ML 2 Foundation concepts for activity diagrams, there are eight object nodes in total. Here's a breakdown of the elements:
Object Nodes:
* Order: This rectangle near the start of the diagram represents an object node.
* Cust Name: This rectangle following the "Get Customer Details" action is another object node.
* Order Details: This rectangle after the "Get Order Details" action is an object node as well.
* New Order: The rectangle positioned after the decision diamond (approved) is an object node.
* Repeat (text near the decision diamond): This is not an object node. It likely indicates a loopback or repetition, but it doesn't represent an object itself.
* Cust Order: The rectangle after the "Place Order" action is an object node.
* Invoice: The rectangle following the "Create Invoice" action is an object node.
* OrderAck: The rectangle at the end signifies another object node.
Counting the Nodes:
There are eight rectangles that represent object nodes in the diagram (Order, Cust Name, Order Details, New Order, Cust Order, Invoice, OrderAck).
References
* UML 2.5.1 Specification (Superstructure): Sections on Activity Diagrams and Object Nodes https://www.omg.org/spec/UML/2.5.1/