RML Service

Github repository: https://github.com/ATTX-project/rml-service

RML service is implemented as a SpringBoot application. It uses spring-boot-starter-amqp package to communicate with the RabbitMQ messagebroker, spring-boot-starter-web package to implement the application specific REST API and spring-boot-starter-actuator package to implement the introspection related APIs.

Service can receive transformation request documents through REST API and RabbitMQ request queue.

Table of Contents

• Endpoints
• Building and running RML service
• Environment Variables (required)
• RML Mapping
• Request/response documents

Endpoints

• GET /health - returns status of the service. Will return "not available", if the connection to the message broker is not available, otherwise returns status=up.
• GET /metrics - Spring actuator's basic implementation.
• POST /version/transform

Current version is: 0.1

Building and running RML service

Build with Gradle and run as Spring boot application:

gradle bootRun

Environment Variables (required)

• MHOST - container name or address for the MessageBroker-RabbitMQ database (default='amqp://localhost')
• MEXCHANGE - exchange to use (default='')
• MQUEUE - request queue in the MessageBroker (default:'rmlservice')
• MUSER - user name for MessageBroker (default='user')
• MPASS - password for MessageBroker (default='password')

RML Mapping

Logical source must always use variable {filename} Example:

  rml:logicalSource [
    rml:source "{filename}"  ;
    rml:referenceFormulation ql:JSONPath ;
    rml:iterator "$.[*]"
  ];

Request/response documents

See RML examples