Interactive communication and transport system for still pictures

Claim 1

Interactive communication and transport system for requesting, transmitting and receiving bulk data, more particularly of still pictures, comprising: a data communication path (6) operable at relatively low speed in a first data communication network, a plurality of workstations (A,B) which are coupled to the first data communication network and which are able to communicate with each other via the said data communication path (6), said plurality of workstations including at least one request-processing workstation (A) and at least one destination workstation (B), a transmission path (10) operable at relatively high speed in a second data communication network to which said workstations are also coupled, said at least one request-processing workstation (A) being coupled both to said communication path (6) and to said transmission path (10), at least one bulk data source (1-4) provided at said at least one request-processing workstation (A), via which separately specifiable quantities of related bulk data in the at least one bulk data source (1-4) are accessible to the workstations on request, transmitting means (14-17), provided at each request-processing workstation (A), for forwarding, on a request from a workstation initiated by a communication via said data communication path (6), to the request-processing station (A), bulk data specified in said request to at least one destination workstation (B), also specified in said request, via a reserved data channel which is reserved for the purpose along said transmission path (10), supervisor means for regulating access to, and transport over, the reserved data channel of said transmitting means by means of communication via said data communication path (6), said transmitting means (14-17) comprising packet assembling means (16) which assembles the specified bulk data to be transmitted into a single data packet having a predefined structure from which at least a start and an end, and the destination station of the packet, can be deduced, each destination workstation comprising receiving means (11) which, at least for a time in which a data packet intended for the respective destination station is to be expected, continuously scans the reserved data channel along said transmission path (10) for a data packet intended for it and picks up a data packet as soon as it is recognized as intended for it, detection means (18) provided at each request-processing workstation (A) for detecting a packet end on the reserved channel, and wherein a request-processing station (A) which has received permission from the supervisor means for the transmission of a subsequent data packet, giving an instruction to the transmitting means (14-17) thereof for transmission when the detection means (18) has detected the packet end of the last packet to be transmitted previously.