Configuration and Usage
Below are the details to configure and use ComDeX through its command-line interface and to set up broker federations using MQTT bridges.
Command-Line Usage
ComDeX provides a flexible command-line interface for managing entities, subscriptions, and other operations.
Usage:
python3 actionhandler.py [options]
Options
| Option | Long Form | Description |
|---|---|---|
| -h | --help | Show help information about available commands and options. |
| -c | --command | Specify the operation to perform. Possible commands include:
|
| -f | --file | Specify the input file for the command (e.g., an entity configuration file). |
| -b | --broker_address | Specify the MQTT broker address for the ComDeX node. |
| -p | --port | Specify the port number of the MQTT broker for the ComDeX node. |
| -q | --qos | Define the Quality of Service level (0, 1, or 2) for the command. |
| -H | --HLink | Provide the context link (HLink) for the GET request. |
| -A | --singleidadvertisement | Set to 1 to enable single ID advertisement; default is 0. |
Example:
python3 actionhandler.py -c POST/entities -f entity.ngsild -b localhost -p 1026 -q 1 -H HLink -A 0
Setting Up Broker Federations
ComDeX supports MQTT-based broker federation for propagating context between brokers. The implementation relies on advertisement messages containing:
- Provider ID
- Broker address and port
- Region covered
- NGSI-LD entity context and type
Configuration Guidelines
To set up a federation:
- Configure MQTT bridges between brokers using advertisement messages to propagate exported contexts.
- Ensure proper filtering to avoid redundant message transmissions and network overload.
- Avoid bidirectional linkages in MQTT bridges to reduce network loops.
Example MQTT Broker Configuration
# Mosquitto .conf example for allowing all advertisements
max_queued_messages 4000
persistence true
persistence_location ./Port_Area_B_Broker/
log_dest stdout
listener 1029 localhost
allow_anonymous true
connection Port_Area_B_Broker_to_Port_Administration_Central_Broker
address localhost:1026
topic provider/# out 2 "" ""
With this configuration, the broker propagates advertisements and entity data as defined.