Abstract: Method, apparatus and program products for increasing the performance of communications using differencing data communications over a message queue supporting asynchronous communications from a variety of applications executing on a source device over a shared external communication link to destination devices are provided. A data stream between the source device and the destination device is segmented based on the type of the data stream to provide a logical segmentation which increases the occurrence of repeated transmissions of a segment. The segments are then placed in the message queue as a message for transport to a destination computer. Differencing is provided by replacing the segment with an associated identifier for segments which have previously been transported to provide a reduced volume of data for transmittal based on recognition and replacement of data segments which have previously been transmitted by the source device.

Abstract: Methods, systems, and computer program products are provided for communicating between a source device and a destination device over an external communication link by transmitting a message stored in a source persistent queue at the source device over the external communication link to the destination device. The transmitted message has transmitted with it an associated sequence identifier which identifies the message stored in the source persistent queue. The transmitted message and the associated sequence identifier are received at the destination device and stored in a destination persistent queue at the destination device. Occasionally, a commit message is transmitted to the source device from the destination device which identifies a sequence identifier associated with received message which has been persistently stored in the destination persistent queue.

Abstract: Method, apparatus and program products for increasing the performance of communications using differencing data communications over a message queue supporting asynchronous communications from a variety of applications executing on a source device over a shared external communication link to destination devices are provided. A data stream between the source device and the destination device is segmented based on the type of the data stream to provide a logical segmentation which increases the occurrence of repeated transmissions of a segment. The segments are then placed in the message queue as a message for transport to a destination computer. Differencing is provided by replacing the segment with an associated identifier for segments which have previously been transported to provide a reduced volume of data for transmittal based on recognition and replacement of data segments which have previously been transmitted by the source device.

Abstract: Packet messages transmitted on a packet communications network include origin and destination addresses in the form of stacked address elements which can be pushed or popped off of the stack. A plurality of interconnected packet communications network include routing nodes which utilize the top address element on the destination stack to route the message. Such routing nodes also include stack element editing facilities for popping elements from the stacks, constructing new elements to be pushed onto the stacks, and amending the contents of elements on the stack. This arrangement allows messages to be launched on the networks where the originating station does not have full knowledge of the destination station, and the routing nodes add the necessary destination information as it becomes necessary for routing.

Abstract: A common general parser and applications program interface for use in a data processing system. The parser encodes data from a program for transmission onto a channel and decodes incoming data for handoff to an applications program. Initialization of the parser includes allocating private storage for the individual data items to be encoded or decoded. The program requests data that is received by the parser or transmits data onto the channel by issuing a call to the parser. The call identifies the parse table to be used by the parser. In response, the parser encodes of decodes the data in accordance with the identified parse table to extract the individual data items. The parser stores the individual data items in their respective allocated storage areas for the program during decoding or extracts the data items from the storage for encoding.

Abstract: A method and apparatus for maintaining active sessions between communicating logical units in a computer network when an application system fails without having to re-establish the active sessions. By activating a persistent sessions capability at one of the logical units, the active sessions can be suspended and maintained while attempts at recovery are made. Recovery attempts include restarting the failed application or switching the suspended sessions to an alternate instance of the logical unit. The suspended sessions are resynchronized with the application system and session activity is resumed.