MarbleSoft.FlowModule.MQTTLogger 1.4.1

MarbleSoft.FlowModule.MQTTLogger

MQTTLogger publishes log messages over MQTT and enriches flow messages with logging context. It reads log entries from a configurable source property, adds metadata (timestamp, module info, flow info), and publishes them to an MQTT broker.

How It Works

1. Receives a message from the flow with a log entry at the configured source property (default: data)
2. Extracts log level from the message payload or uses the configured default (default: Info)
3. Enriches with metadata: adds timestamp, module ID, module name, flow ID, flow version, and the original payload
4. Stores in flow message at the configured target property (default: data.logging)
5. Publishes to MQTT using the configured topic and settings

Example Input

{
  "data": {
    "Msg": "Error in flow: division by zero",
    "LogLevel": "Error"
  }
}

Example Output (Flow Message)

{
  "data": {
    "Msg": "Error in flow: division by zero",
    "LogLevel": "Error"
  },
  "data.logging": {
    "LogLevel": "Error",
    "TimestampUtc": "2026-07-21T10:15:30Z",
    "ModuleId": "550e8400-e29b-41d4-a716-446655440000",
    "ModuleName": "ErrorHandler",
    "ModuleVersion": "1.0.0",
    "FlowId": "f47ac10b-58cc-4372-a567-0e02b2c3d479",
    "FlowVersion": "1.0",
    "Payload": {
      "Msg": "Error in flow: division by zero",
      "LogLevel": "Error"
    }
  }
}

MQTT Publication Example

When MQTT is enabled, the module publishes:

Topic: logging (default topic, configurable)

Message:

{
  "LogLevel": "Error",
  "TimestampUtc": "2026-07-21T10:15:30Z",
  "ModuleId": "550e8400-e29b-41d4-a716-446655440000",
  "ModuleName": "ErrorHandler",
  "ModuleVersion": "1.0.0",
  "FlowId": "f47ac10b-58cc-4372-a567-0e02b2c3d479",
  "FlowVersion": "1.0",
  "Msg": "Error in flow: division by zero"
}

Configuration

• Source (default: data): Property path to read the log entry from
• Target (default: data.logging): Property path to write the enriched log context to
• DefaultLogLevel (default: Info): Log level when not specified in the message
• Topic (default: logging): MQTT topic to publish to
• Enabled: Set to true to enable MQTT publishing; when false, logs are only added to the flow message

Log Levels

Valid log levels (case-insensitive):

• Debug
• Info
• Warning
• Error
• Critical

Settings

1. Source

• Type: string
• Required: yes
• Validation: min length 1, max length 256
• Default: data
• Purpose: path used to read an existing log context

2. Target

• Type: string
• Required: yes
• Validation: min length 1, max length 256
• Default: data.logging
• Purpose: path used to write the log context

3. Default Log Level

• Type: string
• Required: no
• Default: Info
• Purpose: default level used when no LogLevel field is present in the message payload

4. MQTT publish settings (optional)

• Enable MQTT Publish: bool, default true
• MQTT Source Property: string path, default data, if empty the payload from Source is used
• MQTT Topic: string, required when MQTT is enabled, default logging
• MQTT Brokers: comma or line separated host:port list, default localhost:1883
• MQTT Protocol Version: enum V311 or V500
• Use TLS: bool, default true
• SSL Protocol: enum None, Tls12, Tls13
• Allow Untrusted Certificates: bool
• ClientId: optional string, generated automatically when empty
• CA Certificate: optional Crosser Certificate credential selector
• Client Certificate: optional Crosser Certificate credential selector
• MQTT User Credential: optional Crosser UsernamePassword credential selector
• QoS: AtMostOnce, AtLeastOnce, ExactlyOnce
• Retain: bool

Runtime behavior

• Reads payload from Source.
• Creates a log context object with LogLevel, TimestampUtc, ModuleName, and Payload.
• If payload contains LogLevel, that value overrides the configured default level per message.
• Writes log context to Target.
• Publishes log context to MQTT topic when enabled.