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Chen, Junjie
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Reviewed-by: Hasko, Vladimir <vladimir.hasko@t-systems.com> Co-authored-by: Chen, Junjie <chenjunjie@huawei.com> Co-committed-by: Chen, Junjie <chenjunjie@huawei.com>
31 lines
3.6 KiB
HTML
31 lines
3.6 KiB
HTML
<a name="glossary-kafka"></a><a name="glossary-kafka"></a>
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<h1 class="topictitle1">Basic Concepts</h1>
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<div id="body1555421158910"><p id="glossary-kafka__p1362824712140">DMS for Kafka of the cloud service platform uses Kafka as the message engine. This chapter presents explanations of basic concepts of Kafka.</p>
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<div class="section" id="glossary-kafka__section42471521131411"><h4 class="sectiontitle">Topic</h4><p id="glossary-kafka__p15624299192">A topic is a category for messages. Messages are created, retrieved, and managed in the form of topics.</p>
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<p id="glossary-kafka__p13714822151413">Topics adopt the publish-subscribe pattern. Producers publish messages into topics. One or more consumers subscribe to the messages in the topics. The producers and consumers are not directly linked to each other.</p>
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</div>
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<div class="section" id="glossary-kafka__section069613812487"><h4 class="sectiontitle">Producer</h4><p id="glossary-kafka__p17477357133116">A producer publishes messages into topics. The messages are then delivered to other systems or modules for processing as agreed.</p>
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</div>
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<div class="section" id="glossary-kafka__section123045457485"><h4 class="sectiontitle">Consumer</h4><p id="glossary-kafka__p117355418313">A consumer subscribes to messages in topics and processes the messages. For example, a monitoring and alarm platform (a consumer) subscribing to log messages in certain topics can identify alarm logs and then send SMS or email alarm notifications.</p>
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</div>
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<div class="section" id="glossary-kafka__section8248205211017"><h4 class="sectiontitle">Broker</h4><p id="glossary-kafka__p12160182118334">A broker is a Kafka process in a Kafka cluster. Each process runs on a server, so a broker includes the storage, bandwidth, and other server resources.</p>
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</div>
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<div class="section" id="glossary-kafka__section1652345013486"><h4 class="sectiontitle">Partition</h4><p id="glossary-kafka__p31291552101910">A topic is divided into partitions. Messages are distributed to multiple partitions to achieve scalability and fault tolerance.</p>
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</div>
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<div class="section" id="glossary-kafka__section10446104394412"><h4 class="sectiontitle">Replica</h4><p id="glossary-kafka__p1479264184920">A replica is a redundant copy of a partition in a topic. Each partition can have one or more replicas, enabling message reliability.</p>
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<p id="glossary-kafka__p386435083017">Messages in each partition are fully replicated and synchronized, preventing data loss if one replica fails.</p>
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<p id="glossary-kafka__p88152053608">Each partition has one replica as the leader which handles the creation and retrievals of all messages. The rest replicas are followers which replicate the leader.</p>
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</div>
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<p id="glossary-kafka__p18209733111212">Topics and partitions are logical concepts, while replicas and brokers are physical concepts. The following diagram shows the relationships between partitions, brokers, and topics in messages streaming.</p>
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<div class="fignone" id="glossary-kafka__fig1964914751312"><span class="figcap"><b>Figure 1 </b>Kafka message streaming</span><br><span><img id="glossary-kafka__image1555217911352" src="en-us_image_0169395994.png"></span></div>
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<div class="section" id="glossary-kafka__section155347743710"><h4 class="sectiontitle">Aging Time</h4><p id="glossary-kafka__p49692147377">The period that messages are retained for. Consumers must retrieve messages before this period ends. Otherwise, the messages will be deleted and can no longer be retrieved.</p>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="kafka-ug-0723001.html">Service Overview</a></div>
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