diff --git a/protocol/src/main/java/com/zfoo/protocol/collection/FixedSizeBooleanList.java b/protocol/src/main/java/com/zfoo/protocol/collection/FixedSizeBooleanList.java
new file mode 100644
index 00000000..231de816
--- /dev/null
+++ b/protocol/src/main/java/com/zfoo/protocol/collection/FixedSizeBooleanList.java
@@ -0,0 +1,157 @@
+/*
+ * Copyright (C) 2020 The zfoo Authors
+ * 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 com.zfoo.protocol.collection;
+
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.List;
+import java.util.ListIterator;
+
+/**
+ * @author godotg
+ * @version 3.0
+ */
+public class FixedSizeBooleanList implements List<Boolean> {
+
+    private final boolean[] array;
+
+    public FixedSizeBooleanList(int initialCapacity) {
+        this.array = new boolean[initialCapacity];
+    }
+
+    @Override
+    public int size() {
+        return array.length;
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return ArrayUtils.isEmpty(array);
+    }
+
+    @Override
+    public Boolean get(int index) {
+        return array[index];
+    }
+
+    public boolean getRaw(int index) {
+        return array[index];
+    }
+
+    @Override
+    public Boolean set(int index, Boolean ele) {
+        var old = array[index];
+        array[index] = ele;
+        return old;
+    }
+
+    public void set(int index, boolean ele) {
+        array[index] = ele;
+    }
+
+    @Override
+    public boolean contains(Object ele) {
+        return ArrayUtils.toList(array).stream().anyMatch(it -> ele.equals(it));
+    }
+
+    @Override
+    public Object[] toArray() {
+        return ArrayUtils.toList(array).toArray();
+    }
+
+    @Override
+    public <T> T[] toArray(T[] arrays) {
+        ArrayUtils.toList(array).toArray(arrays);
+        return arrays;
+    }
+
+    @Override
+    public boolean containsAll(Collection<?> collection) {
+        return ArrayUtils.toList(array).containsAll(collection);
+    }
+
+    @Override
+    public int indexOf(Object ele) {
+        return ArrayUtils.toList(array).indexOf(ele);
+    }
+
+    @Override
+    public int lastIndexOf(Object ele) {
+        return ArrayUtils.toList(array).lastIndexOf(ele);
+    }
+
+    @Override
+    public Iterator<Boolean> iterator() {
+        return ArrayUtils.toList(array).iterator();
+    }
+
+    @Override
+    public ListIterator<Boolean> listIterator() {
+        return ArrayUtils.toList(array).listIterator();
+    }
+
+    @Override
+    public ListIterator<Boolean> listIterator(int index) {
+        return ArrayUtils.toList(array).listIterator(index);
+    }
+
+    @Override
+    public List<Boolean> subList(int fromIndex, int toIndex) {
+        return ArrayUtils.toList(array).subList(fromIndex, toIndex);
+    }
+
+    @Override
+    public boolean add(Boolean e) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void add(int index, Boolean element) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean addAll(Collection<? extends Boolean> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean addAll(int index, Collection<? extends Boolean> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean remove(Object o) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public Boolean remove(int index) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean removeAll(Collection<?> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean retainAll(Collection<?> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void clear() {
+        throw new UnsupportedOperationException();
+    }
+}
diff --git a/protocol/src/main/java/com/zfoo/protocol/collection/FixedSizeDoubleList.java b/protocol/src/main/java/com/zfoo/protocol/collection/FixedSizeDoubleList.java
new file mode 100644
index 00000000..9b995831
--- /dev/null
+++ b/protocol/src/main/java/com/zfoo/protocol/collection/FixedSizeDoubleList.java
@@ -0,0 +1,157 @@
+/*
+ * Copyright (C) 2020 The zfoo Authors
+ * 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 com.zfoo.protocol.collection;
+
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.List;
+import java.util.ListIterator;
+
+/**
+ * @author godotg
+ * @version 3.0
+ */
+public class FixedSizeDoubleList implements List<Double> {
+
+    private final double[] array;
+
+    public FixedSizeDoubleList(int initialCapacity) {
+        this.array = new double[initialCapacity];
+    }
+
+    @Override
+    public int size() {
+        return array.length;
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return ArrayUtils.isEmpty(array);
+    }
+
+    @Override
+    public Double get(int index) {
+        return array[index];
+    }
+
+    public double getRaw(int index) {
+        return array[index];
+    }
+
+    @Override
+    public Double set(int index, Double ele) {
+        var old = array[index];
+        array[index] = ele;
+        return old;
+    }
+
+    public void set(int index, double ele) {
+        array[index] = ele;
+    }
+
+    @Override
+    public boolean contains(Object ele) {
+        return ArrayUtils.toList(array).stream().anyMatch(it -> ele.equals(it));
+    }
+
+    @Override
+    public Object[] toArray() {
+        return ArrayUtils.toList(array).toArray();
+    }
+
+    @Override
+    public <T> T[] toArray(T[] arrays) {
+        ArrayUtils.toList(array).toArray(arrays);
+        return arrays;
+    }
+
+    @Override
+    public boolean containsAll(Collection<?> collection) {
+        return ArrayUtils.toList(array).containsAll(collection);
+    }
+
+    @Override
+    public int indexOf(Object ele) {
+        return ArrayUtils.toList(array).indexOf(ele);
+    }
+
+    @Override
+    public int lastIndexOf(Object ele) {
+        return ArrayUtils.toList(array).lastIndexOf(ele);
+    }
+
+    @Override
+    public Iterator<Double> iterator() {
+        return ArrayUtils.toList(array).iterator();
+    }
+
+    @Override
+    public ListIterator<Double> listIterator() {
+        return ArrayUtils.toList(array).listIterator();
+    }
+
+    @Override
+    public ListIterator<Double> listIterator(int index) {
+        return ArrayUtils.toList(array).listIterator(index);
+    }
+
+    @Override
+    public List<Double> subList(int fromIndex, int toIndex) {
+        return ArrayUtils.toList(array).subList(fromIndex, toIndex);
+    }
+
+    @Override
+    public boolean add(Double e) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void add(int index, Double element) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean addAll(Collection<? extends Double> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean addAll(int index, Collection<? extends Double> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean remove(Object o) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public Double remove(int index) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean removeAll(Collection<?> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean retainAll(Collection<?> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void clear() {
+        throw new UnsupportedOperationException();
+    }
+}
diff --git a/protocol/src/main/java/com/zfoo/protocol/collection/FixedSizeFloatList.java b/protocol/src/main/java/com/zfoo/protocol/collection/FixedSizeFloatList.java
new file mode 100644
index 00000000..c831a82d
--- /dev/null
+++ b/protocol/src/main/java/com/zfoo/protocol/collection/FixedSizeFloatList.java
@@ -0,0 +1,157 @@
+/*
+ * Copyright (C) 2020 The zfoo Authors
+ * 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 com.zfoo.protocol.collection;
+
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.List;
+import java.util.ListIterator;
+
+/**
+ * @author godotg
+ * @version 3.0
+ */
+public class FixedSizeFloatList implements List<Float> {
+
+    private final float[] array;
+
+    public FixedSizeFloatList(int initialCapacity) {
+        this.array = new float[initialCapacity];
+    }
+
+    @Override
+    public int size() {
+        return array.length;
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return ArrayUtils.isEmpty(array);
+    }
+
+    @Override
+    public Float get(int index) {
+        return array[index];
+    }
+
+    public float getRaw(int index) {
+        return array[index];
+    }
+
+    @Override
+    public Float set(int index, Float ele) {
+        var old = array[index];
+        array[index] = ele;
+        return old;
+    }
+
+    public void set(int index, float ele) {
+        array[index] = ele;
+    }
+
+    @Override
+    public boolean contains(Object ele) {
+        return ArrayUtils.toList(array).stream().anyMatch(it -> ele.equals(it));
+    }
+
+    @Override
+    public Object[] toArray() {
+        return ArrayUtils.toList(array).toArray();
+    }
+
+    @Override
+    public <T> T[] toArray(T[] arrays) {
+        ArrayUtils.toList(array).toArray(arrays);
+        return arrays;
+    }
+
+    @Override
+    public boolean containsAll(Collection<?> collection) {
+        return ArrayUtils.toList(array).containsAll(collection);
+    }
+
+    @Override
+    public int indexOf(Object ele) {
+        return ArrayUtils.toList(array).indexOf(ele);
+    }
+
+    @Override
+    public int lastIndexOf(Object ele) {
+        return ArrayUtils.toList(array).lastIndexOf(ele);
+    }
+
+    @Override
+    public Iterator<Float> iterator() {
+        return ArrayUtils.toList(array).iterator();
+    }
+
+    @Override
+    public ListIterator<Float> listIterator() {
+        return ArrayUtils.toList(array).listIterator();
+    }
+
+    @Override
+    public ListIterator<Float> listIterator(int index) {
+        return ArrayUtils.toList(array).listIterator(index);
+    }
+
+    @Override
+    public List<Float> subList(int fromIndex, int toIndex) {
+        return ArrayUtils.toList(array).subList(fromIndex, toIndex);
+    }
+
+    @Override
+    public boolean add(Float e) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void add(int index, Float element) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean addAll(Collection<? extends Float> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean addAll(int index, Collection<? extends Float> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean remove(Object o) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public Float remove(int index) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean removeAll(Collection<?> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean retainAll(Collection<?> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void clear() {
+        throw new UnsupportedOperationException();
+    }
+}
diff --git a/protocol/src/main/java/com/zfoo/protocol/collection/FixedSizeIntList.java b/protocol/src/main/java/com/zfoo/protocol/collection/FixedSizeIntList.java
new file mode 100644
index 00000000..a751826a
--- /dev/null
+++ b/protocol/src/main/java/com/zfoo/protocol/collection/FixedSizeIntList.java
@@ -0,0 +1,158 @@
+/*
+ * Copyright (C) 2020 The zfoo Authors
+ * 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 com.zfoo.protocol.collection;
+
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.List;
+import java.util.ListIterator;
+
+/**
+ * @author godotg
+ * @version 3.0
+ */
+public class FixedSizeIntList implements List<Integer> {
+
+    private final int[] array;
+
+    public FixedSizeIntList(int initialCapacity) {
+        this.array = new int[initialCapacity];
+    }
+
+
+    @Override
+    public int size() {
+        return array.length;
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return ArrayUtils.isEmpty(array);
+    }
+
+    @Override
+    public boolean contains(Object ele) {
+        return ArrayUtils.toList(array).stream().anyMatch(it -> ele.equals(it));
+    }
+
+    @Override
+    public Integer get(int index) {
+        return array[index];
+    }
+
+    public int getRaw(int index) {
+        return array[index];
+    }
+
+    @Override
+    public Integer set(int index, Integer ele) {
+        var old = array[index];
+        array[index] = ele;
+        return old;
+    }
+
+    public void set(int index, int ele) {
+        array[index] = ele;
+    }
+
+    @Override
+    public Object[] toArray() {
+        return ArrayUtils.toList(array).toArray();
+    }
+
+    @Override
+    public <T> T[] toArray(T[] arrays) {
+        ArrayUtils.toList(array).toArray(arrays);
+        return arrays;
+    }
+
+    @Override
+    public boolean containsAll(Collection<?> collection) {
+        return ArrayUtils.toList(array).containsAll(collection);
+    }
+
+    @Override
+    public int indexOf(Object ele) {
+        return ArrayUtils.toList(array).indexOf(ele);
+    }
+
+    @Override
+    public int lastIndexOf(Object ele) {
+        return ArrayUtils.toList(array).lastIndexOf(ele);
+    }
+
+    @Override
+    public Iterator<Integer> iterator() {
+        return ArrayUtils.toList(array).iterator();
+    }
+
+    @Override
+    public ListIterator<Integer> listIterator() {
+        return ArrayUtils.toList(array).listIterator();
+    }
+
+    @Override
+    public ListIterator<Integer> listIterator(int index) {
+        return ArrayUtils.toList(array).listIterator(index);
+    }
+
+    @Override
+    public List<Integer> subList(int fromIndex, int toIndex) {
+        return ArrayUtils.toList(array).subList(fromIndex, toIndex);
+    }
+
+    @Override
+    public boolean add(Integer e) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void add(int index, Integer element) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean addAll(Collection<? extends Integer> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean addAll(int index, Collection<? extends Integer> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean remove(Object o) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public Integer remove(int index) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean removeAll(Collection<?> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean retainAll(Collection<?> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void clear() {
+        throw new UnsupportedOperationException();
+    }
+}
diff --git a/protocol/src/main/java/com/zfoo/protocol/collection/FixedSizeLongList.java b/protocol/src/main/java/com/zfoo/protocol/collection/FixedSizeLongList.java
new file mode 100644
index 00000000..dcae016e
--- /dev/null
+++ b/protocol/src/main/java/com/zfoo/protocol/collection/FixedSizeLongList.java
@@ -0,0 +1,157 @@
+/*
+ * Copyright (C) 2020 The zfoo Authors
+ * 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 com.zfoo.protocol.collection;
+
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.List;
+import java.util.ListIterator;
+
+/**
+ * @author godotg
+ * @version 3.0
+ */
+public class FixedSizeLongList implements List<Long> {
+
+    private final long[] array;
+
+    public FixedSizeLongList(int initialCapacity) {
+        this.array = new long[initialCapacity];
+    }
+
+    @Override
+    public int size() {
+        return array.length;
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return ArrayUtils.isEmpty(array);
+    }
+
+    @Override
+    public Long get(int index) {
+        return array[index];
+    }
+
+    public long getRaw(int index) {
+        return array[index];
+    }
+
+    @Override
+    public Long set(int index, Long ele) {
+        var old = array[index];
+        array[index] = ele;
+        return old;
+    }
+
+    public void set(int index, long ele) {
+        array[index] = ele;
+    }
+
+    @Override
+    public boolean contains(Object ele) {
+        return ArrayUtils.toList(array).stream().anyMatch(it -> ele.equals(it));
+    }
+
+    @Override
+    public Object[] toArray() {
+        return ArrayUtils.toList(array).toArray();
+    }
+
+    @Override
+    public <T> T[] toArray(T[] arrays) {
+        ArrayUtils.toList(array).toArray(arrays);
+        return arrays;
+    }
+
+    @Override
+    public boolean containsAll(Collection<?> collection) {
+        return ArrayUtils.toList(array).containsAll(collection);
+    }
+
+    @Override
+    public int indexOf(Object ele) {
+        return ArrayUtils.toList(array).indexOf(ele);
+    }
+
+    @Override
+    public int lastIndexOf(Object ele) {
+        return ArrayUtils.toList(array).lastIndexOf(ele);
+    }
+
+    @Override
+    public Iterator<Long> iterator() {
+        return ArrayUtils.toList(array).iterator();
+    }
+
+    @Override
+    public ListIterator<Long> listIterator() {
+        return ArrayUtils.toList(array).listIterator();
+    }
+
+    @Override
+    public ListIterator<Long> listIterator(int index) {
+        return ArrayUtils.toList(array).listIterator(index);
+    }
+
+    @Override
+    public List<Long> subList(int fromIndex, int toIndex) {
+        return ArrayUtils.toList(array).subList(fromIndex, toIndex);
+    }
+
+    @Override
+    public boolean add(Long e) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void add(int index, Long element) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean addAll(Collection<? extends Long> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean addAll(int index, Collection<? extends Long> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean remove(Object o) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public Long remove(int index) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean removeAll(Collection<?> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean retainAll(Collection<?> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void clear() {
+        throw new UnsupportedOperationException();
+    }
+}
diff --git a/protocol/src/main/java/com/zfoo/protocol/collection/FixedSizeShortList.java b/protocol/src/main/java/com/zfoo/protocol/collection/FixedSizeShortList.java
new file mode 100644
index 00000000..74a4e5bc
--- /dev/null
+++ b/protocol/src/main/java/com/zfoo/protocol/collection/FixedSizeShortList.java
@@ -0,0 +1,157 @@
+/*
+ * Copyright (C) 2020 The zfoo Authors
+ * 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 com.zfoo.protocol.collection;
+
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.List;
+import java.util.ListIterator;
+
+/**
+ * @author godotg
+ * @version 3.0
+ */
+public class FixedSizeShortList implements List<Short> {
+
+    private final short[] array;
+
+    public FixedSizeShortList(int initialCapacity) {
+        this.array = new short[initialCapacity];
+    }
+
+    @Override
+    public int size() {
+        return array.length;
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return ArrayUtils.isEmpty(array);
+    }
+
+    @Override
+    public Short get(int index) {
+        return array[index];
+    }
+
+    public short getRaw(int index) {
+        return array[index];
+    }
+
+    @Override
+    public Short set(int index, Short ele) {
+        var old = array[index];
+        array[index] = ele;
+        return old;
+    }
+
+    public void set(int index, short ele) {
+        array[index] = ele;
+    }
+
+    @Override
+    public boolean contains(Object ele) {
+        return ArrayUtils.toList(array).stream().anyMatch(it -> ele.equals(it));
+    }
+
+    @Override
+    public Object[] toArray() {
+        return ArrayUtils.toList(array).toArray();
+    }
+
+    @Override
+    public <T> T[] toArray(T[] arrays) {
+        ArrayUtils.toList(array).toArray(arrays);
+        return arrays;
+    }
+
+    @Override
+    public boolean containsAll(Collection<?> collection) {
+        return ArrayUtils.toList(array).containsAll(collection);
+    }
+
+    @Override
+    public int indexOf(Object ele) {
+        return ArrayUtils.toList(array).indexOf(ele);
+    }
+
+    @Override
+    public int lastIndexOf(Object ele) {
+        return ArrayUtils.toList(array).lastIndexOf(ele);
+    }
+
+    @Override
+    public Iterator<Short> iterator() {
+        return ArrayUtils.toList(array).iterator();
+    }
+
+    @Override
+    public ListIterator<Short> listIterator() {
+        return ArrayUtils.toList(array).listIterator();
+    }
+
+    @Override
+    public ListIterator<Short> listIterator(int index) {
+        return ArrayUtils.toList(array).listIterator(index);
+    }
+
+    @Override
+    public List<Short> subList(int fromIndex, int toIndex) {
+        return ArrayUtils.toList(array).subList(fromIndex, toIndex);
+    }
+
+    @Override
+    public boolean add(Short e) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void add(int index, Short element) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean addAll(Collection<? extends Short> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean addAll(int index, Collection<? extends Short> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean remove(Object o) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public Short remove(int index) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean removeAll(Collection<?> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean retainAll(Collection<?> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void clear() {
+        throw new UnsupportedOperationException();
+    }
+}
diff --git a/protocol/src/main/java/com/zfoo/protocol/collection/FixedSizeStringList.java b/protocol/src/main/java/com/zfoo/protocol/collection/FixedSizeStringList.java
new file mode 100644
index 00000000..a20d95b4
--- /dev/null
+++ b/protocol/src/main/java/com/zfoo/protocol/collection/FixedSizeStringList.java
@@ -0,0 +1,149 @@
+/*
+ * Copyright (C) 2020 The zfoo Authors
+ * 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 com.zfoo.protocol.collection;
+
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.List;
+import java.util.ListIterator;
+
+/**
+ * @author godotg
+ * @version 3.0
+ */
+public class FixedSizeStringList implements List<String> {
+
+    private final String[] array;
+
+    public FixedSizeStringList(int initialCapacity) {
+        this.array = new String[initialCapacity];
+    }
+
+    @Override
+    public int size() {
+        return array.length;
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return ArrayUtils.isEmpty(array);
+    }
+
+    @Override
+    public String get(int index) {
+        return array[index];
+    }
+
+    @Override
+    public String set(int index, String ele) {
+        var old = array[index];
+        array[index] = ele;
+        return old;
+    }
+
+    @Override
+    public boolean contains(Object ele) {
+        return ArrayUtils.toList(array).stream().anyMatch(it -> ele.equals(it));
+    }
+
+    @Override
+    public Object[] toArray() {
+        return ArrayUtils.toList(array).toArray();
+    }
+
+    @Override
+    public <T> T[] toArray(T[] arrays) {
+        ArrayUtils.toList(array).toArray(arrays);
+        return arrays;
+    }
+
+    @Override
+    public boolean containsAll(Collection<?> collection) {
+        return ArrayUtils.toList(array).containsAll(collection);
+    }
+
+    @Override
+    public int indexOf(Object ele) {
+        return ArrayUtils.toList(array).indexOf(ele);
+    }
+
+    @Override
+    public int lastIndexOf(Object ele) {
+        return ArrayUtils.toList(array).lastIndexOf(ele);
+    }
+
+    @Override
+    public Iterator<String> iterator() {
+        return ArrayUtils.toList(array).iterator();
+    }
+
+    @Override
+    public ListIterator<String> listIterator() {
+        return ArrayUtils.toList(array).listIterator();
+    }
+
+    @Override
+    public ListIterator<String> listIterator(int index) {
+        return ArrayUtils.toList(array).listIterator(index);
+    }
+
+    @Override
+    public List<String> subList(int fromIndex, int toIndex) {
+        return ArrayUtils.toList(array).subList(fromIndex, toIndex);
+    }
+
+    @Override
+    public boolean add(String e) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void add(int index, String element) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean addAll(Collection<? extends String> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean addAll(int index, Collection<? extends String> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean remove(Object o) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public String remove(int index) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean removeAll(Collection<?> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean retainAll(Collection<?> collection) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void clear() {
+        throw new UnsupportedOperationException();
+    }
+}
diff --git a/protocol/src/test/java/com/zfoo/protocol/collection/ListTest.java b/protocol/src/test/java/com/zfoo/protocol/collection/ListTest.java
new file mode 100644
index 00000000..58d0a705
--- /dev/null
+++ b/protocol/src/test/java/com/zfoo/protocol/collection/ListTest.java
@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2020 The zfoo Authors
+ * 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 com.zfoo.protocol.collection;
+
+import org.junit.Test;
+
+/**
+ * @author godotg
+ * @version 3.0
+ */
+public class ListTest {
+
+    @Test
+    public void testFixedSizeIntList() {
+        var list = new FixedSizeIntList(3);
+        list.set(0, 1);
+        list.set(1, 2);
+        list.set(2, 3);
+        for (int i = 0; i < list.size(); i++) {
+            for (var ele : list) {
+                // test iterator
+            }
+        }
+    }
+
+    @Test
+    public void testFixedSizeStringList() {
+        var list = new FixedSizeStringList(3);
+        list.set(0, "1");
+        list.set(1, "2");
+        list.set(2, "3");
+        for (int i = 0; i < list.size(); i++) {
+            for (var ele : list) {
+                // test iterator
+            }
+        }
+    }
+
+}