????????上篇講述gateway的部署和使用，gateway統(tǒng)一管理和轉(zhuǎn)發(fā)了HTTP請求，在互聯(lián)網(wǎng)中大型項目一定存在復(fù)雜的業(yè)務(wù)關(guān)系，尤其在商城類軟件中如淘寶、PDD等商城，尤其在秒殺場景中，并發(fā)量可以到達千萬級別，此時數(shù)據(jù)庫就會顯得很無力。

? ? ? ? 以Mysql為例，熟悉數(shù)據(jù)庫的童鞋都知道數(shù)據(jù)庫有原子性、隔離性、一致性、持久性四大特性，隔離級別分為臟讀、幻讀、可重復(fù)讀、序列化四種。Mysql默認的隔離級別在可重復(fù)讀，在高并發(fā)中顯然會出現(xiàn)大量可重復(fù)度數(shù)據(jù)，分布式數(shù)據(jù)庫顯然是最適合的解決方案?。

1、Seata介紹

? ? ? ? Seata是一款開源的分布式事務(wù)解決方案，致力于提供高性能和簡單易用的分布式事務(wù)服務(wù)。Seata 將為用戶提供了 AT、TCC、SAGA 和 XA 事務(wù)模式，為用戶打造一站式的分布式解決方案。

模式
TC? - 事務(wù)協(xié)調(diào)者	維護全局和分支事務(wù)的狀態(tài)，驅(qū)動全局事務(wù)提交或回滾。
TM - 事務(wù)管理器	RM (Resource Manager) - 資源管理器
RM? - 資源管理器	管理分支事務(wù)處理的資源，與TC交談以注冊分支事務(wù)和報告分支事務(wù)的狀態(tài)，并驅(qū)動分支事務(wù)提交或回滾。

2、Seata服務(wù)部署

? ? ? ? 官網(wǎng)鏈接：http://seata.io/zh-cn/

? ? ? ? seata數(shù)據(jù)庫腳本：https://github.com/seata/seata/blob/1.5.2/script/server/db/mysql.sql

? ? ? ? seata配置文件：https://github.com/seata/seata/blob/1.5.2/script/config-center/config.txt

? ? ? ? 下載seata的壓縮包，并且解壓，在seata/script/server/db/下找到sql腳本

????????在mysql中創(chuàng)建名為seata的數(shù)據(jù)庫，并執(zhí)行腳本：

-- -------------------------------- The script used when storeMode is 'db' --------------------------------
-- the table to store GlobalSession data
CREATE TABLE IF NOT EXISTS `global_table`
(`xid`                       VARCHAR(128) NOT NULL,`transaction_id`            BIGINT,`status`                    TINYINT      NOT NULL,`application_id`            VARCHAR(32),`transaction_service_group` VARCHAR(32),`transaction_name`          VARCHAR(128),`timeout`                   INT,`begin_time`                BIGINT,`application_data`          VARCHAR(2000),`gmt_create`                DATETIME,`gmt_modified`              DATETIME,PRIMARY KEY (`xid`),KEY `idx_status_gmt_modified` (`status` , `gmt_modified`),KEY `idx_transaction_id` (`transaction_id`)
) ENGINE = InnoDBDEFAULT CHARSET = utf8mb4;-- the table to store BranchSession data
CREATE TABLE IF NOT EXISTS `branch_table`
(`branch_id`         BIGINT       NOT NULL,`xid`               VARCHAR(128) NOT NULL,`transaction_id`    BIGINT,`resource_group_id` VARCHAR(32),`resource_id`       VARCHAR(256),`branch_type`       VARCHAR(8),`status`            TINYINT,`client_id`         VARCHAR(64),`application_data`  VARCHAR(2000),`gmt_create`        DATETIME(6),`gmt_modified`      DATETIME(6),PRIMARY KEY (`branch_id`),KEY `idx_xid` (`xid`)
) ENGINE = InnoDBDEFAULT CHARSET = utf8mb4;-- the table to store lock data
CREATE TABLE IF NOT EXISTS `lock_table`
(`row_key`        VARCHAR(128) NOT NULL,`xid`            VARCHAR(128),`transaction_id` BIGINT,`branch_id`      BIGINT       NOT NULL,`resource_id`    VARCHAR(256),`table_name`     VARCHAR(32),`pk`             VARCHAR(36),`status`         TINYINT      NOT NULL DEFAULT '0' COMMENT '0:locked ,1:rollbacking',`gmt_create`     DATETIME,`gmt_modified`   DATETIME,PRIMARY KEY (`row_key`),KEY `idx_status` (`status`),KEY `idx_branch_id` (`branch_id`),KEY `idx_xid_and_branch_id` (`xid` , `branch_id`)
) ENGINE = InnoDBDEFAULT CHARSET = utf8mb4;CREATE TABLE IF NOT EXISTS `distributed_lock`
(`lock_key`       CHAR(20) NOT NULL,`lock_value`     VARCHAR(20) NOT NULL,`expire`         BIGINT,primary key (`lock_key`)
) ENGINE = InnoDBDEFAULT CHARSET = utf8mb4;INSERT INTO `distributed_lock` (lock_key, lock_value, expire) VALUES ('AsyncCommitting', ' ', 0);
INSERT INTO `distributed_lock` (lock_key, lock_value, expire) VALUES ('RetryCommitting', ' ', 0);
INSERT INTO `distributed_lock` (lock_key, lock_value, expire) VALUES ('RetryRollbacking', ' ', 0);
INSERT INTO `distributed_lock` (lock_key, lock_value, expire) VALUES ('TxTimeoutCheck', ' ', 0);

????????在seata/script/config-center/下找到config.txt?配置文件。

????????seata需要集成到微服務(wù)中去，所以配置文件我們依然使用nacos管理。

#For details about configuration items, see https://seata.io/zh-cn/docs/user/configurations.html
#Transport configuration, for client and server
transport.type=TCP
transport.server=NIO
transport.heartbeat=true
transport.enableTmClientBatchSendRequest=false
transport.enableRmClientBatchSendRequest=true
transport.enableTcServerBatchSendResponse=false
transport.rpcRmRequestTimeout=30000
transport.rpcTmRequestTimeout=30000
transport.rpcTcRequestTimeout=30000
transport.threadFactory.bossThreadPrefix=NettyBoss
transport.threadFactory.workerThreadPrefix=NettyServerNIOWorker
transport.threadFactory.serverExecutorThreadPrefix=NettyServerBizHandler
transport.threadFactory.shareBossWorker=false
transport.threadFactory.clientSelectorThreadPrefix=NettyClientSelector
transport.threadFactory.clientSelectorThreadSize=1
transport.threadFactory.clientWorkerThreadPrefix=NettyClientWorkerThread
transport.threadFactory.bossThreadSize=1
transport.threadFactory.workerThreadSize=default
transport.shutdown.wait=3
transport.serialization=seata
transport.compressor=none#Transaction routing rules configuration, only for the client
service.vgroupMapping.default_tx_group=default
#If you use a registry, you can ignore it
service.default.grouplist=127.0.0.1:8091
service.enableDegrade=false
service.disableGlobalTransaction=false#Transaction rule configuration, only for the client
client.rm.asyncCommitBufferLimit=10000
client.rm.lock.retryInterval=10
client.rm.lock.retryTimes=30
client.rm.lock.retryPolicyBranchRollbackOnConflict=true
client.rm.reportRetryCount=5
client.rm.tableMetaCheckEnable=true
client.rm.tableMetaCheckerInterval=60000
client.rm.sqlParserType=druid
client.rm.reportSuccessEnable=false
client.rm.sagaBranchRegisterEnable=false
client.rm.sagaJsonParser=fastjson
client.rm.tccActionInterceptorOrder=-2147482648
client.tm.commitRetryCount=5
client.tm.rollbackRetryCount=5
client.tm.defaultGlobalTransactionTimeout=60000
client.tm.degradeCheck=false
client.tm.degradeCheckAllowTimes=10
client.tm.degradeCheckPeriod=2000
client.tm.interceptorOrder=-2147482648
client.undo.dataValidation=true
client.undo.logSerialization=jackson
client.undo.onlyCareUpdateColumns=true
server.undo.logSaveDays=7
server.undo.logDeletePeriod=86400000
client.undo.logTable=undo_log
client.undo.compress.enable=true
client.undo.compress.type=zip
client.undo.compress.threshold=64k
#For TCC transaction mode
tcc.fence.logTableName=tcc_fence_log
tcc.fence.cleanPeriod=1h#Log rule configuration, for client and server
log.exceptionRate=100#Transaction storage configuration, only for the server. The file, DB, and redis configuration values are optional.
store.mode=file
store.lock.mode=file
store.session.mode=file
#Used for password encryption
store.publicKey=#If `store.mode,store.lock.mode,store.session.mode` are not equal to `file`, you can remove the configuration block.
store.file.dir=file_store/data
store.file.maxBranchSessionSize=16384
store.file.maxGlobalSessionSize=512
store.file.fileWriteBufferCacheSize=16384
store.file.flushDiskMode=async
store.file.sessionReloadReadSize=100#These configurations are required if the `store mode` is `db`. If `store.mode,store.lock.mode,store.session.mode` are not equal to `db`, you can remove the configuration block.
store.db.datasource=druid
store.db.dbType=mysql
store.db.driverClassName=com.mysql.jdbc.Driver
store.db.url=jdbc:mysql://127.0.0.1:3306/seata?useUnicode=true&rewriteBatchedStatements=true
store.db.user=username
store.db.password=password
store.db.minConn=5
store.db.maxConn=30
store.db.globalTable=global_table
store.db.branchTable=branch_table
store.db.distributedLockTable=distributed_lock
store.db.queryLimit=100
store.db.lockTable=lock_table
store.db.maxWait=5000#These configurations are required if the `store mode` is `redis`. If `store.mode,store.lock.mode,store.session.mode` are not equal to `redis`, you can remove the configuration block.
store.redis.mode=single
store.redis.single.host=127.0.0.1
store.redis.single.port=6379
store.redis.sentinel.masterName=
store.redis.sentinel.sentinelHosts=
store.redis.maxConn=10
store.redis.minConn=1
store.redis.maxTotal=100
store.redis.database=0
store.redis.password=
store.redis.queryLimit=100#Transaction rule configuration, only for the server
server.recovery.committingRetryPeriod=1000
server.recovery.asynCommittingRetryPeriod=1000
server.recovery.rollbackingRetryPeriod=1000
server.recovery.timeoutRetryPeriod=1000
server.maxCommitRetryTimeout=-1
server.maxRollbackRetryTimeout=-1
server.rollbackRetryTimeoutUnlockEnable=false
server.distributedLockExpireTime=10000
server.xaerNotaRetryTimeout=60000
server.session.branchAsyncQueueSize=5000
server.session.enableBranchAsyncRemove=false
server.enableParallelRequestHandle=false#Metrics configuration, only for the server
metrics.enabled=false
metrics.registryType=compact
metrics.exporterList=prometheus
metrics.exporterPrometheusPort=9898

?????????將上面seata的t配置文件config.tx導(dǎo)入到nacos：

????????修改seata的配置文件內(nèi)容 ：

# 修改store.mode為db，配置數(shù)據(jù)庫連接
store.mode=db
store.db.dbType=mysql
store.db.driverClassName=com.mysql.cj.jdbc.Driver
store.db.url=jdbc:mysql://localhost:3306/seata?useUnicode=true&rewriteBatchedStatements=true
store.db.user=數(shù)據(jù)庫用戶名
store.db.password=數(shù)據(jù)庫密碼

? ? ? ? 在seata/config/application.yml 修改seata配置信息：

seata:config:type: nacosnacos:server-addr: 127.0.0.1:8848namespace:group: SEATA_GROUPdata-id: seataServer.propertiesregistry:type: nacospreferred-networks: 30.240.*nacos:application: seata-serverserver-addr: 127.0.0.1:8848namespace:group: SEATA_GROUPcluster: default#store:#mode: file

?????????最后到seata/bin目錄下運行seata-server.bat即可啟動seata服務(wù)。在nacos服務(wù)列表里可以看到seata已經(jīng)被注冊到nacos中：

?3、項目集成

? ? ? ? 在父級工程下創(chuàng)建seata子級工，添加seata依賴：

<dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-seata</artifactId><exclusions><exclusion><groupId>io.seata</groupId><artifactId>seata-spring-boot-starter</artifactId></exclusion></exclusions>
</dependency>
<dependency><groupId>io.seata</groupId><artifactId>seata-spring-boot-starter</artifactId><version>1.5.2</version>
</dependency>

?????????在需要使用全局事務(wù)管理的服務(wù)中添加seata子級工程依賴，在處理數(shù)據(jù)庫業(yè)務(wù)的時候添加@GlobalTransactional注解代替@Transactional注解就可以了。