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  • MQTT QoS 2

  • Arbitrary MQTT topics and subscriptions. For topic requirements, see connecting devices using MQTT

  • Last will and testament (LWT)

  • Retained messages

  • Persistent sessions

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Each resource’s permitted characters and sizes

Resource

Limitations

Registry IDs

  • Permitted characters: [a-zA-Z][-a-zA-Z0-9._+~%]+

  • The first character must be a letter ([a-zA-Z])

  • Cannot start with "goog"

  • Minimum length: 3 characters

  • Maximum length: 255 characters

Device IDs

  • Must be unique within the parent device registry

  • Permitted characters: [a-zA-Z][-a-zA-Z0-9._+~%]+

  • The first character must be a letter ([a-zA-Z])

  • Cannot start with "goog"

  • Minimum length: 3 characters

  • Maximum length: 255 characters

Device metadata keys

  • Permitted characters: [a-zA-Z][-a-zA-Z0-9._+~%]+

  • The first character must be a letter ([a-zA-Z])

  • Minimum length: 1 character

  • Maximum length: 128 characters

  • Maximum combined total size of all device metadata key-value pairs: 256 KB

Device metadata values

  • Minimum size: 0 KB

  • Maximum size: 32 KB

  • Maximum combined total size of all device metadata key-value pairs: 256 KB

Subfolders*

  • Permitted characters: [a-zA-Z][-a-zA-Z0-9._+~%]+

  • The first character must be a letter ([a-zA-Z])

  • Maximum size: 256 bytes

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