diff --git a/lib/rb/ext/struct.h b/lib/rb/ext/struct.h
new file mode 100644
index 0000000..37b1b35
--- /dev/null
+++ b/lib/rb/ext/struct.h
@@ -0,0 +1,67 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you 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.
+ */
+
+#include <stdbool.h>
+#include <ruby.h>
+
+typedef struct native_proto_method_table {
+  VALUE (*write_bool)(VALUE, VALUE);
+  VALUE (*write_byte)(VALUE, VALUE);
+  VALUE (*write_i16)(VALUE, VALUE);
+  VALUE (*write_i32)(VALUE, VALUE);
+  VALUE (*write_i64)(VALUE, VALUE);
+  VALUE (*write_double)(VALUE, VALUE);
+  VALUE (*write_string)(VALUE, VALUE);
+  VALUE (*write_list_begin)(VALUE, VALUE, VALUE);
+  VALUE (*write_list_end)(VALUE);
+  VALUE (*write_set_begin)(VALUE, VALUE, VALUE);
+  VALUE (*write_set_end)(VALUE);
+  VALUE (*write_map_begin)(VALUE, VALUE, VALUE, VALUE);
+  VALUE (*write_map_end)(VALUE);
+  VALUE (*write_struct_begin)(VALUE, VALUE);
+  VALUE (*write_struct_end)(VALUE);
+  VALUE (*write_field_begin)(VALUE, VALUE, VALUE, VALUE);
+  VALUE (*write_field_end)(VALUE);
+  VALUE (*write_field_stop)(VALUE);
+  VALUE (*write_message_begin)(VALUE, VALUE, VALUE, VALUE);
+  VALUE (*write_message_end)(VALUE);
+  
+  VALUE (*read_message_begin)(VALUE);
+  VALUE (*read_message_end)(VALUE);
+  VALUE (*read_field_begin)(VALUE);
+  VALUE (*read_field_end)(VALUE);
+  VALUE (*read_map_begin)(VALUE);
+  VALUE (*read_map_end)(VALUE);
+  VALUE (*read_list_begin)(VALUE);
+  VALUE (*read_list_end)(VALUE);
+  VALUE (*read_set_begin)(VALUE);
+  VALUE (*read_set_end)(VALUE);
+  VALUE (*read_byte)(VALUE);
+  VALUE (*read_bool)(VALUE);
+  VALUE (*read_i16)(VALUE);
+  VALUE (*read_i32)(VALUE);
+  VALUE (*read_i64)(VALUE);
+  VALUE (*read_double)(VALUE);
+  VALUE (*read_string)(VALUE);
+  VALUE (*read_struct_begin)(VALUE);
+  VALUE (*read_struct_end)(VALUE);
+  
+} native_proto_method_table;
+
+void Init_struct();