BOOST.ThumbnailGenerator

A Java microservice that generates thumbnail images from various file formats (images, PDFs, etc.). It operates as a message queue consumer, receiving requests via AMQP/JMS, generating 200px PNG thumbnails, and responding with the result and image metadata.

Architecture

BOOST.ThumbnailGenerator runs as a standalone service that:

1. Connects to an AMQP message broker
2. Listens on the queue boostv3.thumbnailgenerator
3. Receives file generation requests containing a pre-signed URL
4. Downloads and processes the file using ImageMagick
5. Responds via JMS with the thumbnail path and metadata

Prerequisites

• Java 21
• ImageMagick (must be installed and accessible on the system PATH)
• AMQP Message Broker (e.g., RabbitMQ)

Configuration

Configuration is defined in config.properties:

broker_url=amqp://172.16.200.32:5672
message_queue_name=boostv3.thumbnailgenerator
source_path=c:/x
output_path=c:/x
log_file=

Property	Description
broker_url	AMQP broker connection URL
message_queue_name	Queue name to consume from
source_path	Temporary directory for downloaded source files
output_path	Root directory for generated thumbnails
log_file	Optional log file path

Message Format

Request (Incoming JMS Message)

{
  "tenantUUID": "string",
  "preSignedUrl": "string"
}

Field	Description
tenantUUID	Tenant identifier for multi-tenant file organization
preSignedUrl	Pre-signed URL to download the source file

Response (JMS Reply)

{
  "success": true,
  "thumbnailFileName": "uuid.png",
  "pathPrefix": "tenantUUID/2025-01",
  "mimeType": "image/png",
  "metaData": {
    "width": 800,
    "height": 600,
    "format": "PNG",
    "colorSpace": "sRGB",
    "depth": 8
  }
}

Field	Description
success	Whether thumbnail generation succeeded
thumbnailFileName	Generated thumbnail filename (UUID-based)
pathPrefix	Storage path prefix: {tenantUUID}/{YYYY-MM}
mimeType	Detected MIME type of the source file
metaData	Extracted image properties

Thumbnail Generation Process

1. The source file is downloaded from the pre-signed URL via HTTP
2. MIME type is detected using Apache Tika
3. Image orientation (landscape/portrait) is determined via ImageMagick's identify command
4. The image is resized to 200px (width for portrait, height for landscape) with a white background
5. Output is saved as PNG in the path {output_path}/{tenantUUID}/{YYYY-MM}/{uuid}.png
6. Source file is deleted after processing

File Organization

Generated thumbnails are organized by tenant and date:

{output_path}/
  {tenantUUID}/
    {YYYY-MM}/
      {uuid}.png

Dependencies

Dependency	Version	Purpose
qpid-jms-client	2.5.0	AMQP messaging client
jakarta.jms-api	3.1.0	JMS API
im4java	1.4.0	ImageMagick Java wrapper
tika-core	3.0.0	MIME type detection
okhttp	4.12.0	HTTP file downloads
BoostMiddleware	internal	Shared BOOST utilities
Json	internal	JSON handling

Running the Service

java -cp target/classes com.luqon.boost.thumbnailgenerator.ThumbnailServer

The service connects to the configured broker and blocks until stdin is closed.