The general idea about workflows and triggers is to attach separate written code at a specific place. The workflow is the code (advice) that will be attached to the specific place. The triggers are hardcoded places (joinpoints) where the code can be applied.

The trigger page (setup, trigger) contains five triggers, of which
three apply to the shop module. Currently, the (shop) workflows can be placed:

• Before a confirm order,
• Before a check out, and
• After a check out.

The process between a product checkout and the order overview is presented in the following figure:

The Paypal Payment Service should be inserted before the checkout. After the confirm order page will the paypal service popup.