diff --git a/core/api/src/main/java/org/onosproject/net/pi/runtime/data/PiHeaderUnion.java b/core/api/src/main/java/org/onosproject/net/pi/runtime/data/PiHeaderUnion.java
new file mode 100644
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+++ b/core/api/src/main/java/org/onosproject/net/pi/runtime/data/PiHeaderUnion.java
@@ -0,0 +1,124 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.net.pi.runtime.data;
+
+import com.google.common.annotations.Beta;
+import com.google.common.base.Objects;
+import org.onosproject.net.pi.model.PiData;
+
+import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * PiHeaderUnion entity in a protocol-independent pipeline.
+ */
+@Beta
+public final class PiHeaderUnion implements PiData {
+    private final String validHeaderName;
+    private final PiHeader header;
+    private final boolean isValid;
+
+    /**
+     * Creates a new protocol-independent header union instance for the given header name and header.
+     *
+     * @param isValid indicates whether this header union is valid
+     * @param validHeaderName header name
+     * @param header the header
+     */
+    private PiHeaderUnion(boolean isValid, String validHeaderName, PiHeader header) {
+        this.isValid = isValid;
+        this.validHeaderName = validHeaderName;
+        this.header = header;
+    }
+
+    /**
+     * Returns a new invalid protocol-independent header union.
+     *
+     * @return header union
+     */
+    public static PiHeaderUnion ofInvalid() {
+        return new PiHeaderUnion(false, null, null);
+    }
+
+    /**
+     * Returns a new valid protocol-independent header union.
+     * @param validHeaderName header name
+     * @param header the header
+     * @return header union
+     */
+    public static PiHeaderUnion of(String validHeaderName, PiHeader header) {
+        checkNotNull(validHeaderName);
+        checkArgument(!validHeaderName.isEmpty(), "The header name must not be empty");
+        checkNotNull(header);
+        return new PiHeaderUnion(true, validHeaderName, header);
+    }
+
+    /**
+     * Returns true if this header is valid, false otherwise.
+     *
+     * @return a boolean value
+     */
+    public boolean isValid() {
+        return this.isValid;
+    }
+
+    /**
+     * Return the header name.
+     *
+     * @return header name, return null if the header union invalid
+     */
+    public String headerName() {
+        return this.validHeaderName;
+    }
+
+    /**
+     * Return the header.
+     *
+     * @return header, return null if the header union invalid
+     */
+    public PiHeader header() {
+        return this.header;
+    }
+
+    @Override
+    public Type type() {
+        return Type.HEADERUNION;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+        PiHeaderUnion headerUnion = (PiHeaderUnion) o;
+        return Objects.equal(validHeaderName, headerUnion.validHeaderName) &&
+                Objects.equal(header, headerUnion.header);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hashCode(validHeaderName, header);
+    }
+
+    @Override
+    public String toString() {
+        return !isValid ? "INVALID" : validHeaderName + ":" + header.toString();
+    }
+}
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