From 6c9e6545ca953ec53a97435ee3d15947a60e6038 Mon Sep 17 00:00:00 2001
From: Jochen Mader <jochen.mader@hivemq.com>
Date: Thu, 27 Nov 2025 16:10:50 +0100
Subject: [PATCH] Enable keep-alive for ADS and S7

---
 .../plc4x/types/ads/ADSProtocolAdapter.java      |  5 +++++
 .../ads/config/ADSSpecificAdapterConfig.java     | 16 +++++++++++++++-
 .../plc4x/types/siemens/S7ProtocolAdapter.java   |  6 ++++--
 .../siemens/config/S7SpecificAdapterConfig.java  | 14 ++++++++++++++
 .../ads/config/ADSProtocolAdapterConfigTest.java |  1 +
 .../config/S7ProtocolAdapterConfigTest.java      |  1 +
 6 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/modules/hivemq-edge-module-plc4x/src/main/java/com/hivemq/edge/adapters/plc4x/types/ads/ADSProtocolAdapter.java b/modules/hivemq-edge-module-plc4x/src/main/java/com/hivemq/edge/adapters/plc4x/types/ads/ADSProtocolAdapter.java
index 2de9055b79..d744578ec4 100644
--- a/modules/hivemq-edge-module-plc4x/src/main/java/com/hivemq/edge/adapters/plc4x/types/ads/ADSProtocolAdapter.java
+++ b/modules/hivemq-edge-module-plc4x/src/main/java/com/hivemq/edge/adapters/plc4x/types/ads/ADSProtocolAdapter.java
@@ -35,6 +35,7 @@ public class ADSProtocolAdapter extends AbstractPlc4xAdapter<ADSSpecificAdapterC
     private static final @NotNull String SOURCE_AMS_PORT = "source-ams-port";
     private static final @NotNull String TARGET_AMS_PORT = "target-ams-port";
     private static final @NotNull String TARGET_AMS_NET_ID = "target-ams-net-id";
+    private static final @NotNull String TCP_KEEP_ALIVE = "tcp.keep-alive";
 
     public ADSProtocolAdapter(
             final @NotNull ProtocolAdapterInformation adapterInformation,
@@ -65,6 +66,10 @@ public ADSProtocolAdapter(
 
         map.put(TARGET_AMS_PORT, nullSafe(config.getTargetAmsPort()));
         map.put(TARGET_AMS_NET_ID, nullSafe(config.getTargetAmsNetId()));
+
+        if (config.isKeepAlive()) {
+            map.put(TCP_KEEP_ALIVE, "true");
+        }
         return map;
     }
 }
diff --git a/modules/hivemq-edge-module-plc4x/src/main/java/com/hivemq/edge/adapters/plc4x/types/ads/config/ADSSpecificAdapterConfig.java b/modules/hivemq-edge-module-plc4x/src/main/java/com/hivemq/edge/adapters/plc4x/types/ads/config/ADSSpecificAdapterConfig.java
index 127ed9f5cf..820725858f 100644
--- a/modules/hivemq-edge-module-plc4x/src/main/java/com/hivemq/edge/adapters/plc4x/types/ads/config/ADSSpecificAdapterConfig.java
+++ b/modules/hivemq-edge-module-plc4x/src/main/java/com/hivemq/edge/adapters/plc4x/types/ads/config/ADSSpecificAdapterConfig.java
@@ -71,6 +71,12 @@ public class ADSSpecificAdapterConfig extends Plc4XSpecificAdapterConfig<ADSToMq
                        description = "The AMS Net ID of the device to connect to")
     private final @NotNull String targetAmsNetId;
 
+    @JsonProperty("keepAlive")
+    @ModuleConfigField(title = "Keep-Alive",
+                       description = "Enable TCP keep-alive to maintain the connection during periods of inactivity.",
+                       defaultValue = "false")
+    private final boolean keepAlive;
+
     @JsonProperty(value = "adsToMqtt", required = true)
     @ModuleConfigField(title = "ADS To MQTT Config",
                        description = "The configuration for a data stream from ADS to MQTT",
@@ -85,13 +91,15 @@ public ADSSpecificAdapterConfig(
             @JsonProperty(value = "sourceAmsPort", required = true) final int sourceAmsPort,
             @JsonProperty(value = "targetAmsNetId", required = true) final @NotNull String targetAmsNetId,
             @JsonProperty(value = "sourceAmsNetId", required = true) final @NotNull String sourceAmsNetId,
+            @JsonProperty(value = "keepAlive") final @Nullable Boolean keepAlive,
             @JsonProperty(value = "adsToMqtt") final @Nullable ADSToMqttConfig adsToMqttConfig) {
-        super( port, host);
+        super(port, host);
         this.port = port;
         this.targetAmsPort = targetAmsPort;
         this.sourceAmsPort = sourceAmsPort;
         this.sourceAmsNetId = sourceAmsNetId;
         this.targetAmsNetId = targetAmsNetId;
+        this.keepAlive = Objects.requireNonNullElse(keepAlive, false);
         if (adsToMqttConfig == null) {
             this.adsToMqttConfig = new ADSToMqttConfig(null, null, null);
         } else {
@@ -121,6 +129,10 @@ public int getTargetAmsPort() {
         return targetAmsNetId;
     }
 
+    public boolean isKeepAlive() {
+        return keepAlive;
+    }
+
     @Override
     public @Nullable ADSToMqttConfig getPlc4xToMqttConfig() {
         return adsToMqttConfig;
@@ -133,6 +145,7 @@ public boolean equals(final Object o) {
         return getPort() == that.getPort() &&
                 getTargetAmsPort() == that.getTargetAmsPort() &&
                 getSourceAmsPort() == that.getSourceAmsPort() &&
+                isKeepAlive() == that.isKeepAlive() &&
                 Objects.equals(getSourceAmsNetId(), that.getSourceAmsNetId()) &&
                 Objects.equals(getTargetAmsNetId(), that.getTargetAmsNetId()) &&
                 Objects.equals(adsToMqttConfig, that.adsToMqttConfig);
@@ -145,6 +158,7 @@ public int hashCode() {
                 getSourceAmsPort(),
                 getSourceAmsNetId(),
                 getTargetAmsNetId(),
+                keepAlive,
                 adsToMqttConfig);
     }
 }
diff --git a/modules/hivemq-edge-module-plc4x/src/main/java/com/hivemq/edge/adapters/plc4x/types/siemens/S7ProtocolAdapter.java b/modules/hivemq-edge-module-plc4x/src/main/java/com/hivemq/edge/adapters/plc4x/types/siemens/S7ProtocolAdapter.java
index 8b3456fffa..8d68230086 100644
--- a/modules/hivemq-edge-module-plc4x/src/main/java/com/hivemq/edge/adapters/plc4x/types/siemens/S7ProtocolAdapter.java
+++ b/modules/hivemq-edge-module-plc4x/src/main/java/com/hivemq/edge/adapters/plc4x/types/siemens/S7ProtocolAdapter.java
@@ -115,8 +115,10 @@ public S7ProtocolAdapter(
         map.put(REMOTE_SLOT_2, nullSafe(config.getRemoteSlot2()));
         map.put(REMOTE_TSAP, nullSafe(config.getRemoteTsap()));
 
-        //ping if polling interval greater than default read timeout - 1s grace
-        if (config.getPlc4xToMqttConfig() != null && config.getPlc4xToMqttConfig().getPollingIntervalMillis() >= 7000) {
+        // Enable ping if explicitly configured OR if polling interval >= 7s (existing behavior)
+        boolean autoEnablePing = config.getPlc4xToMqttConfig() != null &&
+                config.getPlc4xToMqttConfig().getPollingIntervalMillis() >= 7000;
+        if (config.isKeepAlive() || autoEnablePing) {
             map.put(PING, "true");
             map.put(PING_TIME, "4");
         }
diff --git a/modules/hivemq-edge-module-plc4x/src/main/java/com/hivemq/edge/adapters/plc4x/types/siemens/config/S7SpecificAdapterConfig.java b/modules/hivemq-edge-module-plc4x/src/main/java/com/hivemq/edge/adapters/plc4x/types/siemens/config/S7SpecificAdapterConfig.java
index a65442fd4d..ce241e2109 100644
--- a/modules/hivemq-edge-module-plc4x/src/main/java/com/hivemq/edge/adapters/plc4x/types/siemens/config/S7SpecificAdapterConfig.java
+++ b/modules/hivemq-edge-module-plc4x/src/main/java/com/hivemq/edge/adapters/plc4x/types/siemens/config/S7SpecificAdapterConfig.java
@@ -84,6 +84,12 @@ public enum ControllerType {
                        defaultValue = "0")
     private final int remoteTsap;
 
+    @JsonProperty("keepAlive")
+    @ModuleConfigField(title = "Keep-Alive",
+                       description = "Enable keep-alive ping to prevent TCP connection timeouts during long polling intervals. Recommended when polling interval exceeds 7 seconds.",
+                       defaultValue = "false")
+    private final boolean keepAlive;
+
     @JsonProperty(value = "s7ToMqtt", required = true)
     @ModuleConfigField(title = "S7 To MQTT Config",
                        description = "The configuration for a data stream from S7 to MQTT",
@@ -100,6 +106,7 @@ public S7SpecificAdapterConfig(
             @JsonProperty(value = "remoteSlot") final @Nullable Integer remoteSlot,
             @JsonProperty(value = "remoteSlot2") final @Nullable Integer remoteSlot2,
             @JsonProperty(value = "remoteTsap") final @Nullable Integer remoteTsap,
+            @JsonProperty(value = "keepAlive") final @Nullable Boolean keepAlive,
             @JsonProperty(value = "s7ToMqtt") final @Nullable S7ToMqttConfig s7ToMqttConfig) {
         super(port, host);
         this.port = port;
@@ -109,6 +116,7 @@ public S7SpecificAdapterConfig(
         this.remoteSlot = Objects.requireNonNullElse(remoteSlot, 0);
         this.remoteSlot2 = Objects.requireNonNullElse(remoteSlot2, 0);
         this.remoteTsap = Objects.requireNonNullElse(remoteTsap, 0);
+        this.keepAlive = Objects.requireNonNullElse(keepAlive, false);
         if (s7ToMqttConfig == null) {
             this.s7ToMqttConfig = new S7ToMqttConfig(null, null, null);
         } else {
@@ -142,6 +150,10 @@ public int getRemoteTsap() {
         return remoteTsap;
     }
 
+    public boolean isKeepAlive() {
+        return keepAlive;
+    }
+
     public @NotNull ControllerType getControllerType() {
         return controllerType;
     }
@@ -161,6 +173,7 @@ public boolean equals(final Object o) {
                 getRemoteSlot() == that.getRemoteSlot() &&
                 getRemoteSlot2() == that.getRemoteSlot2() &&
                 getRemoteTsap() == that.getRemoteTsap() &&
+                isKeepAlive() == that.isKeepAlive() &&
                 getControllerType() == that.getControllerType() &&
                 Objects.equals(s7ToMqttConfig, that.s7ToMqttConfig);
     }
@@ -174,6 +187,7 @@ public int hashCode() {
                 getRemoteSlot(),
                 getRemoteSlot2(),
                 getRemoteTsap(),
+                keepAlive,
                 s7ToMqttConfig);
     }
 }
diff --git a/modules/hivemq-edge-module-plc4x/src/test/java/com/hivemq/edge/adapters/plc4x/types/ads/config/ADSProtocolAdapterConfigTest.java b/modules/hivemq-edge-module-plc4x/src/test/java/com/hivemq/edge/adapters/plc4x/types/ads/config/ADSProtocolAdapterConfigTest.java
index 5c2c651dcc..5a92a047bc 100644
--- a/modules/hivemq-edge-module-plc4x/src/test/java/com/hivemq/edge/adapters/plc4x/types/ads/config/ADSProtocolAdapterConfigTest.java
+++ b/modules/hivemq-edge-module-plc4x/src/test/java/com/hivemq/edge/adapters/plc4x/types/ads/config/ADSProtocolAdapterConfigTest.java
@@ -157,6 +157,7 @@ public void unconvertConfigObject_full_valid() {
                 16,
                 "1.2.3.4.5.6",
                 "1.2.3.4.5.7",
+                false,
                 new ADSToMqttConfig(
                         12,
                         13,
diff --git a/modules/hivemq-edge-module-plc4x/src/test/java/com/hivemq/edge/adapters/plc4x/types/siemens/config/S7ProtocolAdapterConfigTest.java b/modules/hivemq-edge-module-plc4x/src/test/java/com/hivemq/edge/adapters/plc4x/types/siemens/config/S7ProtocolAdapterConfigTest.java
index e596ddae92..e03a4fd563 100644
--- a/modules/hivemq-edge-module-plc4x/src/test/java/com/hivemq/edge/adapters/plc4x/types/siemens/config/S7ProtocolAdapterConfigTest.java
+++ b/modules/hivemq-edge-module-plc4x/src/test/java/com/hivemq/edge/adapters/plc4x/types/siemens/config/S7ProtocolAdapterConfigTest.java
@@ -146,6 +146,7 @@ public void unconvertConfigObject_full_valid() {
                 3,
                 4,
                 5,
+                false,
                 new S7ToMqttConfig(
                         12,
                         13,