Add OCPP 2.1 support

[robert-s-ubi]

Add Java classes for all OCPP 2.1 messages and types as well as client and server event handler interfaces and function classes corresponding to the OCPP 2.1 "functional blocks."

Add OCPP 2.1 to the ProtocolVersion enum.

Specify UTF-8 encoding for the Java source files in build.gradle and pom.xml to avoid compiler warnings about the UTF-8 sequences in the source files.

[neinhart]

Bug: ReportDERControl message direction is reversed

While integrating this PR, I found that ReportDERControl has its message direction (ownership) reversed compared to all other Report* messages in the codebase.

Issue

Per OCPP 2.1 spec, ReportDERControl follows the same Get→Report pattern as GetChargingProfiles → ReportChargingProfiles: the Charging Station (Client) sends ReportDERControlRequest to the CSMS (Server).

However, the current implementation has it backwards:

File	Current (Wrong)	Expected
ServerDERControlFunction	new ReportDERControlFeature(null)	new ReportDERControlFeature(this)
ClientDERControlFunction	new ReportDERControlFeature(this)	new ReportDERControlFeature(null)
ServerDERControlEventHandler	missing handleReportDERControlRequest	should have it
ClientDERControlEventHandler	has handleReportDERControlRequest	should not have it
ServerDERControlFunction	has createReportDERControlRequest	should not have it
ClientDERControlFunction	missing createReportDERControlRequest	should have it

Cross-reference with correct pattern

ReportChargingProfiles in SmartCharging follows the correct pattern:

• ServerSmartChargingFunction: new ReportChargingProfilesFeature(this) — server receives
• ClientSmartChargingFunction: new ReportChargingProfilesFeature(null) — client sends

Affected files

• ClientDERControlEventHandler.java
• ClientDERControlFunction.java
• ServerDERControlEventHandler.java
• ServerDERControlFunction.java

Happy to submit a PR with the fix if helpful.

[neinhart]

Spec reference for the ReportDERControl direction fix

Confirmed against OCPP 2.1 Edition 2 (2025-12-03), Part 2 - Specification:

R04 Requirements (p.561) — GetDERControl section:

• R04.FR.31: "The Charging Station SHALL set the requestId in every ReportDERControlRequest to the value of requestId in GetDERControlRequest."
• R04.FR.32: "Charging Station SHALL set the tbc flag to true for all ReportDERControlRequest messages except the last."
• R04.FR.33: "Charging Station … SHALL return a status = Accepted and send one or more ReportDERControlRequest messages for all controls."

All three requirements explicitly state that the Charging Station (CS) sends ReportDERControlRequest.

Message definitions (p.607-608):

• §1.64.1 ReportDERControlRequest: "Reports DER controls requested by a GetDERControlRequest message." (CS → CSMS)
• §1.64.2 ReportDERControlResponse: "This is an empty message sent by CSMS in response to a ReportDERControlRequest message." (CSMS → CS)

GetDERControl definition (p.592):

• §1.29.1 GetDERControlRequest.requestId: "Required. RequestId to be used in ReportDERControlRequest." — confirming CSMS sends GetDERControl, CS responds with ReportDERControl.

This matches the ReportChargingProfiles pattern (GetChargingProfiles → ReportChargingProfiles, CS → CSMS) and is consistent with all other Report/Notify messages in the codebase.

[neinhart]

Patch for the ReportDERControl direction fix

Here is the patch to fix the reversed message ownership. Apply with git apply:

Click to expand patch

diff --git a/ocpp-v2/src/main/java/eu/chargetime/ocpp/v21/feature/function/ClientDERControlEventHandler.java b/ocpp-v2/src/main/java/eu/chargetime/ocpp/v21/feature/function/ClientDERControlEventHandler.java
index fbf62591..6cb24543 100644
--- a/ocpp-v2/src/main/java/eu/chargetime/ocpp/v21/feature/function/ClientDERControlEventHandler.java
+++ b/ocpp-v2/src/main/java/eu/chargetime/ocpp/v21/feature/function/ClientDERControlEventHandler.java
@@ -44,14 +44,6 @@ public interface ClientDERControlEventHandler {
    */
   GetDERControlResponse handleGetDERControlRequest(GetDERControlRequest request);
 
-  /**
-   * Handle a {@link ReportDERControlRequest} and return a {@link ReportDERControlResponse}.
-   *
-   * @param request incoming {@link ReportDERControlRequest} to handle.
-   * @return outgoing {@link ReportDERControlResponse} to reply with.
-   */
-  ReportDERControlResponse handleReportDERControlRequest(ReportDERControlRequest request);
-
   /**
    * Handle a {@link SetDERControlRequest} and return a {@link SetDERControlResponse}.
    *
diff --git a/ocpp-v2/src/main/java/eu/chargetime/ocpp/v21/feature/function/ClientDERControlFunction.java b/ocpp-v2/src/main/java/eu/chargetime/ocpp/v21/feature/function/ClientDERControlFunction.java
index c22bf8ec..5bc842de 100644
--- a/ocpp-v2/src/main/java/eu/chargetime/ocpp/v21/feature/function/ClientDERControlFunction.java
+++ b/ocpp-v2/src/main/java/eu/chargetime/ocpp/v21/feature/function/ClientDERControlFunction.java
@@ -48,7 +48,7 @@ public class ClientDERControlFunction implements Function {
     features.add(new GetDERControlFeature(this));
     features.add(new NotifyDERAlarmFeature(null));
     features.add(new NotifyDERStartStopFeature(null));
-    features.add(new ReportDERControlFeature(this));
+    features.add(new ReportDERControlFeature(null));
     features.add(new SetDERControlFeature(this));
   }
 
@@ -63,8 +63,6 @@ public class ClientDERControlFunction implements Function {
       return eventHandler.handleClearDERControlRequest((ClearDERControlRequest) request);
     } else if (request instanceof GetDERControlRequest) {
       return eventHandler.handleGetDERControlRequest((GetDERControlRequest) request);
-    } else if (request instanceof ReportDERControlRequest) {
-      return eventHandler.handleReportDERControlRequest((ReportDERControlRequest) request);
     } else if (request instanceof SetDERControlRequest) {
       return eventHandler.handleSetDERControlRequest((SetDERControlRequest) request);
     }
@@ -96,4 +94,14 @@ public class ClientDERControlFunction implements Function {
       String controlId, Boolean started, ZonedDateTime timestamp) {
     return new NotifyDERStartStopRequest(controlId, started, timestamp);
   }
+
+  /**
+   * Create a client {@link ReportDERControlRequest} with all required fields.
+   *
+   * @param requestId RequestId from GetDERControlRequest.
+   * @return an instance of {@link ReportDERControlRequest}
+   */
+  public ReportDERControlRequest createReportDERControlRequest(Integer requestId) {
+    return new ReportDERControlRequest(requestId);
+  }
 }
diff --git a/ocpp-v2/src/main/java/eu/chargetime/ocpp/v21/feature/function/ServerDERControlEventHandler.java b/ocpp-v2/src/main/java/eu/chargetime/ocpp/v21/feature/function/ServerDERControlEventHandler.java
index 875b053b..d4dd0ad6 100644
--- a/ocpp-v2/src/main/java/eu/chargetime/ocpp/v21/feature/function/ServerDERControlEventHandler.java
+++ b/ocpp-v2/src/main/java/eu/chargetime/ocpp/v21/feature/function/ServerDERControlEventHandler.java
@@ -48,4 +48,14 @@ public interface ServerDERControlEventHandler {
    */
   NotifyDERStartStopResponse handleNotifyDERStartStopRequest(
       UUID sessionIndex, NotifyDERStartStopRequest request);
+
+  /**
+   * Handle a {@link ReportDERControlRequest} and return a {@link ReportDERControlResponse}.
+   *
+   * @param sessionIndex identifier of the session on which the request was received.
+   * @param request incoming {@link ReportDERControlRequest} to handle.
+   * @return outgoing {@link ReportDERControlResponse} to reply with.
+   */
+  ReportDERControlResponse handleReportDERControlRequest(
+      UUID sessionIndex, ReportDERControlRequest request);
 }
diff --git a/ocpp-v2/src/main/java/eu/chargetime/ocpp/v21/feature/function/ServerDERControlFunction.java b/ocpp-v2/src/main/java/eu/chargetime/ocpp/v21/feature/function/ServerDERControlFunction.java
index 5614d63e..10d543d3 100644
--- a/ocpp-v2/src/main/java/eu/chargetime/ocpp/v21/feature/function/ServerDERControlFunction.java
+++ b/ocpp-v2/src/main/java/eu/chargetime/ocpp/v21/feature/function/ServerDERControlFunction.java
@@ -47,7 +47,7 @@ public class ServerDERControlFunction implements Function {
     features.add(new GetDERControlFeature(null));
     features.add(new NotifyDERAlarmFeature(this));
     features.add(new NotifyDERStartStopFeature(this));
-    features.add(new ReportDERControlFeature(null));
+    features.add(new ReportDERControlFeature(this));
     features.add(new SetDERControlFeature(null));
   }
 
@@ -64,6 +64,9 @@ public class ServerDERControlFunction implements Function {
     } else if (request instanceof NotifyDERStartStopRequest) {
       return eventHandler.handleNotifyDERStartStopRequest(
           sessionIndex, (NotifyDERStartStopRequest) request);
+    } else if (request instanceof ReportDERControlRequest) {
+      return eventHandler.handleReportDERControlRequest(
+          sessionIndex, (ReportDERControlRequest) request);
     }
     return null;
   }
@@ -88,16 +91,6 @@ public class ServerDERControlFunction implements Function {
     return new GetDERControlRequest(requestId);
   }
 
-  /**
-   * Create a server {@link ReportDERControlRequest} with all required fields.
-   *
-   * @param requestId RequestId from GetDERControlRequest.
-   * @return an instance of {@link ReportDERControlRequest}
-   */
-  public ReportDERControlRequest createReportDERControlRequest(Integer requestId) {
-    return new ReportDERControlRequest(requestId);
-  }
-
   /**
    * Create a server {@link SetDERControlRequest} with all required fields.
    *

Summary of changes:

• ReportDERControlFeature ownership swapped: Server=this (receives), Client=null (sends)
• handleReportDERControlRequest moved from ClientDERControlEventHandler → ServerDERControlEventHandler (with UUID sessionIndex parameter)
• createReportDERControlRequest moved from ServerDERControlFunction → ClientDERControlFunction
• Request dispatch in handleRequest() updated accordingly

[robert-s-ubi]

Hi @neinhart, thank you very much for pointing this out! I took another look at all the new messages added in OCPP 2.1 and found that I got the direction wrong on three messages:

1. ClosePeriodicEventStreamRequest
2. ReportDERControlRequest (as you pointed out)
3. RequestBatterySwapRequest

I'll prepare a commit to fix all these.

[robert-s-ubi]

@neinhart these two commits incorporate your fix (thank you very much for so diligently preparing this!) and fix the other two messages as well. Please let me know if you run into any further issues.

[robert-s-ubi]

I noticed that the Battery Swapping messages have a dedicated chapter in OCPP 2.1, so they belong in a dedicated function (functions mirror OCPP chapters) as well.

Added a commit which adds the "BatterySwapping" function and moves these messages there.