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<title>Structured Data ยท NATS</title>
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Introduction
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What's New in 2.0
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<li class="header">Concepts</li>
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What is NATS
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Subject-Based Messaging
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Publish-Subscribe
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Request-Reply
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Queue Groups
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Acknowledgements
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Sequence Numbers
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<li class="header">Developing With NATS</li>
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Introduction
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Connecting
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Connecting to the Default Server
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Connecting to a Specific Server
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Connecting to a Cluster
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Setting a Connect Timeout
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Ping/Pong Protocol
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Controlling the Client/Server Protocol
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Turning Off Echo'd Messages
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Automatic Reconnections
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Disabling Reconnect
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Set the Number of Reconnect Attempts
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Pausing Between Reconnect Attempts
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Avoiding the Thundering Herd
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Listening for Reconnect Events
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Buffering Messages During Reconnect Attempts
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Securing Connections
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Authenticating with a User and Password
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Authenticating with a Token
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Authenticating with an NKey
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Authenticating with a Credentials File
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Encrypting Connections with TLS
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Receiving Messages
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Synchronous Subscriptions
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Asynchronous Subscriptions
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Unsubscribing
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Unsubscribing After N Messages
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Replying to a Message
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Wildcard Subscriptions
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Queue Subscriptions
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Draining Messages Before Disconnect
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Structured Data
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Sending Messages
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Including a Reply Subject
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Request-Reply Semantics
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Caches, Flush and Ping
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Sending Structured Data
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Monitoring the Connection
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Listen for Connection Events
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Slow Consumers
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Tutorials
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<a href="../tutorials/pubsub.html">
Explore NATS Pub/Sub
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<li class="chapter " data-level="3.8.2" data-path="../tutorials/reqreply.html">
<a href="../tutorials/reqreply.html">
Explore NATS Request/Reply
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<li class="chapter " data-level="3.8.3" data-path="../tutorials/queues.html">
<a href="../tutorials/queues.html">
Explore NATS Queueing
</a>
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<li class="chapter " data-level="3.8.4" data-path="../tutorials/custom_dialer.html">
<a href="../tutorials/custom_dialer.html">
Advanced Connect and Custom Dialer in Go
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</ul>
</li>
<li class="header">NATS Server</li>
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Installing
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<a href="../../nats_server/running.html">
Running
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Window Service
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Clients
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Flags
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Configuration
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Securing NATS
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Enabling TLS
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Authentication
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Tokens
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Username/Password
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TLS Authentication
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NKeys
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Accounts
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<a href="../../nats_server/jwt_auth.html">
JWTs
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<a href="../../nats_server/auth_timeout.html">
Authentication Timeout
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<li class="chapter " data-level="4.5.1.3" data-path="../../nats_server/authorization.html">
<a href="../../nats_server/authorization.html">
Authorization
</a>
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</ul>
</li>
<li class="chapter " data-level="4.5.2" data-path="../../nats_server/clustering.html">
<a href="../../nats_server/clustering.html">
Clustering
</a>
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<li class="chapter " data-level="4.5.2.1" data-path="../../nats_server/cluster_config.html">
<a href="../../nats_server/cluster_config.html">
Configuration
</a>
</li>
<li class="chapter " data-level="4.5.2.2" data-path="../../nats_server/cluster_tls.html">
<a href="../../nats_server/cluster_tls.html">
TLS Authentication
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="4.5.3" data-path="../../gateways/">
<a href="../../gateways/">
Gateways
</a>
<ul class="articles">
<li class="chapter " data-level="4.5.3.1" data-path="../../gateways/gateway.html">
<a href="../../gateways/gateway.html">
Configuration
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="4.5.4" data-path="../../leafnodes/">
<a href="../../leafnodes/">
Leaf Nodes
</a>
<ul class="articles">
<li class="chapter " data-level="4.5.4.1" data-path="../../leafnodes/leafnode_conf.html">
<a href="../../leafnodes/leafnode_conf.html">
Configuration
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="4.5.5" data-path="../../nats_server/logging.html">
<a href="../../nats_server/logging.html">
Logging
</a>
</li>
<li class="chapter " data-level="4.5.6" data-path="../../nats_server/monitoring.html">
<a href="../../nats_server/monitoring.html">
Monitoring
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="4.6" data-path="../../nats_admin/">
<a href="../../nats_admin/">
Managing A NATS Server
</a>
<ul class="articles">
<li class="chapter " data-level="4.6.1" data-path="../../nats_admin/upgrading_cluster.html">
<a href="../../nats_admin/upgrading_cluster.html">
Upgrading a Cluster
</a>
</li>
<li class="chapter " data-level="4.6.2" data-path="../../nats_admin/slow_consumers.html">
<a href="../../nats_admin/slow_consumers.html">
Slow Consumers
</a>
</li>
<li class="chapter " data-level="4.6.3" data-path="../../nats_admin/signals.html">
<a href="../../nats_admin/signals.html">
Signals
</a>
</li>
<li class="chapter " data-level="4.6.4" data-path="../../sys_accounts/">
<a href="../../sys_accounts/">
System Accounts
</a>
<ul class="articles">
<li class="chapter " data-level="4.6.4.1" data-path="../../sys_accounts/sys_accounts.html">
<a href="../../sys_accounts/sys_accounts.html">
Configuration
</a>
</li>
</ul>
</li>
</ul>
</li>
<li class="chapter " data-level="4.7" data-path="../../nats_docker/">
<a href="../../nats_docker/">
NATS and Docker
</a>
<ul class="articles">
<li class="chapter " data-level="4.7.1" data-path="../../nats_docker/tutorial.html">
<a href="../../nats_docker/tutorial.html">
Tutorial
</a>
</li>
<li class="chapter " data-level="4.7.2" data-path="../../nats_docker/docker_swarm.html">
<a href="../../nats_docker/docker_swarm.html">
Docker Swarm
</a>
</li>
</ul>
</li>
<li class="header">NATS Tools</li>
<li class="chapter " data-level="5.1" data-path="../../nats_tools/mkpasswd.html">
<a href="../../nats_tools/mkpasswd.html">
mkpasswd
</a>
</li>
<li class="chapter " data-level="5.2" data-path="../../nats_tools/nk.html">
<a href="../../nats_tools/nk.html">
nk
</a>
</li>
<li class="chapter " data-level="5.3" data-path="../../nats_tools/nsc/">
<a href="../../nats_tools/nsc/">
nsc
</a>
<ul class="articles">
<li class="chapter " data-level="5.3.1" data-path="../../nats_tools/nsc/nsc.html">
<a href="../../nats_tools/nsc/nsc.html">
Basics
</a>
</li>
<li class="chapter " data-level="5.3.2" data-path="../../nats_tools/nsc/streams.html">
<a href="../../nats_tools/nsc/streams.html">
Streams
</a>
</li>
<li class="chapter " data-level="5.3.3" data-path="../../nats_tools/nsc/services.html">
<a href="../../nats_tools/nsc/services.html">
Services
</a>
</li>
<li class="chapter " data-level="5.3.4" data-path="../../nats_tools/nsc/signing_keys.html">
<a href="../../nats_tools/nsc/signing_keys.html">
Signing Keys
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="5.4" data-path="../../nats_tools/nas/">
<a href="../../nats_tools/nas/">
nats-account-server
</a>
<ul class="articles">
<li class="chapter " data-level="5.4.1" data-path="../../nats_tools/nas/nas_conf.html">
<a href="../../nats_tools/nas/nas_conf.html">
Basics
</a>
</li>
<li class="chapter " data-level="5.4.2" data-path="../../nats_tools/nas/inspecting_jwts.html">
<a href="../../nats_tools/nas/inspecting_jwts.html">
Inspecting JWTs
</a>
</li>
<li class="chapter " data-level="5.4.3" data-path="../../nats_tools/nas/mem_resolver.html">
<a href="../../nats_tools/nas/mem_resolver.html">
Memory Resolver
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="5.5" data-path="../../nats_tools/nats_top/">
<a href="../../nats_tools/nats_top/">
nats-top
</a>
<ul class="articles">
<li class="chapter " data-level="5.5.1" data-path="../../nats_tools/nats_top/tutorial.html">
<a href="../../nats_tools/nats_top/tutorial.html">
Tutorial
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="5.6" data-path="../../nats_tools/natsbench.html">
<a href="../../nats_tools/natsbench.html">
nats-bench
</a>
</li>
<li class="header">NATS Streaming Concepts</li>
<li class="chapter " data-level="6.1" data-path="../../nats_streaming/intro.html">
<a href="../../nats_streaming/intro.html">
Introduction
</a>
<ul class="articles">
<li class="chapter " data-level="6.1.1" data-path="../../nats_streaming/relation-to-nats.html">
<a href="../../nats_streaming/relation-to-nats.html">
Relation to NATS
</a>
</li>
</ul>
</li>
<li class="chapter " data-level="6.2" data-path="../../nats_streaming/client-connections.html">
<a href="../../nats_streaming/client-connections.html">
Client Connections
</a>
</li>
<li class="chapter " data-level="6.3" data-path="../../nats_streaming/channels/channels.html">
<a href="../../nats_streaming/channels/channels.html">
Channels
</a>
<ul class="articles">
<li class="chapter " data-level="6.3.1" data-path="../../nats_streaming/channels/message-log.html">
<a href="../../nats_streaming/channels/message-log.html">
Message Log
</a>
</li>
<li class="chapter " data-level="6.3.2" data-path="../../nats_streaming/channels/subscriptions/subscriptions.html">
<a href="../../nats_streaming/channels/subscriptions/subscriptions.html">
Subscriptions
</a>
<ul class="articles">
<li class="chapter " data-level="6.3.2.1" data-path="../../nats_streaming/channels/subscriptions/regular.html">
<a href="../../nats_streaming/channels/subscriptions/regular.html">
Regular
</a>
</li>
<li class="chapter " data-level="6.3.2.2" data-path="../../nats_streaming/channels/subscriptions/durable.html">
<a href="../../nats_streaming/channels/subscriptions/durable.html">
Durable
</a>
</li>
<li class="chapter " data-level="6.3.2.3" data-path="../../nats_streaming/channels/subscriptions/queue-group.html">
<a href="../../nats_streaming/channels/subscriptions/queue-group.html">
Queue Group
</a>
</li>
<li class="chapter " data-level="6.3.2.4" data-path="../../nats_streaming/channels/subscriptions/redelivery.html">
<a href="../../nats_streaming/channels/subscriptions/redelivery.html">
Redelivery
</a>
</li>
</ul>
</li>
</ul>
</li>
<li class="chapter " data-level="6.4" data-path="../../nats_streaming/store-interface.html">
<a href="../../nats_streaming/store-interface.html">
Store Interface
</a>
</li>
<li class="chapter " data-level="6.5" data-path="../../nats_streaming/store-encryption.html">
<a href="../../nats_streaming/store-encryption.html">
Store Encryption
</a>
</li>
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<h1>
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<a href="../.." >Structured Data</a>
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<h1 id="receiving-structured-data"><a name="receiving-structured-data" class="plugin-anchor" href="#receiving-structured-data"><i class="fa fa-link" aria-hidden="true"></i></a>Receiving Structured Data</h1>
<p>Client libraries may provide tools to help receive structured data, like JSON. The core traffic to the NATS server will always be byte arrays. For libraries that don&apos;t provide helpers, you can always encode and decode data before sending the associated bytes to the NATS client.</p>
<p>For example, to receive JSON you could do:</p>
<div class="tab-wrap">
<input type="radio" id="subscribe_json_go" name="subscribe_json" class="tab" checked>
<label for="subscribe_json_go" class="api-lang" data-language="go">Go</label>
<input type="radio" id="subscribe_json_java" name="subscribe_json" class="tab">
<label for="subscribe_json_java" class="api-lang" data-language="java">Java</label>
<input type="radio" id="subscribe_json_js" name="subscribe_json" class="tab">
<label for="subscribe_json_js" class="api-lang" data-language="js">JavaScript</label>
<input type="radio" id="subscribe_json_py" name="subscribe_json" class="tab">
<label for="subscribe_json_py" class="api-lang" data-language="py">Python</label>
<input type="radio" id="subscribe_json_ruby" name="subscribe_json" class="tab">
<label for="subscribe_json_ruby" class="api-lang" data-language="ruby">Ruby</label>
<input type="radio" id="subscribe_json_ts" name="subscribe_json" class="tab">
<label for="subscribe_json_ts" class="api-lang" data-language="ts">TypeScript</label>
<div class="tab__content">
<pre id="subscribe_json_go_content"><a class="toolbar-icons pull-right" target="_blank" href="https://github.com/nats-io/go-nats-examples/blob/master/api-examples/subscribe_json/main.go#L11-45"><i class="mdi mdi-github-circle" title="View on GitHub"></i></a><a class="toolbar-icons pull-right"><i class="mdi mdi-content-copy js-copy" title="Copy to Clipboard"></i></a><span class="copy-msg pull-right"></span><code class="language-go">nc<span class="token punctuation">,</span> err <span class="token operator">:=</span> nats<span class="token punctuation">.</span><span class="token function">Connect</span><span class="token punctuation">(</span><span class="token string">&quot;demo.nats.io&quot;</span><span class="token punctuation">)</span>
<span class="token keyword">if</span> err <span class="token operator">!=</span> <span class="token boolean">nil</span> <span class="token punctuation">{</span>
log<span class="token punctuation">.</span><span class="token function">Fatal</span><span class="token punctuation">(</span>err<span class="token punctuation">)</span>
<span class="token punctuation">}</span>
<span class="token keyword">defer</span> nc<span class="token punctuation">.</span><span class="token function">Close</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
ec<span class="token punctuation">,</span> err <span class="token operator">:=</span> nats<span class="token punctuation">.</span><span class="token function">NewEncodedConn</span><span class="token punctuation">(</span>nc<span class="token punctuation">,</span> nats<span class="token punctuation">.</span>JSON_ENCODER<span class="token punctuation">)</span>
<span class="token keyword">if</span> err <span class="token operator">!=</span> <span class="token boolean">nil</span> <span class="token punctuation">{</span>
log<span class="token punctuation">.</span><span class="token function">Fatal</span><span class="token punctuation">(</span>err<span class="token punctuation">)</span>
<span class="token punctuation">}</span>
<span class="token keyword">defer</span> ec<span class="token punctuation">.</span><span class="token function">Close</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
<span class="token comment">// Define the object</span>
<span class="token keyword">type</span> stock <span class="token keyword">struct</span> <span class="token punctuation">{</span>
Symbol <span class="token builtin">string</span>
Price <span class="token builtin">int</span>
<span class="token punctuation">}</span>
wg <span class="token operator">:=</span> sync<span class="token punctuation">.</span>WaitGroup<span class="token punctuation">{</span><span class="token punctuation">}</span>
wg<span class="token punctuation">.</span><span class="token function">Add</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span>
<span class="token comment">// Subscribe</span>
<span class="token keyword">if</span> <span class="token boolean">_</span><span class="token punctuation">,</span> err <span class="token operator">:=</span> ec<span class="token punctuation">.</span><span class="token function">Subscribe</span><span class="token punctuation">(</span><span class="token string">&quot;updates&quot;</span><span class="token punctuation">,</span> <span class="token keyword">func</span><span class="token punctuation">(</span>s <span class="token operator">*</span>stock<span class="token punctuation">)</span> <span class="token punctuation">{</span>
log<span class="token punctuation">.</span><span class="token function">Printf</span><span class="token punctuation">(</span><span class="token string">&quot;Stock: %s - Price: %v&quot;</span><span class="token punctuation">,</span> s<span class="token punctuation">.</span>Symbol<span class="token punctuation">,</span> s<span class="token punctuation">.</span>Price<span class="token punctuation">)</span>
wg<span class="token punctuation">.</span><span class="token function">Done</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span> err <span class="token operator">!=</span> <span class="token boolean">nil</span> <span class="token punctuation">{</span>
log<span class="token punctuation">.</span><span class="token function">Fatal</span><span class="token punctuation">(</span>err<span class="token punctuation">)</span>
<span class="token punctuation">}</span>
<span class="token comment">// Wait for a message to come in</span>
wg<span class="token punctuation">.</span><span class="token function">Wait</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
<span class="token comment">// Close the connection</span>
ec<span class="token punctuation">.</span><span class="token function">Close</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
</code></pre>
</div>
<div class="tab__content">
<pre id="subscribe_json_java_content"><a class="toolbar-icons pull-right" target="_blank" href="https://github.com/nats-io/java-nats-examples/blob/master/src/main/java/io/nats/examples/SubscribeJSON.java#L12-57"><i class="mdi mdi-github-circle" title="View on GitHub"></i></a><a class="toolbar-icons pull-right"><i class="mdi mdi-content-copy js-copy" title="Copy to Clipboard"></i></a><span class="copy-msg pull-right"></span><code class="language-java"><span class="token keyword">class</span> <span class="token class-name">StockForJsonSub</span> <span class="token punctuation">{</span>
<span class="token keyword">public</span> <span class="token class-name">String</span> symbol<span class="token punctuation">;</span>
<span class="token keyword">public</span> <span class="token keyword">float</span> price<span class="token punctuation">;</span>
<span class="token keyword">public</span> <span class="token class-name">String</span> <span class="token function">toString</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token keyword">return</span> symbol <span class="token operator">+</span> <span class="token string">&quot; is at &quot;</span> <span class="token operator">+</span> price<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
<span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">SubscribeJSON</span> <span class="token punctuation">{</span>
<span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token class-name">String</span><span class="token punctuation">[</span><span class="token punctuation">]</span> args<span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token keyword">try</span> <span class="token punctuation">{</span>
<span class="token class-name">Connection</span> nc <span class="token operator">=</span> <span class="token class-name">Nats</span><span class="token punctuation">.</span><span class="token function">connect</span><span class="token punctuation">(</span><span class="token string">&quot;nats://demo.nats.io:4222&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">// Use a latch to wait for 10 messages to arrive</span>
<span class="token class-name">CountDownLatch</span> latch <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">CountDownLatch</span><span class="token punctuation">(</span><span class="token number">10</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">// Create a dispatcher and inline message handler</span>
<span class="token class-name">Dispatcher</span> d <span class="token operator">=</span> nc<span class="token punctuation">.</span><span class="token function">createDispatcher</span><span class="token punctuation">(</span><span class="token punctuation">(</span>msg<span class="token punctuation">)</span> <span class="token operator">-&gt;</span> <span class="token punctuation">{</span>
<span class="token class-name">Gson</span> gson <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Gson</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token class-name">String</span> json <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">String</span><span class="token punctuation">(</span>msg<span class="token punctuation">.</span><span class="token function">getData</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token class-name">StandardCharsets</span><span class="token punctuation">.</span>UTF_8<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token class-name">StockForJsonSub</span> stk <span class="token operator">=</span> gson<span class="token punctuation">.</span><span class="token function">fromJson</span><span class="token punctuation">(</span>json<span class="token punctuation">,</span> <span class="token class-name">StockForJsonSub</span><span class="token punctuation">.</span><span class="token keyword">class</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">// Use the object</span>
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>stk<span class="token punctuation">)</span><span class="token punctuation">;</span>
latch<span class="token punctuation">.</span><span class="token function">countDown</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">// Subscribe</span>
d<span class="token punctuation">.</span><span class="token function">subscribe</span><span class="token punctuation">(</span><span class="token string">&quot;updates&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">// Wait for a message to come in</span>
latch<span class="token punctuation">.</span><span class="token function">await</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">// Close the connection</span>
nc<span class="token punctuation">.</span><span class="token function">close</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span> <span class="token keyword">catch</span> <span class="token punctuation">(</span><span class="token class-name">Exception</span> e<span class="token punctuation">)</span> <span class="token punctuation">{</span>
e<span class="token punctuation">.</span><span class="token function">printStackTrace</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
</code></pre>
</div>
<div class="tab__content">
<pre id="subscribe_json_js_content"><a class="toolbar-icons pull-right" target="_blank" href="https://github.com/nats-io/node-nats-examples/blob/master/src/subscriber_samples.js#L76-88"><i class="mdi mdi-github-circle" title="View on GitHub"></i></a><a class="toolbar-icons pull-right"><i class="mdi mdi-content-copy js-copy" title="Copy to Clipboard"></i></a><span class="copy-msg pull-right"></span><code class="language-javascript"><span class="token keyword">let</span> nc <span class="token operator">=</span> <span class="token constant">NATS</span><span class="token punctuation">.</span><span class="token function">connect</span><span class="token punctuation">(</span><span class="token punctuation">{</span>
url<span class="token punctuation">:</span> <span class="token string">&quot;nats://demo.nats.io:4222&quot;</span><span class="token punctuation">,</span>
json<span class="token punctuation">:</span> <span class="token boolean">true</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
nc<span class="token punctuation">.</span><span class="token function">subscribe</span><span class="token punctuation">(</span><span class="token string">&apos;updates&apos;</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token parameter">msg</span><span class="token punctuation">)</span> <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
<span class="token keyword">if</span><span class="token punctuation">(</span>msg <span class="token operator">&amp;&amp;</span> msg<span class="token punctuation">.</span>ticker <span class="token operator">===</span> <span class="token string">&apos;TSLA&apos;</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
t<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">&apos;got message:&apos;</span><span class="token punctuation">,</span> msg<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre>
</div>
<div class="tab__content">
<pre id="subscribe_json_py_content"><a class="toolbar-icons pull-right" target="_blank" href="https://github.com/nats-io/asyncio-nats-examples/blob/master/subscribe_json.py#L1-23"><i class="mdi mdi-github-circle" title="View on GitHub"></i></a><a class="toolbar-icons pull-right"><i class="mdi mdi-content-copy js-copy" title="Copy to Clipboard"></i></a><span class="copy-msg pull-right"></span><code class="language-python"><span class="token keyword">import</span> asyncio
<span class="token keyword">import</span> json
<span class="token keyword">from</span> nats<span class="token punctuation">.</span>aio<span class="token punctuation">.</span>client <span class="token keyword">import</span> Client <span class="token keyword">as</span> NATS
<span class="token keyword">from</span> nats<span class="token punctuation">.</span>aio<span class="token punctuation">.</span>errors <span class="token keyword">import</span> ErrTimeout
<span class="token keyword">async</span> <span class="token keyword">def</span> <span class="token function">run</span><span class="token punctuation">(</span>loop<span class="token punctuation">)</span><span class="token punctuation">:</span>
nc <span class="token operator">=</span> NATS<span class="token punctuation">(</span><span class="token punctuation">)</span>
<span class="token keyword">await</span> nc<span class="token punctuation">.</span>connect<span class="token punctuation">(</span>servers<span class="token operator">=</span><span class="token punctuation">[</span><span class="token string">&quot;nats://127.0.0.1:4222&quot;</span><span class="token punctuation">]</span><span class="token punctuation">,</span> loop<span class="token operator">=</span>loop<span class="token punctuation">)</span>
<span class="token keyword">async</span> <span class="token keyword">def</span> <span class="token function">message_handler</span><span class="token punctuation">(</span>msg<span class="token punctuation">)</span><span class="token punctuation">:</span>
data <span class="token operator">=</span> json<span class="token punctuation">.</span>loads<span class="token punctuation">(</span>msg<span class="token punctuation">.</span>data<span class="token punctuation">.</span>decode<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
<span class="token keyword">print</span><span class="token punctuation">(</span>data<span class="token punctuation">)</span>
sid <span class="token operator">=</span> <span class="token keyword">await</span> nc<span class="token punctuation">.</span>subscribe<span class="token punctuation">(</span><span class="token string">&quot;updates&quot;</span><span class="token punctuation">,</span> cb<span class="token operator">=</span>message_handler<span class="token punctuation">)</span>
<span class="token keyword">await</span> nc<span class="token punctuation">.</span>flush<span class="token punctuation">(</span><span class="token punctuation">)</span>
<span class="token keyword">await</span> nc<span class="token punctuation">.</span>auto_unsubscribe<span class="token punctuation">(</span>sid<span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">)</span>
<span class="token keyword">await</span> nc<span class="token punctuation">.</span>publish<span class="token punctuation">(</span><span class="token string">&quot;updates&quot;</span><span class="token punctuation">,</span> json<span class="token punctuation">.</span>dumps<span class="token punctuation">(</span><span class="token punctuation">{</span><span class="token string">&quot;symbol&quot;</span><span class="token punctuation">:</span> <span class="token string">&quot;GOOG&quot;</span><span class="token punctuation">,</span> <span class="token string">&quot;price&quot;</span><span class="token punctuation">:</span> <span class="token number">1200</span> <span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">.</span>encode<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
<span class="token keyword">await</span> asyncio<span class="token punctuation">.</span>sleep<span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span> loop<span class="token operator">=</span>loop<span class="token punctuation">)</span>
<span class="token keyword">await</span> nc<span class="token punctuation">.</span>close<span class="token punctuation">(</span><span class="token punctuation">)</span>
</code></pre>
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<pre id="subscribe_json_ruby_content"><a class="toolbar-icons pull-right" target="_blank" href="https://github.com/nats-io/ruby-nats-examples/blob/master/subscribe_json.rb#L1-13"><i class="mdi mdi-github-circle" title="View on GitHub"></i></a><a class="toolbar-icons pull-right"><i class="mdi mdi-content-copy js-copy" title="Copy to Clipboard"></i></a><span class="copy-msg pull-right"></span><code class="language-ruby"><span class="token keyword">require</span> <span class="token string">&apos;nats/client&apos;</span>
<span class="token keyword">require</span> <span class="token string">&apos;json&apos;</span>
<span class="token constant">NATS</span><span class="token punctuation">.</span>start<span class="token punctuation">(</span>servers<span class="token punctuation">:</span><span class="token punctuation">[</span><span class="token string">&quot;nats://127.0.0.1:4222&quot;</span><span class="token punctuation">]</span><span class="token punctuation">)</span> <span class="token keyword">do</span> <span class="token operator">|</span>nc<span class="token operator">|</span>
nc<span class="token punctuation">.</span>subscribe<span class="token punctuation">(</span><span class="token string">&quot;updates&quot;</span><span class="token punctuation">)</span> <span class="token keyword">do</span> <span class="token operator">|</span>msg<span class="token operator">|</span>
m <span class="token operator">=</span> <span class="token constant">JSON</span><span class="token punctuation">.</span>parse<span class="token punctuation">(</span>msg<span class="token punctuation">)</span>
<span class="token comment"># {&quot;symbol&quot;=&gt;&quot;GOOG&quot;, &quot;price&quot;=&gt;12}</span>
p m
<span class="token keyword">end</span>
<span class="token keyword">end</span>
</code></pre>
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<pre id="subscribe_json_ts_content"><a class="toolbar-icons pull-right" target="_blank" href="https://github.com/nats-io/ts-nats-examples/blob/master/src/subscriber_samples.ts#L70-80"><i class="mdi mdi-github-circle" title="View on GitHub"></i></a><a class="toolbar-icons pull-right"><i class="mdi mdi-content-copy js-copy" title="Copy to Clipboard"></i></a><span class="copy-msg pull-right"></span><code class="language-javascript"><span class="token keyword">let</span> nc <span class="token operator">=</span> <span class="token keyword">await</span> <span class="token function">connect</span><span class="token punctuation">(</span><span class="token punctuation">{</span>
url<span class="token punctuation">:</span> <span class="token string">&quot;nats://demo.nats.io:4222&quot;</span><span class="token punctuation">,</span>
payload<span class="token punctuation">:</span> Payload<span class="token punctuation">.</span><span class="token constant">JSON</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
nc<span class="token punctuation">.</span><span class="token function">subscribe</span><span class="token punctuation">(</span><span class="token string">&apos;updates&apos;</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token parameter">err<span class="token punctuation">,</span> msg</span><span class="token punctuation">)</span> <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
t<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">&apos;got message:&apos;</span><span class="token punctuation">,</span> msg<span class="token punctuation">.</span>data <span class="token operator">?</span> msg<span class="token punctuation">.</span>data <span class="token punctuation">:</span> <span class="token string">&quot;no payload&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre>
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