FireWire is capable of safely operating critical systems due to the way multiple devices interact with the bus and how the bus allocates bandwidth to the devices. FireWire is capable of both asynchronous and isochronous transfer methods at once. Isochronous data transfers are transfers for devices that require continuous, guaranteed bandwidth. In an aircraft, for instance, Isochronous devices include control of the rudder, mouse operations and data from pressure sensors outside the aircraft. All these elements require constant, uninterrupted bandwidth. To support both elements, FireWire dedicates a certain percentage to isochronous data and the rest to asynchronous data. In IEEE 1394 80% of the bus is reserved for isochronous cycles, leaving asynchronous data with a minimum of 20% of the bus.
Also from Wiki on the USB page:
USB device communication is based on pipes (logical channels). A pipe is a connection from the host controller to a logical entity, found on a device, and named an endpoint. Because pipes correspond 1-to-1 to endpoints, the terms are sometimes used interchangeably. A USB device can have up to 32 endpoints, though USB devices seldom have this many endpoints. An endpoint is built into the USB device by the manufacturer and therefore exists permanently, while a pipe may be opened and closed.
There are two types of pipes: stream and message pipes. A message pipe is bi-directional and is used for control transfers. Message pipes are typically used for short, simple commands to the device, and a status response, used, for example, by the bus control pipe number 0. A stream pipe is a uni-directional pipe connected to a uni-directional endpoint that transfers data using an isochronous, interrupt, or bulk transfer:
isochronous transfers: at some guaranteed data rate (often, but not necessarily, as fast as possible) but with possible data loss (e.g., realtime audio or video).
interrupt transfers: devices that need guaranteed quick responses (bounded latency) (e.g., pointing devices and keyboards).
bulk transfers: large sporadic transfers using all remaining available bandwidth, but with no guarantees on bandwidth or latency (e.g., file transfers).
To me, it seems a shame that so many IP lawyers got involved. I think that is the biggest issue that's killing off Firewire.