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English | [简体中文](https://github.com/dtm-labs/dtm/blob/main/helper/README-cn.md)
# Distributed Transactions Manager
## What is DTM
DTM is a distributed transaction framework which provides cross-service eventually data consistency. It provides saga, tcc, xa, 2-phase message strategies for a variety of application scenarios. It also supports multiple languages and multiple store engine to form up a transaction as following:
## Who's using DTM (partial)
[Tencent](https://www.tencent.com/)
[Ivydad](https://ivydad.com)
[Eglass](https://epeijing.cn)
## Features
* Language-agnostic
- Suit for companies with multiple-language stacks.
Easy to write bindings for Go, Python, PHP, Node.js, Ruby, and other languages.
* Support for multiple distributed transaction solutions
- TCC, SAGA, XA, 2-phases message.
* Extremely easy to adapt
- Support HTTP and gRPC, provide easy-to-use programming interfaces, lower substantially the barrier of getting started with distributed transactions. Newcomers can adapt quickly.
* Easy to use
- Relieving developers from worrying about suspension, null compensation, idempotent transaction, and other tricky problems, the framework layer handles them all.
* Easy to deploy, easy to extend
- DTM depends only on MySQL/Redis, easy to deploy, cluster, and scale horizontally.
## [Cook Book](https://en.dtm.pub)
## Quick start
### run dtm
``` bash
git clone https://github.com/dtm-labs/dtm && cd dtm
go run main.go
```
### Start an example
Suppose we want to perform an inter-bank transfer. The operations of transfer out (TransOut) and transfer in (TransIn) are coded in separate micro-services.
Here is an example to illustrate a solution of dtm to this problem:
``` bash
git clone https://github.com/dtm-labs/dtmcli-go-sample && cd dtmcli-go-sample
go run main.go
```
## Code
### Use
``` go
// business micro-service address
const qsBusi = "http://localhost:8081/api/busi_saga"
// The address where DtmServer serves DTM, which is a url
DtmServer := "http://localhost:36789/api/dtmsvr"
req := &gin.H{"amount": 30} // micro-service payload
// DtmServer is the address of DTM micro-service
saga := dtmcli.NewSaga(DtmServer, dtmcli.MustGenGid(DtmServer)).
// add a TransOut subtraction，forward operation with url: qsBusi+"/TransOut", reverse compensation operation with url: qsBusi+"/TransOutCom"
Add(qsBusi+"/TransOut", qsBusi+"/TransOutCom", req).
// add a TransIn subtraction, forward operation with url: qsBusi+"/TransIn", reverse compensation operation with url: qsBusi+"/TransInCom"
Add(qsBusi+"/TransIn", qsBusi+"/TransInCom", req)
// submit the created saga transaction，dtm ensures all subtractions either complete or get revoked
err := saga.Submit()
```
When the above code runs, we can see in the console that services TransOut, TransIn has been called.
#### Timing diagram
A timing diagram for a successfully completed SAGA transaction would be as follows:
#### Rollback upon failure
If any forward operation fails, DTM invokes the corresponding compensating operation of each sub-transaction to roll back, after which the transaction is successfully rolled back.
Let's purposely fail the forward operation of the second sub-transaction and watch what happens
``` go
app.POST(qsBusiAPI+"/TransIn", func(c *gin.Context) {
log.Printf("TransIn")
// c.JSON(200, "")
c.JSON(409, "") // Status 409 for Failure. Won't be retried
})
```
The timing diagram for the intended failure is as follows:
## More examples
Refer to [dtm-examples](https://github.com/dtm-labs/dtm-examples).
## Slack
You can join the [DTM slack channel here](https://join.slack.com/t/dtm-w6k9662/shared_invite/zt-vkrph4k1-eFqEFnMkbmlXqfUo5GWHWw).
## Give a star! ⭐
If you think this project is good, or helpful to you, please give a star!