====== Graph modifications ======

According to the [[:groimp-platform:xl-language|XL language specification]], the XL queries are applied in parallel. In order to make sure the queries and rules are applied in parallel without concurrency access, GroIMP implementation use transactions and queues.

===== Transaction =====

GroIMP transactions work as buffers of operations on the graph. A transaction includes a set of queues that contains the list of modifications to be applied on the graph.

When applied, each RGG method get a transaction automatically (created if needed) and all modifications are pushed into the queues of the current transaction.


===== Queues =====

There are four main queues: 
  * Added node
  * Deleted Node
  * Attribute changed
  * Edge changed