1. Variable Overview

1.1 General Variables (Available for all uplinks)

Variable	Type	Description
app_id	string	App ID (Number converted to string)
app_name	string	App Name
plugin_type	string	Plugin Type (e.g., kafka / pulsar)
event_kind	string	Event Type (e.g., telemetry/attributes/device_connected/device_disconnected)
ts_ms	string	Millisecond Timestamp (String)
device_id	string	Device ID (String)
device_name	string	Device Name

1.2 Conditional Variables (May be empty for some event types)

Variable	Type	Description	Reason for Potential Emptiness
device_type	string	Device Type	Telemetry/Attributes currently may not have device_type
channel_name	string	Channel Name	Telemetry/Attributes inferred via point meta, may not be available if meta missing or values empty

TIP

For variables that may be empty, recommend using default helper as fallback, avoiding empty segments in topic/key.

1.3 Time Partition Variables (UTC)

These variables are used to build time-partitioned topics (e.g., writing to data lake):

Variable	Example	Description
yyyy	2026	Year (4 digits)
MM	01	Month (2 digits)
dd	19	Day (2 digits)
HH	08	Hour (2 digits, UTC)

Example:

lake.{{yyyy}}.{{MM}}.{{dd}}.{{HH}}.ng.uplink.{{event_kind}}

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2. Behavior of "Missing Variables"

The template engine is non-strict:

• Variable missing → Renders as empty string
• No error (And does not block sending)

Therefore:

• Want stable topic: Use default helper
• Want to quickly find issues: Observe "Whether topic is rendered as empty/abnormal" during troubleshooting