diff --git a/hugegraph-api/src/main/java/com/baidu/hugegraph/api/gremlin/GremlinClient.java b/hugegraph-api/src/main/java/com/baidu/hugegraph/api/gremlin/GremlinClient.java
index 55676003b..b3d1d21d3 100644
--- a/hugegraph-api/src/main/java/com/baidu/hugegraph/api/gremlin/GremlinClient.java
+++ b/hugegraph-api/src/main/java/com/baidu/hugegraph/api/gremlin/GremlinClient.java
@@ -30,11 +30,11 @@ import javax.ws.rs.core.MultivaluedMap;
 import javax.ws.rs.core.Response;
 
 import com.baidu.hugegraph.api.filter.CompressInterceptor;
-import com.baidu.hugegraph.rest.RestClient;
+import com.baidu.hugegraph.rest.AbstractRestClient;
 import com.baidu.hugegraph.testutil.Whitebox;
 import com.baidu.hugegraph.util.E;
 
-public class GremlinClient extends RestClient {
+public class GremlinClient extends AbstractRestClient {
 
     private final WebTarget webTarget;
 
diff --git a/hugegraph-cassandra/pom.xml b/hugegraph-cassandra/pom.xml
index ebf0dc10a..3e4e88fcd 100644
--- a/hugegraph-cassandra/pom.xml
+++ b/hugegraph-cassandra/pom.xml
@@ -55,7 +55,7 @@
         <dependency>
             <groupId>com.datastax.cassandra</groupId>
             <artifactId>cassandra-driver-core</artifactId>
-            <version>3.2.0</version>
+            <version>3.6.0</version>
         </dependency>
         <dependency>
             <groupId>io.netty</groupId>
diff --git a/hugegraph-core/pom.xml b/hugegraph-core/pom.xml
index e19b25397..e09192766 100644
--- a/hugegraph-core/pom.xml
+++ b/hugegraph-core/pom.xml
@@ -19,7 +19,7 @@
         <dependency>
             <groupId>com.baidu.hugegraph</groupId>
             <artifactId>hugegraph-common</artifactId>
-            <version>1.7.6</version>
+            <version>1.7.8</version>
         </dependency>
 
         <!-- tinkerpop -->
@@ -50,15 +50,16 @@
             <artifactId>gremlin-driver</artifactId>
         </dependency>
 
-        <dependency>
-            <groupId>com.google.guava</groupId>
-            <artifactId>guava</artifactId>
-        </dependency>
-
         <dependency>
             <groupId>org.caffinitas.ohc</groupId>
             <artifactId>ohc-core</artifactId>
             <version>0.7.0</version>
+            <exclusions>
+                <exclusion>
+                    <groupId>com.google.guava</groupId>
+                    <artifactId>guava</artifactId>
+                </exclusion>
+            </exclusions>
         </dependency>
 
         <dependency>
diff --git a/hugegraph-core/src/main/java/com/baidu/hugegraph/util/DateUtil.java b/hugegraph-core/src/main/java/com/baidu/hugegraph/util/DateUtil.java
deleted file mode 100644
index 71e89b5e7..000000000
--- a/hugegraph-core/src/main/java/com/baidu/hugegraph/util/DateUtil.java
+++ /dev/null
@@ -1,95 +0,0 @@
-/*
- * Copyright 2017 HugeGraph Authors
- *
- * 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.
- */
-
-package com.baidu.hugegraph.util;
-
-import java.text.ParseException;
-import java.util.Date;
-import java.util.Map;
-import java.util.concurrent.ConcurrentHashMap;
-
-import com.baidu.hugegraph.date.SafeDateFormat;
-import com.google.common.collect.ImmutableMap;
-
-public final class DateUtil {
-
-    public static final Date DATE_ZERO = new Date(0L);
-
-    private static final Map<String, String> VALID_DFS = ImmutableMap.of(
-            "^\\d{4}-\\d{1,2}-\\d{1,2}",
-            "yyyy-MM-dd",
-            "^\\d{4}-\\d{1,2}-\\d{1,2}\\s\\d{2}:\\d{2}:\\d{2}",
-            "yyyy-MM-dd HH:mm:ss",
-            "^\\d{4}-\\d{1,2}-\\d{1,2}\\s\\d{2}:\\d{2}:\\d{2}\\.\\d{1,3}",
-            "yyyy-MM-dd HH:mm:ss.SSS"
-    );
-
-    private static final Map<String, SafeDateFormat> DATE_FORMATS =
-                                                     new ConcurrentHashMap<>();
-
-    public static Date parse(String value) {
-        for (Map.Entry<String, String> entry : VALID_DFS.entrySet()) {
-            if (value.matches(entry.getKey())) {
-                try {
-                    return parse(value, entry.getValue());
-                } catch (ParseException e) {
-                    throw new IllegalArgumentException(String.format(
-                              "%s, expect format: %s",
-                              e.getMessage(), entry.getValue()));
-                }
-            }
-        }
-        throw new IllegalArgumentException(String.format(
-                  "Expected date format is: %s, but got '%s'",
-                  VALID_DFS.values(), value));
-    }
-
-    public static Date parse(String value, String df) throws ParseException {
-        SafeDateFormat dateFormat = getDateFormat(df);
-        return dateFormat.parse(value);
-    }
-
-    public static Date now() {
-        return new Date();
-    }
-
-    private static SafeDateFormat getDateFormat(String df) {
-        SafeDateFormat dateFormat = DATE_FORMATS.get(df);
-        if (dateFormat == null) {
-            dateFormat = new SafeDateFormat(df);
-            /*
-             * Specify whether or not date/time parsing is to be lenient.
-             * With lenient parsing, the parser may use heuristics to interpret
-             * inputs that do not precisely match this object's format.
-             * With strict parsing, inputs must match this object's format.
-             */
-            dateFormat.setLenient(false);
-            SafeDateFormat previous = DATE_FORMATS.putIfAbsent(df, dateFormat);
-            if (previous != null) {
-                dateFormat = previous;
-            }
-        }
-        return dateFormat;
-    }
-
-    public static Object toPattern(String df) {
-        SafeDateFormat dateFormat = getDateFormat(df);
-        return dateFormat.toPattern();
-    }
-}
diff --git a/hugegraph-dist/pom.xml b/hugegraph-dist/pom.xml
index 49ce1f4b9..582db5ec2 100644
--- a/hugegraph-dist/pom.xml
+++ b/hugegraph-dist/pom.xml
@@ -64,11 +64,6 @@
             <artifactId>hugegraph-postgresql</artifactId>
             <version>${project.version}</version>
         </dependency>
-        <dependency>
-            <groupId>io.airlift</groupId>
-            <artifactId>airline</artifactId>
-            <version>0.6</version>
-        </dependency>
 
         <dependency>
             <groupId>org.apache.tinkerpop</groupId>
diff --git a/hugegraph-palo/src/main/java/com/baidu/hugegraph/backend/store/palo/PaloHttpClient.java b/hugegraph-palo/src/main/java/com/baidu/hugegraph/backend/store/palo/PaloHttpClient.java
index 76c828200..6f46b26f0 100644
--- a/hugegraph-palo/src/main/java/com/baidu/hugegraph/backend/store/palo/PaloHttpClient.java
+++ b/hugegraph-palo/src/main/java/com/baidu/hugegraph/backend/store/palo/PaloHttpClient.java
@@ -26,6 +26,7 @@ import javax.ws.rs.core.MultivaluedMap;
 import javax.ws.rs.core.Response;
 
 import com.baidu.hugegraph.config.HugeConfig;
+import com.baidu.hugegraph.rest.AbstractRestClient;
 import com.baidu.hugegraph.rest.RestClient;
 import com.google.common.collect.ImmutableMap;
 
@@ -60,7 +61,7 @@ public class PaloHttpClient {
         this.client.put(path, body, headers, params);
     }
 
-    private static class Client extends RestClient {
+    private static class Client extends AbstractRestClient {
 
         private static final int SECOND = 1000;
 
diff --git a/pom.xml b/pom.xml
index d4856077e..a48c26f70 100644
--- a/pom.xml
+++ b/pom.xml
@@ -100,7 +100,7 @@
         <junit.version>4.12</junit.version>
         <tinkerpop.version>3.4.3</tinkerpop.version>
         <commons.io.version>2.4</commons.io.version>
-        <guava.version>19.0</guava.version>
+        <guava.version>25.1-jre</guava.version>
         <httpclient.version>4.5.2</httpclient.version>
         <jersey.version>2.25.1</jersey.version>
         <metrics.version>3.1.0</metrics.version>