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XML
XML (eXtensible Markup Language) is moderately popular in IoT.
With JSON gaining popularity, XML is still used in Legacy systems and regulated environments such as Govt/Military systems.
It uses XSD (Extended Schema Definition) to enforce strict data validation, ensuring integrity in critical applications like healthcare.
Legacy systesm use SOAP-based web services (newer ones use REST API) often use XML, rquiring IoT devices to adopt XML for compatibility.
<sensorData>
<deviceId>TEMP_SENSOR_01</deviceId>
<location>living_room</location>
<reading>
<temperature>23.5</temperature>
<unit>Celsius</unit>
<timestamp>2025-01-29T14:30:00</timestamp>
</reading>
</sensorData>
Limitations of XML in IoT
- Verbosity: Larger payloads increase bandwidth and storage costs.
- Processing Overhead: Parsing XML can strain low-power IoT devices.
- Modern Alternatives: JSON and binary formats (e.g., Protocol Buffers) are more efficient for most IoT use cases.
Here’s the XML vs. JSON Trade-offs comparison formatted as a markdown table:
| Factor | XML | JSON |
|---|---|---|
| Payload Size | Verbose (larger files) | Compact (better for low-bandwidth IoT) |
| Parsing Speed | Slower (complex structure) | Faster (lightweight parsing) |
| Validation | Mature (XSD) | Growing (JSON Schema) |
| Adoption in New Projects | Rare (outside legacy/regulated use cases) | Dominant (preferred for new IoT systems) |