OCPP-RS

OCPP-RS is a Rust library for implementing the Open Charge Point Protocol (OCPP) in Rust.

It supports OCPP 1.6 and OCPP 2.1 (2.0.1-compatible additive schemas).

Full implementation of OCPP 1.6 and OCPP 2.1 message payloads
Batteries included: OCPP-J parse/serialize for both versions
CallResult typing via PendingCalls / action-name correlation (no untagged guessing)
#![no_std] + alloc — library code never uses std (baremetal-friendly). You must provide a global allocator (e.g. embedded-alloc, linked_list_allocator, or your RTOS heap).
Inspired by a python ocpp library; 2.1 layout inspired by rust-ocpp

`no_std` / firmware

The published library (src/) is #![no_std] + alloc end-to-end: zero std:: usage, and dependencies are built with default-features = false (chrono without clock/std). Integration tests and example/ may use std for host runners only — that does not leak into firmware consumers.

You must provide a global allocator on baremetal (e.g. embedded-alloc, linked_list_allocator, or your RTOS heap).

# Typical embedded consumer
[dependencies]
ocpp_rs = { version = "0.3", default-features = false }
# plus your allocator crate / #[global_allocator]

Sanity checks:

# Library must build under #![no_std] (host is enough to catch std usage in src/)
cargo build --lib

# Optional: freestanding target (requires rustup target)
cargo build --lib --target thumbv7em-none-eabi

# Chrono must not enable std/clock via feature unification
cargo tree -p chrono -f '{p} {f}' | head -5
# expect: chrono … alloc,serde   (not std/clock)

Usage

[dependencies]
ocpp-rs = "^0.3"

Upgrading from 0.2.x: see guides/migration-0.3.md.

Particularities

OCPP 1.6 CallResult

CALLRESULT has no action on the wire. Blind parse yields CallResultRaw. Correlate with PendingCalls (same idea as 2.1):

use ocpp_rs::v16::call::{Action, Call, Heartbeat};
use ocpp_rs::v16::parse::TypedMessage;
use ocpp_rs::v16::pending::PendingCalls;
use ocpp_rs::v16::typed_call_result::TypedCallResult;

let mut pending = PendingCalls::new();
let _wire = pending.send_call(Call::new("1".into(), Action::Heartbeat(Heartbeat {})))?;
let typed = pending.deserialize_typed(r#"[3, "1", {"currentTime": "2024-01-01T00:00:00.000Z"}]"#)?;
assert!(matches!(typed, TypedMessage::CallResult(TypedCallResult::Heartbeat(_))));

Sticky sessions or Redis messageId → action name + resolve_with_action_name for load-balanced deploys
Datetime: always parse RFC3339; serialize defaults to %.3fZ (optional datetime_serialize_rfc3339) — guides/datetime-features.md
Last resort: try_resolve_unique / probe_candidates (often ambiguous for {})

Details: v16::pending, migration guide.

OCPP 2.1

Same CallResult correlation model under v21::pending. Framing includes types 2–6 (CALL, CALLRESULT, CALLERROR, CALLRESULTERROR, SEND).

use ocpp_rs::v21::call::{Action, Call};
use ocpp_rs::v21::messages::heartbeat::HeartbeatRequest;
use ocpp_rs::v21::parse::TypedMessage;
use ocpp_rs::v21::pending::PendingCalls;
use ocpp_rs::v21::typed_call_result::TypedCallResult;

let mut pending = PendingCalls::new();
let call = Call::new(
    "1".into(),
    Action::Heartbeat(HeartbeatRequest { custom_data: None }),
);
// For Redis / multi-node: store call.action_kind() (== "Heartbeat") with the message id
assert_eq!(call.action_kind(), "Heartbeat");
let _wire = pending.send_call(call)?;
let typed = pending.deserialize_typed(
    r#"[3, "1", {"currentTime": "2024-01-01T00:00:00.000Z"}]"#,
)?;
assert!(matches!(
    typed,
    TypedMessage::CallResult(TypedCallResult::Heartbeat(_))
));

Load-balanced example (2.1)

use ocpp_rs::v21::pending::resolve_with_action_name;
use ocpp_rs::v21::parse::{deserialize_to_message, Message};

let Message::CallResult(raw) = deserialize_to_message(wire)? else { /* … */ };
let typed = resolve_with_action_name(raw, &redis_getdel(&raw.unique_id)?)?;

Example (1.6 CALL)

use ocpp_rs::v16::parse::{self, Message};
use ocpp_rs::v16::call::Action;

let incoming_text = "[2, \"19223201\", \"BootNotification\", { \"chargePointVendor\": \"VendorX\", \"chargePointModel\": \"SingleSocketCharger\" }]";
let incoming_message = parse::deserialize_to_message(incoming_text);
if let Ok(Message::Call(call)) = incoming_message {
    match call.payload {
        Action::BootNotification(_boot_notification) => { /* … */ }
        _ => {}
    }
}

Sending a CALLRESULT:

use ocpp_rs::v16::call_result::CallResultRaw;
use ocpp_rs::v16::parse::{self, Message};

let response = Message::CallResult(CallResultRaw::new(
    "1234".into(),
    serde_json::to_value(/* your *Response struct */)?,
));
let json = parse::serialize_message(&response)?;

Contributing

Contributions are welcome. Please add/update tests with behavior changes.

Roadmap

Harden OCPP 2.1 field coverage against Part 3 schemas / errata
Fuzzing for v16 and v21 wire parsers

ocpp_rs 0.3.0