mxaccessgw/clients/rust/README.md

Rust Client Workspace

The Rust client workspace contains the MXAccess Gateway client library, a test CLI, and tests for generated contract wiring plus wrapper behavior. The library uses the shared protobuf inputs documented in ../../docs/ClientProtoGeneration.md so the Rust bindings compile against the same public gateway and worker contracts as the server.

Layout

clients/rust/
  Cargo.toml
  build.rs
  src/
  tests/
  crates/mxgw-cli/

build.rs reads the .proto files from ../../src/ZB.MOM.WW.MxGateway.Contracts/Protos and generates tonic/prost bindings into Cargo build output. src/generated.rs declares the Rust modules that include those generated files. src/generated remains reserved for checked-in generator output if the crate later changes to source-tree generation.

Build And Test

Run the Rust workspace checks from clients/rust:

cargo fmt --all --check
cargo test --workspace
cargo check --workspace
cargo clippy --workspace --all-targets -- -D warnings

The build script uses protoc from PATH or the Windows path recorded in ../../docs/ToolchainLinks.md.

Packaging

Create local release artifacts from clients/rust:

cargo build --workspace --release
cargo install --path crates/mxgw-cli --locked --force

cargo check --workspace regenerates the tonic and prost modules into Cargo build output through build.rs.

CLI

The CLI exposes version, session, command, event stream, write, and smoke commands over the same client wrapper used by tests:

cargo run -p mxgw-cli -- version --json
cargo run -p mxgw-cli -- open-session --endpoint http://localhost:5000 --api-key-env MXGATEWAY_API_KEY --json
cargo run -p mxgw-cli -- register --session-id <session-id> --client-name mxgw-rust-cli --json
cargo run -p mxgw-cli -- add-item --session-id <session-id> --server-handle 1 --item TestChildObject.TestInt --json
cargo run -p mxgw-cli -- advise --session-id <session-id> --server-handle 1 --item-handle 1 --json
cargo run -p mxgw-cli -- stream-events --session-id <session-id> --max-events 1 --json
cargo run -p mxgw-cli -- stream-alarms --session-id <session-id> --max-messages 1 --json
cargo run -p mxgw-cli -- acknowledge-alarm --session-id <session-id> --alarm-reference "\\Galaxy\Area001.Pump001.PumpFault" --json
cargo run -p mxgw-cli -- write --session-id <session-id> --server-handle 1 --item-handle 1 --value-type int32 --value 123 --json

Use --tls, --ca-file, and --server-name-override for TLS endpoints. The CLI reads the API key from --api-key or from --api-key-env, which defaults to MXGATEWAY_API_KEY. API keys are redacted by the library option and secret types.

cargo run -p mxgw-cli -- smoke --endpoint https://mxgateway.example.local:5001 --tls --ca-file C:\certs\mxgateway-ca.pem --server-name-override mxgateway.example.local --api-key-env MXGATEWAY_API_KEY --item TestChildObject.TestInt --json

Library Surface

ClientOptions configures endpoint, API key, plaintext or TLS transport, timeouts, custom CA files, and server name override. GatewayClient::connect creates an authenticated tonic client and attaches authorization: Bearer <api-key> metadata to unary and streaming calls.

GatewayClient exposes raw generated calls through open_session_raw, close_session_raw, invoke_raw, stream_events, query_active_alarms, stream_alarms, acknowledge_alarm, and raw_client. stream_alarms returns an AlarmFeedStream async stream of alarm-feed messages and shares the gateway's central alarm monitor with every other client. The session helpers keep MXAccess handles visible:

let session = client.open_session(request).await?;
let server_handle = session.register("mxgw-rust").await?;
let item_handle = session.add_item(server_handle, "TestChildObject.TestInt").await?;
session.advise(server_handle, item_handle).await?;
let mut events = session.events().await?;
session.close().await?;

MxValue, MxArrayValue, and MxStatus wrap generated protobuf messages while preserving the raw message for parity diagnostics. Command replies whose protocol status is not PROTOCOL_STATUS_CODE_OK become Error::Command and retain the raw MxCommandReply.

Galaxy Repository browse

The Galaxy Repository service exposes a read-only browse over the AVEVA System Platform Galaxy Repository (ZB SQL database). It uses the same API-key auth as the gateway service but requires the metadata:read scope on the server.

GalaxyClient wraps the generated Galaxy bindings the same way GatewayClient wraps the gateway bindings:

let mut galaxy = GalaxyClient::connect(
    ClientOptions::new("http://localhost:5000")
        .with_api_key(ApiKey::new(api_key)),
).await?;

let ok = galaxy.test_connection().await?;
let last_deploy = galaxy.get_last_deploy_time().await?; // Option<prost_types::Timestamp>
let objects = galaxy.discover_hierarchy().await?;       // Vec<GalaxyObject>

get_last_deploy_time returns None when the server reports present = false. discover_hierarchy returns the generated GalaxyObject proto type (re-exported via zb_mom_ww_mxgateway_client::generated::galaxy_repository::v1) with all attributes attached.

The CLI ships matching subcommands under galaxy:

cargo run -p mxgw-cli -- galaxy test-connection --endpoint http://localhost:5000 --api-key-env MXGATEWAY_API_KEY --json
cargo run -p mxgw-cli -- galaxy last-deploy-time --endpoint http://localhost:5000 --api-key-env MXGATEWAY_API_KEY --json
cargo run -p mxgw-cli -- galaxy discover-hierarchy --endpoint http://localhost:5000 --api-key-env MXGATEWAY_API_KEY --json

Browsing lazily

For UI trees or OPC UA bridges, use browse_children to walk one level at a time instead of paging the full hierarchy. Pass a default request for root objects; subsequent calls set parent_gobject_id, parent_tag_name, or parent_contained_path. Filter fields match discover_hierarchy. Each response pairs children with child_has_children so you know which nodes to expand. See Galaxy Repository for full request and filter semantics.

use zb_mom_ww_mxgateway_client::generated::galaxy_repository::v1::BrowseChildrenRequest;

let reply = galaxy.browse_children(BrowseChildrenRequest::default()).await?.into_inner();
for (child, has_children) in reply.children.iter().zip(reply.child_has_children.iter()) {
    println!("{} expand={}", child.tag_name, has_children);
}

High-level walker

For UI trees, the client provides a LazyBrowseNode walker that handles sibling pagination and the child_has_children hint for you:

let mut client = GalaxyClient::connect(
    ClientOptions::new("http://localhost:5000").with_api_key(ApiKey::new(api_key)),
).await?;
let roots = client.browse(None).await?;
for root in &roots {
    if root.has_children_hint() {
        root.expand().await?;
    }
    for child in root.children().await {
        let kind = if child.has_children_hint() { "has children" } else { "leaf" };
        println!("{} ({kind})", child.object().tag_name);
    }
}

expand is idempotent — calling it twice fires only one RPC, and is safe under concurrent callers. To refresh after a Galaxy redeploy, call browse again from the root.

Watching deploy events

watch_deploy_events opens the WatchDeployEvents server stream. The server emits a bootstrap DeployEvent describing the current cache state on subscribe, then one event each time the cached galaxy.time_of_last_deploy changes. sequence is monotonic per server start; gaps signal that the per-subscriber buffer dropped older events. Pass last_seen_deploy_time to suppress the bootstrap event when the client's cached deploy time matches the server's.

use futures_util::StreamExt;

let mut stream = galaxy.watch_deploy_events(None).await?;
while let Some(event) = stream.next().await {
    let event = event?;
    println!(
        "seq={} objects={} attributes={}",
        event.sequence, event.object_count, event.attribute_count,
    );
}
// Drop the stream to cancel the gRPC call.

The matching CLI subcommand prints one line per event (--json switches to one JSON object per event). --last-seen-deploy-time accepts an RFC3339 timestamp and is forwarded to the server. --max-events (default 0 = no cap) lets you stop after a fixed number of events; otherwise the command runs until the stream ends or Ctrl+C is pressed.

cargo run -p mxgw-cli -- galaxy watch --endpoint http://localhost:5000 --api-key-env MXGATEWAY_API_KEY
cargo run -p mxgw-cli -- galaxy watch --endpoint http://localhost:5000 --api-key-env MXGATEWAY_API_KEY --json
cargo run -p mxgw-cli -- galaxy watch --endpoint http://localhost:5000 --api-key-env MXGATEWAY_API_KEY --last-seen-deploy-time 2026-04-28T15:30:00Z

Integration Checks

Run live checks only when a gateway and MXAccess-backed worker are available:

$env:MXGATEWAY_INTEGRATION = '1'
$env:MXGATEWAY_ENDPOINT = 'http://127.0.0.1:5000'
$env:MXGATEWAY_API_KEY = '<gateway-api-key>'
$env:MXGATEWAY_TEST_ITEM = 'TestChildObject.TestInt'
cargo run -p mxgw-cli -- smoke --endpoint $env:MXGATEWAY_ENDPOINT --plaintext --api-key-env MXGATEWAY_API_KEY --item $env:MXGATEWAY_TEST_ITEM --json

Related Documentation

• Client Packaging
• Client Proto Generation
• Rust Client Detailed Design
• Rust Style Guide