diff --git a/cosid-core/src/test/java/me/ahoo/cosid/accessor/NotFoundCosIdAccessorTest.java b/cosid-core/src/test/java/me/ahoo/cosid/accessor/NotFoundCosIdAccessorTest.java
new file mode 100644
index 0000000000..729dc22084
--- /dev/null
+++ b/cosid-core/src/test/java/me/ahoo/cosid/accessor/NotFoundCosIdAccessorTest.java
@@ -0,0 +1,51 @@
+/*
+ * Copyright [2021-present] [ahoo wang <ahoowang@qq.com> (https://github.com/Ahoo-Wang)].
+ * 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 me.ahoo.cosid.accessor;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.*;
+
+import org.junit.jupiter.api.Test;
+
+class NotFoundCosIdAccessorTest {
+    @Test
+    public void getIdDefinition() {
+        assertThat(CosIdAccessor.NOT_FOUND.getIdDefinition(), nullValue());
+    }
+    
+    @Test
+    public void getIdGenerator() {
+        assertThat(CosIdAccessor.NOT_FOUND.getIdGenerator(), nullValue());
+    }
+    
+    @Test
+    public void getIdField() {
+        assertThat(CosIdAccessor.NOT_FOUND.getIdField(), nullValue());
+    }
+    
+    @Test
+    public void getId() {
+        assertThat(CosIdAccessor.NOT_FOUND.getId(new Object()), nullValue());
+    }
+    
+    @Test
+    public void setId() {
+        CosIdAccessor.NOT_FOUND.setId(new Object(), new Object());
+    }
+    
+    @Test
+    public void ensureId() {
+        assertThat(CosIdAccessor.NOT_FOUND.ensureId(new Object()), equalTo(false));
+    }
+}
\ No newline at end of file
diff --git a/cosid-core/src/test/java/me/ahoo/cosid/accessor/registry/DefaultAccessorRegistryTest.java b/cosid-core/src/test/java/me/ahoo/cosid/accessor/registry/DefaultAccessorRegistryTest.java
index 5cd8fae2d0..6d82b798fc 100644
--- a/cosid-core/src/test/java/me/ahoo/cosid/accessor/registry/DefaultAccessorRegistryTest.java
+++ b/cosid-core/src/test/java/me/ahoo/cosid/accessor/registry/DefaultAccessorRegistryTest.java
@@ -13,8 +13,12 @@
 
 package me.ahoo.cosid.accessor.registry;
 
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.*;
+
 import me.ahoo.cosid.accessor.parser.DefaultAccessorParser;
 import me.ahoo.cosid.annotation.AnnotationDefinitionParser;
+import me.ahoo.cosid.annotation.entity.IntIdEntity;
 import me.ahoo.cosid.annotation.entity.LongIdEntity;
 import me.ahoo.cosid.annotation.entity.MissingIdGenEntity;
 import me.ahoo.cosid.annotation.entity.StringIdEntity;
@@ -30,9 +34,9 @@
  * @author ahoo wang
  */
 class DefaultAccessorRegistryTest {
-
+    
     CosIdAccessorRegistry accessorRegistry = new DefaultAccessorRegistry(new DefaultAccessorParser(AnnotationDefinitionParser.INSTANCE));
-
+    
     @Test
     void ensureIdExistsByAnnotation() {
         DefaultIdGeneratorProvider.INSTANCE.setShare(AtomicLongGenerator.INSTANCE);
@@ -41,7 +45,7 @@ void ensureIdExistsByAnnotation() {
         accessorRegistry.ensureId(entity);
         Assertions.assertEquals(888, entity.getId());
     }
-
+    
     @Test
     void ensureIdNotFindByAnnotation() {
         MissingIdGenEntity entity = new MissingIdGenEntity();
@@ -49,7 +53,7 @@ void ensureIdNotFindByAnnotation() {
             accessorRegistry.ensureId(entity);
         });
     }
-
+    
     @Test
     void ensureStringId() {
         DefaultIdGeneratorProvider.INSTANCE.setShare(AtomicLongGenerator.INSTANCE);
@@ -57,5 +61,12 @@ void ensureStringId() {
         accessorRegistry.ensureId(entity);
         Assertions.assertFalse(Strings.isNullOrEmpty(entity.getId()));
     }
-
+    
+    @Test
+    void ensureIntId() {
+        DefaultIdGeneratorProvider.INSTANCE.setShare(AtomicLongGenerator.INSTANCE);
+        IntIdEntity entity = new IntIdEntity();
+        accessorRegistry.ensureId(entity);
+        assertThat(entity.getId(), not(0));
+    }
 }
diff --git a/cosid-core/src/test/java/me/ahoo/cosid/accessor/scanner/DefaultCosIdScannerTest.java b/cosid-core/src/test/java/me/ahoo/cosid/accessor/scanner/DefaultCosIdScannerTest.java
index 23dcadd929..0b5ea4e36e 100644
--- a/cosid-core/src/test/java/me/ahoo/cosid/accessor/scanner/DefaultCosIdScannerTest.java
+++ b/cosid-core/src/test/java/me/ahoo/cosid/accessor/scanner/DefaultCosIdScannerTest.java
@@ -14,7 +14,6 @@
 package me.ahoo.cosid.accessor.scanner;
 
 import me.ahoo.cosid.accessor.CosIdAccessor;
-import me.ahoo.cosid.accessor.parser.CosIdAccessorParser;
 import me.ahoo.cosid.accessor.parser.DefaultAccessorParser;
 import me.ahoo.cosid.accessor.parser.NamedDefinitionParser;
 import me.ahoo.cosid.accessor.registry.CosIdAccessorRegistry;
@@ -23,6 +22,7 @@
 import me.ahoo.cosid.accessor.scanner.entity.OrderItemEntity;
 import me.ahoo.cosid.annotation.AnnotationDefinitionParser;
 import me.ahoo.cosid.annotation.entity.ChildEntity;
+import me.ahoo.cosid.annotation.entity.IntIdEntity;
 import me.ahoo.cosid.annotation.entity.LongIdEntity;
 import me.ahoo.cosid.annotation.entity.MissingIdGenEntity;
 import me.ahoo.cosid.annotation.entity.PrimitiveLongIdEntity;
@@ -35,56 +35,62 @@
  * @author ahoo wang
  */
 class DefaultCosIdScannerTest {
-
+    
     @Test
     void scanAnnotationDefinitionParser() {
         CosIdAccessorRegistry registry = new DefaultAccessorRegistry(new DefaultAccessorParser(AnnotationDefinitionParser.INSTANCE));
         DefaultCosIdScanner scanner =
             new DefaultCosIdScanner(new String[] {"me.ahoo.cosid.accessor.annotation.entity"}, AnnotationDefinitionParser.INSTANCE, registry);
         scanner.scan();
-
+        
         CosIdAccessor cosIdAccessor = registry.get(LongIdEntity.class);
         Assertions.assertNotNull(cosIdAccessor);
         Assertions.assertNotEquals(CosIdAccessor.NOT_FOUND, cosIdAccessor);
         Assertions.assertEquals(LongIdEntity.class, cosIdAccessor.getIdDeclaringClass());
-
+        
         cosIdAccessor = registry.get(MissingIdGenEntity.class);
         Assertions.assertNotNull(cosIdAccessor);
         Assertions.assertNotEquals(CosIdAccessor.NOT_FOUND, cosIdAccessor);
         Assertions.assertEquals(MissingIdGenEntity.class, cosIdAccessor.getIdDeclaringClass());
-
+        
         cosIdAccessor = registry.get(PrimitiveLongIdEntity.class);
         Assertions.assertNotNull(cosIdAccessor);
         Assertions.assertNotEquals(CosIdAccessor.NOT_FOUND, cosIdAccessor);
         Assertions.assertEquals(PrimitiveLongIdEntity.class, cosIdAccessor.getIdDeclaringClass());
-
+        
+        cosIdAccessor = registry.get(IntIdEntity.class);
+        Assertions.assertNotNull(cosIdAccessor);
+        Assertions.assertNotEquals(CosIdAccessor.NOT_FOUND, cosIdAccessor);
+        Assertions.assertEquals(IntIdEntity.class, cosIdAccessor.getIdDeclaringClass());
+        
         cosIdAccessor = registry.get(StringIdEntity.class);
         Assertions.assertNotNull(cosIdAccessor);
         Assertions.assertNotEquals(CosIdAccessor.NOT_FOUND, cosIdAccessor);
         Assertions.assertEquals(StringIdEntity.class, cosIdAccessor.getIdDeclaringClass());
-
+        
         cosIdAccessor = registry.get(ChildEntity.class);
         Assertions.assertNotNull(cosIdAccessor);
         Assertions.assertNotEquals(CosIdAccessor.NOT_FOUND, cosIdAccessor);
         Assertions.assertEquals(LongIdEntity.class, cosIdAccessor.getIdDeclaringClass());
     }
-
+    
     @Test
     void scanNamedDefinitionParser() {
         CosIdAccessorRegistry registry = new DefaultAccessorRegistry(new DefaultAccessorParser(AnnotationDefinitionParser.INSTANCE));
         DefaultCosIdScanner scanner =
             new DefaultCosIdScanner(new String[] {"me.ahoo.cosid.accessor.scanner.entity"}, new NamedDefinitionParser("id"), registry);
         scanner.scan();
-
+        
         CosIdAccessor cosIdAccessor = registry.get(OrderEntity.class);
         Assertions.assertNotNull(cosIdAccessor);
         Assertions.assertNotEquals(CosIdAccessor.NOT_FOUND, cosIdAccessor);
         Assertions.assertEquals(OrderEntity.class, cosIdAccessor.getIdDeclaringClass());
-
+        
         cosIdAccessor = registry.get(OrderItemEntity.class);
         Assertions.assertNotNull(cosIdAccessor);
         Assertions.assertNotEquals(CosIdAccessor.NOT_FOUND, cosIdAccessor);
         Assertions.assertEquals(OrderItemEntity.class, cosIdAccessor.getIdDeclaringClass());
+        
     }
-
+    
 }
diff --git a/cosid-core/src/test/java/me/ahoo/cosid/annotation/entity/IntIdEntity.java b/cosid-core/src/test/java/me/ahoo/cosid/annotation/entity/IntIdEntity.java
new file mode 100644
index 0000000000..ccb276182a
--- /dev/null
+++ b/cosid-core/src/test/java/me/ahoo/cosid/annotation/entity/IntIdEntity.java
@@ -0,0 +1,32 @@
+/*
+ * Copyright [2021-present] [ahoo wang <ahoowang@qq.com> (https://github.com/Ahoo-Wang)].
+ * 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 me.ahoo.cosid.annotation.entity;
+
+import me.ahoo.cosid.annotation.CosId;
+
+/**
+ * @author ahoo wang
+ */
+public class IntIdEntity {
+    @CosId
+    private int id;
+
+    public int getId() {
+        return id;
+    }
+
+    public void setId(int id) {
+        this.id = id;
+    }
+}
diff --git a/cosid-dependencies/build.gradle.kts b/cosid-dependencies/build.gradle.kts
index 5a0cfe3bd3..4c40e188b4 100644
--- a/cosid-dependencies/build.gradle.kts
+++ b/cosid-dependencies/build.gradle.kts
@@ -20,6 +20,7 @@ dependencies {
         api(libs.guava)
         api(libs.mybatis)
         api(libs.mybatisSpringBoot)
+        api(libs.springDocStarterWebfluxUi)
         api(libs.junitPioneer)
         api(libs.hamcrest)
         api(libs.jmhCore)
diff --git a/cosid-proxy-server/build.gradle.kts b/cosid-proxy-server/build.gradle.kts
index 11bd449075..a45e3dc681 100644
--- a/cosid-proxy-server/build.gradle.kts
+++ b/cosid-proxy-server/build.gradle.kts
@@ -35,13 +35,13 @@ application {
     mainClass.set("me.ahoo.cosid.proxy.server.ProxyServer")
 
     applicationDefaultJvmArgs = listOf(
-        "-Xms512M",
-        "-Xmx512M",
-        "-XX:MaxMetaspaceSize=128M",
-        "-XX:MaxDirectMemorySize=256M",
+        "-Xms1280M",
+        "-Xmx1280M",
+        "-XX:MaxMetaspaceSize=256M",
+        "-XX:MaxDirectMemorySize=512M",
         "-Xss1m",
         "-server",
-        "-XX:+UseG1GC",
+        "-XX:+UseZGC",
         "-Xlog:gc*:file=logs/${applicationName}-gc.log:time,tags:filecount=10,filesize=32M",
         "-XX:+HeapDumpOnOutOfMemoryError",
         "-XX:HeapDumpPath=data",
@@ -79,6 +79,7 @@ dependencies {
     implementation("com.google.guava:guava")
     implementation("io.netty:netty-all")
     implementation("org.springframework.boot:spring-boot-starter-webflux")
+    implementation("org.springdoc:springdoc-openapi-starter-webflux-ui")
     compileOnly("org.projectlombok:lombok")
     annotationProcessor("org.projectlombok:lombok")
     annotationProcessor("org.springframework.boot:spring-boot-configuration-processor")
diff --git a/cosid-proxy-server/src/dist/config/application.yaml b/cosid-proxy-server/src/dist/config/application.yaml
index a08fa7eda6..717a29a864 100644
--- a/cosid-proxy-server/src/dist/config/application.yaml
+++ b/cosid-proxy-server/src/dist/config/application.yaml
@@ -1,14 +1,24 @@
+management:
+  endpoints:
+    web:
+      exposure:
+        include:
+          - cosid
+          - cosidGenerator
+          - cosidStringGenerator
+springdoc:
+  show-actuator: true
 server:
   port: 8688
 spring:
   application:
     name: ${service.name:cosid-proxy}
-  #  redis:
-  #    url: redis://localhost:6379
+#  redis:
+#    url: redis://localhost:6379
   autoconfigure:
     exclude:
-      #     - org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration
-      - org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration
+#     - org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration
+     - org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration
 #  datasource:
 #    url: jdbc:mysql://localhost:3306/cosid_db
 #    username: root
@@ -19,15 +29,13 @@ cosid:
     enabled: true
     distributor:
       type: redis
-    guarder:
-      enabled: true
   snowflake:
     enabled: true
   segment:
     enabled: true
-    mode: chain
     distributor:
       type: redis
 logging:
   level:
     me.ahoo.cosid: debug
+
diff --git a/cosid-proxy-server/src/main/java/me/ahoo/cosid/proxy/server/configuration/SwaggerConfiguration.java b/cosid-proxy-server/src/main/java/me/ahoo/cosid/proxy/server/configuration/SwaggerConfiguration.java
new file mode 100644
index 0000000000..f82a7ef6c3
--- /dev/null
+++ b/cosid-proxy-server/src/main/java/me/ahoo/cosid/proxy/server/configuration/SwaggerConfiguration.java
@@ -0,0 +1,40 @@
+/*
+ * Copyright [2021-present] [ahoo wang <ahoowang@qq.com> (https://github.com/Ahoo-Wang)].
+ * 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 me.ahoo.cosid.proxy.server.configuration;
+
+import com.google.common.base.MoreObjects;
+import io.swagger.v3.oas.models.info.Contact;
+import io.swagger.v3.oas.models.info.Info;
+import io.swagger.v3.oas.models.info.License;
+import org.springdoc.core.customizers.OpenApiCustomizer;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+public class SwaggerConfiguration {
+    
+    @Bean
+    public OpenApiCustomizer openApiCustomizer() {
+        var version = MoreObjects.firstNonNull(getClass().getPackage().getImplementationVersion(), "2.3.0");
+        return openApi -> {
+            var info = new Info()
+                .title("CosId Proxy Server")
+                .description("Universal, flexible, high-performance distributed ID generator.")
+                .contact(new Contact().name("Ahoo Wang").url("https://github.com/Ahoo-Wang/CosId"))
+                .license(new License().url("https://github.com/Ahoo-Wang/CosId/blob/main/LICENSE").name("Apache 2.0"))
+                .version(version);
+            openApi.info(info);
+        };
+    }
+}
diff --git a/cosid-proxy-server/src/main/java/me/ahoo/cosid/proxy/server/controller/IdController.java b/cosid-proxy-server/src/main/java/me/ahoo/cosid/proxy/server/controller/IdController.java
index 7ba42ebcde..0a85521d1f 100644
--- a/cosid-proxy-server/src/main/java/me/ahoo/cosid/proxy/server/controller/IdController.java
+++ b/cosid-proxy-server/src/main/java/me/ahoo/cosid/proxy/server/controller/IdController.java
@@ -15,6 +15,7 @@
 
 import me.ahoo.cosid.provider.IdGeneratorProvider;
 
+import io.swagger.v3.oas.annotations.Operation;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.RequestMapping;
@@ -38,6 +39,7 @@ public IdController(IdGeneratorProvider provider) {
         this.provider = provider;
     }
     
+    @Operation(summary = "Generate a ID by share.")
     @GetMapping
     public long generate() {
         return provider
@@ -45,6 +47,7 @@ public long generate() {
             .generate();
     }
     
+    @Operation(summary = "Generate a ID by id name.")
     @GetMapping("{name}")
     public long generate(@PathVariable String name) {
         return provider
@@ -52,6 +55,7 @@ public long generate(@PathVariable String name) {
             .generate();
     }
     
+    @Operation(summary = "Generate a ID as String by share.")
     @GetMapping("/as-string")
     public String generateAsString() {
         return provider
@@ -59,6 +63,7 @@ public String generateAsString() {
             .generateAsString();
     }
     
+    @Operation(summary = "Generate a ID as String by id name.")
     @GetMapping("/as-string/{name}")
     public String generateAsString(@PathVariable String name) {
         return provider
diff --git a/cosid-proxy-server/src/main/java/me/ahoo/cosid/proxy/server/controller/MachineController.java b/cosid-proxy-server/src/main/java/me/ahoo/cosid/proxy/server/controller/MachineController.java
index 092cc758ee..a3b3c67d26 100644
--- a/cosid-proxy-server/src/main/java/me/ahoo/cosid/proxy/server/controller/MachineController.java
+++ b/cosid-proxy-server/src/main/java/me/ahoo/cosid/proxy/server/controller/MachineController.java
@@ -19,6 +19,7 @@
 import me.ahoo.cosid.machine.MachineIdOverflowException;
 import me.ahoo.cosid.machine.MachineState;
 
+import io.swagger.v3.oas.annotations.Operation;
 import org.springframework.web.bind.annotation.DeleteMapping;
 import org.springframework.web.bind.annotation.PatchMapping;
 import org.springframework.web.bind.annotation.PathVariable;
@@ -46,6 +47,7 @@ public MachineController(MachineIdDistributor distributor) {
     /**
      * Distribute a machine ID, the operation is idempotent.
      */
+    @Operation(summary = "Distribute a machine ID, the operation is idempotent.")
     @PostMapping("/{namespace}")
     public MachineState distribute(@PathVariable String namespace, int machineBit, InstanceId instanceId, String safeGuardDuration) throws MachineIdOverflowException {
         return distributor.distribute(namespace, machineBit, instanceId, Duration.parse(safeGuardDuration));
@@ -54,6 +56,7 @@ public MachineState distribute(@PathVariable String namespace, int machineBit, I
     /**
      * Revert a machine ID, the operation is idempotent.
      */
+    @Operation(summary = "Revert a machine ID, the operation is idempotent.")
     @DeleteMapping("/{namespace}")
     public void revert(@PathVariable String namespace, InstanceId instanceId) {
         distributor.revert(namespace, instanceId);
@@ -63,6 +66,7 @@ public void revert(@PathVariable String namespace, InstanceId instanceId) {
      * Guard a machine ID.
      */
     @PatchMapping("/{namespace}")
+    @Operation(summary = "Guard a machine ID.")
     public void guard(@PathVariable String namespace, InstanceId instanceId, String safeGuardDuration) throws MachineIdLostException {
         distributor.guard(namespace, instanceId, Duration.parse(safeGuardDuration));
     }
diff --git a/cosid-proxy-server/src/main/java/me/ahoo/cosid/proxy/server/controller/SegmentController.java b/cosid-proxy-server/src/main/java/me/ahoo/cosid/proxy/server/controller/SegmentController.java
index 4817eaa362..bb84969cfc 100644
--- a/cosid-proxy-server/src/main/java/me/ahoo/cosid/proxy/server/controller/SegmentController.java
+++ b/cosid-proxy-server/src/main/java/me/ahoo/cosid/proxy/server/controller/SegmentController.java
@@ -18,6 +18,7 @@
 import me.ahoo.cosid.segment.IdSegmentDistributorFactory;
 
 import com.google.common.base.Preconditions;
+import io.swagger.v3.oas.annotations.Operation;
 import org.springframework.web.bind.annotation.PatchMapping;
 import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.PostMapping;
@@ -45,6 +46,7 @@ public SegmentController(IdSegmentDistributorFactory distributorFactory) {
     /**
      * Create an ID segment dispatcher, the operation is idempotent.
      */
+    @Operation(summary = "Create an ID segment dispatcher, the operation is idempotent.")
     @PostMapping("/distributor/{namespace}/{name}")
     public void createDistributor(@PathVariable String namespace, @PathVariable String name, long offset, long step) {
         String namespacedName = IdSegmentDistributor.getNamespacedName(namespace, name);
@@ -52,6 +54,7 @@ public void createDistributor(@PathVariable String namespace, @PathVariable Stri
             key -> distributorFactory.create(new IdSegmentDistributorDefinition(namespace, name, offset, step)));
     }
     
+    @Operation(summary = "Get next max id.")
     @PatchMapping("/{namespace}/{name}")
     public long nextMaxId(@PathVariable String namespace, @PathVariable String name, long step) {
         String namespacedName = IdSegmentDistributor.getNamespacedName(namespace, name);
diff --git a/cosid-proxy-server/src/main/java/me/ahoo/cosid/proxy/server/error/ErrorResponse.java b/cosid-proxy-server/src/main/java/me/ahoo/cosid/proxy/server/error/ErrorResponse.java
index 8217f91b90..150bea5900 100644
--- a/cosid-proxy-server/src/main/java/me/ahoo/cosid/proxy/server/error/ErrorResponse.java
+++ b/cosid-proxy-server/src/main/java/me/ahoo/cosid/proxy/server/error/ErrorResponse.java
@@ -25,10 +25,13 @@
 public class ErrorResponse {
     
     public static final String BAD_REQUEST = "400";
+    public static final String MACHINE_ID_OVERFLOW = "M-01";
+    public static final String NOT_FOUND_MACHINE_STATE = "M-02";
+    public static final String MACHINE_ID_LOST = "M-03";
     
     private final String code;
     private final String msg;
-    @Nullable
+    
     private final List<?> errors;
     
     public ErrorResponse(String code, String msg, List<?> errors) {
@@ -45,6 +48,7 @@ public String getMsg() {
         return msg;
     }
     
+    @Nullable
     public List<?> getErrors() {
         return errors;
     }
diff --git a/cosid-proxy-server/src/main/java/me/ahoo/cosid/proxy/server/error/GlobalRestExceptionHandler.java b/cosid-proxy-server/src/main/java/me/ahoo/cosid/proxy/server/error/GlobalRestExceptionHandler.java
index 7566466a37..cd8a328c8a 100644
--- a/cosid-proxy-server/src/main/java/me/ahoo/cosid/proxy/server/error/GlobalRestExceptionHandler.java
+++ b/cosid-proxy-server/src/main/java/me/ahoo/cosid/proxy/server/error/GlobalRestExceptionHandler.java
@@ -13,6 +13,10 @@
 
 package me.ahoo.cosid.proxy.server.error;
 
+import static me.ahoo.cosid.proxy.server.error.ErrorResponse.MACHINE_ID_LOST;
+import static me.ahoo.cosid.proxy.server.error.ErrorResponse.MACHINE_ID_OVERFLOW;
+import static me.ahoo.cosid.proxy.server.error.ErrorResponse.NOT_FOUND_MACHINE_STATE;
+
 import me.ahoo.cosid.machine.MachineIdLostException;
 import me.ahoo.cosid.machine.MachineIdOverflowException;
 import me.ahoo.cosid.machine.NotFoundMachineStateException;
@@ -56,21 +60,21 @@ public ResponseEntity<ErrorResponse> handleClientException(IllegalArgumentExcept
     public ResponseEntity<ErrorResponse> handleCosIdException(MachineIdOverflowException ex) {
         return ResponseEntity
             .badRequest()
-            .body(ErrorResponse.of("M-01", ex.getMessage()));
+            .body(ErrorResponse.of(MACHINE_ID_OVERFLOW, ex.getMessage()));
     }
     
     @ExceptionHandler(NotFoundMachineStateException.class)
     public ResponseEntity<ErrorResponse> handleCosIdException(NotFoundMachineStateException ex) {
         return ResponseEntity
             .badRequest()
-            .body(ErrorResponse.of("M-02", ex.getMessage()));
+            .body(ErrorResponse.of(NOT_FOUND_MACHINE_STATE, ex.getMessage()));
     }
     
     @ExceptionHandler(MachineIdLostException.class)
     public ResponseEntity<ErrorResponse> handleCosIdException(MachineIdLostException ex) {
         return ResponseEntity
             .badRequest()
-            .body(ErrorResponse.of("M-03", ex.getMessage()));
+            .body(ErrorResponse.of(MACHINE_ID_LOST, ex.getMessage()));
     }
     
     @ResponseStatus(HttpStatus.BAD_REQUEST)
diff --git a/cosid-proxy-server/src/main/resources/application.yaml b/cosid-proxy-server/src/main/resources/application.yaml
index abe91e1457..717a29a864 100644
--- a/cosid-proxy-server/src/main/resources/application.yaml
+++ b/cosid-proxy-server/src/main/resources/application.yaml
@@ -1,3 +1,13 @@
+management:
+  endpoints:
+    web:
+      exposure:
+        include:
+          - cosid
+          - cosidGenerator
+          - cosidStringGenerator
+springdoc:
+  show-actuator: true
 server:
   port: 8688
 spring:
@@ -19,15 +29,13 @@ cosid:
     enabled: true
     distributor:
       type: redis
-    guarder:
-      enabled: true
   snowflake:
     enabled: true
   segment:
     enabled: true
-    mode: chain
     distributor:
       type: redis
 logging:
   level:
     me.ahoo.cosid: debug
+
diff --git a/cosid-proxy/src/main/java/me/ahoo/cosid/proxy/ErrorResponse.java b/cosid-proxy/src/main/java/me/ahoo/cosid/proxy/ErrorResponse.java
index f67a2d7dcc..496a990b66 100644
--- a/cosid-proxy/src/main/java/me/ahoo/cosid/proxy/ErrorResponse.java
+++ b/cosid-proxy/src/main/java/me/ahoo/cosid/proxy/ErrorResponse.java
@@ -29,6 +29,9 @@
 public class ErrorResponse {
     
     public static final String BAD_REQUEST = "400";
+    public static final String MACHINE_ID_OVERFLOW = "M-01";
+    public static final String NOT_FOUND_MACHINE_STATE = "M-02";
+    public static final String MACHINE_ID_LOST = "M-03";
     
     private final String code;
     private final String msg;
@@ -54,23 +57,6 @@ public List<?> getErrors() {
         return errors;
     }
     
-    @Override
-    public boolean equals(Object o) {
-        if (this == o) {
-            return true;
-        }
-        if (!(o instanceof ErrorResponse)) {
-            return false;
-        }
-        ErrorResponse that = (ErrorResponse) o;
-        return Objects.equals(getCode(), that.getCode()) && Objects.equals(getMsg(), that.getMsg()) && Objects.equals(getErrors(), that.getErrors());
-    }
-    
-    @Override
-    public int hashCode() {
-        return Objects.hash(getCode(), getMsg(), getErrors());
-    }
-    
     public static ErrorResponse of(String code, String msg) {
         return new ErrorResponse(code, msg, Collections.emptyList());
     }
diff --git a/cosid-proxy/src/main/java/me/ahoo/cosid/proxy/ProxyIdSegmentDistributor.java b/cosid-proxy/src/main/java/me/ahoo/cosid/proxy/ProxyIdSegmentDistributor.java
index 799ce853ec..6abdfadda5 100644
--- a/cosid-proxy/src/main/java/me/ahoo/cosid/proxy/ProxyIdSegmentDistributor.java
+++ b/cosid-proxy/src/main/java/me/ahoo/cosid/proxy/ProxyIdSegmentDistributor.java
@@ -13,8 +13,6 @@
 
 package me.ahoo.cosid.proxy;
 
-import static me.ahoo.cosid.proxy.ProxyMachineIdDistributor.JSON;
-
 import me.ahoo.cosid.segment.IdSegmentDistributor;
 
 import com.google.common.base.Preconditions;
@@ -23,9 +21,9 @@
 import lombok.extern.slf4j.Slf4j;
 import okhttp3.OkHttpClient;
 import okhttp3.Request;
-import okhttp3.RequestBody;
 import okhttp3.Response;
 import okhttp3.ResponseBody;
+import okhttp3.internal.Util;
 
 import javax.annotation.Nonnull;
 
@@ -77,7 +75,7 @@ public long nextMaxId(long step) {
         
         Request request = new Request.Builder()
             .url(apiUrl)
-            .patch(RequestBody.create(JSON, ""))
+            .patch(Util.EMPTY_REQUEST)
             .build();
         try (Response response = client.newCall(request).execute()) {
             ResponseBody responseBody = response.body();
diff --git a/cosid-proxy/src/main/java/me/ahoo/cosid/proxy/ProxyIdSegmentDistributorFactory.java b/cosid-proxy/src/main/java/me/ahoo/cosid/proxy/ProxyIdSegmentDistributorFactory.java
index 2c322760d9..d187050e2d 100644
--- a/cosid-proxy/src/main/java/me/ahoo/cosid/proxy/ProxyIdSegmentDistributorFactory.java
+++ b/cosid-proxy/src/main/java/me/ahoo/cosid/proxy/ProxyIdSegmentDistributorFactory.java
@@ -13,8 +13,6 @@
 
 package me.ahoo.cosid.proxy;
 
-import static me.ahoo.cosid.proxy.ProxyMachineIdDistributor.JSON;
-
 import me.ahoo.cosid.segment.IdSegmentDistributor;
 import me.ahoo.cosid.segment.IdSegmentDistributorDefinition;
 import me.ahoo.cosid.segment.IdSegmentDistributorFactory;
@@ -24,9 +22,9 @@
 import lombok.extern.slf4j.Slf4j;
 import okhttp3.OkHttpClient;
 import okhttp3.Request;
-import okhttp3.RequestBody;
 import okhttp3.Response;
 import okhttp3.ResponseBody;
+import okhttp3.internal.Util;
 
 import javax.annotation.Nonnull;
 
@@ -60,7 +58,7 @@ public IdSegmentDistributor create(IdSegmentDistributorDefinition definition) {
         
         Request request = new Request.Builder()
             .url(apiUrl)
-            .post(RequestBody.Companion.create("", JSON))
+            .post(Util.EMPTY_REQUEST)
             .build();
         try (Response response = client.newCall(request).execute()) {
             ResponseBody responseBody = response.body();
diff --git a/cosid-proxy/src/main/java/me/ahoo/cosid/proxy/ProxyMachineIdDistributor.java b/cosid-proxy/src/main/java/me/ahoo/cosid/proxy/ProxyMachineIdDistributor.java
index 35b61b24e3..c945dafcbe 100644
--- a/cosid-proxy/src/main/java/me/ahoo/cosid/proxy/ProxyMachineIdDistributor.java
+++ b/cosid-proxy/src/main/java/me/ahoo/cosid/proxy/ProxyMachineIdDistributor.java
@@ -13,8 +13,12 @@
 
 package me.ahoo.cosid.proxy;
 
-import me.ahoo.cosid.machine.ClockBackwardsSynchronizer;
+import static me.ahoo.cosid.proxy.ErrorResponse.MACHINE_ID_LOST;
+import static me.ahoo.cosid.proxy.ErrorResponse.MACHINE_ID_OVERFLOW;
+import static me.ahoo.cosid.proxy.ErrorResponse.NOT_FOUND_MACHINE_STATE;
+
 import me.ahoo.cosid.machine.AbstractMachineIdDistributor;
+import me.ahoo.cosid.machine.ClockBackwardsSynchronizer;
 import me.ahoo.cosid.machine.InstanceId;
 import me.ahoo.cosid.machine.MachineIdLostException;
 import me.ahoo.cosid.machine.MachineIdOverflowException;
@@ -25,12 +29,11 @@
 import com.google.common.base.Strings;
 import lombok.SneakyThrows;
 import lombok.extern.slf4j.Slf4j;
-import okhttp3.MediaType;
 import okhttp3.OkHttpClient;
 import okhttp3.Request;
-import okhttp3.RequestBody;
 import okhttp3.Response;
 import okhttp3.ResponseBody;
+import okhttp3.internal.Util;
 
 import java.time.Duration;
 
@@ -43,8 +46,6 @@
 @Slf4j
 public class ProxyMachineIdDistributor extends AbstractMachineIdDistributor {
     
-    public static final MediaType JSON
-        = MediaType.get("application/json; charset=utf-8");
     private final OkHttpClient client;
     
     private final String proxyHost;
@@ -67,7 +68,7 @@ protected MachineState distributeRemote(String namespace, int machineBit, Instan
         
         Request request = new Request.Builder()
             .url(apiUrl)
-            .post(RequestBody.create(JSON, ""))
+            .post(Util.EMPTY_REQUEST)
             .build();
         try (Response response = client.newCall(request).execute()) {
             ResponseBody responseBody = response.body();
@@ -81,12 +82,10 @@ protected MachineState distributeRemote(String namespace, int machineBit, Instan
                 return Jsons.OBJECT_MAPPER.readValue(bodyStr, MachineStateDto.class);
             }
             ErrorResponse errorResponse = Jsons.OBJECT_MAPPER.readValue(bodyStr, ErrorResponse.class);
-            switch (errorResponse.getCode()) {
-                case "M-01":
-                    throw new MachineIdOverflowException(machineBit, instanceId);
-                default:
-                    throw new IllegalStateException(Strings.lenientFormat("Unexpected code:[%s] - message:[%s].", errorResponse.getCode(), errorResponse.getMsg()));
+            if (errorResponse.getCode().equals(MACHINE_ID_OVERFLOW)) {
+                throw new MachineIdOverflowException(machineBit, instanceId);
             }
+            throw new IllegalStateException(Strings.lenientFormat("Unexpected code:[%s] - message:[%s].", errorResponse.getCode(), errorResponse.getMsg()));
         }
     }
     
@@ -124,7 +123,7 @@ protected void guardRemote(String namespace, InstanceId instanceId, MachineState
         
         Request request = new Request.Builder()
             .url(apiUrl)
-            .patch(RequestBody.create(JSON, ""))
+            .patch(Util.EMPTY_REQUEST)
             .build();
         try (Response response = client.newCall(request).execute()) {
             ResponseBody responseBody = response.body();
@@ -139,12 +138,9 @@ protected void guardRemote(String namespace, InstanceId instanceId, MachineState
             
             ErrorResponse errorResponse = Jsons.OBJECT_MAPPER.readValue(bodyStr, ErrorResponse.class);
             switch (errorResponse.getCode()) {
-                case "M-02":
-                    throw new NotFoundMachineStateException(namespace, instanceId);
-                case "M-03":
-                    throw new MachineIdLostException(namespace, instanceId, machineState);
-                default:
-                    throw new IllegalStateException("Unexpected value: " + errorResponse.getCode());
+                case NOT_FOUND_MACHINE_STATE -> throw new NotFoundMachineStateException(namespace, instanceId);
+                case MACHINE_ID_LOST -> throw new MachineIdLostException(namespace, instanceId, machineState);
+                default -> throw new IllegalStateException("Unexpected value: " + errorResponse.getCode());
             }
         }
     }
diff --git a/cosid-proxy/src/test/java/me/ahoo/cosid/proxy/JsonsTest.java b/cosid-proxy/src/test/java/me/ahoo/cosid/proxy/JsonsTest.java
index e8f169daab..0e1046b712 100644
--- a/cosid-proxy/src/test/java/me/ahoo/cosid/proxy/JsonsTest.java
+++ b/cosid-proxy/src/test/java/me/ahoo/cosid/proxy/JsonsTest.java
@@ -25,7 +25,9 @@ void serialize() {
         ErrorResponse errorResponse = ErrorResponse.badRequest("badRequest");
         String jsonStr = Jsons.serialize(errorResponse);
         ErrorResponse actual = Jsons.deserialize(jsonStr, ErrorResponse.class);
-        assertThat(actual, equalTo(errorResponse));
+        assertThat(actual.getCode(), equalTo(errorResponse.getCode()));
+        assertThat(actual.getMsg(), equalTo(errorResponse.getMsg()));
+        assertThat(actual.getErrors(), equalTo(errorResponse.getErrors()));
     }
     
 }
diff --git a/cosid-proxy/src/test/java/me/ahoo/cosid/proxy/ProxyMachineIdDistributorTest.java b/cosid-proxy/src/test/java/me/ahoo/cosid/proxy/ProxyMachineIdDistributorTest.java
index 86691f3592..16895c6829 100644
--- a/cosid-proxy/src/test/java/me/ahoo/cosid/proxy/ProxyMachineIdDistributorTest.java
+++ b/cosid-proxy/src/test/java/me/ahoo/cosid/proxy/ProxyMachineIdDistributorTest.java
@@ -14,11 +14,16 @@
 package me.ahoo.cosid.proxy;
 
 import me.ahoo.cosid.machine.ClockBackwardsSynchronizer;
+import me.ahoo.cosid.machine.InstanceId;
 import me.ahoo.cosid.machine.MachineIdDistributor;
 import me.ahoo.cosid.machine.MachineStateStorage;
+import me.ahoo.cosid.machine.NotFoundMachineStateException;
+import me.ahoo.cosid.test.Assert;
+import me.ahoo.cosid.test.MockIdGenerator;
 import me.ahoo.cosid.test.machine.distributor.MachineIdDistributorSpec;
 
 import okhttp3.OkHttpClient;
+import org.junit.jupiter.api.Test;
 
 class ProxyMachineIdDistributorTest extends MachineIdDistributorSpec {
     
@@ -29,7 +34,19 @@ protected MachineIdDistributor getDistributor() {
     
     @Override
     public void guardLost() {
-        //TODO
-        //super.guardLost();
+        //ignore
+    }
+    
+    @Test
+    public void guardIfNotFoundMachineState() {
+        MachineIdDistributor distributor = getDistributor();
+        String namespace = MockIdGenerator.usePrefix("guardIfNotFoundMachineState").generateAsString();
+        InstanceId instanceId = mockInstance(0, false);
+        MachineStateStorage.IN_MEMORY.set(namespace, 10, instanceId);
+        
+        Assert.assertThrows(NotFoundMachineStateException.class, () -> {
+            distributor.guard(namespace, instanceId, MachineIdDistributor.FOREVER_SAFE_GUARD_DURATION);
+        });
+        
     }
 }
diff --git a/cosid-proxy/src/test/java/me/ahoo/cosid/proxy/ProxyServerLauncher.java b/cosid-proxy/src/test/java/me/ahoo/cosid/proxy/ProxyServerLauncher.java
index bff6d0752e..44549cbe5f 100644
--- a/cosid-proxy/src/test/java/me/ahoo/cosid/proxy/ProxyServerLauncher.java
+++ b/cosid-proxy/src/test/java/me/ahoo/cosid/proxy/ProxyServerLauncher.java
@@ -34,7 +34,7 @@ public class ProxyServerLauncher {
         REDIS_CONTAINER.start();
         
         int cosidProxyExposedPort = 8688;
-        COSID_PROXY_CONTAINER = new GenericContainer(DockerImageName.parse("ahoowang/cosid-proxy:2.2.1"))
+        COSID_PROXY_CONTAINER = new GenericContainer(DockerImageName.parse("ahoowang/cosid-proxy:2.3.0"))
             .withNetwork(NETWORK_CONTAINER)
             .withExposedPorts(cosidProxyExposedPort)
             .withReuse(true)
diff --git a/cosid-test/src/main/java/me/ahoo/cosid/test/machine/distributor/MachineIdDistributorSpec.java b/cosid-test/src/main/java/me/ahoo/cosid/test/machine/distributor/MachineIdDistributorSpec.java
index f13d64c096..10ad224ee2 100644
--- a/cosid-test/src/main/java/me/ahoo/cosid/test/machine/distributor/MachineIdDistributorSpec.java
+++ b/cosid-test/src/main/java/me/ahoo/cosid/test/machine/distributor/MachineIdDistributorSpec.java
@@ -32,7 +32,7 @@ public abstract class MachineIdDistributorSpec {
     private static final int TEST_MACHINE_BIT = 5;
     private static final Duration TEST_SAFE_GUARD_DURATION = Duration.ofSeconds(5);
     
-    static InstanceId mockInstance(int port, boolean stable) {
+    protected static InstanceId mockInstance(int port, boolean stable) {
         return InstanceId.of(TEST_HOST, port, stable);
     }
     
diff --git a/gradle.properties b/gradle.properties
index 3af26ac2eb..a893eabe2c 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -11,7 +11,7 @@
 # limitations under the License.
 #
 group=me.ahoo.cosid
-version=2.3.0
+version=2.3.1
 description=Universal, flexible, high-performance distributed ID generator.
 website=https://github.com/Ahoo-Wang/CosId
 issues=https://github.com/Ahoo-Wang/CosId/issues
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index b787cdf5dc..494137ad17 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -9,6 +9,7 @@ mybatis = "3.5.13"
 mybatisSpringBoot = "3.0.2"
 junitPioneer = "2.0.1"
 axon = "4.8.1"
+springDoc = "2.1.0"
 hamcrest = "2.2"
 mockk = "1.13.5"
 detektFormatting = "1.23.1"
@@ -27,6 +28,7 @@ testcontainersBom = { module = "org.testcontainers:testcontainers-bom", version.
 guava = { module = "com.google.guava:guava", version.ref = "guava" }
 mybatis = { module = "org.mybatis:mybatis", version.ref = "mybatis" }
 mybatisSpringBoot = { module = "org.mybatis.spring.boot:mybatis-spring-boot-starter", version.ref = "mybatisSpringBoot" }
+springDocStarterWebfluxUi = { module = "org.springdoc:springdoc-openapi-starter-webflux-ui", version.ref = "springDoc" }
 junitPioneer = { module = "org.junit-pioneer:junit-pioneer", version.ref = "junitPioneer" }
 hamcrest = { module = "org.hamcrest:hamcrest", version.ref = "hamcrest" }
 mockk = { module = "io.mockk:mockk", version.ref = "mockk" }