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&#x27;Reference&#x27;" type="button" class="clean-btn menu__caret"></button></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">Client Libraries</span><meta itemprop="position" content="1"></li><li class="breadcrumbs__item"><span class="breadcrumbs__link">Get started</span><meta itemprop="position" content="2"></li><li itemscope="" itemprop="itemListElement" itemtype="https://schema.org/ListItem" class="breadcrumbs__item"><a class="breadcrumbs__link" itemprop="item" href="/docs/next/client-libraries-cpp/"><span itemprop="name">C++ client</span></a><meta itemprop="position" content="3"></li><li itemscope="" itemprop="itemListElement" itemtype="https://schema.org/ListItem" class="breadcrumbs__item breadcrumbs__item--active"><span class="breadcrumbs__link" itemprop="name">Use</span><meta itemprop="position" content="4"></li></ul></nav><span class="theme-doc-version-badge badge badge--secondary">Version: Next</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"><header><h1>Use C++ client</h1></header><h2 class="anchor anchorWithStickyNavbar_LWe7" id="create-a-producer">Create a producer<a href="#create-a-producer" class="hash-link" aria-label="Direct link to Create a producer" title="Direct link to Create a producer">​</a></h2><p>To use Pulsar as a producer, you need to create a producer on the C++ client. There are two main ways of using a producer:</p><ul><li><a href="#simple-blocking-example">Blocking style</a> : each call to <code>send</code> waits for an ack from the broker.</li><li><a href="#non-blocking-example">Non-blocking asynchronous style</a> : <code>sendAsync</code> is called instead of <code>send</code> and a callback is supplied for when the ack is received from the broker.</li></ul><h3 class="anchor anchorWithStickyNavbar_LWe7" id="simple-blocking-example">Simple blocking example<a href="#simple-blocking-example" class="hash-link" aria-label="Direct link to Simple blocking example" title="Direct link to Simple blocking example">​</a></h3><p>This example sends 100 messages using the blocking style. While simple, it does not produce high throughput as it waits for each ack to come back before sending the next message.</p><div class="language-cpp codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#F8F8F2;--prism-background-color:#282A36"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-cpp codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#F8F8F2"><span class="token macro property directive-hash">#</span><span class="token macro property directive keyword" style="color:rgb(189, 147, 249);font-style:italic">include</span><span class="token macro property"> </span><span class="token macro property string" style="color:rgb(255, 121, 198)">&lt;pulsar/Client.h&gt;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token macro property directive-hash">#</span><span class="token macro property directive keyword" style="color:rgb(189, 147, 249);font-style:italic">include</span><span class="token macro property"> </span><span class="token macro property string" style="color:rgb(255, 121, 198)">&lt;thread&gt;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">using</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">namespace</span><span class="token plain"> pulsar</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">int</span><span class="token plain"> </span><span class="token function" style="color:rgb(80, 250, 123)">main</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> Client </span><span class="token function" style="color:rgb(80, 250, 123)">client</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token string" style="color:rgb(255, 121, 198)">&quot;pulsar://localhost:6650&quot;</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> Producer producer</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> Result result </span><span class="token operator">=</span><span class="token plain"> client</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">createProducer</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token string" style="color:rgb(255, 121, 198)">&quot;persistent://public/default/my-topic&quot;</span><span class="token punctuation" style="color:rgb(248, 248, 242)">,</span><span class="token plain"> producer</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">if</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">result </span><span class="token operator">!=</span><span class="token plain"> ResultOk</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">cout </span><span class="token operator">&lt;&lt;</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">&quot;Error creating producer: &quot;</span><span class="token plain"> </span><span class="token operator">&lt;&lt;</span><span class="token plain"> result </span><span class="token operator">&lt;&lt;</span><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">endl</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">return</span><span class="token plain"> </span><span class="token operator">-</span><span class="token number">1</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token comment" style="color:rgb(98, 114, 164)">// Send 100 messages synchronously</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">int</span><span class="token plain"> ctr </span><span class="token operator">=</span><span class="token plain"> </span><span class="token number">0</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">while</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">ctr </span><span class="token operator">&lt;</span><span class="token plain"> </span><span class="token number">100</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">string content </span><span class="token operator">=</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">&quot;msg&quot;</span><span class="token plain"> </span><span class="token operator">+</span><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token function" style="color:rgb(80, 250, 123)">to_string</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">ctr</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> Message msg </span><span class="token operator">=</span><span class="token plain"> </span><span class="token function" style="color:rgb(80, 250, 123)">MessageBuilder</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">setContent</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">content</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">setProperty</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token string" style="color:rgb(255, 121, 198)">&quot;x&quot;</span><span class="token punctuation" style="color:rgb(248, 248, 242)">,</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">&quot;1&quot;</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">build</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> Result result </span><span class="token operator">=</span><span class="token plain"> producer</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">send</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">msg</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">if</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">result </span><span class="token operator">!=</span><span class="token plain"> ResultOk</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">cout </span><span class="token operator">&lt;&lt;</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">&quot;The message &quot;</span><span class="token plain"> </span><span class="token operator">&lt;&lt;</span><span class="token plain"> content </span><span class="token operator">&lt;&lt;</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">&quot; could not be sent, received code: &quot;</span><span class="token plain"> </span><span class="token operator">&lt;&lt;</span><span class="token plain"> result </span><span class="token operator">&lt;&lt;</span><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">endl</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">else</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">cout </span><span class="token operator">&lt;&lt;</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">&quot;The message &quot;</span><span class="token plain"> </span><span class="token operator">&lt;&lt;</span><span class="token plain"> content </span><span class="token operator">&lt;&lt;</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">&quot; sent successfully&quot;</span><span class="token plain"> </span><span class="token operator">&lt;&lt;</span><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">endl</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">this_thread</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token function" style="color:rgb(80, 250, 123)">sleep_for</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">chrono</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token function" style="color:rgb(80, 250, 123)">milliseconds</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token number">100</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> ctr</span><span class="token operator">++</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">cout </span><span class="token operator">&lt;&lt;</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">&quot;Finished producing synchronously!&quot;</span><span class="token plain"> </span><span class="token operator">&lt;&lt;</span><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">endl</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> client</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">close</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">return</span><span class="token plain"> </span><span class="token number">0</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div><h3 class="anchor anchorWithStickyNavbar_LWe7" id="non-blocking-example">Non-blocking example<a href="#non-blocking-example" class="hash-link" aria-label="Direct link to Non-blocking example" title="Direct link to Non-blocking example">​</a></h3><p>This example sends 100 messages using the non-blocking style calling <code>sendAsync</code> instead of <code>send</code>. This allows the producer to have multiple messages in-flight at a time which increases throughput.</p><p>The producer configuration <code>blockIfQueueFull</code> is useful here to avoid <code>ResultProducerQueueIsFull</code> errors when the internal queue for outgoing send requests becomes full. Once the internal queue is full, <code>sendAsync</code> becomes blocking which can make your code simpler.</p><p>Without this configuration, the result code <code>ResultProducerQueueIsFull</code> is passed to the callback. You must decide how to deal with that (retry, discard etc).</p><div class="language-cpp codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#F8F8F2;--prism-background-color:#282A36"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-cpp codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#F8F8F2"><span class="token macro property directive-hash">#</span><span class="token macro property directive keyword" style="color:rgb(189, 147, 249);font-style:italic">include</span><span class="token macro property"> </span><span class="token macro property string" style="color:rgb(255, 121, 198)">&lt;pulsar/Client.h&gt;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token macro property directive-hash">#</span><span class="token macro property directive keyword" style="color:rgb(189, 147, 249);font-style:italic">include</span><span class="token macro property"> </span><span class="token macro property string" style="color:rgb(255, 121, 198)">&lt;thread&gt;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token macro property directive-hash">#</span><span class="token macro property directive keyword" style="color:rgb(189, 147, 249);font-style:italic">include</span><span class="token macro property"> </span><span class="token macro property string" style="color:rgb(255, 121, 198)">&lt;atomic&gt;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">using</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">namespace</span><span class="token plain"> pulsar</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">atomic</span><span class="token operator">&lt;</span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">uint32_t</span><span class="token operator">&gt;</span><span class="token plain"> acksReceived</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">void</span><span class="token plain"> </span><span class="token function" style="color:rgb(80, 250, 123)">callback</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">Result code</span><span class="token punctuation" style="color:rgb(248, 248, 242)">,</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">const</span><span class="token plain"> MessageId</span><span class="token operator">&amp;</span><span class="token plain"> msgId</span><span class="token punctuation" style="color:rgb(248, 248, 242)">,</span><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">string msgContent</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token comment" style="color:rgb(98, 114, 164)">// message processing logic here</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">cout </span><span class="token operator">&lt;&lt;</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">&quot;Received ack for msg: &quot;</span><span class="token plain"> </span><span class="token operator">&lt;&lt;</span><span class="token plain"> msgContent </span><span class="token operator">&lt;&lt;</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">&quot; with code: &quot;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token operator">&lt;&lt;</span><span class="token plain"> code </span><span class="token operator">&lt;&lt;</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">&quot; -- MsgID: &quot;</span><span class="token plain"> </span><span class="token operator">&lt;&lt;</span><span class="token plain"> msgId </span><span class="token operator">&lt;&lt;</span><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">endl</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> acksReceived</span><span class="token operator">++</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">int</span><span class="token plain"> </span><span class="token function" style="color:rgb(80, 250, 123)">main</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> Client </span><span class="token function" style="color:rgb(80, 250, 123)">client</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token string" style="color:rgb(255, 121, 198)">&quot;pulsar://localhost:6650&quot;</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> ProducerConfiguration producerConf</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> producerConf</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">setBlockIfQueueFull</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token boolean">true</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> Producer producer</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> Result result </span><span class="token operator">=</span><span class="token plain"> client</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">createProducer</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token string" style="color:rgb(255, 121, 198)">&quot;persistent://public/default/my-topic&quot;</span><span class="token punctuation" style="color:rgb(248, 248, 242)">,</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> producerConf</span><span class="token punctuation" style="color:rgb(248, 248, 242)">,</span><span class="token plain"> producer</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">if</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">result </span><span class="token operator">!=</span><span class="token plain"> ResultOk</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">cout </span><span class="token operator">&lt;&lt;</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">&quot;Error creating producer: &quot;</span><span class="token plain"> </span><span class="token operator">&lt;&lt;</span><span class="token plain"> result </span><span class="token operator">&lt;&lt;</span><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">endl</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">return</span><span class="token plain"> </span><span class="token operator">-</span><span class="token number">1</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token comment" style="color:rgb(98, 114, 164)">// Send 100 messages asynchronously</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">int</span><span class="token plain"> ctr </span><span class="token operator">=</span><span class="token plain"> </span><span class="token number">0</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">while</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">ctr </span><span class="token operator">&lt;</span><span class="token plain"> </span><span class="token number">100</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">string content </span><span class="token operator">=</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">&quot;msg&quot;</span><span class="token plain"> </span><span class="token operator">+</span><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token function" style="color:rgb(80, 250, 123)">to_string</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">ctr</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> Message msg </span><span class="token operator">=</span><span class="token plain"> </span><span class="token function" style="color:rgb(80, 250, 123)">MessageBuilder</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">setContent</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">content</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">setProperty</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token string" style="color:rgb(255, 121, 198)">&quot;x&quot;</span><span class="token punctuation" style="color:rgb(248, 248, 242)">,</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">&quot;1&quot;</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">build</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> producer</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">sendAsync</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">msg</span><span class="token punctuation" style="color:rgb(248, 248, 242)">,</span><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token function" style="color:rgb(80, 250, 123)">bind</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">callback</span><span class="token punctuation" style="color:rgb(248, 248, 242)">,</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">placeholders</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">_1</span><span class="token punctuation" style="color:rgb(248, 248, 242)">,</span><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">placeholders</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">_2</span><span class="token punctuation" style="color:rgb(248, 248, 242)">,</span><span class="token plain"> content</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">this_thread</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token function" style="color:rgb(80, 250, 123)">sleep_for</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">chrono</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token function" style="color:rgb(80, 250, 123)">milliseconds</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token number">100</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> ctr</span><span class="token operator">++</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token comment" style="color:rgb(98, 114, 164)">// wait for 100 messages to be acked</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">while</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">acksReceived </span><span class="token operator">&lt;</span><span class="token plain"> </span><span class="token number">100</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">this_thread</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token function" style="color:rgb(80, 250, 123)">sleep_for</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">chrono</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token function" style="color:rgb(80, 250, 123)">milliseconds</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token number">100</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">cout </span><span class="token operator">&lt;&lt;</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">&quot;Finished producing asynchronously!&quot;</span><span class="token plain"> </span><span class="token operator">&lt;&lt;</span><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">endl</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> client</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">close</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">return</span><span class="token plain"> </span><span class="token number">0</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div><h3 class="anchor anchorWithStickyNavbar_LWe7" id="partitioned-topics-and-lazy-producers">Partitioned topics and lazy producers<a href="#partitioned-topics-and-lazy-producers" class="hash-link" aria-label="Direct link to Partitioned topics and lazy producers" title="Direct link to Partitioned topics and lazy producers">​</a></h3><p>When scaling out a Pulsar topic, you may configure a topic to have hundreds of partitions. Likewise, you may have also scaled out your producers so there are hundreds or even thousands of producers. This can put some strain on the Pulsar brokers as when you create a producer on a partitioned topic, internally it creates one internal producer per partition which involves communications to the brokers for each one. So for a topic with 1000 partitions and 1000 producers, it ends up creating 1,000,000 internal producers across the producer applications, each of which has to communicate with a broker to find out which broker it should connect to and then perform the connection handshake.</p><p>You can reduce the load caused by this combination of a large number of partitions and many producers by doing the following:</p><ul><li>use SinglePartition partition routing mode (this ensures that all messages are only sent to a single, randomly selected partition)</li><li>use non-keyed messages (when messages are keyed, routing is based on the hash of the key and so messages will end up being sent to multiple partitions)</li><li>use lazy producers (this ensures that an internal producer is only created on demand when a message needs to be routed to a partition)</li></ul><p>With our example above, that reduces the number of internal producers spread out over the 1000 producer apps from 1,000,000 to just 1000.</p><p>Note that there can be extra latency for the first message sent. If you set a low send timeout, this timeout could be reached if the initial connection handshake is slow to complete.</p><div class="language-cpp codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#F8F8F2;--prism-background-color:#282A36"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-cpp codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#F8F8F2"><span class="token plain">ProducerConfiguration producerConf</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">producerConf</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">setPartitionsRoutingMode</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">ProducerConfiguration</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">UseSinglePartition</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain">producerConf</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">setLazyStartPartitionedProducers</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token boolean">true</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div><h2 class="anchor anchorWithStickyNavbar_LWe7" id="create-a-consumer">Create a consumer<a href="#create-a-consumer" class="hash-link" aria-label="Direct link to Create a consumer" title="Direct link to Create a consumer">​</a></h2><p>To use Pulsar as a consumer, you need to create a consumer on the C++ client. There are two main ways of using the consumer:</p><ul><li><a href="#blocking-example">Blocking style</a>: synchronously calling <code>receive(msg)</code>.</li><li><a href="#consumer-with-a-message-listener">Non-blocking</a> (event-based) style: using a message listener.</li></ul><h3 class="anchor anchorWithStickyNavbar_LWe7" id="blocking-example">Blocking example<a href="#blocking-example" class="hash-link" aria-label="Direct link to Blocking example" title="Direct link to Blocking example">​</a></h3><p>The benefit of this approach is that it is the simplest code. Simply keeps calling <code>receive(msg)</code> which blocks until a message is received.</p><p>This example starts a subscription at the earliest offset and consumes 100 messages.</p><div class="language-cpp codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#F8F8F2;--prism-background-color:#282A36"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-cpp codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#F8F8F2"><span class="token macro property directive-hash">#</span><span class="token macro property directive keyword" style="color:rgb(189, 147, 249);font-style:italic">include</span><span class="token macro property"> </span><span class="token macro property string" style="color:rgb(255, 121, 198)">&lt;pulsar/Client.h&gt;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">using</span><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">namespace</span><span class="token plain"> pulsar</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">int</span><span class="token plain"> </span><span class="token function" style="color:rgb(80, 250, 123)">main</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> Client </span><span class="token function" style="color:rgb(80, 250, 123)">client</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token string" style="color:rgb(255, 121, 198)">&quot;pulsar://localhost:6650&quot;</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> Consumer consumer</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> ConsumerConfiguration config</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> config</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">setSubscriptionInitialPosition</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">InitialPositionEarliest</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> Result result </span><span class="token operator">=</span><span class="token plain"> client</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">subscribe</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token string" style="color:rgb(255, 121, 198)">&quot;persistent://public/default/my-topic&quot;</span><span class="token punctuation" style="color:rgb(248, 248, 242)">,</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">&quot;consumer-1&quot;</span><span class="token punctuation" style="color:rgb(248, 248, 242)">,</span><span class="token plain"> config</span><span class="token punctuation" style="color:rgb(248, 248, 242)">,</span><span class="token plain"> consumer</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">if</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">result </span><span class="token operator">!=</span><span class="token plain"> ResultOk</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">cout </span><span class="token operator">&lt;&lt;</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">&quot;Failed to subscribe: &quot;</span><span class="token plain"> </span><span class="token operator">&lt;&lt;</span><span class="token plain"> result </span><span class="token operator">&lt;&lt;</span><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">endl</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">return</span><span class="token plain"> </span><span class="token operator">-</span><span class="token number">1</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> Message msg</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">int</span><span class="token plain"> ctr </span><span class="token operator">=</span><span class="token plain"> </span><span class="token number">0</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token comment" style="color:rgb(98, 114, 164)">// consume 100 messages</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">while</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">ctr </span><span class="token operator">&lt;</span><span class="token plain"> </span><span class="token number">100</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">{</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> consumer</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">receive</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">msg</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">cout </span><span class="token operator">&lt;&lt;</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">&quot;Received: &quot;</span><span class="token plain"> </span><span class="token operator">&lt;&lt;</span><span class="token plain"> msg</span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token operator">&lt;&lt;</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">&quot; with payload &#x27;&quot;</span><span class="token plain"> </span><span class="token operator">&lt;&lt;</span><span class="token plain"> msg</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">getDataAsString</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token plain"> </span><span class="token operator">&lt;&lt;</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">&quot;&#x27;&quot;</span><span class="token plain"> </span><span class="token operator">&lt;&lt;</span><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">endl</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> consumer</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">acknowledge</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token plain">msg</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> ctr</span><span class="token operator">++</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">cout </span><span class="token operator">&lt;&lt;</span><span class="token plain"> </span><span class="token string" style="color:rgb(255, 121, 198)">&quot;Finished consuming synchronously!&quot;</span><span class="token plain"> </span><span class="token operator">&lt;&lt;</span><span class="token plain"> std</span><span class="token double-colon punctuation" style="color:rgb(248, 248, 242)">::</span><span class="token plain">endl</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain" style="display:inline-block"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> client</span><span class="token punctuation" style="color:rgb(248, 248, 242)">.</span><span class="token function" style="color:rgb(80, 250, 123)">close</span><span class="token punctuation" style="color:rgb(248, 248, 242)">(</span><span class="token punctuation" style="color:rgb(248, 248, 242)">)</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"> </span><span class="token keyword" style="color:rgb(189, 147, 249);font-style:italic">return</span><span class="token plain"> </span><span class="token number">0</span><span class="token punctuation" style="color:rgb(248, 248, 242)">;</span><span class="token plain"></span><br></span><span class="token-line" style="color:#F8F8F2"><span class="token plain"></span><span class="token punctuation" style="color:rgb(248, 248, 242)">}</span><br></span></code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><span class="copyButtonIcons_eSgA" aria-hidden="true"><svg class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div></div><footer class="theme-doc-footer docusaurus-mt-lg"><div class="theme-doc-footer-edit-meta-row row"><div class="col"><a href="https://github.com/apache/pulsar-site/edit/main/docs/client-libraries-cpp-use.md" target="_blank" rel="noreferrer noopener" class="theme-edit-this-page"><svg 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