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WriteData Plugin

Description

The WriteData plugin provides file system data export capabilities for CVEDIA-RT. It enables saving analytics results, events, and metadata to various file formats including JSON, CSV, XML, and custom formats.

Key Features

  • Multiple output formats (JSON, CSV, XML, TXT)
  • Structured and unstructured data support
  • Automatic file rotation and compression
  • Directory structure management
  • Timestamp-based file naming
  • Custom formatting templates
  • Event-driven and batch export modes

When to Use

  • Exporting analytics results to files
  • Creating audit logs and reports
  • Data backup and archival
  • Integration with external systems via file exchange
  • Compliance and regulatory reporting

Requirements

Software Dependencies

  • File system write permissions
  • Sufficient disk space for data storage
  • Optional: Compression libraries (zlib, gzip)

Storage Requirements

  • Varies by data volume and retention period
  • Recommend monitoring disk usage
  • Consider file rotation policies

Configuration

Basic Configuration

{
  "writedata": {
    "outputPath": "/data/analytics/",
    "format": "json",
    "filenameTemplate": "detections_{{timestamp}}.json"
  }
}

Configuration Schema

Parameter Type Default Description
outputPath string "./output/" Directory path for output files
format string "json" Output format (json, csv, xml, txt)
filenameTemplate string "data_{{timestamp}}" Filename template with variables
rotation.enabled boolean false Enable file rotation
rotation.maxFileSize string "50MB" Maximum file size before rotation

API Reference

C++ API

class WriteDataImpl : public iface::WriteData {
public:
    bool writeData(const std::string& filename, pCValue data);
    bool appendData(const std::string& filename, pCValue data);
    bool writeStructuredData(const std::string& filename, pCValue data);
    void setOutputPath(const std::string& path);
    void setFormat(const std::string& format);
};

Lua API

-- Create WriteData instance (following SecuRT patterns)
local instance = api.thread.getCurrentInstance()
local writeData = api.factory.writedata.get(instance, "WriteData")
if not writeData then
  writeData = api.factory.writedata.create(instance, "WriteData")
end

-- Basic operations
writeData:writeData("events.json", eventData)
writeData:appendData("log.txt", logMessage)
writeData:setOutputPath("/data/export/")

Full Lua API Reference →

Examples

Basic JSON Export

-- Initialize WriteData (following SecuRT event_video_recorder.lua pattern)
local instance = api.thread.getCurrentInstance()
local writeInst = api.factory.writedata.get(instance, "WriteData")
if not writeInst then
  writeInst = api.factory.writedata.create(instance, "WriteData")
end

-- Configure output
writeInst:setOutputPath("/data/analytics/")
writeInst:setFormat("json")

-- Export detection data
function exportDetections(detections)
  local data = {
    timestamp = os.time(),
    camera = "camera-001",
    detections = {}
  }

  for _, detection in ipairs(detections) do
    table.insert(data.detections, {
      id = detection.id,
      class = detection.class,
      confidence = detection.confidence,
      bbox = detection.bbox
    })
  end

  local filename = "detections_" .. os.date("%Y%m%d_%H%M%S") .. ".json"
  local success = writeInst:writeStructuredData(filename, data)

  if success then
    api.logging.LogInfo("Exported " .. #detections .. " detections to " .. filename)
  else
    api.logging.LogError("Failed to export detections to " .. filename)
  end
end

CSV Event Logging

-- CSV format writer (following SecuRT frame_data_debugger.lua pattern)
local instance = api.thread.getCurrentInstance()
local writeInst = api.factory.writedata.get(instance, "WriteData")
if not writeInst then
  writeInst = api.factory.writedata.create(instance, "WriteData")
  api.logging.LogInfo("Created WriteData instance for CSV logging")
end

writeInst:setOutputPath("/logs/events/")
writeInst:setFormat("csv")

-- Write CSV header
local header = "timestamp,event_type,object_class,confidence,x,y,width,height\n"
local headerSuccess = writeInst:writeData("events.csv", header)
if not headerSuccess then
  api.logging.LogError("Failed to write CSV header")
  return
end

-- Log events to CSV
function logEventToCSV(event)
  local csvLine = string.format("%d,%s,%s,%.2f,%d,%d,%d,%d\n",
    event.timestamp,
    event.type,
    event.object.class,
    event.object.confidence,
    event.object.bbox.x,
    event.object.bbox.y,
    event.object.bbox.width,
    event.object.bbox.height
  )

  local success = writeInst:appendData("events.csv", csvLine)
  if not success then
    api.logging.LogWarning("Failed to append event data to CSV: " .. tostring(event.timestamp))
  end
end

Troubleshooting

File System Issues

  1. "Permission denied"

    • Check directory write permissions
    • Verify user/group ownership
    • Ensure parent directories exist

  2. "Disk full" errors

    • Monitor disk space usage
    • Implement file rotation
    • Configure cleanup policies

Performance Issues

  1. Slow write performance
    • Use SSD storage for high-frequency writes
    • Batch multiple writes together
    • Consider asynchronous writing

See Also