The Open Charge Point Protocol (OCPP) is a network protocol for communication between electric vehicle chargers and a central backoffice system. It is developed by the Open Charge Alliance (OCA). You can find more details on the official website of the OCA.
This library is the implementation of OCPP developed and used by NewMotion, one of Europe's largest Electric Vehicle Charge Point Operators.
The library is designed with versatility in mind. OCPP comes in 3 versions (1.2, 1.5 and 1.6), two transport variants (SOAP/XML aka OCPP-S and WebSocket/JSON aka OCPP-J), and two roles ("Charge Point" and "Central System"). This library will help you with almost any combination of those. Only version 1.2 with WebSocket/JSON and version 1.6 with SOAP/XML are not possible.
Also, you will probably want to use different WebSocket libraries for different scenarios: a production back-office server with tens of thousands of concurrent connections, a client in a load testing tool, or a simple one-off script to test a certain behavior. This library uses the cake pattern to make it easy to swap out the underlying WebSocket implementation while still using the same concise high-level API.
The library is divided into a bunch of separate modules so applications using it won't get too many dependencies dragged in. Those are:
-
ocpp-j-api
: high-level interface to OCPP-J connections -
ocpp-json
: serialization of OCPP messages to/from JSON -
ocpp-messages
: A model of OCPP messaging that is independent of protocol version and transport variant -
ocpp-soap
: A version-independent interface to OCPP-SOAP -
ocpp-spray
: A library to help handling OCPP SOAP messages with Akka and the Spray HTTP library -
ocpp-12
andocpp-15
: WSDL files and generated code for the OCPP 1.2 and 1.5 SOAP services
So if you want to use the high-level OCPP-J connection interface, and you're
using SBT, you can declare the dependency by adding this to your plugins.sbt
:
resolvers += "TNM" at "http://nexus.thenewmotion.com/content/groups/public"
and this to your build.sbt
:
libraryDependencies += "com.thenewmotion" %% "ocpp-j-api" % "6.0.0"
With Maven, you'd set up the repository in your pom.xml:
<repository>
<id>thenewmotion</id>
<name>The New Motion Repository</name>
<url>http://nexus.thenewmotion.com/content/repositories/releases-public</url>
</repository>
and add this to your dependencies:
<dependency>
<groupId>com.thenewmotion.ocpp</groupId>
<artifactId>ocpp-j-api_2.11</artifactId>
<version>6.0.0</version>
</dependency>
An example OCPP-J client application included. You can run it like this:
sbt "project example-json-client" "run 01234567 ws://localhost:8017/ocppws 1.5,1.6"
This means: connect to the Central System running at
ws://localhost:8017/ocppws
, as a charge point with ID 01234567, using OCPP
version 1.5 and if that is not supported try 1.6 instead. If you don't specify
a version, 1.6 is used by default.
If you look at the code of the example by clicking here, you can see how the client API is used:
-
A connection is established by creating an instance of
OcppJsonClient
. The server endpoint URI, charge point ID and OCPP version to use are passed to the constructor. -
To specify how your application handles incoming messages, you override the
requestHandler
andonError
members. -
To send OCPP messages to the Central System, you call the
send
method on theOcppJsonClient
instance. You will get aFuture
back that will be completed with the Central System's response. If the Central System fails to respond to your request, theFuture
will fail. -
OcppJsonClient
is an instance of theOcppEndpoint
trait. This trait defines this interface.
To specify the request handler, we use a magnet pattern.
You can specify the request handler in different ways. After the
val requestHandler: ChargePointRequestHandler =
, you see a
ChargePoint
instance in the example program. But you can also specify the request handler
as a function from ChargePointReq
to Future[ChargePointRes]
:
val requestHandler: ChargePointRequestHandler = { (req: ChargePointReq) =>
req match {
case GetConfigurationReq(keys) =>
System.out.println(s"Received GetConfiguration for $keys")
Future.successful(GetConfigurationRes(
values = List(),
unknownKeys = keys
))
case x =>
val opName = x.getClass.getSimpleName
Future.failed(OcppException(
PayloadErrorCode.NotSupported,
s"Demo app doesn't support $opName"
))
}
}
This behavior of this request handler is more or less equivalent to that of the one in the example app. It is shorter at the price of being less type-safe: this code does not check if you generate the right response type for the request, so if you generate a GetConfigurationRes in response to a GetConfigurationReq for instance.
Sending requests is simple, as explained. You call the send
method of your
endpoint and off you go, like this:
connection.send(HeartbeatReq)
The set of messages you can send is defined in ocpp-messages.
For every request type, you represent requests as instances of a case class
named <Operation Name>Req
, e.g. StatusNotificationReq
, HeartbeatReq
.
These case classes in ocpp-messages
are designed according to two principles:
- They are independent of OCPP version, so you have one interface to charging stations that use different versions
- They sometimes group and rearrange fields to make it impossible to specify
nonsense messages (e.g., no
vendorErrorCode
in status notifications that are not about errors). This makes it easier to write the code dealing with those requests, which does not have to validate things first.
This does mean that sometimes the way these case classes are defined may be a bit surprising to people familiar with the OCPP specification. It be so. Use the link to the file above, or use ⌘P in IntelliJ IDEA, to see how to give these case classes the right parameters to formulate the request you want to send.
This also means that it is possible to send requests that cannot be represented
in the OCPP version that is used for the connection you send them over. In that
case send
will return a failed future with an OcppError
with error code
NotSupported
.
The result of the send
method is a Future[RES]
, where RES
is the type
of the response that belongs to the request you sent. So the type of this
expression:
connection.send(AuthorizeReq(idTag = "12345678"))
is Future[AuthorizeRes]
.
And if you want to do something with the result, the code could look like this:
connection.send(AuthorizeReq(idTag = "12345678")).map { res =>
if (res.idTag.status == AuthorizationStatus.Accepted)
System.out.println("12345678 is authorized.")
else
System.out.println("12345678 has been rejected. No power to you!")
}
Note that the library does not by itself
enforce the OCPP requirement that you wait for the response before sending the
next request. A simple way to obey it is chaining the send operations in a for
comprehension, as shown in the example app.
If you want to build an OCPP-J client using a different WebSocket implementation, or an OCPP-J server, you'll have to use the cake layers directly.
The OCPP cake has three layers:
OcppConnectionComponent
: matches requests to responses, and handles serialization and deserialization between OCPP request/response objects and SRPC messagesSrpcComponent
: serializes and deserializes SRPC messages to JSONWebSocketComponent
: reads and writes JSON messages from and to a WebSocket connection
There are default implementations for the OcppConnectionComponent
and
SrpcComponent
. The WebSocketComponent
you will have to create yourself to
integrate with your WebSocket implementation of choice.
To put it in a diagram:
+--------------V--------------------^--------------+
| com.thenewmotion.ocpp.messages.{Req, Res} |
| |
| OcppConnectionComponent layer |
| |
+--------------V--------------------^--------------+
| com.thenewmotion.ocpp.json.TransportMessage |
| |
| SrpcComponent layer |
| |
+--------------V--------------------^--------------+
| org.json4s.JValue |
| |
| WebSocketComponent layer |
| |
+--------------V--------------------^--------------+
(WebSocket lib specific types)
So the OcppConnectionComponent
layer exchanges OCPP requests and responses
with your app. It exchanges SRPC messages, represented as
TransportMessage
objects, with the SrpcComponent
layer. The SrpcComponent
layer exchanges
JSON messages, represented as org.json4s.JValue
objects, with the WebSocket
layer. The WebSocket layer then speaks to the WebSocket library, using whatever
types that library uses, usually just String
s.
Now this is not the whole picture yet: besides just OCPP messages, the layers
also exchange connection commands and events, like "close this connection!" or
"an error occurred sending that request". The traits also define methods to
exchange those, and so the total amount of methods in your
OcppConnectionComponent with SrpcComponent with WebSocketComponent
instance
may be intimidating at first. Let's make a version of the above diagram that
shows the methods defined by each layer:
OcppConnectionComponent.onRequest (override)
OcppConnectionComponent.ocppConnection.sendRequest (call) OcppConnectionComponent.onOcppError (override)
+------------------V-----------------------------------------------^--------------------------------------------------+
| |
| OcppConnectionComponent layer |
| |
| |
| SrpcConnectionComponent.srpcConnection.send (call) SrpcConnectionComponent.onSrpcMessage (override) |
+------------------V-----------------------------------------------^--------------------------------------------------+
| |
| SrpcComponent layer |
| |
| WebSocketConnectionComponent.onMessage (override) |
| WebSocketConnectionComponent.webSocketConnection.send (call) WebSocketConnectionComponent.onDisconnect (override) |
| WebSocketConnectionComponent.webSocketConnection.close (call) WebSocketConnectionComponent.onError (override) |
+------------------V-----------------------------------------------^--------------------------------------------------+
| |
| WebSocketComponent layer |
| |
| (WebSocket library dependent) (WebSocket library dependent) |
+------------------V-----------------------------------------------^--------------------------------------------------+
So each layer defines the interface that the higher layers can use to communicate with it. For every layer, you see on the left how the higher layer can give it information, and on the right how the higher layer gets information from it.
For instance, on top you see that the user of the whole cake can give
information to the OCPP layer by calling the ocppConnection.sendRequest
method. And on the lower middle right you see that the SRPC cake layer
can get information from the WebSocket layer by overriding the
onMessage
, onDisconnect
and onError
methods of the
WebSocketComponent
.
There has to be one instance of the whole cake for every open WebSocket
connection in the system. A server would typically maintain a mapping of
WebSocket connection IDs from the underlying library to
OcppConnectionComponent with SrpcComponent with WebSocketComponent
instances
for them. When it receives an incoming WebSocket message, it will look up the
cake for that connection, and pass the message to the WebSocket layer of that
cake.
So now with this background information, the steps to constructing your cake would be:
-
Determine the kind of interface you want to the logic in the rest of your app
-
Create a trait extending
WebSocketComponent
that uses your WebSocket implementation of choice -
Create the cake:
-
Do either
new CentralSystemOcppConnectionComponent with DefaultSrpcComponent with MyWebSocketComponent { ... }
ornew ChargePointCentralSystemOcppConnectionComponent with DefaultSrpcComponent with MyWebSocketComponent { ... }
-
Define in it a
val webSocketConnection
,val srpcConnection
andval ocppConnection
. ForocppConnection
, use one of thedefaultChargePointOcppConnection
anddefaultCentralSystemOcppConnection
methods defined by the DefaultOcppConnectionComponent traits. Forval srpcConnection
, usenew DefaultSrpcConnection
.
-
-
Define all the "(override)" methods shown at the top of the cake to connect your app's request and response processing to the OCPP cake
-
Make the WebSocket layer call your WebSocket library to send messages over the socket, and make your WebSocket library call the cake for it to receive messages
Because that bit about the cake pattern is still quite abstract, let's look at how we can implement an OCPP server using the cake pattern.
According to the list of steps above, we first have to determine the interface that we want or OCPP server component to have.
The interface I am thinking of here is something like this:
abstract class OcppJsonServer(listenPort: Int, ocppVersion: Version) {
type OutgoingEndpoint = OutgoingOcppEndpoint[ChargePointReq, ChargePointRes, ChargePointReqRes]
type IncomingEndpoint = IncomingOcppEndpoint[CentralSystemReq, CentralSystemRes, CentralSystemReqRes]
def handleConnection: OutgoingEndpoint => IncomingEndpoint
}
So if someone writes a back-office system using this server component, she has to provide three things:
-
the TCP port to listen on, as a constructor argument
-
The OCPP version to use, as a constructor argument (I'm too lazy to worry about version negotiation right now)
-
Her own logic for how to handle and send OCPP messages over the connections to this server. She should specify this as a method
handleConnection
that gets an endpoint for sending outgoing requests as an argument, and returns to the server component an endpoint for handling incoming requests and close or error events.
So now we have decided on an interface and we move to step two: create
a trait extending WebSocketComponent
that uses our WebSocket
implementation of choice. Here we are using java-websocket, so we'll
end up using WebSocketServer.
If we look at the WebSocketServer API, we see that it is based on
instantiating a WebSocketServer
object with overridden methods to
handle incoming messages. The interface looks like this:
public abstract class WebSocketServer extends AbstractWebSocket implements Runnable {
// These methods are provided by the implementation...
public WebSocketServer(InetSocketAddress address) { ... }
public void start() { ... }
public void stop() { ... }
// ...and these are to be overridden by the user
public abstract void onStart();
public abstract void onOpen( WebSocket conn, ClientHandshake handshake );
public abstract void onClose( WebSocket conn, int code, String reason, boolean remote );
public abstract void onMessage( WebSocket conn, String message );
public abstract void onError( WebSocket conn, Exception ex );
}
So for each connection, WebSocketServer
creates a WebSocket
object,
and then passes that into the callback. We will create our
WebSocketComponent
instance so that it calls the send
method on such
a WebSocket
to send outgoing messages. That means a first stab at our
WebSocketComponent
looks like this:
import org.java_websocket.WebSocket
import org.json4s.JValue
import org.json4s.native.JsonMethods.{compact, render}
trait SimpleServerWebSocketComponent extends WebSocketComponent {
trait SimpleServerWebSocketConnection extends WebSocketConnection {
def webSocket: WebSocket
def send(msg: JValue): Unit = webSocket.send(compact(render(msg)))
def close(): Unit = webSocket.close()
}
}
That brings us to step 3: creating the cake. Now we want to create a
cake for every incoming WebSocket connection to the server, so that
means we also have to create a WebSocket server that will create a cake
in its onOpen
method:
import java.net.InetSocketAddress
import scala.concurrent.ExecutionContext
import org.java_websocket.WebSocket
import org.java_websocket.handshake.ClientHandshake
import org.java_websocket.server.WebSocketServer
import messages._
abstract class OcppJsonServer(listenPort: Int, ocppVersion: Version)
extends WebSocketServer(new InetSocketAddress(listenPort)) {
type OutgoingEndpoint = OutgoingOcppEndpoint[ChargePointReq, ChargePointRes, ChargePointReqRes]
type IncomingEndpoint = IncomingOcppEndpoint[CentralSystemReq, CentralSystemRes, CentralSystemReqRes]
def handleConnection: OutgoingEndpoint => IncomingEndpoint
override def onStart(): Unit = {}
override def onOpen(conn: WebSocket, hndshk: ClientHandshake): Unit = {
val ocppConnection = new CentralSystemOcppConnectionComponent with DefaultSrpcComponent with SimpleServerWebSocketComponent {
override val ocppConnection: DefaultOcppConnection = defaultCentralSystemOcppConnection
override val srpcConnection: DefaultSrpcConnection = new DefaultSrpcConnection()
override val webSocketConnection: SimpleServerWebSocketConnection = new SimpleServerWebSocketConnection {
val webSocket: WebSocket = conn
}
def onRequest[REQ <: CentralSystemReq, RES <: CentralSystemRes](req: REQ)(implicit reqRes: CentralSystemReqRes[REQ, RES]) = ???
def onOcppError(error: OcppError): Unit = ???
def onDisconnect() = ???
implicit val executionContext: ExecutionContext = ???
def ocppVersion: Version = ???
}
}
override def onClose(
conn: WebSocket,
code: Int,
reason: IdTag,
remote: Boolean
): Unit = ???
override def onMessage(conn: WebSocket, message: IdTag): Unit = ???
override def onError(conn: WebSocket, ex: Exception): Unit = ???
}
Ouch, that's a big load of code there. Still, it came about after a few simple steps:
- Take the interface template for OcppJsonServer that we started this example with
- Make it extend WebSocketServer, and add
???
implementations of its abstract methods - In the
onOpen
method from theWebSocketServer
abstract class, create a cake with the three layers:CentralSystemOcppConnectionComponent with DefaultSrpcComponent with SimpleServerWebSOcketComponent
- Add
???
implementations of all the abstract methods in the cake - Add actual definitions of the
ocppConnection
,srpcConnection
andwebSocketConnection
members of the three cake layers.
Note that at step 5, we have passed the WebSocket
argument to the
onOpen
method on into the SimpleServerWebSocketConnection
so that
the cake can later use this WebSocket
to send OCPP messages over.
So by now we're at the fourth point of the five-step cake plan: connect our
app's logic to the OCPP cake. The app's logic, in our case, is the
handleConnection
that the library user specifies. And then, inside
the OCPP cake definition in onOpen
, we create the incoming endpoint,
and call the user-defined handleConnection
on it so an endpoint for
the incoming messages is created:
private val outgoingEndpoint = new OutgoingEndpoint {
def send[REQ <: ChargePointReq, RES <: ChargePointRes](req: REQ)(implicit reqRes: ChargePointReqRes[REQ, RES]): Future[RES] =
ocppConnection.sendRequest(req)
def close(): Unit = webSocketConnection.close()
}
private val incomingEndpoint = handleConnection(outgoingEndpoint)
Now that we have the incoming endpoint, we can also fill in definitions for the
onRequest
, onError
and onDisconnect
handlers in the OCPP cake:
def onRequest[REQ <: CentralSystemReq, RES <: CentralSystemRes](req: REQ)(implicit reqRes: CentralSystemReqRes[REQ, RES]) =
incomingEndpoint.requestHandler(req)
def onOcppError(error: OcppError): Unit =
incomingEndpoint.onError(error)
def onDisconnect() =
incomingEndpoint.onDisconnect()
And then, there is the ocppVersion
method in OcppConnectionComponent
that will tell it which OCPP version to use to serialize and deserialize
OCPP messages to JSON. We have to fill in the OCPP version that was
passed in to the OcppJsonServer
constructor. To avoid name clashes,
we rename the argument to OcppJsonServer
:
abstract class OcppJsonServer(listenPort: Int, requestedOcppVersion: Version)
and then fill in this requestedOcppVersion
argument in the cake's
ocppVersion
method:
def ocppVersion: Version = requestedOcppVersion
By now, the OCPP cake definition body is free of any reference to "???". The cake is fully linked to the app's business logic.
That means we're at the fifth and last step of the five-step plan: We have to
make sure that when a new connection is opened, we will call this function to
create an IncomingEndpoint
, and that we later call this IncomingEndpoint
whenever a message comes in on the connection. To make this happen, we will need
a map from WebSocket
instances that the server gets in its onMessage
method,
to the OCPP cake instance that will process messages for that connection.
So let's add this to the OcppJsonServer
class: link the WebSocket library
we're using to our OCPP cake.
private type OcppCake = CentralSystemOcppConnectionComponent with DefaultSrpcComponent with SimpleServerWebSocketComponent
private val ocppConnections: mutable.Map[WebSocket, OcppCake] = mutable.HashMap()
and to fill the map, we add this line at the bottom of onOpen
in our
OcppJsonServer
:
ocppConnections.put(conn, ocppConnection)
and as responsible professionals, let's also remove the entry from the map again
when a connection is closed, by changing the definition of onClose
to this:
override def onClose(
conn: WebSocket,
code: Int,
reason: IdTag,
remote: Boolean
): Unit = ocppConnections.remove(conn)
Now the last thing to be done on the way to a working server, is making the
onMessage
, onDisconnect
and onError
callbacks of WebSocketServer
actually call into the connection's OCPP cake to let it process the message. It
turns out that to do this, we have to add two methods to the
SimpleWebSocketServerComponent
:
def feedIncomingMessage(msg: String) = self.onMessage(org.json4s.native.JsonMethods.parse(msg))
def feedIncomingDisconnect(): Unit = self.onDisconnect()
def feedIncomingError(err: Exception) = self.onError(err)
to make that work, we also have to make SimpleServerWebSocketComponent aware that it is to be mixed into something that is also an SrpcComponent, by adding a self-type:
trait SimpleServerWebSocketComponent extends WebSocketComponent {
self: SrpcComponent =>
...
and back in OcppJsonServer
, we change the implementation of onMessage
,
onClose
and onError
to feed those events into the cake for the right
connection:
override def onClose(
conn: WebSocket,
code: Int,
reason: IdTag,
remote: Boolean
): Unit = {
ocppConnections.remove(conn) foreach { c =>
c.feedIncomingDisconnect()
}
}
override def onMessage(conn: WebSocket, message: String): Unit =
ocppConnections.get(conn) foreach { c =>
c.feedIncomingMessage(message)
}
override def onError(conn: WebSocket, ex: Exception): Unit =
ocppConnections.get(conn) foreach { c =>
c.feedIncomingError(ex)
}
That's it, it should work now!
In fact, upon testing it, I realize that with this interface, the server-side
code doesn't know the ChargePointIdentity of the client. That's not very
helpful; an OCPP back-office system will probably want to know which charge
points are connected to it. So let's change the definition of handleConnection
in OcppJsonServer
to this:
def handleConnection(clientChargePointIdentity: String, remote: OutgoingEndpoint): IncomingEndpoint
and let's pass the ChargePointIdentity into it by changing onOpen
to this:
override def onOpen(conn: WebSocket, hndshk: ClientHandshake): Unit = {
val uri = hndshk.getResourceDescriptor
uri.split("/").lastOption match {
case None =>
conn.close(1003, "No ChargePointIdentity in path")
case Some(chargePointIdentity) =>
onOpenWithCPIdentity(conn, chargePointIdentity)
}
}
private def onOpenWithCPIdentity(conn : WebSocket, chargePointIdentity: String): Unit = {
val ocppConnection = new CentralSystemOcppConnectionComponent with DefaultSrpcComponent with SimpleServerWebSocketComponent {
... // continues as in earlier definition of onOpen
So there we check if the URL includes the charge point identity. If it doesn't, we immediately close the WebSocket connection with an error message. If we do have a ChargePointIdentity, we proceed to handle the open as we did before. And now it should really be done.
In order to save you the typing and bugfixing, an actual tested version of the server developed while writing this is included.
And there is also a small
example app
that shows how to use the OcppJsonServer
interface. It will listen on port
2345, and return NotImplemented
to any request except BootNotification. In
response to a BootNotification, it will send a response and also send a
GetConfiguration request back to the client. To run it, you do:
$ sbt "project example-json-server" run
If you do not need the connection management provided by the high-level API,
you can still use the ocpp-json
module for serializing and deserializing OCPP
messages that you will send or receive using other libraries.
To do so, call the methods in the OcppJ
object after importing either
com.thenewmotion.ocpp.json.v15.SerializationV15._
or com.thenewmotion.ocpp.json.v16.SerializationV16._
to select which OCPP
version to use:
import com.thenewmotion.ocpp.json.OcppJ
import com.thenewmotion.ocpp.messages
import com.thenewmotion.ocpp.Version
import com.thenewmotion.ocpp.json.v16.SerializationV16._
OcppJ.write(AuthorizeReq(idTag = "ABCDEF012"))
// this results in:
// res6: String = {"idTag":"ABCDEF012"}
OcppJ.read[AuthorizeReq, Version.V16.type]("""{"idTag":"ABCDEF012"}""")
// this results in:
// res10: com.thenewmotion.ocpp.messages.AuthorizeReq = AuthorizeReq(ABCDEF012)
There are also serialize
and deserialize
methods on the OcppJ
object that
use json4s JValue
s as the representation of JSON instead of raw String
s.
You can use those to build the SRPC
messages that are sent over the WebSocket. See TransportMessage
and TransportMessageJsonSerializers
for how to work with those.
OCPP-S is what this library started with, but by now it is undocumented legacy. It may be split off to enjoy retirement in its own little project on the next major version.
- Support DataTransfer messages from Charge Point to Central System also over SOAP
- Support DataTransfer messages from Charge Point to Central System
- Throw more meaningful exceptions instead of always
VersionMismatch
when anOcppJsonClient
fails to connect
This library had been stable for a few years between 2014 and 2017, with 4.x.x version numbers, supporting OCPP-S 1.2 and 1.5, and OCPP-J 1.5, but not 1.6. Now that 1.6 support has been added with version 6.0.0, many wildly incompatible changes to the library interface were made while we were at it. The most important ones to be aware of when porting older code:
- The
CentralSystem
andChargePoint
traits were renamed toSyncCentralSystem
andSyncChargePoint
. The namesCentralSystem
andChargePoint
are now used for asynchronous versions of these traits that returnFuture
s. - In the high-level JSON API, request-response-handling has become more
type-safe. Your request handler is no longer just a function from requests
to responses, but now a
RequestHandler
which will also verify that you produce the right response type for the given request. - The library now uses enum-utils
instead of Scala's
Enumeration
s - The library now uses Java 8's
java.time
for date and time handling instead ofcom.thenewmotion.time
. JsonDeserializable
was renamed toJsonOperation
and now handles not only deserialization but also serialization of OCPP messages for OCPP-J.OcppJsonClient
now takes a version parameter
- Building for Scala 2.12. May require dropping the SOAP and/or switching JSON libraries.
The contents of this repository are © 2012 - 2017 The New Motion B.V., licensed under the GPL version 3, except:
-
The example messages for OCPP 1.5 in the ocpp-json unit tests, which were taken from GIR ocppjs.
-
The JSON schema files for OCPP 1.6 are part of the OCPP 1.6 Specification, distributed under the following conditions:
Copyright © 2010 – 2015 Open Charge Alliance. All rights reserved. This document is made available under the *Creative Commons Attribution- NoDerivatives 4.0 International Public License* (https://creativecommons.org/licenses/by-nd/4.0/legalcode).