Transactions

A MetaTransition also contains information about the transaction handling.

By default, each node is run in its own separate database transaction. A transaction is the same as a logical unit of work on the database. This is the 'amount of processing' between two COMMIT operations.

If several updates depend on each other in order to make sense or be consistent, then it will be incorrect to commit one to the database before the others. If an error is encountered, the data can stay in an inconsistent state. In such a case, the updates belong to one transaction and should be committed or rolled back together.

A Flag on the MetaTransition called Keep current transaction indicates that the target node is a part of the same transaction as the source node. Such a transition is represented by a solid line.

Activities joined by a transition displayed as a solid line (regardless of colour) are the part of the same transaction

Warning: The whole transaction will always either succeed or fail. So, if more than one node is a part of the same transaction and one of the nodes fails to complete, then even the 'successful' node(s) will remain 'undone'. For this reason, gathering more than one node into a transaction should be used only where appropriate.