add dubbo-samples-seata (#650)

at-sample/dubbo-samples-seata/README.md

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+
+在Dubbo中可以使用Seata来实现分布式事务功能
+
+## 开始之前
+Apache Seata 是一款开源的分布式事务解决方案，致力于在微服务架构下提供高性能和简单易用的分布式事务服务。
+在Dubbo中集成Seata实现分布式事务非常方便，只需简单几步即可完成，本文将带你快速体验。开始前，请先完成以下内容:
+- 请克隆[seata-samples](https://github.com/apache/incubator-seata-samples)至本地并导入到开发工具中，并找到/at-sample/dubbo-samples-seata子项目。
+- 请下载最新版的[seata-server二进制包](https://seata.apache.org/zh-cn/unversioned/download/seata-server)至本地。
+
+
+### 步骤 1：建立数据库并初始化相关测试数据
+- 本文将使用MySQL 5.7 (更多支持的数据库可在文末查看附录)。
+  进入dubbo-samples-seata的script目录，找到dubbo_biz.sql和undo_log.sql两个数据库脚本文件，内容如下:
+
+undo_log.sql是Seata AT 模式需要 `UNDO_LOG` 表
+```sql
+-- for AT mode you must to init this sql for you business database. the seata server not need it.
+CREATE TABLE IF NOT EXISTS `undo_log`
+(
+    `branch_id`     BIGINT       NOT NULL COMMENT 'branch transaction id',
+    `xid`           VARCHAR(128) NOT NULL COMMENT 'global transaction id',
+    `context`       VARCHAR(128) NOT NULL COMMENT 'undo_log context,such as serialization',
+    `rollback_info` LONGBLOB     NOT NULL COMMENT 'rollback info',
+    `log_status`    INT(11)      NOT NULL COMMENT '0:normal status,1:defense status',
+    `log_created`   DATETIME(6)  NOT NULL COMMENT 'create datetime',
+    `log_modified`  DATETIME(6)  NOT NULL COMMENT 'modify datetime',
+    UNIQUE KEY `ux_undo_log` (`xid`, `branch_id`)
+    ) ENGINE = InnoDB AUTO_INCREMENT = 1 DEFAULT CHARSET = utf8mb4 COMMENT ='AT transaction mode undo table';
+ALTER TABLE `undo_log` ADD INDEX `ix_log_created` (`log_created`);
+
+```
+dubbo_biz.sql是示例业务表以及初始化数据
+
+```sql
+DROP TABLE IF EXISTS `stock_tbl`;
+CREATE TABLE `stock_tbl`
+(
+    `id`             int(11) NOT NULL AUTO_INCREMENT,
+    `commodity_code` varchar(255) DEFAULT NULL,
+    `count`          int(11) DEFAULT 0,
+    PRIMARY KEY (`id`),
+    UNIQUE KEY (`commodity_code`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8;
+
+
+DROP TABLE IF EXISTS `order_tbl`;
+CREATE TABLE `order_tbl`
+(
+    `id`             int(11) NOT NULL AUTO_INCREMENT,
+    `user_id`        varchar(255) DEFAULT NULL,
+    `commodity_code` varchar(255) DEFAULT NULL,
+    `count`          int(11) DEFAULT 0,
+    `money`          int(11) DEFAULT 0,
+    PRIMARY KEY (`id`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8;
+
+
+DROP TABLE IF EXISTS `account_tbl`;
+CREATE TABLE `account_tbl`
+(
+    `id`      int(11) NOT NULL AUTO_INCREMENT,
+    `user_id` varchar(255) DEFAULT NULL,
+    `money`   int(11) DEFAULT 0,
+    PRIMARY KEY (`id`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8;
+
+---INITIALIZE THE ACCOUNT TABLE
+INSERT INTO account_tbl(`user_id`,`money`) VALUES('ACC_001','1000');
+---INITIALIZE THE STOCK TABLE
+INSERT INTO stock_tbl(`commodity_code`,`count`) VALUES('STOCK_001','100');
+
+```
+#### 请依次执行以下操作:
+* 1.1 创建seata数据库(实际业务场景中会使用不同的数据库，本文为了方便演示仅创建一个数据库，所有的表都在该数据库中创建)
+* 1.2 执行undo_log.sql表中的脚本完成AT模式所需的undo_log表创建
+* 1.3 执行dubbo_biz.sql表中的脚本完成示例业务表创建以及测试数据的初始化
+
+### 步骤 2：更新spring-boot应用配置中的数据库连接信息
+
+请将以下3个子模块的数据库连接信息更新为你的信息，其他配置无需更改，至此，客户端的配置已经完毕。
+
+* dubbo-samples-seata-account
+* dubbo-samples-seata-order
+* dubbo-samples-seata-stock
+```yaml
+url: jdbc:mysql://127.0.0.1:3306/seata?serverTimezone=Asia/Shanghai&useSSL=false&useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useOldAliasMetadataBehavior=true
+username: root
+password: 123456
+```
+
+### 步骤 3：启动Seata-Server
+- 本文使用的是Seata-Server V2.0.0版本。
+
+请将下载的Seata-Server二进制包解压，并进入bin目录，然后执行以下命令即可启动Seata-Server。
+
+如果你是Mac OS 或者Linux操作系统，请执行:
+```
+./seata-server.sh
+```
+或者你是Windows操作系统，请执行:
+```
+./seata-server.bat
+```
+
+### 步骤 4：启动示例
+
+一切准备就绪，开始启动示例
+
+#### 请依次启动以下子项目:
+* 4.1 Account Service
+* 4.2 Order Service
+* 4.3 Stock Service
+* 4.4 Business Service
+
+### 步骤 5：查看分布式事务执行结果
+通过访问以下链接，可以测试分布式事务成功提交流程:
+
+http://127.0.0.1:9999/test/commit?userId=ACC_001&commodityCode=STOCK_001&orderCount=1
+
+**分布式事务成功提交时，业务表的数据将正常更新，请注意观察数据库表中的数据。**
+
+通过访问以下链接，可以测试分布式事务失败回滚流程:
+
+http://127.0.0.1:9999/test/rollback?userId=ACC_001&commodityCode=STOCK_001&orderCount=1
+
+**分布式事务失败回滚时，业务表的数据将没有任何改变，请注意观察数据库表中的数据。**
+
+### 附录
+* 支持的事务模式:Seata目前支持AT、TCC、SAGA、XA等模式，详情请访问[Seata官网](https://seata.apache.org/zh-cn/docs/user/mode/at)进行了解
+* 支持的配置中心:Seata支持丰富的配置中心，如zookeeper、nacos、consul、apollo、etcd、file(本文使用此配置中心，无需第三方依赖，方便快速演示)，详情请访问[Seata配置中心](https://seata.apache.org/zh-cn/docs/user/configuration/)进行了解
+* 支持的注册中心:Seata支持丰富的注册中心，如eureka、sofa、redis、zookeeper、nacos、consul、etcd、file(本文使用此注册中心，无需第三方依赖，方便快速演示)，详情请访问[Seata注册中心](https://seata.apache.org/zh-cn/docs/user/registry/)进行了解
+* 支持的部署方式:直接部署、Docker、K8S、Helm等部署方式，详情请访问[Seata部署方式](https://seata.apache.org/zh-cn/docs/ops/deploy-guide-beginner)进行了解
+* 支持的API:Seata的API分为两大类：High-Level API 和 Low-Level API，详情请访问[Seata API](https://seata.apache.org/zh-cn/docs/user/api)进行了解
+* 支持的数据库:Seata支持MySQL、Oracle、PostgreSQL、TiDB、MariaDB等数据库，不同的事务模式会有差别，详情请访问[Seata支持的数据库](https://seata.apache.org/zh-cn/docs/user/datasource)进行了解
+* 支持ORM框架:Seata 虽然是保证数据一致性的组件，但对于 ORM 框架并没有特殊的要求，像主流的Mybatis，Mybatis-Plus，Spring Data JPA, Hibernate等都支持。这是因为ORM框架位于JDBC结构的上层，而 Seata 的 AT,XA 事务模式是对 JDBC 标准接口操作的拦截和增强。详情请访问[Seata支持的ORM框架](https://seata.apache.org/zh-cn/docs/user/ormframework)进行了解
+* 支持的微服务框架:Seata目前支持Dubbo、gRPC、hsf、http、motan、sofa等框架，同时seata提供了丰富的拓展机制，理论上可以支持任何微服务框架。详情请访问[Seata支持的微服务框架](https://seata.apache.org/zh-cn/docs/user/microservice)进行了解
+* SQL限制:Seata 事务目前支持 INSERT、UPDATE、DELETE 三类 DML 语法的部分功能，这些类型都是已经经过Seata开源社区的验证。SQL 的支持范围还在不断扩大，建议在本文限制的范围内使用。详情请访问[Seata SQL限制](https://seata.apache.org/zh-cn/docs/user/sqlreference/sql-restrictions)进行了解

at-sample/dubbo-samples-seata/dubbo-samples-seata-account/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  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.
+  -->
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <groupId>org.apache.dubbo</groupId>
+        <artifactId>dubbo-samples-seata</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+    <artifactId>dubbo-samples-seata-account</artifactId>
+    <name>dubbo-samples-seata-account</name>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.dubbo</groupId>
+            <artifactId>dubbo-samples-seata-api</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.dubbo</groupId>
+            <artifactId>dubbo-spring-boot-starter</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.mysql</groupId>
+            <artifactId>mysql-connector-j</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-jdbc</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.seata</groupId>
+            <artifactId>seata-spring-boot-starter</artifactId>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>3.8.1</version>
+                <configuration>
+                    <source>1.8</source>
+                    <target>1.8</target>
+                    <encoding>UTF-8</encoding>
+                </configuration>
+            </plugin>
+            <plugin>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-maven-plugin</artifactId>
+                <version>${spring-boot.version}</version>
+                <configuration>
+                    <mainClass>org.apache.dubbo.samples.seata.account.AccountApplication</mainClass>
+                </configuration>
+                <executions>
+                    <execution>
+                        <id>repackage</id>
+                        <goals>
+                            <goal>repackage</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

at-sample/dubbo-samples-seata/dubbo-samples-seata-account/src/main/java/org/apache/dubbo/samples/seata/account/AccountApplication.java

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+/*
+ *   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 org.apache.dubbo.samples.seata.account;
+
+import org.apache.dubbo.config.spring.context.annotation.EnableDubbo;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+@EnableDubbo
+public class AccountApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(AccountApplication.class, args);
+    }
+
+}

at-sample/dubbo-samples-seata/dubbo-samples-seata-account/src/main/java/org/apache/dubbo/samples/seata/account/service/AccountServiceImpl.java

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+/*
+ *   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 org.apache.dubbo.samples.seata.account.service;
+
+import io.seata.core.context.RootContext;
+import org.apache.dubbo.config.annotation.DubboService;
+import org.apache.dubbo.samples.seata.api.AccountService;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.jdbc.core.JdbcTemplate;
+
+@DubboService
+public class AccountServiceImpl implements AccountService {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(AccountService.class);
+
+    private final JdbcTemplate jdbcTemplate;
+
+    public AccountServiceImpl(JdbcTemplate jdbcTemplate) {
+        this.jdbcTemplate = jdbcTemplate;
+    }
+
+    @Override
+    public void debit(String userId, int money) {
+        LOGGER.info("Account Service ... xid: " + RootContext.getXID());
+        LOGGER.info("Deducting balance SQL: update account_tbl set money = money - {} where user_id = {}", money,
+                userId);
+
+        jdbcTemplate.update("update account_tbl set money = money - ? where user_id = ?", new Object[]{money, userId});
+        LOGGER.info("Account Service End ... ");
+    }
+
+}

at-sample/dubbo-samples-seata/dubbo-samples-seata-account/src/main/resources/application.yml

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+# 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.
+spring:
+    application:
+        name: AccountApplication
+    datasource:
+        driver-class-name: com.mysql.cj.jdbc.Driver
+        url: jdbc:mysql://${mysql.address:127.0.0.1}:${mysql.port:3306}/seata?serverTimezone=Asia/Shanghai&useSSL=false&useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useOldAliasMetadataBehavior=true
+        username: root
+        password: helloworld
+        hikari:
+            connection-timeout: 30000
+            idle-timeout: 600000
+            max-lifetime: 1800000
+            maximum-pool-size: 100
+            minimum-idle: 10
+            pool-name: HikaraPool-1
+dubbo:
+    application:
+        logger: slf4j
+        name: ${spring.application.name}
+        qos-enable: false
+    registry:
+        address: multicast://224.5.6.7:1234
+    protocol:
+        port: 20881
+        name: dubbo
+seata:
+    enabled: true
+    application-id: dubbo-samples-seata
+    tx-service-group: default_tx_group
+    service:
+        vgroup-mapping:
+            default_tx_group: default
+        grouplist:
+            default: ${seata.address:127.0.0.1}:${seata.port:8091}
+    registry:
+        type: file
+    config:
+        type: file

at-sample/dubbo-samples-seata/dubbo-samples-seata-account/src/test/java/org/apache/dubbo/samples/seata/AccountApplicationTests.java

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+/*
+ *   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 org.apache.dubbo.samples.seata;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.test.context.SpringBootTest;
+
+@SpringBootTest
+class AccountApplicationTests {
+
+    @Test
+    void contextLoads() {
+    }
+
+}