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Guide</a></div></li></ul></nav></div></div></aside><main class="docMainContainer_gTbr"><div class="container padding-top--md padding-bottom--lg"><div class="row"><div class="col docItemCol_VOVn"><div class="docItemContainer_Djhp"><article><nav class="theme-doc-breadcrumbs breadcrumbsContainer_Z_bl" aria-label="Breadcrumbs"><ul class="breadcrumbs" itemscope="" itemtype="https://schema.org/BreadcrumbList"><li class="breadcrumbs__item"><a aria-label="Home page" class="breadcrumbs__link" href="/"><svg viewBox="0 0 24 24" class="breadcrumbHomeIcon_YNFT"><path d="M10 19v-5h4v5c0 .55.45 1 1 1h3c.55 0 1-.45 1-1v-7h1.7c.46 0 .68-.57.33-.87L12.67 3.6c-.38-.34-.96-.34-1.34 0l-8.36 7.53c-.34.3-.13.87.33.87H5v7c0 .55.45 1 1 1h3c.55 0 1-.45 1-1z" fill="currentColor"></path></svg></a></li><li class="breadcrumbs__item"><span class="breadcrumbs__link">Domain Model</span><meta itemprop="position" content="1"></li><li itemscope="" itemprop="itemListElement" itemtype="https://schema.org/ListItem" class="breadcrumbs__item breadcrumbs__item--active"><span class="breadcrumbs__link" itemprop="name">Domain Model</span><meta itemprop="position" content="2"></li></ul></nav><span class="theme-doc-version-badge badge badge--secondary">Version: 5.0</span><div class="tocCollapsible_ETCw theme-doc-toc-mobile tocMobile_ITEo"><button type="button" class="clean-btn tocCollapsibleButton_TO0P">On this page</button></div><div class="theme-doc-markdown markdown"><h1>Domain Model</h1><p>This section describes the domain model of Apache RocketMQ.</p><p>Apache RocketMQ is a distributed middleware service that adopts an asynchronous communication model and a publish/subscribe message transmission model.</p><p>For more information about the communication model and transmission model, see <strong>Communication model</strong> and <strong>Message transmission model</strong>.</p><p>The asynchronous communication model of Apache RocketMQ features simple system topology and weak upstream-downstream coupling. Apache RocketMQ is used in asynchronous decoupling and load shifting scenarios.</p><h2 class="anchor anchorWithStickyNavbar_LWe7" id="domain-model-of-apache-rocketmq">Domain model of Apache RocketMQ<a href="#domain-model-of-apache-rocketmq" class="hash-link" aria-label="Direct link to heading" title="Direct link to heading"></a></h2><p><img loading="lazy" alt="领域模型" src="/assets/images/mainarchi-9b036e7ff5133d050950f25838367a17.png" width="2333" height="856" class="img_ev3q"></p><p>As shown in the preceding figure, the lifecycle of a Apache RocketMQ message consists of three stages: production, storage, and consumption.</p><p>A producer generates a message and sends it to a Apache RocketMQ broker. The message is stored in a topic on the broker. A consumer subscribes to the topic to consume the message.</p><p><strong>Message production</strong></p><p><a href="/docs/domainModel/04producer">Producer</a>：</p><p>The running entity that is used to generate messages in Apache RocketMQ. Producers are the upstream parts of business call links. Producers are lightweight, anonymous, and do not have identities.</p><p><strong>Message storage</strong></p><ul><li><p><a href="/docs/domainModel/02topic">Topic</a>：</p><p>The grouping container that is used for message transmission and storage in Apache RocketMQ. A topic consists of multiple message queues, which are used to store messages and scale out the topic.</p></li><li><p><a href="/docs/domainModel/03messagequeue">MessageQueue</a>：</p><p>The unit container that is used for message transmission and storage in Apache RocketMQ. Message queues are similar to partitions in Kafka. Apache RocketMQ stores messages in a streaming manner based on an infinite queue structure. Messages are stored in order in a queue.</p></li><li><p><a href="/docs/domainModel/04message">Message</a>：</p><p>The minimum unit of data transmission in Apache RocketMQ. Messages are immutable after they are initialized and stored.</p></li></ul><p><strong>Message consumption</strong></p><ul><li><p><a href="/docs/domainModel/07consumergroup">ConsumerGroup</a>：</p><p>An independent group of consumption identities defined in the publish/subscribe model of Apache RocketMQ. A consumer group is used to centrally manage consumers that run at the bottom layer. Consumers in the same group must maintain the same consumption logic and configurations with each other, and consume the messages subscribed by the group together to scale out the consumption capacity of the group.</p></li><li><p><a href="/docs/domainModel/08consumer">Consumer</a>：</p><p>The running entity that is used to consume messages in Apache RocketMQ. Consumers are the downstream parts of business call links, A consumer must belong to a specific consumer group.</p></li><li><p><a href="/docs/domainModel/09subscription">Subscription</a>：</p><p>The collection of configurations in the publish/subscribe model of Apache RocketMQ. The configurations include message filtering, retry, and consumer progress Subscriptions are managed at the consumer group level. You use consumer groups to specify subscriptions to manage how consumers in the group filter messages, retry consumption, and restore a consumer offset.</p><p>The configurations in a Apache RocketMQ subscription are all persistent, except for filter expressions. Subscriptions are unchanged regardless of whether the broker restarts or the connection is closed.</p></li></ul><h2 class="anchor anchorWithStickyNavbar_LWe7" id="communication-model">Communication model<a href="#communication-model" class="hash-link" aria-label="Direct link to heading" title="Direct link to heading"></a></h2><p>According to the concept of distributed system architecture, a complex system can be split into multiple independent modules, such as microservice modules. Remote communication between the modules must be ensured in the system. There are two typical communication models for this purpose: RPC-based synchronous communication model and middleware-based asynchronous communication model.</p><p>RPC-based synchronous model</p><p><img loading="lazy" alt="Synchronous invocation" src="/assets/images/syncarchi-ebbd41e1afd6adf432792ee2d7a91748.png" width="1258" height="856" class="img_ev3q"></p><p>In this model, remote systems communicate with each other directly. Each request is sent directly from the caller to the callee, and the callee returns the call result immediately to the caller. |
