k">else</span> <span class="o">{</span>
<span class="k">throw</span> <span class="k">new</span> <span class="nf">IllegalArgumentException</span><span class="o">(</span><span class="s">"The Product is out of stock!"</span><span class="o">);</span>
<span class="o">}</span>
<span class="o">}</span>
<span class="kd">public</span> <span class="kt">void</span> <span class="nf">confirm</span><span class="o">(</span><span class="nc">ProductOrder</span> <span class="n">order</span><span class="o">)</span> <span class="o">{</span>
<span class="n">order</span><span class="o">.</span><span class="na">setConfirmed</span><span class="o">(</span><span class="kc">true</span><span class="o">);</span>
<span class="o">}</span>
<span class="nd">@Transactional</span>
<span class="kd">public</span> <span class="kt">void</span> <span class="nf">cancel</span><span class="o">(</span><span class="nc">ProductOrder</span> <span class="n">order</span><span class="o">)</span> <span class="o">{</span>
<span class="nc">Product</span> <span class="n">product</span> <span class="o">=</span> <span class="n">productDao</span><span class="o">.</span><span class="na">findProduceByName</span><span class="o">(</span><span class="n">order</span><span class="o">.</span><span class="na">getProductName</span><span class="o">());</span>
<span class="n">product</span><span class="o">.</span><span class="na">setInStock</span><span class="o">(</span><span class="n">product</span><span class="o">.</span><span class="na">getInStock</span><span class="o">()</span> <span class="o">+</span> <span class="n">order</span><span class="o">.</span><span class="na">getUnits</span><span class="o">());</span>
<span class="n">productDao</span><span class="o">.</span><span class="na">saveAndFlush</span><span class="o">(</span><span class="n">product</span><span class="o">);</span>
<span class="n">order</span><span class="o">.</span><span class="na">setCancelled</span><span class="o">(</span><span class="kc">true</span><span class="o">);</span>
<span class="o">}</span>
<span class="nd">@Transactional</span>
<span class="kd">private</span> <span class="nc">Product</span> <span class="nf">getProduct</span><span class="o">(</span><span class="nc">String</span> <span class="n">productName</span><span class="o">)</span> <span class="o">{</span>
<span class="nc">Product</span> <span class="n">product</span> <span class="o">=</span> <span class="n">productDao</span><span class="o">.</span><span class="na">findProduceByName</span><span class="o">(</span><span class="n">productName</span><span class="o">);</span>
<span class="k">if</span> <span class="o">(</span><span class="nc">Objects</span><span class="o">.</span><span class="na">isNull</span><span class="o">(</span><span class="n">product</span><span class="o">))</span> <span class="o">{</span>
<span class="k">throw</span> <span class="k">new</span> <span class="nf">IllegalArgumentException</span><span class="o">(</span><span class="s">"Product not exists at all!"</span><span class="o">);</span>
<span class="o">}</span>
<span class="k">return</span> <span class="n">product</span><span class="o">;</span>
<span class="o">}</span>
</code></pre></div></div>
<h3 id="小结">小结</h3>
<p>在本文中我们先从分布式事务场景入手，采用交互图的方式，向大家介绍分布式Saga以及TCC分布式事务协调协议交互，最后结合ServiceComb Pack所提供的示例向大家介绍如何编写Saga以及TCC的应用代码。</p>
</section>
<footer class="page__meta">
<p class="page__taxonomy">
<strong><i class="fa fa-fw fa-tags" aria-hidden="true"></i> 标签: </strong>
<span itemprop="keywords">
<a href="/tags/#pack" class="page__taxonomy-item" rel="tag">Pack</a><span class="sep">, </span>
<a href="/tags/#saga" class="page__taxonomy-item" rel="tag">Saga</a>
</span>
</p>
<p class="page__date"><strong><i class="fa fa-fw fa-calendar" aria-hidden="true"></i> 最新的:</strong> <time datetime="2019-01-10">2019年1月10日</time></p>
</footer>
<section class="page__share">
<h4 class="page__share-title">分享</h4>
<a href="https://twitter.com/intent/tweet?via=ServiceComb&text=基于服务的分布式事务(下篇) /cn/docs/distributed-transaction-of-services-2/" class="btn btn--twitter" title="分享 Twitter"><i class="fa fa-fw fa-twitter" aria-hidden="true"></i><span> Twitter</span></a>
<a href="https://www.facebook.com/sharer/sharer.php?u=/cn/docs/distributed-transaction-of-services-2/" class="btn btn--facebook" title="分享 Facebook"><i class="fa fa-fw fa-facebook" aria-hidden="true"></i><span> Facebook</span></a>
<a href="https://plus.google.com/share?url=/cn/docs/distributed-transaction-of-services-2/" class="btn btn--google-plus" title="分享 Google Plus"><i class="fa fa-fw fa-google-plus" aria-hidden="true"></i><span> Google+</span></a>
<a href="https://www.linkedin.com/shareArticle?mini=true&url=/cn/docs/distributed-transaction-of-services-2/" class="btn btn--linkedin" title="分享 LinkedIn"><i class="fa fa-fw fa-linkedin" aria-hidden="true"></i><span> LinkedIn</span></a>
</section>
<nav class="pagination">
<a href="/cn/docs/distributed-transaction-of-services-1/" class="pagination--pager" title="基于服务的分布式事务(上篇)
">向前</a>
<a href="/cn/docs/servicecomb-springcloud-zuul-demo/" class="pagination--pager" title="基于 ServiceComb 和 SpringCloud Zuul 快速构建微服务系统
">向后</a>
</nav>
</div>
<div class="page__comments">
<section id="static-comments">
<!-- Start static comments -->
<div class="js-comments">
</div>
<!-- End static comments -->
<!-- Start new comment form -->
<h4 class="page__comments-title">留下评论</h4>
<p class="small">您的电子邮箱地址并不会被展示。请填写标记为必须的字段。 <span class="required">*</span></p>
<form id="new_comment" class="page__comments-form js-form form" method="post" action="https://api.staticman.net/v1/entry/apache/incubator-servicecomb-website/master">
<div class="form__spinner">
<i class="fa fa-spinner fa-spin fa-3x fa-fw"></i>
<span class="sr-only">正在加载...</span>
</div>
<fieldset>
<label for="comment-form-message">评论 <small class="required">*</small></label>
<textarea type="text" rows="3" id="comment-form-message" name="fields[message]" tabindex="1"></textarea>
<div class="small help-block"><a href="https://daringfireball.net/projects/markdown/">Markdown语法已支持。</a></div>
</fieldset>
<fieldset>
<label for="comment-form-name">姓名 <small class="required">*</small></label>
<input type="text" id="comment-form-name" name="fields[name]" tabindex="2" />
</fieldset>
<fieldset>
<label for="comment-form-email">电子邮箱 <small class="required">*</small></label>
<input type="email" id="comment-form-email" name="fields[email]" tabindex="3" />
</fieldset>
<fieldset>
<label for="comment-form-url">网站（可选）</label>
<input type="url" id="comment-form-url" name="fields[url]" tabindex="4"/>
</fieldset>
<fieldset class="hidden" style="display: none;">
<input type="hidden" name="options[slug]" value="distributed-transaction-of-services-2">
<label for="comment-form-location">Not used. Leave blank if you are a human.</label>
<input type="text" id="comment-form-location" name="fields[hidden]" autocomplete="off"/>
</fieldset>
<!-- Start comment form alert messaging -->
<p class="hidden js-notice">
<strong class="js-notice-text"></strong>
</p>
<!-- End comment form alert messaging -->
<fieldset>
<button type="submit" id="comment-form-submit" tabindex="5" class="btn btn--large">提交评论</button>
</fieldset>
</form>
<!-- End new comment form -->
</section>
</div>
</article>
<div class="page__related">
<h4 class="page__related-title">猜您还喜欢</h4>
<div class="grid__wrapper">
<div class="grid__item">
<article class="archive__item" itemscope itemtype="http://schema.org/CreativeWork">
<h2 class="archive__item-title" itemprop="headline">
<a href="/cn/docs/playing-on-the-open-source-community-with-Apache-ServiceComb-GDUT/" rel="permalink">与Apache ServiceComb一起玩开源-广工站 (PPT Download)
</a>
</h2>
<p class="archive__item-excerpt" itemprop="description">与Apache ServiceComb一起玩开源-广工站 (PPT Download)
</p>
<p class="page__meta"><i class="fa fa-clock-o" aria-hidden="true"></i>
少于 1 分钟 阅读
</p>
</article>
</div>
<div class="grid__item">
<article class="archive__item" itemscope itemtype="http://schema.org/CreativeWork">
<h2 class="archive__item-title" itemprop="headline">
<a href="/cn/docs/servicecomb-service-center-client/" rel="permalink">使用ServiceComb客户端轻松调用ServiceCenter
</a>
</h2>
<p class="archive__item-excerpt" itemprop="description">使用ServiceComb客户端轻松调用ServiceCenter
</p>
<p class="page__meta"><i class="fa fa-clock-o" aria-hidden="true"></i>
2 分钟 阅读
</p>
</article>
</div>
<div class="grid__item">
<article class="archive__item" itemscope itemtype="http://schema.org/CreativeWork">
<h2 class="archive__item-title" itemprop="headline">
<a href="/cn/docs/playing-on-the-open-source-community-with-Apache-ServiceComb-BUPT/" rel="permalink">与Apache ServiceComb一起玩开源-北邮站 (PPT Download)
</a>
</h2>
<p class="archive__item-excerpt" itemprop="description">与Apache ServiceComb一起玩开源-北邮站 (PPT Download)
</p>
<p class="page__meta"><i class="fa fa-clock-o" aria-hidden="true"></i>
少于 1 分钟 阅读
</p>
</article>
</div>
<div class="grid__item">
<article class="archive__item" itemscope itemtype="http://schema.org/CreativeWork">
<h2 class="archive__item-title" itemprop="headline">
<a href="/docs/servicecomb-accept-newcapec-institute-code-donation/" rel="permalink">Apache ServiceComb Accept Code Donation From NewCapec Institute
</a>
</h2>
<p class="archive__item-excerpt" itemprop="description">Apache ServiceComb Accept Code Donation From NewCapec Institute
</p>
<p class="page__meta"><i class="fa fa-clock-o" aria-hidden="true"></i>
少于 1 分钟 阅读
</p>
</article>
</div>
</div>
</div>
</div>
<script async src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script>
<div align="center" style="margin: 0 0;">
<ins class="adsbygoogle"
style="display:block; border-bottom: initial;"
data-ad-client="ca-pub-7328585512091257"
data-ad-slot="3049671934"
data-ad-format="auto"></ins>
</div>
<div class="page__footer">
<footer>
<!-- start custom footer snippets -->
<!-- end custom footer snippets -->
<div class="container">
<div class="row justify-content-md-center">
<div class="col">
<ul>
<p class="header">活动</p>
<a class="acevent" data-format="square" data-mode="dark" data-event="random"></a>
</ul>
</div>
<div class="col">
<ul>
<p class="header">资源</p>
<li><a href="/cn/docs/getting-started/">入门指南</a></li>
<li><a href="/cn/docs/users/">用户指南</a></li>
<li><a href="/cn/slides/">资料</a></li>
<li><a href="/cn/users/faq/">常见问题</a></li>
</ul>
</div>
<div class="col">
<ul>
<p class="header">ASF</p>
<li><a href="http://www.apache.org">基金会</a></li>
<li><a href="http://www.apache.org/licenses/">许可证</a></li>
<li><a href="http://www.apache.org/events/current-event">活动</a></li>
<li><a href="http://www.apache.org/foundation/sponsorship.html">赞助</a></li>
<li><a href="http://www.apache.org/foundation/thanks.html">鸣谢</a></li>
</ul>
</div>
<div class="col">
<ul>
<p class="header">贡献</p>
<li><a href="http://issues.apache.org/jira/browse/SCB">报告本网页问题</a></li>
<li><a href="https://github.com/apache/servicecomb-website/edit/master/_posts/cn/2019-01-10-distributed-transaction-of-services-2.md">在Github上编辑此页</a></li>
<li><a href="/cn/developers/submit-codes/">代码提交指南</a></li>
<li><a href="/cn/security">安全</a></li>
</ul>
</div>
<div class="col">
<ul class="social-icons">
<p class="header">社区</p>
<li>
<a href="mailto:dev-subscribe@servicecomb.incubator.apache.org" rel="nofollow"><span class="mail">邮件列表</span></a>
</li>
<li>
<a href="https://github.com/apache?q=ServiceComb" target="_blank"><span class="github">Github</span></a>
</li>
<li>
<a href="https://twitter.com/ServiceComb" target="_blank"><span class="twitter">Twitter</span></a>
</li>
<li>
<a href="/feed.xml" target="_blank"><span class="rss">Feed</span></a>
</li>
</ul>
</div>
</div>
</div>
<div class="page__footer-bottom">
<div>&copy; 2024 Apache ServiceComb. 技术来自于 <a href="http://jekyllrb.com" rel="nofollow">Jekyll</a> &amp; <a href="https://mademistakes.com/work/minimal-mistakes-jekyll-theme/" rel="nofollow">Minimal Mistakes</a>.</div>
<div>All other marks mentioned may be trademarks or registered trademarks of their respective owners.</div>
</div>
</footer>
</div>
<script src="/assets/js/main.min.js"></script>
<script>
(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
})(window,document,'script','https://www.google-analytics.com/analytics.js','ga');
ga('create', 'UA-101622733-1', 'auto');
ga('send', 'pageview');
</script>
<script>
(function ($) {
var $comments = $('.js-comments');
$('#new_comment').submit(function () {
var form = this;
$(form).addClass('disabled');
$('#comment-form-submit').html('<i class="fa fa-spinner fa-spin fa-fw"></i> 正在加载...');
$.ajax({
type: $(this).attr('method'),
url: $(this).attr('action'),
data: $(this).serialize(),
contentType: 'application/x-www-form-urlencoded',
success: function (data) {
$('#comment-form-submit').html('已提交');
$('.page__comments-form .js-notice').removeClass('notice--danger');
$('.page__comments-form .js-notice').addClass('notice--success');
showAlert('感谢您的评论！被批准后它会立即在此站点展示。');
},
error: function (err) {
console.log(err);
$('#comment-form-submit').html('提交评论');
$('.page__comments-form .js-notice').removeClass('notice--success');
$('.page__comments-form .js-notice').addClass('notice--danger');
showAlert('很抱歉，您的提交存在错误。请确保所有必填字段都已填写正确，然后再试一次。');
$(form).removeClass('disabled');
}
});
return false;
});
function showAlert(message) {
$('.page__comments-form .js-notice').removeClass('hidden');
$('.page__comments-form .js-notice-text').html(message);
}
})(jQuery);
</script>
</body>
</html>