A High Performance Serial Bus Peer-to-Peer Data Transport Protocol (PPDT)
|Publication Date:||11 September 2003|
This is a full-use standard whose scope is the definition of a peer-to-peer data transport (PPDT) protocol between Serial Bus devices that implement ANSI INCITS 325-1998 1 . The facilities specified include, but are not limited to, the following:
- Device and service discovery. PPDT devices may use uniform discovery procedures to locate other PPDT devices on the same bus. These procedures are extensible to an interconnected net of buses, when specified by IEEE P1394.1™ [B2]. Once other PPDT devices are identified, facilities are provided to permit client applications to discover services;
- Self-configurable (plug and play) binding of device drivers to PPDT devices in a dynamic environment where users are free to insert and remove devices at will; and
- Connection management. A PPDT device [either a Serial Bus Protocol 2 (SBP-2) initiator or target] may establish and manage uni- or bi-directional connections for data transfer with other PPDT devices. The connections may be blocking or nonblocking, dependent upon application requirements, and operate independently of each other.
Although this standard was developed by printer and scanner experts, it is relevant to any application that requires efficient, peer-to-peer transport of data between SBP-2 devices.
Experience with SBP-2 has demonstrated its high efficiency for the confirmed transport of large quantities of data between two devices. For historical reasons, SBP-2 is tailored to an environment where one device is the client (initiator) and the other the server (target); this is not necessarily the most natural approach when client applications and their associated servers may be located within initiator, target or both. Because SBP- 2 is already widely implemented in operating systems, this standard leverages that effort in order to enhance the value of Serial Bus to devices in a wider range of operational circumstances.
This standard creates a new layer of protocol services based upon SBP-2, but that provides building blocks more suited to a peer-to-peer environment which includes printers, facsimile devices, and scanners (or multifunction devices that present some combination of these capabilities) when a computer is present-but it is also intended to address the peer-to-peer needs of devices to communicate with each other in the absence of a computer.
1 Information on references can be found in Clause 2.