DTM tutorial

SDK

Supported languages

go

Repository client here are a copy of the contents inside the dtm project. Using the packages here, instead of dtm, will give your application fewer dependencies and smaller packages

client: https://github.com/dtm-labs/client

Minimalist example: https://github.com/dtm-labs/quick-start-sample

The most complete examples of SDK usage, including grpc/http/xa/msg/saga/tcc/barrier, etc., are combined in the following project

https://github.com/dtm-labs/dtm-examples

php

Client sdk concurrent version (supports Hyperf, SAGA, TCC, MSG, XA, subtransaction barriers) https://github.com/dtm-php/dtm-client

Example: https://github.com/dtm-php/dtm-sample

The above SDK is designed and reviewed by Huang Chaohui, a famous coder in PHP, and is mainly contributed by (PandaLIU-1111)[https://github.com/PandaLIU-1111]. It is with high code quality and has a active community, and also recommended by the founder of Swool.

Common client sdk (currently only support TCC): https://github.com/dtm-labs/dtmcli-php

Example: https://github.com/dtm-labs/dtmcli-php-sample

Thanks to onlyshow for help with the php sdk and examples, mainly done by him

dotnet

Client sdk http version (supports TCC, SAGA, MSG, subtransaction barriers): https://github.com/dtm-labs/dtmcli-csharp

Example: https://github.com/dtm-labs/dtmcli-csharp-sample

Thanks to catcherwong, geffzhang for their help with the C sdk and examples, mainly contributed by them

Client-side sdk grpc version: https://github.com/catcherwong/dtmgrpc-csharp

python

Client sdk (currently supports TCC, SAGA, subtransaction barriers): https://github.com/dtm-labs/dtmcli-py

Example: https://github.com/dtm-labs/dtmcli-py-sample

Java

Client sdk (TCC, subtransaction barrier): https://github.com/dtm-labs/dtmcli-java

Example: https://github.com/dtm-labs/dtmcli-java-sample

Thanks to li-xiao-shuang, viticis for their help with the Java sdk and examples, mainly contributed by them

node

Client sdk (currently only supports TCC): https://github.com/dtm-labs/dtmcli-node

Example: https://github.com/dtm-labs/dtmcli-node-sample

Other

If you don't find a language you are familiar with here, and you want to run dtm to see what a distributed transaction looks like, you can refer here.

DTM installation and operation

If you are installing via brew, then you can just run

dtm-qs

The above dtm-qs command will run a simple quick start example, which is a saga transaction, you can compare the saga timing diagram and logs to get a deeper understanding of dtm

Supported databases

The SDK of dtm provides subtransaction barrier function and also provides XA related support, this part of the support is related to the specific database. Currently several common database transactions are supported, including Mysql series, Postgres, Redis, Mongo and more database transactions will be considered for access in the future

Mysql series

including Mysql, MariaDB, TiDB, TDSQL

Postgres

Postgres is fully supported, if you use Postgres, you need to make the following calls before using the SDK

dtmcli.SetCurrentDBType("postgres")

For a detailed example, you can refer to the code in dtm/app/main.go

Redis

DTM has supported Redis transactions, so that users can use a combination of Redis and Mysql in a distributed transaction, you can put the deducted inventory in Redis, to provide accurate deducted inventory architecture, so that the order system can easily cope with the spike scenario

Mongo

DTM has supported Mongo

ORM access

Overview

The subtransaction barrier in dtm, which requires interaction with the database, and the xa transaction model, which also requires interaction with the database. The current interaction interface defined by dtm adopts a standard library sql compatible way, users can pass sql.DB/sql.Tx directly.

Because the barrier needs to manipulate the barrier-related tables inside the transaction, its interface needs to be passed a *sql.Tx or *sql.

func (bb *BranchBarrier) Call(tx *sql.Tx, busiCall BusiFunc) error
func (bb *BranchBarrier) CallWithDB(db *sql.DB, busiCall BusiFunc) error

In Xa transaction mode, the local database connection is created and managed by dtmcli, so the argument type for calling the callback function is *sql.DB . If you are using another library, such as gorm, then you can just build the relevant orm object based on *sql.DB.

type XaLocalFunc func(db *sql.DB, xa *Xa) (interface{}, error)

The current dtm example, only shows how to use gorm. Other orm's access is only described here.

GORM

Example in dtm-examples

barrier example.

  barrier := MustBarrierFromGin(c)
  // gdb is a *gorm.DB
  tx := gdb.Begin()
	return dtmcli.ResultSuccess, barrier.Call(tx.Statement.ConnPool.(*sql.Tx), func(tx1 *sql.Tx) error {
		return tx.Exec("update dtm_busi.user_account set balance = balance + ? where user_id = ?" , -req.Amount, 2).Error
	})

xa Example.

  dtmcli.XaLocalTransaction(c.Request.URL.Query(), BusiConf, func(db *sql.DB, xa *dtmcli.Xa) error {
    // gorm provides an interface to construct gorm.DB from the standard sql.
    gdb, err := gorm.Open(mysql.New(mysql.Config{
      Conn: db,
    }), &gorm.Config{})
    if err ! = nil {
      return nil, err
    }
    dbr := gdb.Exec("update dtm_busi.user_account set balance=balance-? where user_id=?" , reqFrom(c).Amount, 1)
    return dbr.Error
  })

GOQU

Example of a barrier.

	dialect := goqu.Dialect("mysql")
	sdb, err := dbGet().DB.DB()
	if err ! = nil {
		return nil, err
  }
  gdb := dialect.DB(sdb)
  // gdb is goqu dialect.DB, the following code shows how to get tx
	tx, err := gdb.Begin()
	return dtmcli.ResultSuccess, barrier.Call(tx, func(tx1 *sql.Tx) error {
		_, err := tx.Exec("update dtm_busi.user_account set balance = balance + ? where user_id = ? ", -req.Amount, 2)
		Return err
	})

xa example

  dtmcli.XaLocalTransaction(c.Request.URL.Query(), BusiConf, func(db *sql.DB, xa *dtmcli.Xa) error {
    dialect := goqu.Dialect("mysql")
    godb := dialect.DB(db)
    _, err := godb.Exec("update dtm_busi.user_account set balance=balance-? where user_id=?" , reqFrom(c).Amount, 1)
    return err
  })

XORM

Example of an barrier.

	x, _ := xorm.NewEngineWithDB("mysql", "dtm", core.FromDB(sdbGet()) )
	se := x.NewSession()
	defer se.Close()
	err := se.Begin()
	if err ! = nil {
		return nil, err
	}
  // se is an xorm session, the following code shows how to get tx
	return dtmcli.ResultSuccess, barrier.Call(se.Tx().Tx, func(tx1 *sql.Tx) error {
		_, err := se.Exec("update dtm_busi.user_account set balance = balance + ? where user_id = ? ", -req.Amount, 2)
		Return err
	})

xa example

  return dtmcli.XaLocalTransaction(c.Request.URL.Query(), BusiConf, func(db *sql.DB, xa *dtmcli.Xa) error {
    xdb, _ := xorm.NewEngineWithDB("mysql", "dtm", core.FromDB(db))
    _, err := xdb.Exec("update dtm_busi.user_account set balance=balance-? where user_id=?" , reqFrom(c).Amount, 1)
    return err
  })

go-zero

Example of a barrier.

  // Assuming conn is sqlx.SqlConn inside go-zero
  db, err := conn.RawDB()
  if err ! = nil {
    return err
  }
	return dtmcli.ResultSuccess, barrier.CallWithDB(db, func(tx *sql.Tx) error {
		_, err := tx.Exec("update dtm_busi.user_account set balance = balance + ? where user_id = ? ", -req.Amount, 2)
		Return err
	})

xa example

  return dtmcli.XaLocalTransaction(c.Request.URL.Query(), BusiConf, func(db *sql.DB, xa *dtmcli.Xa) error {
    conn := NewSqlConnFromDB(db)
    _, err := conn.Exec("update dtm_busi.user_account set balance=balance-? where user_id=?" , reqFrom(c).Amount, 1)
    return err
  })

ent

Can be supported, code example to be added