LDMX - Land Data Model Explorer¶

LDMX (Land Data Model Explorer) is a powerful debugging and diagnostic tool for monitoring and analysing GVA DDS traffic in real-time. It provides comprehensive visibility into the LDM message bus, making it an essential tool for development, integration testing, and troubleshooting GVA systems.

Key Capabilities¶

LDMX provides the following capabilities:

Running LDMX¶

Launch LDMX from the build directory:

cd build/bin
./ldmx

Configuration¶

LDMX can be configured via a JSON configuration file. The configuration file is searched in the following locations (in order):

1. ./ldmx-config.json (current directory)
2. ~/.config/ldmx/config.json (user configuration)
3. Qt standard AppConfigLocation
4. /etc/ldmx/config.json (system-wide)

Example configuration:

{
  "dds_domain_id": 0,
  "window_title": "LDMX - Land Data Model Explorer",
  "auto_refresh_interval": 0
}

Tabs Overview¶

LDMX organises its functionality into several tabs under the DDS / LDM section:

Registry Status Tab¶

The Registry Status tab provides visibility into the GVA registration system, showing which resources have registered on the network and their descriptor mappings.

Features:

• Registered Resources Table: Displays all resources that have registered via the Registration Service, including:

  • UUID - Unique identifier for the resource
  • Resource ID - Allocated LDM resource ID
  • Instance ID - Instance number
  • Manufacturer, Model, Version, Serial - Device metadata
  • Timestamp - When the resource registered

• Descriptor Mappings Table: Shows the mapping between human-readable descriptors and resource IDs:

  • Descriptor - Human-readable name (e.g., "Main Display", "BMS Controller")
  • Resource ID / Instance ID - Mapped resource identification
  • Status - Active or Unmapped
  • Timestamp - When mapping was created

• Map/Unmap Button: Allows toggling descriptor mappings on/off for testing

Alarms Tab¶

The Alarms tab provides comprehensive alarm monitoring and management capabilities.

Features:

• Alarm Table: Real-time display of all active alarms with columns for:

  • Alarm ID - Unique alarm identifier
  • Category - Warning, Caution, or Advisory
  • State - Active, Acknowledged, Overridden, etc.
  • Description - Human-readable alarm text
  • Source - Originating resource
  • Timestamp - When alarm was raised

• Alarm Actions: Buttons to interact with selected alarms:

  • Acknowledge - Mark alarm as acknowledged
  • Clear - Clear the alarm (if clearable)
  • Annotate - Add operator notes to alarm
  • Override - Override alarm condition (if supported)

• Status Bar Counters: Shows count of active alarms by priority level (Warning/Caution/Advisory)

UACM Monitor Tab¶

The UACM Monitor tab displays resource health status from the Usage and Condition Monitoring system.

Features:

• Monitored Resources Table: Shows health status of all monitored resources:

  • ID - Row identifier
  • Timestamp - Last update time
  • Resource ID / Instance ID - Resource identification
  • Health Status - RAG status (Red/Amber/Green)
  • Spec Resource ID / Instance ID - Link to resource specification

• RAG Status Indicators: Health status displayed with colour coding:

  • 🟢 GREEN - Normal operation
  • 🟡 AMBER - Degraded performance or warning
  • 🔴 RED - Fault or failure condition

• Refresh Button: Manually refresh UACM data from DDS

UACM Faults Tab¶

The UACM Faults tab provides detailed fault event tracking and diagnostics.

Features:

• Fault Events Table: Displays all fault events received via DDS:

  • Source Resource ID / Instance ID - Where the fault originated
  • Fault State - Current, Rectified, or Intermittent
  • Description - Human-readable fault description
  • Comment - Additional context or operator notes
  • Occurrence Time - When the fault occurred
  • Time Rectified - When fault was cleared (if applicable)
  • Root Cause - Link to root cause resource (if identified)

• Refresh Button: Manually refresh fault data from DDS

Analyser Tab¶

The Analyser tab is a powerful message inspection tool that captures and displays all DDS traffic.

Features:

• Message List (Upper Pane): Scrolling list of all captured DDS messages:

  • Timestamp - Message receive time
  • Source - Originating resource
  • Destination - Target resource (if applicable)
  • Topic - DDS topic name
  • Details - Brief message summary

• Message Details (Lower Pane): Hierarchical tree view of selected message:

  • Expandable field structure
  • Field names and values
  • Nested complex types fully expanded
  • Easy navigation of message content

• Auto-scroll: Table automatically scrolls to show newest messages

Topics Tab¶

The Topics tab provides statistics on DDS topic activity.

Features:

• Topic Statistics Table: Overview of all DDS topics with:

  • Topic Name - Full DDS topic name
  • Message Count - Total messages received on this topic
  • Last Received - Timestamp of most recent message

• Reset Counters Button: Clear all message counters to start fresh measurement

• Automatic Refresh: Statistics update in real-time as messages arrive

Use Cases¶

Development & Debugging¶

• Verify that your application is publishing correct DDS messages
• Inspect message content to debug serialisation issues
• Monitor registration flow during application startup

Integration Testing¶

• Verify end-to-end message flow between systems
• Confirm alarm propagation and handling
• Validate UACM health reporting

System Diagnostics¶

• Identify communication issues between GVA components
• Monitor system health and fault conditions
• Track resource registration status

Training & Documentation¶

• Demonstrate GVA message flows
• Capture screenshots for documentation
• Understand LDM topic structure

Keyboard Shortcuts¶

Related Topics¶

• DDS Topics Reference - Complete list of LDM DDS topics
• Registration Service - Registration service details
• Alarms Service - Alarm management service
• UACM Service - Usage and Condition Monitoring