diff --git a/protocol/src/main/java/com/zfoo/protocol/serializer/protobuf/GeneratePbUtils.java b/protocol/src/main/java/com/zfoo/protocol/serializer/protobuf/GeneratePbUtils.java
index a860e3d8..835d7dca 100644
--- a/protocol/src/main/java/com/zfoo/protocol/serializer/protobuf/GeneratePbUtils.java
+++ b/protocol/src/main/java/com/zfoo/protocol/serializer/protobuf/GeneratePbUtils.java
@@ -14,15 +14,16 @@
 package com.zfoo.protocol.serializer.protobuf;
 
 import com.zfoo.protocol.collection.CollectionUtils;
-import com.zfoo.protocol.serializer.protobuf.codegen.IfaceGenerator;
+import com.zfoo.protocol.serializer.protobuf.builder.JavaBuilder;
+import com.zfoo.protocol.serializer.protobuf.wire.Option;
+import com.zfoo.protocol.serializer.protobuf.wire.ProtoMessage;
 import com.zfoo.protocol.serializer.protobuf.wire.parser.Proto;
 import com.zfoo.protocol.serializer.protobuf.wire.parser.ProtoParser;
 import com.zfoo.protocol.util.FileUtils;
 import com.zfoo.protocol.util.StringUtils;
 
 import java.io.File;
-import java.util.ArrayList;
-import java.util.List;
+import java.util.*;
 
 public class GeneratePbUtils {
 
@@ -41,11 +42,8 @@ public class GeneratePbUtils {
             throw new RuntimeException(StringUtils.format("There are no proto files to build in proto path:[{}]", buildOption.getProtoPath()));
         }
 
-        var srcPath = new File(buildOption.getOutputPath());
-
         var protos = parseProtoFile(protoFiles);
-        IfaceGenerator ifaceGenerator = new IfaceGenerator(srcPath, protos);
-        ifaceGenerator.generate();
+        generate(buildOption, protos);
     }
 
     public static List<Proto> parseProtoFile(List<File> protoFiles) {
@@ -67,4 +65,51 @@ public class GeneratePbUtils {
         return protos;
     }
 
+
+    public static void generate(PbBuildOption buildOption, List<Proto> protos) {
+        Map<String, Proto> allProtos = new HashMap<>();
+        for (Proto proto : protos) {
+            allProtos.put(proto.getName(), proto);
+        }
+
+        for (var proto : protos) {
+            List<Option> options = proto.getOptions();
+            Map<String, String> protoOptions = new HashMap<>();
+            if (options != null) {
+                options.forEach(o -> protoOptions.put(o.getName(), o.getValue()));
+            }
+
+            generateDtoMessage(buildOption, proto, allProtos);
+        }
+    }
+
+
+    private static void generateDtoMessage(PbBuildOption buildOption, Proto proto, Map<String, Proto> protos) {
+        JavaBuilder builder = new JavaBuilder();
+
+        Map<String, String> msgComments = new HashMap<>();
+
+        List<ProtoMessage> msgs = proto.getMessages();
+        if (CollectionUtils.isNotEmpty(msgs)) {
+            String msgPath = buildOption.getOutputPath() + File.separator;
+            msgs.stream()
+                    .sorted(Comparator.comparing(ProtoMessage::getName))
+                    .forEach(it -> {
+                        StringBuilder mc = new StringBuilder();
+                        if (it.getComment() != null) {
+                            mc.append(it.getComment());
+                        } else {
+                            if (it.getComment() != null && it.getComment().getLines() != null) {
+                                it.getComment().getLines().forEach(c -> mc.append(c));
+                            }
+                        }
+                        msgComments.put(it.getName(), mc.toString());
+                        var code = builder.buildMessage(proto, it, 1, null, protos);
+                        var filePath = msgPath + File.separator + it.getName() + ".java";
+                        FileUtils.writeStringToFile(new File(filePath), code, false);
+                    });
+
+        }
+    }
+
 }
diff --git a/protocol/src/main/java/com/zfoo/protocol/serializer/protobuf/builder/JavaBuilder.java b/protocol/src/main/java/com/zfoo/protocol/serializer/protobuf/builder/JavaBuilder.java
index 756fcf62..4ddf5cd7 100644
--- a/protocol/src/main/java/com/zfoo/protocol/serializer/protobuf/builder/JavaBuilder.java
+++ b/protocol/src/main/java/com/zfoo/protocol/serializer/protobuf/builder/JavaBuilder.java
@@ -47,7 +47,7 @@ public class JavaBuilder {
         return jType;
     }
 
-    public String getJavaType(Field field, List<String> imps, PbBuildOption buildOps) {
+    public String getJavaType(Field field, List<String> imps) {
         String type = field.getTypeString();
         if (field instanceof MapField) {
             MapField mf = (MapField) field;
@@ -120,11 +120,10 @@ public class JavaBuilder {
         }
     }
 
-    private void buildMsgImps(ProtoMessage msg, List<Field> tmp, List<String> imps,
-                              PbBuildOption buildOps) {
+    private void buildMsgImps(ProtoMessage msg, List<Field> tmp, List<String> imps) {
         if (msg.getFields() != null) {
             msg.getFields().forEach(e -> {
-                getJavaType(e, imps, buildOps);
+                getJavaType(e, imps);
                 tmp.add(e);
             });
         }
@@ -160,21 +159,21 @@ public class JavaBuilder {
         return StringUtils.EMPTY;
     }
 
-    public String buildMessage(Proto proto, ProtoMessage msg, int indent, Map<String, String> defineMsgs, PbBuildOption buildOps, Map<String, Proto> protos) {
+    public String buildMessage(Proto proto, ProtoMessage msg, int indent, Map<String, String> defineMsgs, Map<String, Proto> protos) {
         int level = Math.max(indent, 1);
         final CodeBuilder cb = new CodeBuilder();
         List<Field> tmp = new ArrayList<>();
         List<String> imps = new ArrayList<>();
-        buildMsgImps(msg, tmp, imps, buildOps);
+        buildMsgImps(msg, tmp, imps);
 
         List<Field> fields = new ArrayList<>();
         tmp.stream().sorted(Comparator.comparingInt(Field::getTag))
                 .forEach(fields::add);
 
-        if (!buildOps.isIsNested()) {
-            imps.stream().sorted(Comparator.naturalOrder())
-                    .forEach(e -> cb.t(level - 1).e("import $cls$;").arg(e).ln());
-        }
+        // not nested
+        imps.stream().sorted(Comparator.naturalOrder())
+                .forEach(e -> cb.t(level - 1).e("import $cls$;").arg(e).ln());
+
         cb.ln();
         buildDocComment(cb, msg.getComment(), level - 1);
         cb.t(level - 1).e("public class $name$ {").arg(msg.getName()).ln(2);
@@ -198,10 +197,10 @@ public class JavaBuilder {
                 typeName = Proto.class.getPackage().getName() + ".wire.Field." + typeName;
             }
             buildDocComment(cb, f.getComment(), level);
-            String type = getJavaType(f, imps, buildOps);
+            String type = getJavaType(f, imps);
             String name = f.getName();
             if (f.getCardinality() == Field.Cardinality.REPEATED) {
-                String boxedTypeName = getBoxedTypeName(f, buildOps);
+                String boxedTypeName = getBoxedTypeName(f);
                 type = "List<" + boxedTypeName + ">";
             }
 
@@ -249,8 +248,8 @@ public class JavaBuilder {
         return cb.toString();
     }
 
-    private String getBoxedTypeName(Field f, PbBuildOption buildOps) {
-        String type = getJavaType(f, null, buildOps);
+    private String getBoxedTypeName(Field f) {
+        String type = getJavaType(f, null);
         if (BASE_TYPES.contains(f.getTypeString())) {
             JavaType javaType = null;
             javaType = Type.valueOf(f.getTypeString().toUpperCase(Locale.ENGLISH)).javaType();
@@ -269,10 +268,8 @@ public class JavaBuilder {
             return;
         }
         cb.ln();
-        PbBuildOption nestedOps = new PbBuildOption();
-        nestedOps.setIsNested(true);
         msgs.stream().sorted(Comparator.comparing(ProtoMessage::getName))
-                .forEach(e -> cb.c(buildMessage(proto, e, level + 1, defineMsgs, nestedOps, protos)));
+                .forEach(e -> cb.c(buildMessage(proto, e, level + 1, defineMsgs, protos)));
     }
 
 
diff --git a/protocol/src/main/java/com/zfoo/protocol/serializer/protobuf/codegen/IfaceGenerator.java b/protocol/src/main/java/com/zfoo/protocol/serializer/protobuf/codegen/IfaceGenerator.java
deleted file mode 100644
index 7a1d0150..00000000
--- a/protocol/src/main/java/com/zfoo/protocol/serializer/protobuf/codegen/IfaceGenerator.java
+++ /dev/null
@@ -1,90 +0,0 @@
-/*
- * Copyright 2021 The edap Project
- *
- * 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.serializer.protobuf.codegen;
-
-import com.zfoo.protocol.collection.CollectionUtils;
-import com.zfoo.protocol.serializer.protobuf.PbBuildOption;
-import com.zfoo.protocol.serializer.protobuf.builder.JavaBuilder;
-import com.zfoo.protocol.serializer.protobuf.wire.Option;
-import com.zfoo.protocol.serializer.protobuf.wire.ProtoMessage;
-import com.zfoo.protocol.serializer.protobuf.wire.parser.Proto;
-import com.zfoo.protocol.util.FileUtils;
-
-import java.io.File;
-import java.util.Comparator;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-
-public class IfaceGenerator {
-    private final File srcPath;
-    private final List<Proto> files;
-
-    public IfaceGenerator(File srcPath, List<Proto> files) {
-        this.srcPath = srcPath;
-        this.files = files;
-    }
-
-
-    public void generate() {
-        List<Proto> protos = files;
-        Map<String, Proto> allProtos = new HashMap<>();
-        for (Proto proto : protos) {
-            allProtos.put(proto.getName(), proto);
-        }
-        protos.forEach(p -> {
-            generateProtoItem(p, allProtos);
-        });
-    }
-
-    private void generateProtoItem(Proto proto, Map<String, Proto> protos) {
-        List<Option> options = proto.getOptions();
-        Map<String, String> protoOptions = new HashMap<>();
-        if (options != null) {
-            options.forEach(o -> protoOptions.put(o.getName(), o.getValue()));
-        }
-
-        PbBuildOption buildOps = new PbBuildOption();
-
-        generateDtoMessage(proto, buildOps, protos);
-    }
-
-    public void generateDtoMessage(Proto proto, PbBuildOption buildOps, Map<String, Proto> protos) {
-        JavaBuilder builder = new JavaBuilder();
-
-        Map<String, String> msgComments = new HashMap<>();
-
-        List<ProtoMessage> msgs = proto.getMessages();
-        if (CollectionUtils.isNotEmpty(msgs)) {
-            String msgPath = srcPath + File.separator;
-            msgs.stream()
-                    .sorted(Comparator.comparing(ProtoMessage::getName))
-                    .forEach(it -> {
-                        StringBuilder mc = new StringBuilder();
-                        if (it.getComment() != null) {
-                            mc.append(it.getComment());
-                        } else {
-                            if (it.getComment() != null && it.getComment().getLines() != null) {
-                                it.getComment().getLines().forEach(c -> mc.append(c));
-                            }
-                        }
-                        msgComments.put(it.getName(), mc.toString());
-                        var code = builder.buildMessage(proto, it, 1, null, buildOps, protos);
-                        var filePath = msgPath + File.separator + it.getName() + ".java";
-                        FileUtils.writeStringToFile(new File(filePath), code, false);
-                    });
-
-        }
-    }
-}