SHDR: ensure UTC-safe timestamps via ToUnixUTCTime to fix #113

libraries/MTConnect.NET-Common/UnixTime.cs

@@ -35,6 +35,39 @@ public static long ToUnixTime(this DateTime d)
         }
 
 
+        /// <summary>
+        /// Convert a DateTime to Unix ticks (1/10,000 of a millisecond) ensuring the value is in UTC.
+        /// If the DateTime.Kind is Local, it will be converted to UTC. If Unspecified, the value will be
+        /// treated as UTC by default (for backwards compatibility) or as the specified kind, then converted to UTC.
+        /// </summary>
+        /// <param name="d">The DateTime to convert.</param>
+        /// <param name="unspecifiedAssume">The kind to assume when DateTime.Kind is Unspecified. Defaults to Utc.</param>
+        /// <returns>Unix ticks since epoch in UTC.</returns>
+        public static long ToUnixUtcTime(this DateTime d, DateTimeKind unspecifiedAssume = DateTimeKind.Utc)
+        {
+            var x = d;
+            if (x.Kind == DateTimeKind.Local)
+            {
+                x = x.ToUniversalTime();
+            }
+            else if (x.Kind == DateTimeKind.Unspecified)
+            {
+                // Specify the assumed kind, then convert to UTC if necessary
+                x = DateTime.SpecifyKind(x, unspecifiedAssume);
+                if (x.Kind == DateTimeKind.Local) x = x.ToUniversalTime();
+            }
+
+            var duration = x - EpochTime;
+            return duration.Ticks;
+        }
+
+        /// <summary>
+        /// Alias to <see cref="ToUnixUtcTime"/> to match requested API name.
+        /// </summary>
+        public static long ToUnixUTCTime(this DateTime d, DateTimeKind unspecifiedAssume = DateTimeKind.Utc)
+            => ToUnixUtcTime(d, unspecifiedAssume);
+
+
         public static DateTime ToDateTime(this long unixTicks)
         {
             return FromUnixTime(unixTicks);

libraries/MTConnect.NET-SHDR/Adapters/ShdrAdapter.cs

@@ -698,7 +698,7 @@ public void AddDataItem(string dataItemKey, object value)
 
         public void AddDataItem(string dataItemKey, object value, DateTime timestamp)
         {
-            AddDataItem(dataItemKey, value, timestamp.ToUnixTime());
+            AddDataItem(dataItemKey, value, timestamp.ToUnixUtcTime());
         }
 
         public void AddDataItem(string dataItemKey, object value, long timestamp)
@@ -735,7 +735,7 @@ public bool SendDataItem(string dataItemKey, object value)
 
         public bool SendDataItem(string dataItemKey, object value, DateTime timestamp)
         {
-            return SendDataItem(dataItemKey, value, timestamp.ToUnixTime());
+            return SendDataItem(dataItemKey, value, timestamp.ToUnixUtcTime());
         }
 
         public bool SendDataItem(string dataItemKey, object value, long timestamp)
@@ -784,7 +784,7 @@ public void AddMessage(string messageId, string value)
 
         public void AddMessage(string messageId, string value, DateTime timestamp)
         {
-            AddMessage(messageId, value, timestamp.ToUnixTime());
+            AddMessage(messageId, value, timestamp.ToUnixUtcTime());
         }
 
         public void AddMessage(string messageId, string value, long timestamp)
@@ -799,7 +799,7 @@ public void AddMessage(string messageId, string value, string nativeCode)
 
         public void AddMessage(string messageId, string value, string nativeCode, DateTime timestamp)
         {
-            AddMessage(messageId, value, nativeCode, timestamp.ToUnixTime());
+            AddMessage(messageId, value, nativeCode, timestamp.ToUnixUtcTime());
         }
 
         public void AddMessage(string messageId, string value, string nativeCode, long timestamp)
@@ -831,7 +831,7 @@ public bool SendMessage(string dataItemId, string value)
 
         public bool SendMessage(string dataItemId, string value, DateTime timestamp)
         {
-            return SendMessage(dataItemId, value, timestamp.ToUnixTime());
+            return SendMessage(dataItemId, value, timestamp.ToUnixUtcTime());
         }
 
         public bool SendMessage(string dataItemId, string value, long timestamp)
@@ -846,7 +846,7 @@ public bool SendMessage(string dataItemId, string value, string nativeCode)
 
         public bool SendMessage(string dataItemId, string value, string nativeCode, DateTime timestamp)
         {
-            return SendMessage(dataItemId, value, nativeCode, timestamp.ToUnixTime());
+            return SendMessage(dataItemId, value, nativeCode, timestamp.ToUnixUtcTime());
         }
 
         public bool SendMessage(string dataItemId, string value, string nativeCode, long timestamp)

libraries/MTConnect.NET-SHDR/Shdr/ShdrDataItem.cs

@@ -66,7 +66,7 @@ public ShdrDataItem(string dataItemKey, object value, DateTime timestamp)
             {
                 new ObservationValue(ValueKeys.Result, value != null ? value.ToString() : string.Empty)
             };
-            Timestamp = timestamp.ToUnixTime();
+            Timestamp = timestamp.ToUnixUtcTime();
         }
 
 
@@ -350,7 +350,7 @@ public static IEnumerable<ShdrDataItem> FromString(string input, bool uppercaseV
                 if (timestamp.HasValue)
                 {
                     var y = ShdrLine.GetNextSegment(input);
-                    return FromKeyValuePairs(y, timestamp.Value.ToUnixTime(), duration.HasValue ? duration.Value : 0, uppercaseValue);
+                    return FromKeyValuePairs(y, timestamp.Value.ToUnixUtcTime(), duration.HasValue ? duration.Value : 0, uppercaseValue);
                 }
                 else
                 {

libraries/MTConnect.NET-SHDR/Shdr/ShdrMessage.cs

@@ -82,7 +82,7 @@ public ShdrMessage(string dataItemKey, string value, DateTime timestamp)
             {
                 new ObservationValue(ValueKeys.Result, value != null ? value.ToString() : string.Empty)
             };
-            Timestamp = timestamp.ToUnixTime();
+            Timestamp = timestamp.ToUnixUtcTime();
         }
 
         public ShdrMessage(string dataItemKey, string value, string nativeCode, DateTime timestamp)
@@ -92,7 +92,7 @@ public ShdrMessage(string dataItemKey, string value, string nativeCode, DateTime
             values.Add(new ObservationValue(ValueKeys.Result, value != null ? value.ToString() : string.Empty));
             if (!string.IsNullOrEmpty(nativeCode)) values.Add(new ObservationValue(ValueKeys.NativeCode, nativeCode));
             Values = values;
-            Timestamp = timestamp.ToUnixTime();
+            Timestamp = timestamp.ToUnixUtcTime();
         }
 
         public ShdrMessage(IObservationInput observation)