gocpp

Go types and message definitions for the Open Charge Point Protocol (OCPP), versions 1.6, 2.0.1 and 2.1, as defined by the Open Charge Alliance.

What this is

gocpp provides spec-compliant Go types for OCPP messages and data types, suitable for use as a foundation when building charge point or central system implementations, for any of the three protocol versions:

• OCPP 1.6 (v16): all 56 message types (Authorize through UpdateFirmware) and their supporting data types.
• OCPP 2.0.1 (v201): all 64 actions (128 request/response types), 54 datatypes, and 88 enumerations.
• OCPP 2.1 (v21): all 91 actions (181 request/response types — one, NotifyPeriodicEventStream, is a one-way message with no response), 121 datatypes, and 110 enumerations.

All three are implemented with validation on unmarshal and full test coverage.

What this is not

This library does not provide a WebSocket transport, message routing, or any networking. It is purely a typed representation of the protocol.

Packages

• v16 — OCPP 1.6 message and data types (enums, request/response structs, suffixed Req/Conf per OCPP 1.6's own terminology).
• v201 — OCPP 2.0.1 message and data types (enums, request/response structs, suffixed Request/Response per OCPP 2.0.1's own terminology).
• v21 — OCPP 2.1 message and data types (enums, request/response structs, suffixed Request/Response per OCPP 2.1's own terminology).
• ocpp — shared, version-agnostic error types used across v16, v201, and v21.

Installation

go get github.com/feightree/gocpp

Requires Go 1.26+.

Usage

import "github.com/feightree/gocpp/v16"

// Unmarshal an incoming message
var req v16.BootNotificationReq
if err := json.Unmarshal(data, &req); err != nil {
    // invalid payload or out-of-spec field values
}

// Construct an outgoing message
conf := v16.BootNotificationConf{
    CurrentTime: time.Now().UTC(),
    Interval:    60,
    Status:      v16.RegistrationStatusAccepted,
}

// Marshal does not validate — call Validate explicitly for messages you build by hand
if err := conf.Validate(); err != nil {
    // constructed message violates the spec
}

data, err := json.Marshal(conf)

v201 and v21 follow the same design (UnmarshalJSON validates, Validate is exposed for hand-built messages you marshal yourself), just with Request/Response naming instead of Req/Conf, e.g. v21.BootNotificationRequest / v21.BootNotificationResponse — each package matches the terminology its own OCPP version uses.

Every type validates itself on unmarshal — enum fields must match a known value, required fields must be present, and constrained fields (string lengths, numeric ranges, cross-field rules like TxProfile-only charging profiles) are checked. Failures return an *ocpp.Error wrapping an ocpp.ErrorCode (e.g. ocpp.ErrPropertyConstraintViolation, ocpp.ErrOccurenceConstraintViolation), matching the error codes OCPP itself uses in CALLERROR messages. Use errors.Is to detect a specific code.

import (
    "errors"

    "github.com/feightree/gocpp/ocpp"
    "github.com/feightree/gocpp/v16"
)

var status v16.AuthorizationStatus
err := json.Unmarshal([]byte(`"Bogus"`), &status)
if errors.Is(err, ocpp.ErrPropertyConstraintViolation) {
    // received an unknown enum value
}

Contributing

See CONTRIBUTING.md.

License

MIT.