Crate macro_traffic_sim

Expand description

§macro_traffic_sim

gRPC interface for macroscopic traffic simulation via 4-step demand model.

This crate provides a tonic-based gRPC client and server for interacting with the macro_traffic_sim_core computation engine. It allows you to:

Create simulation sessions
Define transport networks (meso nodes, links, zones)
Load origin-destination demand matrices
Configure the 4-step model (trip generation, distribution, mode choice, assignment)
Run the pipeline and observe progress
Retrieve results (link volumes, OD matrices, convergence info)

§Architecture

The computation core (macro_traffic_sim_core) implements the classical 4-step traffic demand model (Generation, Distribution, Mode Choice, Assignment). This crate wraps it with a gRPC API defined in Protocol Buffers, enabling language-agnostic access from Go, Python, or any gRPC-compatible client.

§Quick Start (Client)

use macro_traffic_sim::pb::macro_service_client::MacroServiceClient;
use macro_traffic_sim::pb::*;
use tonic::transport::Channel;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let channel = Channel::from_static("http://127.0.0.1:50052")
        .connect()
        .await?;
    let mut client = MacroServiceClient::new(channel);

    // Create a new session
    let response = client.new_session(NewSessionRequest {}).await?;
    let session_id = response.into_inner().session_id.unwrap().value;
    println!("Session created: {}", session_id);

    // Now push network, zones, OD matrix, configure, and run...
    Ok(())
}

For a complete working example, see examples/rust_client.

§Running the Server

The server binary is included when built with the server feature:

cargo run --features server --bin macro_traffic_sim

§Protocol Buffers

All types are generated from .proto files and exposed under the pb module:

pb::macro_service_client::MacroServiceClient - gRPC client stub
pb::macro_service_server::MacroServiceServer - gRPC server trait (with server feature)
Session: pb::NewSessionRequest, pb::NewSessionResponse, pb::InfoSessionResponse
Network: pb::Node, pb::Link, pb::Zone, pb::NetworkChunk
OD Matrix: pb::OdMatrixChunk
Config: pb::ModelConfigRequest, pb::BprConfig, pb::ModeUtility, pb::TimePeriod
Pipeline: pb::RunPipelineRequest, pb::RunPipelineProgress
Results: pb::LinkVolumesChunk, pb::LinkVolume, pb::OdResultChunk, pb::AssignmentInfo

macro_traffic_sim_core - The computation engine (4-step demand model)
micro_traffic_sim - gRPC interface for microscopic simulation
micro_traffic_sim_core - Microscopic engine (cellular automata)

§Clients in Other Languages

Go: clients/go
Python: clients/python

Re-exports§

pub use pb::*;

Modules§

pb: Generated Protocol Buffer types and gRPC service definitions.