问题
JSR 907 JTA 1.2 defines the "global transaction" term:
The UserTransaction.begin method starts a global transaction and associates the transaction with the calling thread.
What does that mean? Is it the outermost transaction or what?
回答1:
Basically the difference between a local transaction and a global transaction is resource bound. A global transaction will span multiple resources. A local transaction is limited to one resource/datasource.
E.g.
In a global transaction you will write to the DB and send a message over a queue.
This is nicely explained here: http://integrationspot.blogspot.co.uk/2011/03/jta-transactions-local-and-global.html
Global Transactions (XA)
When a managed data source is configured for global transactions, it returns connections that can participate in global transactions. A global transaction (also called a distributed transaction) enlists more than one resource in the transaction.
Global Transactions provide the ability to work with multiple transactional resources (typically relational databases and message queues).
来源：https://stackoverflow.com/questions/27165900/what-is-a-global-transaction