A method and apparatus for transmitting document data enabling transfer of document data over a communication path assigned the highest possible priority among a plurality of communication paths. First, an attempt is made to transfer document data over the highest-priority communication path. If the attempt has failed, the document data are transferred over a communication path which is lower in priority than the highest-priority communication path. After information for one page of text data has been transferred over the lower-priority communication path, an attempt is again made to transfer the remaining part of text data over the highest-priority communication path.
A real-time communications system for decentralized management is accomplished which was not implemented conventionally. To achieve this, the following techniques are employed: (1) Overtaking of communication packets based on priority; (2) Path control based on the priority; and (3) Priority change at each node. When carrying out real-time communication between a plurality of information processors, each communication node (information processor) carries out overtaking of the communication packets in accordance with the priority. In the course of this, each communication node can change the priority, and establish different paths for each of the priority.
A technique for providing a portable processing system with "always on, always connected" capability is provided. The portable processing system is equipped with two data communication devices, either or both of which may be implemented on a PC Card. The first communication device is for receiving data over a wireless link over a narrowband link. The second communication device is for both receiving and transmitting data over a communication link over a wider band link, i.e., at a data rate that is substantially higher than that of the first communication device. The first communication device is always on, such that the narrowband link is always established. The second communication device may be activated only when data is to be transferred to or from the portable processing system, such that the wider band link is established only when it is needed. In one mode of operation the first communication device is used primarily to receive messages indicating that data is available for downloading to the portable processing system. When such data is available, the second communication device is used to download the data.
One aspect is directed to a method and apparatus for transferring information, through a shared storage system, between first and second processes running on first and second computers, respectively. Both computers are coupled to a data storage system, with the first computer being coupled through multiple paths. In accordance with one aspect of the invention, at least one of the multiple paths is selected through which to transfer the information between the first process and the data storage system, so that communication between the first process and the shared storage system is not constrained to any particular path. Another aspect is directed to a method and apparatus for processing an out of band control command executed by a host computer in a multi-path system and targeting a device. A path is selected for transmitting the out of band control command to the device based upon a selection criteria that enables the selected path to be other than a specific target path identified by the out of band control command.
