ros2-assignments/doc/architecture/nodes/ExamResultGenerator.md

ExamResultGenerator (assignments::one::g2_2025_exam_result_generator_node)

Overview

The ExamResultGenerator is the core node responsible for simulating exam result generation. It maintains a queue of student-course combinations that need exam results, generates random grades, and publishes them to the system.

Implementation Details

Parameters

• delay_between_grades_ms (int, default: 2000): Delay (in milliseconds) between generated grades.

Constructor

ExamResultGenerator()

• Initializes ROS2 node with name g2_2025_exam_result_generator_node
• Sets up random number generation infrastructure
• Creates DatabaseManager instance with node logger
• Establishes ROS2 publishers, subscribers, and timers
• Loads initial pending combinations from database

Core Functions

void queue_pending_combinations()

• Gets all student-course combinations needing exam results
• Populates operations queue from database
• Called at initialization and when database state changes

void generate_random_result()

• Main exam result generation executed by timer
• Selects random student-course combination from queue
• Stores result in database and publishes to ROS2 topic

void student_management_callback(const g2_2025_assign1_interfaces_pkg::msg::Student::SharedPtr msg)

• Toggles combinations in/out of processing queue
• Updates database with new enrollments

void add_student_course_combination(const StudentCourse& sc)

• Enrolls student into course via database
• Adds combination to processing queue