processing

Many applications involve multiple processing. For example, placing an order might require reserving stock at the warehouse, processing payment, and shipping. In a fully integrated enterprise, you might be able to do all of this in one system and at one time, but most companies aren't entirely integrated. Reserving stock might require someone to physically visit the warehouse, and payment processing might involve purchase order approvals or lengthy credit checks. In these cases, it makes sense to decouple the activities into separate components and connect them with messaging.