Scientific-atlanta, Inc.

Sandraic Logic, Llc.

Tranceive Technologies, Inc.

Gary L Logston

Anthony John Wasilewski

Patrick G Ladd

Douglas F Woodhead

Timothy Hall Addington

William E Wall

Maynard Darvel Hammond

Francis Cheung

William Edgar Wall

An improved method and apparatus for balancing distributed applications within a client/server network, such as a cable television network, is disclosed. In one aspect of the invention, a method of balancing the load of distributed application client portions (DACPs) across various server portions (DASPs) and server machines is disclosed. Statistics are maintained by one or more software processes with respect to the available resources of the servers and their loading; new process threads and/or distributed application server portions are allocated across the servers to maintain optimal system performance as client device loading increases or changes. In another aspect of the invention, a novel object-oriented distributed application software architecture employing both vertical and horizontal partitions and 'mutable' (i.e., transportable) objects is disclosed. The mutable objects may reside on either the server or client portions of the distributed application while maintaining at least one network partition. A runtime environment adapted for the operation of the foregoing object-oriented distributed application, including an efficient message protocol useful for interprocess communication, is also disclosed. Methods for downloading the DACP from the servers, and scaling the DACP at download based on client device configuration, are further disclosed.

Method and apparatus for balancing distributed applications

An improved method and apparatus for balancing distributed applications within a client/server network, such as a cable television network, is disclosed. In one aspect of the invention, a method of balancing the load of distributed application client portions (DACPs) across various server portions (DASPs) and server machines is disclosed. Statistics are maintained by one or more software processes with respect to the available resources of the servers and their loading; new process threads and/or distributed application server portions are allocated across the servers to maintain optimal system performance as client device loading increases or changes. In another aspect of the invention, a novel object-oriented distributed application software architecture employing both vertical and horizontal partitions and &ldquo;mutable&rdquo; (i.e., transportable) objects is disclosed. The mutable objects may reside on either the server or client portions of the distributed application while maintaining at least one network partition. A runtime environment adapted for the operation of the foregoing object-oriented distributed application, including an efficient message protocol useful for interprocess communication, is also disclosed. Methods for downloading the DACP from the servers, and scaling the DACP at download based on client device configuration, are further disclosed.

A control system provides secure transmission of programs, including at least one of video, audio, and data, between a service provider and a customer's set top unit over a digital network. Program bearing data packets are received in a first network protocol over a first data link and removed from the first network protocol. Packets representing a particular program requested by a customer having a set top unit are selected. Conditional access is provided to the selected program. In particular, program bearing packets are encrypted according to a first encryption algorithm using a first key, which is then encrypted according to a second encryption algorithm using a second key. The first keys are transported in packets to the customer's set top units along with the program packets. A public key cryptographic technique encrypts the second key such that the public key used in the encryption corresponds to the private key of the customer's set top unit. After the conditional access layers have been added, the packets are encapsulated and output in a second network protocol destined for the set top unit.

Method and apparatus for providing conditional access in connection-oriented interactive networks with a multiplicity of service providers

A control system provides secure transmission of programs, including at least one of video, audio, and data, between a service provider and a customer's set top unit over a digital network. Program bearing data packets are recieved in a first network protocol over a first data link and removed from the first network protocol. Packets representing a particular program requested by a customer having a set top unit are selected. Conditional access is provided to the selected program. In particular, program bearing packets are encrypted according to a first encryption algorithm using a first key, which is then encrypted according to a second encryption algorithm using a second key. The first keys are transported in packets to the customer's set top units along with the program packets. A public key cryptographic technique encrypts the second key such that the public key used in the encryption corresponds to the private key of the customer's set top unit. After the conditional access layers have been added, the packets are encapsulated and output in a second network protocol destined for the set top unit.

Method and apparatus for providing conditional access in

A digital video, audio and data distribution system which enables a set-top terminal (STT) associated with a customer's television set or other information presentation device to request interactive digital video, audio and data services from a service provider (SP) through the use of control system messages transmitted via a hi-directional signalling path. The requested interactive service is transmitted from the service provider over a portion of the bandwidth of a broadband transmission network which is dedicated to interactive digital services. A Video Session Connection (VSC) is provided for setting up and maintaining interactive sessions between the set-top terminal and a video service provider during the time the interactive programming is provided to the customer. The set-top terminal and service provider establish the Video Session Connection via a two-way signalling path within the bandwidth of the transmission medium into the customer's home. Applications of the system of the invention include 'movie on demand' services where the set-top terminal not only requests a movie to be transmitted from the service provider for immediate transmission, but also the bi-directional command channel permits the set-top terminal to control the video presentation by sending commands such as Play, Pause, Fast-Forward and the like to the Service Provider while the movie is being transmitted. Other applications of the invention include on-line data retrieval services, shop at home services and other services which require the use of an interactive connection.

Interactive information services control system

Packets of data, some of which may carry a timestamp value, are transmitted through an Asynchronous Transfer Mode (ATM) network. Prior to transmission, each packet of data is encapsulated in a respective convergence sublayer protocol data unit (CS-PDU) having a header portion and a payload portion. The header portion of each CS-PDU contains a time correction indicator (TCI), which indicates whether the CS-PDU carries a packet of data having a timestamp value that may require correction after the CS-PDU passes through the network, and a time reference correction (TRC) field. Each CS-PDU is then segmented into a plurality of successive segments; a first one of the segments of each CS-PDU contains the CS-PDU header. Each segment is then inserted into the payload section of a respective ATM cell for transmission through the network. At each node in the network, cells are examined to determine if they contain a CS-PDU header. If a cell contains a CS-PDU header, any variable delays imposed upon that cell as it passed through the node are measured and added to the TRC field in the CS-PDU header prior to sending the cell to the next node. At a destination node, the accumulated TRC value may be added to the time stamp value of the packet carried in the CS-PDU in order to compensate for the variable delays imposed upon that packet as the cells carrying the packet traversed the network.

Methods and apparatus for time stamp correction in an asynchronous

A method is disclosed for providing packet error indication in a multi-hop communications system in which packets of data are transmitted from a transmission site to a reception site via a plurality of successive physical links. According to the method, at the transmission site, a pre-defined bit in a packet to be transmitted is set to a first value, the first value indicating that no errors are present in the packet. Then, at each successive physical link in the communication system, after transmission of the packet over that physical link, the following steps are performed: (a) detecting whether any uncorrectable errors occurred in the packet during transmission over that physical link; (b) if an uncorrectable error is detected, setting the pre-defined bit in the packet to a second value wherein the second value is indicative of an uncorrectable error in the data of the packet; and (c) relaying the packet to the next successive physical link for transmission over that next link. A decoder at the reception site may, upon receiving a given packet, examine the value of the pre-defined bit to determined the integrity of the data contained in that packet.

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Tucker, GA, United States of America

Gary L Logston