Seata submits at details in two stages

Seata Two-phase commit

And traditional 2PC The model of is similar to ,Seata Defined 3 Components to coordinate the processing of distributed transactions

1. Transaction Coordinator（TC）： Transaction coordinator , It's independent middleware , Need to deploy independently to run , It maintains the running state of global transactions , receive TM Instruction initiated commit and rollback , Responsible for working with RM Communication coordinates the submission or rollback of branch transactions .
2. Transaction Manager（TM）： Transaction manager ,TM Need to be embedded and work in the application , It is responsible for opening a global transaction , And finally to TC An instruction to initiate a global commit or global rollback .
3. Resource Manager（RM）： Control branch transactions , Responsible for branch registration , Status report , And receive the transaction coordinator TC Instructions , Drive branch （ Local ） Transaction commit and rollback .

The evolution of the two-stage submission agreement ：

A stage ： Business data and rollback logging are committed in the same local transaction , Release local locks and connection resources .

Two stages ：

Submit asynchronized , Complete... Very quickly .

Rollback is compensated by a phase of rollback log

List of new user registration points Seata Distributed transaction process ：

The specific implementation process is as follows ：

1. User service TM towards TC Request to open a global transaction , The global transaction is created successfully, and a globally unique XID.
2. User service RM towards TC register Branch business , The branch transaction performs the new user logic in the user service , And include it in XID Jurisdiction corresponding to global transaction .
3. The user service performs branch transactions , Insert a record into the user table .
4. When the logic is executed to call the integration service remotely （XID Propagate in the context of the microservice call link ）. Points service RM towards TC Register branch transactions , This branch transaction performs the logic of increasing integral , And include it in XID Jurisdiction corresponding to global transaction .
5. The points service performs branch transactions , Insert a record into the score sheet , After execution , Return to user service .
6. User service branch transaction execution completed .
7.TM towards TC Launch against XID The global commit or rollback resolution for .
8.TC Dispatch XID All branch transactions under the jurisdiction of complete the commit or rollback transaction request .

Seata Realization 2PC With the traditional 2PC The difference between

1. Architecture level , Tradition 2PC Of the plan RM It's actually in the database layer ,RM Essentially, it's the database itself , adopt XA Protocol implementation , and Seata Of RM In order to jar The package is deployed on the application side as a middleware layer .
2. Two phase submission , Tradition 2PC No matter the resolution of the second stage is commit still rollback, The locks of transactional resources should be kept to Phase2 Release when finished . and Seata The way to do this is to Phase1 Commit local transaction , This will save Phase2 Time to hold lock , Improve overall efficiency .