simple_server.py

#!/usr/bin/env python3
"""
Simple Server Example

This example demonstrates a basic single-server queueing system
using the PDQ Python interface.
"""

import pdq


def main():
    """Run simple server example"""
    
    print("=== Simple Server Example ===\\n")
        
    # Model parameters
    num_users = 50
    think_time = 10.0  # seconds between requests
    service_time = 0.5  # seconds per request
    
    print(f"Model Parameters:")
    print(f"  Users: {num_users}")
    print(f"  Think time: {think_time} sec")
    print(f"  Service time: {service_time} sec")
    print()
    
    # Create PDQ model
    model = pdq.PDQModel("Simple Web Server")
    model.set_comment("Single server with terminal users")
    
    # Build the model
    model.create_node("WebServer", pdq.CEN, pdq.FCFS)
    model.create_closed("Users", pdq.TERM, num_users, think_time)
    model.set_demand("WebServer", "Users", service_time)

    # Set units for better reporting
    model.set_work_unit("Requests")
    model.set_time_unit("Seconds")    
    
    # Solve the model
    print("Solving model...")
    model.solve(pdq.EXACT)
    print("Model solved successfully\\n")
    
    # Get performance metrics
    response_time = model.get_response(pdq.TERM, "Users")
    throughput = model.get_throughput(pdq.TERM, "Users")
    utilization = model.get_utilization("WebServer", "Users", pdq.TERM)
    queue_length = model.get_queue_length("WebServer", "Users", pdq.TERM)
    
    print(f"Performance Results:")
    print(f"  Response time: {response_time:.3f} sec")
    print(f"  Throughput: {throughput:.3f} req/sec")
    print(f"  Utilization: {utilization*100:.1f}%")
    print(f"  Queue length: {queue_length:.3f} requests")
    print()
    
    # Show bounds analysis
    max_throughput = model.get_max_throughput(pdq.TERM, "Users")
    optimal_load = model.get_optimal_load(pdq.TERM, "Users")
    
    print(f"Bounds Analysis:")
    print(f"  Max throughput: {max_throughput:.3f} req/sec")
    print(f"  Optimal load: {optimal_load:.1f} users")
    print()
    
    # Generate full report
    print("=== Full PDQ Report ===")
    model.print_report()


if __name__ == "__main__":
    main()