SQL Server Reference Guide > SQL Server 2005 - Service Broker: "If you think about how you go through your day, you'll find that you don't always stand in a line (or a queue, for my non-American readers) for everything you do. You get into your car; stop at a gas (petrol) station, which has been open all morning. That station has serviced many cars, without knowing who would come in first or last. You then drive to a coffee shop to buy a latte, again open since morning and again servicing many customers in multiple orders. You may decide not to stop at the coffee shop, or choose another. You choose one road over another to get to work, park in different parking spaces each day, and so on. Each of the 'objects' you're interacting with in your world on a day-to-day basis provides you a service, and you often have multiple choices of providers of those services.

You can set up your infrastructure to work the same way. Rather than having a single server process a purchase order for your company, you could break up the 'services' in that process and have multiple servers process the request. Your client application can ask the system which server provides a needed service and route the request to a server based on location, load, speed or security. This arrangement is called a 'Service-Oriented Architecture' or SOA, and while it takes a lot of planning and forethought to set up, it's very powerful."