Many integrations are based on pure messaging scenarios, that is, they do not need Orchestrations. They consist of receiving a message through an adapter, applying some form of transformations to the message, routing it to one or more subscribers, and sending them out again, using the same or another adapter. They might also require a response. In cases where that response is synchronous, and the ports are configured with the request-response message exchange pattern, this can be handled without an Orchestration. However, as soon as you require more control, you use an Orchestration. This could, for example, be when you want more control over exception handling or when an integration implies more than one logical step.

It is usually stated that Orchestrations exist to coordinate business processes. You could drop the word "business" from that. In a nutshell, the Orchestration engine is the workflow engine employed by BizTalk Server to allow you to handle various...