Open Charge Point Protocol (OCPP, http://ocppforum.net) is a communication protocol between multiple charging stations ("charge points") and a single management software ("central system").
Currently (december 2012), two OCPP versions (1.2 and 1.5) have been released. There is a draft in progress for a new version (2.0). Both existing versions use SOAP over HTTP as the RPC/transport protocol:
+---------------+ soap/http client soap/http server +---------------+
| |--------------------------------------->| |
| | Operations initiated by ChargePoint | |
| ChargePoint | | CentralSystem |
| | soap/http server soap/http client | |
| |<---------------------------------------| |
+---------------+ Operations initiated by CentralSystem +---------------+
The two main problems with this solution are:
- It requires the CentralSystem to be able to establish a TCP/IP connection to the ChargePoint. This is often not possible on IP based mobile data networks using a public APN, where the ChargePoint is assigned a private IP address on the operator network. In such cases, the ChargePoint can access the Internet (using NAT), but no connection can be made from the Internet to the ChargePoint. A possible solution is to set up a VPN and/or a private APN, but the cost is generally prohibitive for small installations.
- SOAP is very verbose, with a large overhead on every message. This causes a non-optimal bandwidth consumption, which can raise the running cost of an installation.
This project proposes a new RPC/transport for OCPP, that addresses these two issues, using Websocket (http://tools.ietf.org/html/rfc6455) for the transport layer, and SPRC (see Protocol Specification section below) for the RPC layer.
This schema shows objects instances for a system with one ChargePointSimulator and one CentralSystemSimulator.
+------------------------+ +------------------------+
| ChargePointSimulator | | CentralSystemSimulator |
+------------------------+ +------------------------+
|create (param: url) |create (param: listening tcp port)
V V
+------------------------+ connect +------------------------+
| WebSocketClient |------------>| WebSocketServer |
+------------------------+ +------------------------+
When a WebSocket connection (i.e. a transport layer) is established, each peer creates:
- a WampClientConnection, to make RPC calls
- a WampServerConnection, to handle RPC calls
This gives two independant RPC channels on a single TCP connection:
+------------------------+ +------------------------+
+-| ChargePointSimulator | | CentralSystemSimulator |-+
| +------------------------+ +------------------------+ |
| create (param: connection) create (param: connection)|
| |
| +------------------------+ +------------------------+ |
+>| WampClientConnection |------------>| WampServerConnection |<+
| +------------------------+ RPC call +------------------------+ |
| (e.g. MeterValue) |
| |
| +------------------------+ +------------------------+ |
+>| WampServerConnection |<------------| WampClientConnection |<+
+------------------------+ RPC call +------------------------+
(e.g. Reset)
This program requires Node.js (http://nodejs.org/). Third-party packages can be installed with the npm utility. Currently, ocppjs depends on 'websocket', 'xml2js', 'node-expat', 'request' and 'jayschema' packages:
% npm install
To run the OCPP.js simulator, just enter
% node gir-ocppjs.js
You will be given a prompt where you can enter commands.
Commands syntax:
-
start_cs <port> [options]: Start a CentralSystem simulator, listening on the specified TCP<port>. This command can be directly specified on the command line. Options:-i <pingInterval>: websocket ping interval (default: 300s)-u <endpoint>: endpoint URL (default: '/')-p <protocol>: websocket protocol name (default: 'ocpp1.2,ocpp1.5') -
start_cp <url> <id>: Start a ChargePoint simulator, which will try to connect to a CentralSystem on the specified URL, using the specified chargepoint<id>. This command can be directly specified on the command line. Options:-p <protocol>: websocket protocol name (default: 'ocpp1.5')-i <pingInterval>: websocket ping interval (default: 300s)-t <transport>: transport layer mode (websocket or soap), default: websocket-f <from>: in SOAP mode, defines the SOAP From header.-r <remoteActionPort>: in SOAP mode, defines the remote action port. -
remote_<cmd> [options] [custom_arguments]: When a CentralSystem simulator is running and has a connected chargepoint, perform a<cmd>remote action. Seehelpfor available commands. Options:--remote-id <id>: send the remote action to the specified chargepoint<id>. This parameter can be omitted when a single chargepoint is connected. Custom Arguments: see sectionArgument customizationbelow. -
<cmd> [options] [custom_arguments]: When a ChargePoint simulator<id>is running and is connected to a CentralSystem, send a<cmd>message. Seehelpfor available commands. Options:--id id: send the message using the specified chargepoint<id>. This parameter can be omitted when a single chargepoint simulator is running. Custom Arguments: see sectionArgument customizationbelow. -
set <cs|cp> [arguments]: modify the simulator settings from command line interface. Arguments: setting=value ... Supported settings:websocket_ping_interval.set cs websocket_ping_interval=120
-
help: List available commands. -
quit: Exit the program.
Argument customization:
When typing remote_<cmd> or <cmd>, the fields of the payload can be
customized individually from the command line interface using the following
syntax:
argument=value ...
> bootnotification chargePointVendor="DBT"
> bootnotification chargePointVendor="DBT" chargePointModel="NQC-ACDC"
value handles string, number, object and array types.
% node gir-ocppjs.js start_cs 9000
[2012-12-28 14:54:32] CentralSystem started.
[2012-12-28 14:54:32] cs: Server is listening on port 9000
[2012-12-28 14:54:44] cs: ChargePoint #0 connected from 127.0.0.1.
>
[2012-12-28 14:54:54] cs: <<cp#0 [2,"V7NeDL1MnbkaQcaHcYnvxOpCdcI4gpAV",
"BootNotification",{"chargePointVendor":"DBT",
"chargePointModel":"NQC-ACDC",...}]
[2012-12-28 14:54:54] cs: >>cp#0 [3,"V7NeDL1MnbkaQcaHcYnvxOpCdcI4gpAV",
{"status":"Accepted",
"currentTime":"2012-11-28T13:54:44Z",
"heartbeatInterval":300}]
> remote_reset type="Soft"
[2012-12-28 14:56:50] cs: >>cp#0 [2,"tU8hVs8yY6Aleie1kN8fXD7YUJ0PDuyc",
"Reset",{"type":"Soft"}]
[2012-12-28 14:56:50] cs: <<cp#0 [3,"tU8hVs8yY6Aleie1kN8fXD7YUJ0PDuyc",
{"status":"Accepted"}]
>
[2012-12-28 14:58:22] cs: <<cp#0 [2,"Shfrho1gR2NmsjCVeHpCOjImdNxhPPXq",
"MeterValues",{"connectorId":1,values:[{
"timestamp":"2012-12-28T13:58:22Z","value":0}]}]
[2012-12-28 14:58:22] cs: >>cp#0 [3,"Shfrho1gR2NmsjCVeHpCOjImdNxhPPXq",
{}]
>
[2012-12-28 14:59:44] cs: <<cp#0 [2,"yUtxCAuRRv26dKRuQ1fy1AYvE0fZTZ2Z",
"Heartbeat",{}]
[2012-12-28 14:59:44] cs: >>cp#0 [3,"yUtxCAuRRv26dKRuQ1fy1AYvE0fZTZ2Z",
{"currentTime":"2012-12-28T13:59:44Z"}]
% node gir-ocppjs.js start_cp ws://localhost:9000 0
[2012-12-28 14:54:44] ChargePoint #0 started.
[2012-12-28 14:54:44] cp#0: Connected to CentralSystem.
> bootnotification chargePointVendor="DBT" chargePointModel="NQC-ACDC"
[2012-12-28 14:54:54] cp#0: >>cs [2,"V7NeDL1MnbkaQcaHcYnvxOpCdcI4gpAV",
"BootNotification",{"chargePointVendor":"DBT",
"chargePointModel":"NQC-ACDC",...}]
[2012-12-28 14:54:54] cp#0: <<cs [3,"V7NeDL1MnbkaQcaHcYnvxOpCdcI4gpAV",
{"status":"Accepted",
"currentTime":"2012-12-28T13:54:44Z",
"heartbeatInterval":300}]
>
[2012-12-28 14:56:50] cp#0: <<cs [2,"tU8hVs8yY6Aleie1kN8fXD7YUJ0PDuyc",
"Reset",{"type":"Soft"}]
[2012-12-28 14:56:50] cp#0: >>cs [3,"tU8hVs8yY6Aleie1kN8fXD7YUJ0PDuyc",
{"status":"Accepted"}]
> metervalues
[2012-12-28 14:58:22] cp#0: >>cs [2,"Shfrho1gR2NmsjCVeHpCOjImdNxhPPXq",
"MeterValues", {"connectorId":2,
values:[{"timestamp":"2012-12-28T13:58:22Z",
"value":0}]}]
[2012-12-28 14:58:22] cp#0: <<cs [3,"Shfrho1gR2NmsjCVeHpCOjImdNxhPPXq",
{}]
> heartbeat
[2012-12-28 14:59:44] cp#0: >>cs [2,"yUtxCAuRRv26dKRuQ1fy1AYvE0fZTZ2Z",
"Heartbeat",{}]
[2012-12-28 14:59:44] cp#0: <<cs [3,"yUtxCAuRRv26dKRuQ1fy1AYvE0fZTZ2Z",
{"currentTime":"2012-12-28T13:59:44Z"}]
% node gir-ocppjs.js start_cs 9000 -t soap
[2013-04-22 16:44:44] cs: SOAP Server listening on port 9000
[2013-04-22 16:44:44] CentralSystem started.
[2013-04-22 16:57:52] cs: ChargePoint #boxid connected.
[2013-04-22 16:57:52] cs: <<cp#boxid /BootNotification {"chargePointVendor":
"DBT","chargePointModel":"NQC-ACDC", ...}
[2013-04-22 16:57:52] cs: >>cp#boxid /BootNotification {"status":"Accepted",
"currentTime":"2013-02-01T15:09:18.000Z",
"heartbeatInterval":1200}
> remote_starttransaction
[2013-04-22 17:01:48] cs: >>cp#boxid /RemoteStartTransaction {"idTag":
"044943121F1D80","connectorId":2}
[2013-04-22 17:01:48] cs: <<cp#boxid /RemoteStartTransaction {"status":
"Accepted"}
% node gir-ocppjs.js start_cp http://localhost:9000 boxid -t soap \
-f http://localhost:9001
[2013-04-09 14:27:14] cs: SOAP Server listening on port 9001
> bootnotification
[2013-04-09 14:57:29] cp#boxid: >>cs /BootNotification {"chargePointVendor":
"DBT", "chargePointModel":"NQC-ACDC", ...}
[2013-04-09 14:57:29] cs: >>boxid /BootNotification {"status":"Accepted",
"currentTime":"2013-02-01T15:09:18.000Z",
"heartbeatInterval":1200}
...
[2013-04-22 17:01:48] cs: <<cp#boxid /RemoteStartTransaction {"idTag":
"044943121F1D80","connectorId":2}
[2013-04-22 17:01:48] cs: >>cp#boxid /RemoteStartTransaction {"status":
"Accepted"}
> set cp print_xml=true
> heartbeat
[2013-04-09 15:03:02] cp#boxid: >>cs <soap:Envelope ...>
<soap:Header>...</soap:Header><soap:Body>
<tns:heartbeatRequest></tns:heartbeatRequest>
</soap:Body></soap:Envelope>
[2013-04-09 15:03:02] cs: >>boxid <?xml version="1.0" encoding="utf-8"?>
<soap:Envelope ...><soap:Body><tns:HeartbeatResponse>
<currentTime>2013-02-01T15:09:18Z</currentTime>
</tns:HeartbeatResponse></soap:Body></soap:Envelope>
ocppjs provides a framework and four example files (in the test/ folder) for writing unit tests. If a test fails, the errors are printed on the standard output. If it succeeds then nothing is displayed.
% cd test/
% node test-cp-1.2.js
%
ocppjs provides a plugin system which allows developers to define the simulator behavior without modifying the program source code. Plugins consist of extern JavaScript files listed in the plugins/ folder.
From the prompt of the simulator, 3 commands are available:
The gir-ocppjs-doc.js program generates JSON examples from WSDL files. Run it with:
% npm install xml2js
% cd doc
% make
Output files generated:
A draft specification for a WebSocket-based OCPP transport is available: http://www.gir.fr/ocppjs/ocpp_srpc_spec.shtml