How many transactions can you calculate?

A maid was sent to the brook with two vessels that exactly measured $7$ pints and $11$ pints, respectively. She had to bring back exactly $2$ pints of water. What is the least number of transactions necessary?

Notes:

1. A "transaction" is filling a vessel, or emptying it, or pouring from one vessel to another.

2. The last transaction is when there is exactly $2$ pints of water in any of the vessels.