Abstract: A proxy simulation service can be used to test a complex system, such as a fulfillment network, that depends on upstream and downstream processes in order to operate. The proxy simulation service can be configured to send an event, such as an order request, so as to appear to be sent from a process upstream of the system; and can be configured to receive a request from the system, such as a request to charge payment information, so as to appear as a downstream process of the system. The proxy simulation service can then simulate a response to the received system request based on the request and on state information related to the request. The simulated response can then be sent to the system being tested.

Abstract: A workflow management system can be implemented by one or more computing systems or services. The workflow management system may be used with a variety of different types of workflows, such as one or more fulfillment systems. The fulfillment systems can be any type of fulfillment system. For example, the fulfillment systems may fulfill orders for digital items, physical products, gifts, services, or a combination of digital products, physical products, services, and/or gifts. The orders may be electronic orders, orders placed via phone or mail, or the like.