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<h3 class="depth-l0" style="margin-top: 0; border-bottom: 2px solid rgba(255,255,255,0.3); padding-bottom: 10px;">CoAP Protocol</h3>
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<h4 class="depth-l0" style="margin: 10px 0 5px 0; color: #F1C40F;">Connection</h4>
<pre style="background: rgba(0,0,0,0.2); padding: 10px; border-radius: 6px; font-size: 12px; margin: 0;">
Port: 5683 (UDP), 5684 (DTLS)
Max message: 1024 bytes (typical)
URI: coap://host:port/path</pre>
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<h4 class="depth-l0" style="margin: 10px 0 5px 0; color: #F1C40F;">Methods (like HTTP)</h4>
<pre style="background: rgba(0,0,0,0.2); padding: 10px; border-radius: 6px; font-size: 12px; margin: 0;">
GET - Read resource
POST - Create/process
PUT - Update resource
DELETE - Remove resource</pre>
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<h4 class="depth-l0" style="margin: 10px 0 5px 0; color: #F1C40F;">Message Types</h4>
<pre style="background: rgba(0,0,0,0.2); padding: 10px; border-radius: 6px; font-size: 12px; margin: 0;">
CON - Confirmable (needs ACK)
NON - Non-confirmable
ACK - Acknowledgment
RST - Reset (error)</pre>
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<h4 class="depth-l0" style="margin: 10px 0 5px 0; color: #F1C40F;">Response Codes</h4>
<pre style="background: rgba(0,0,0,0.2); padding: 10px; border-radius: 6px; font-size: 12px; margin: 0;">
2.01 Created 4.04 Not Found
2.04 Changed 4.05 Not Allowed
2.05 Content 5.00 Server Error</pre>
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<strong>Key Feature:</strong> Observe option for pub/sub-like notifications on resource changes
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