This is a demo implementation of a CPO using OCPI 1.6 protocol. It is intended as an example of how one can build there own CPO and smart charge solution for a home charger.
Requirements:
- The charger must support OCPI 1.6+
- You must be able to change the charger to point to this CPO implementation.
A simple dashboard is provided to display some state of the charger. A simple rest api is available for external services to get the charge point state and to set a charge limit.
As an example, a Home Assistant configuration is added which can be used to control this CPO via Rest.
To start the CPO, run:
sdk env
./mvn quarkus:devOpen the dashboard on http://localhost:8080.
Open the simulator/better_simulator.html in a browser.
Start Home Assistant
In home-assistant folder, run:
docker compose up [-d]Open Home Assistant in the browser: http://localhost:8123 (user: demo, password: demo)
!!! note HA will show errors in the logs while no charge point is connected and no status notification for connector 1 has been received.
In the simulator, click
- Connect
- Fill in 'Tag1' as Tag and click 'Authorize'
- Set 'Connector uid' to '1' and click 'Status Notification'.
View the state of the connection to be changed because of these action, both in the UI and in Home Assistant.
Perform other functions as part of an OCPI flow. Read the OCPI 1.6 specification to learn more about this.
The CPO is implemented using Java 22 and Quarkus. It supports just a single charger. All state is in memory.
The implementation is just around these basic classes.
classDiagram
class WebSocketEndpoint
class WebSocketSender
class ChargePoint
class Dashboard
class RestApi
WebSocketEndpoint --> ChargePoint : forwards received messages
ChargePoint --> WebSocketSender : sending Call to charge point
Dashboard --> ChargePoint : get state
RestApi --> ChargePoint : get state, set charge limit
| ChargePoint | The main class keeping the state of the charge point and handling all supported operations |
| WebSocketEndpoint | The WebSocket endpoint receiving the websocket connections and forwaring message to the ChargePoint |
| WebSocketSender | Used by ChargePoint to send events to the charge point over websocket |
| DashBoard | A Vaadin UI to display the state of the charge point |
| RestApi | A simple Rest API to get state and put a charge limit |
---
title: Handling Charge Point messages
---
sequenceDiagram
actor CP
CP ->> WebSocketEndpoint : onMessage
activate WebSocketEndpoint
WebSocketEndpoint ->> Charge Point : handleOcppMessage
activate Charge Point
alt Call
Charge Point ->> Charge Point : handleCall
else CallResult
Charge Point ->> Charge Point : handleCall
else CallError
Charge Point ->> Charge Point : handleCall
end
Charge Point -->> WebSocketEndpoint : <response>
deactivate Charge Point
WebSocketEndpoint -->> CP : <response>
deactivate WebSocketEndpoint
---
title: Handling UI/Rest actions
---
sequenceDiagram
actor UI
UI ->> RestApi : GET /chargepoint
activate RestApi
RestApi ->> Charge Point : getState
activate Charge Point
Charge Point -->> RestApi : state
deactivate Charge Point
RestApi -->> UI : state
deactivate RestApi
UI ->> RestApi : PUT /chargepoint/{connector}/chargeLimit
activate RestApi
RestApi ->> Charge Point : setChargingLimit
activate Charge Point
Charge Point ->> Charge Point : sendCommand
activate Charge Point
Charge Point ->> WebSocketSender : sendCommand
activate WebSocketSender
WebSocketSender ->> WebSocketSender : find open connection
WebSocketSender ->> WebSocketSender : create Call
WebSocketSender ->> OpenConnection : sendTextAndWait(call)
WebSocketSender -->> Charge Point : SendAction
deactivate WebSocketSender
Charge Point ->> Charge Point : save SendAction
Charge Point --> RestApi :
deactivate Charge Point
RestApi -->> UI : Ok
deactivate RestApi
To support OCPP-J an OcppJsonMessage interface exists with implementations for each of the type: CALL, CALLRESULT and CALLERROR.
For deserialization, the OcppJsonMessage.fromJsonArray function returns an instance of the subtype.
Serialization is implemented by each subtype via the toJsonArray() function.
classDiagram
direction RL
class MessageType{
<<Enumeration>>
CALL(2)
CALLRESULT(3)
CALLERROR(4)
}
class MessageId
class OcppJsonMessage {
<<interface>>
+messageType(): MessageType
+messageId(): MessageId
+toJsonArray(): JsonArray
+fromJsonArray(JsonArray): Option[OcppJsonMessage]$
}
class Call {
+Action action
+Option[JsonObject] payload
}
class CallResult {
+Option[JsonObject] payload
}
class CallError {
+Option[String] errorCode
+Option[String] errorDescription
+Option[JsonObject] errorDetails
}
Call ..|> OcppJsonMessage
CallResult ..|> OcppJsonMessage
CallError ..|> OcppJsonMessage
OcppJsonMessage --> MessageType
OcppJsonMessage --> MessageId
A simple dashboard is created using Vaadin. The dashboard is live updated with changes.
The simulator folder contains some Charge point simulators to test the CPO.
simulator_1.6.html is a simple simulator. It does nothing by itself. You have to do all state changes manually!
better_simulator.html is a bit 'smarter'. It starts actions based on remote operations. It also supports more operations.
For a demo, the CPO can be controlled via Home Assistant. This demonstrates it is possible to control the CPO based on any data available in Home Assistant.
In a demo view, it is possible to see the state of the charge point.
Via a button and slider it is possible to set the charge limit. By setting it so a value > 0 a new transaction is started. By setting it so 0, the transaction is stopped.
A slider simulating the solar production can also be used to control the CPO.
As soon as the 'solar production' is >1500W (minumum of 6A) the charge limit is set.
When the solar production increases, the charge limit is also increased eventually.
When the solar production decreases, the charge limit is decreased immediately.