Abstract: Methods, apparatus and computer program products are provided for distributing communication packets over multiple concurrent parallel links between a first node and a second node in a communication network based upon link quality information for the links. By utilizing link quality information from the links, the rate at which packets are provided to the links may be made proportional to the quality of the link, and thus, the link's ability to transmit the packet. The rate at which packets are provided to links may be reduced when error rates on a link exceed a specified threshold and eliminated when error rates exceed a higher threshold. Alternatively, timing delays from errors on a link may be used to determine a delay factor for a link and packets scheduled to the links based on the link with the lowest delay. The present invention is particularly useful in High Performance Routing Multilink Transmission Groups.

Abstract: Methods, apparatus and computer program products are provided for distributing communication packets over multiple concurrent parallel links between a first node and a second node in a communication network based upon link quality information for the links. By utilizing link quality information from the links, the rate at which packets are provided to the links may be made proportional to the quality of the link, and thus, the link's ability to transmit the packet. The rate at which packets are provided to links may be reduced when error rates on a link exceed a specified threshold and eliminated when error rates exceed a higher threshold. Alternatively, timing delays from errors on a link may be used to determine a delay factor for a link and packets scheduled to the links based on the link with the lowest delay. The present invention is particularly useful in High Performance Routing Multilink Transmission Groups.

Abstract: Methods, systems and computer program products are provided for automatically generating client/server applications from an application written to execute on a single processing system. The application has program classes and programmed methods associated with the objects. Each program class in the application is identified and the relationships between programmed methods in the classes is determined. The relationships between the programmed methods in the identified classes are then weighted based on the activity of the relationship. Similarly, each identified class in the application is also weighted based on the computing resources required by the identified class. The identified classes are then partitioned into client classes and server classes based on the weighted relationships between the programmed methods in the classes, the weight associated with each class and a computing topology associated with a target client processing system.

Abstract: A flow control system for packet transmission networks is centered in the user applications supplying data to the network. Changes in control are responsive to changes in the transmission parameters of the network, measured in the network and transmitted to the user application. The user application specifies desired ranges of Quality of Service parameters and, when the measured network parameters fall outside of the desired range, the user application modifies the transmission strategy to match the available transmission parameters. Measurements of network parameters are made over a pre-selected observation period to average the values of the transmission parameters.

Abstract: To enhance the security provided by data encryption in a data communication network, the encryption/decryption keys are changed periodically at the source and destination nodes for an established connection. A destination node must know not only the value of any new key but also when to begin using that key to decrypt received data packets. Synchronization (making sure a data packet is decrypted using a decryption key correlated with the encryption key used to encrypt the same packet) is achieved by defining a single bit in each packet header as a key synchronization bit. As long as key synchronization bit value remains unchanged from one received packet to the next, a receiving node will continue to use the same decryption key it has been using. When a change in the key synchronization bit value is detected, the receiving node will begin using a previously-received, new decryption key.

Abstract: To enhance the security provided by data encryption in a data communication network, encryption/decryption keys are changed periodically at the source and destination nodes for an established connection. A destination node must know not only the value of any new key but also when to begin using that key to decrypt received data packets. Synchronization (making sure a data packet is decrypted using a decryption key correlated with the encryption key used to encrypt the same packet) is achieved through the use of marker cells, which are special purpose cells. When a source node decides to activate a new key, previously sent to and stored at the destination node, a marker cell is transmitted by the source node to the destination node. When the destination node recognizes the marker packet, it discards it and activates the previously received key for use in decrypting subsequently received packets.

Abstract: The security provided by encryption of ATM cells is enhanced by testing each cell for low data content level. If a cell has a low data content, its contents are nevertheless compressed and the resulting string is used to replace the original data. A length character and a randomly generated number which are added to the freed-up byte positions in the data field of the cell. The entire, modified data field is encrypted before the cell is transmitted. At a receiving system, a compression indicator is checked to determine whether the cell contains original or compressed data. If necessary, the length field and the random number are stripped and the remaining cell data is decompressed before the cell data is decrypted.

Abstract: A computer system and process efficiently provides resource recovery for a failure during a commit procedure. An application is run on a processor and requests a work operation involving a resource such as a protected conversation with another application in a different real machine. A commit procedure is begun for the work request, and if the commit procedure fails before completion, the following steps are taken to optimize the use of one or both of the applications. At some time after the commit procedure fails, a return code is sent to at least the application that initiated the commit indicating the result of the application commit order and that the application can continue to run and does not have to wait for resynchronization (recovery). Then, while the initiating application continues to run and do other useful work, resynchronization is implemented in parallel, asynchronously.

Abstract: A method and system for establishing multiple parallel conversations between a single pair of instances corresponding to a pair of communicating transaction programs over a data communication network. Each conversation traverses the network between the two communicating transaction program instances over a corresponding logical unit-logical unit session. Each conversation may be independently disconnected or reconnected without the need for invoking additional instances of the communicating transaction programs.

Abstract: A transaction network in which, in appropriate cases, a transaction is allowed to complete at each node and new work to commence, before all transaction resources at the node actually complete a syncpoint operation. This desirable result is obtained without the risk of unreported database corruption. At each node in response to a prepare to commit syncpoint command from a parent node, the node in question determines if it or any of its descendant nodes can make a unilateral heuristic decision to commit or backout the transaction irrespective of whether or not the final syncpoint command is to commit or backout. Each node informs its parent node that it is reliable or unreliable. Reliable means that neither this node nor any of its descendant nodes can make a unilateral heuristic decision. Unreliable means that this node or one or more of the descendant nodes may make such a unilateral decision.

Abstract: A computer system and process efficiently provides resource recovery for a failure during a commit procedure. An application is run on a processor and requests a work operation involving a resource such as a protected conversation with another application in a different real machine. A commit procedure is begun for the work request, and if the commit procedure fails before completion, the following steps are taken to optimize the use of one or both of the applications. At some time after the commit procedure fails, a return code is sent to at least the application that initiated the commit indicating the result of the application commit order and that the application can continue to run and does not have to wait for resynchronization (recovery). Then, while the initiating application continues to run and do other useful work, resynchronization is implemented in parallel, asynchronously.

Abstract: A Transport Layer Protocol Boundary (TLPB) architecture is described which will permit an application program to run over a non-native transport protocol without first generating a protocol compensation package tailored to the transport protocols assumed by the program's application programming interface and by the available transport provider. All transport functions required by the program are converted to standardized or TLPB representations. When a connection between the first application program and a second remote application is requested, the individual required TLPB transport functions are compared to corresponding functions supported by the transport provider. Compensations are invoked only where there is a mismatch. The node on which the remote application program runs is informed of the compensations so that necessary de-compensation operations can be performed before the data is delivered to the remote application program.

Abstract: Data communication nodes in a network comprising a plurality of nodes linked together to form communication paths negotiate by passing messages to identify to one another the maximum supportable degree of data compression capability. Logical comparisons are made at each node between indications received from upstream and downstream nodes, if any, regarding their own or their received indications of data compression capability with the present node's own degree of compression capability. This enables logical decisions to be made to suport the maximum degree of compression capability over each link or portion of a link between terminal nodes which define the ends of the overall link, thus improving data transmission by providing the highest degree of supportable compression over the longest path length.

Abstract: Enhanced type 2.1 nodes for SNA networks provide network routing of information between non-adjacent network nodes and program-to-program linkage across the network. These nodes are called "advanced peer to peer networking" (abbreviated APPN) nodes. Network state information, describing the topology and resources of the network is disseminated betweeen APPN nodes by a first data link control exchange of identification (XID) information indicating node type (and thereby distinguishing APPN nodes from other nodes) and other exchanges conducted over a newly defined control point to control point (abbreviated CP--CP) session having a message architecture unique to APPN type nodes. The XID exchange is conducted whenever a link between nodes is activated, and when the exchanging nodes are both APPN, and if both are available to participate in as CP--CP session, they automatically engage in a second exchange of session binding signals which establish a pair of sessions between the nodes.

Abstract: In a communications network, each network node can maintain its own list of network resources in a topology database. When the state of a resource "owned" by a particular node changes, that node broadcasts a topology database update (TDU) message to adjacent nodes. Each adjacent node updates its own topology database and rebroadcasts the message. To minimize the amount of information that must be included in TDU messages when two nodes are reconnected after an outage, each node assigns flow reduction sequence numbers (FRSNs) to TDU meassages and keeps a record of the FRSN for the last TDU message sent to an adjacent node. The node also records, for each resource in its database, the FRSN of the last TDU message including that resource. When two nodes are reconnected, the sending node includes in the TDU message only those resources having a FRSN greater than the FRSN assigned to the last TDU sent to the adjacent node to which the TDU message is directed.

Abstract: A method for the full duplex exchange of data via a conversation between a pair of transaction programs over a network in which any transaction program which requests a confirmation of previously sent data inhibits the further transmission of data until a response to the request is received and a transaction program which receives a request for confirmation will inhibit the receipt of data until a response to the confirmation request is sent. In addition, when a transaction program attempts to terminate a conversation a definite response is requested and the response to the termination will be queued behind any data which remains to be sent so as to purge that data from the network.

Abstract: A method of operating a communication system which includes a number of host systems each communicating via sessions with other devices over different connections and in which the sessions assigned to a failed connection are suspended for a first and second time period and non-destructively moved to an alternate connection when a unique command is issued by one of the host systems and received by a control unit involved in the failed connection.

Abstract: The links in a data communications network following Systems Network Architecture may be categorized as limited resource links if those links are shared access transport facilities, such as a switched telephone network, X.21, X.25 or token ring local area network facilities. In setting up LU--LU sessions between network users, a limited resource session identifier field is set to a specific value if any of the links in the session data path is defined as a limited resource link. When a conversation between two users ends, the primary logical unit responds by determining whether the session has been identified as a limited resource session. If it has, the primary logical unit initiates action to deactivate the session without waiting for network control operation action. Allowing the primary logical unit to deactivate a limited resources session assures that the limited resource link or links will not remain allocated needlessly to an unused session.

Abstract: The invention enables two nodes in a communications network to dynamically establish the transmission group number used to partially identify a given link between the nodes. When the link is being activated, both nodes simultaneously propose either a zero or a non-zero number to each other in an exchange of exchange identification (XID) messages. If only one of the nodes proposed a non-zero number, that non-zero number is selected as the transmission group number. If both nodes had proposed zero or both had proposed non-zero numbers, predetermined criteria are employed to select a controlling node. The controlling node chooses the final transmission group number and communicates that choice to the non-controlling node.

Abstract: A LOCATE search dynamically locates resources (e.g., logical units (LUs) and transaction program and files associated with LUs) in a computer network so that a session can be established between the origin and the destination of the search.In a network which includes end nodes associated with server nodes, a resource contained in any node is located by a requesting node. The requesting node initiates a search of the resources residing within itself. If the resource does not reside in the requesting node, the server node searches the resources known to the server node that reside anywhere in the nework. If the resource is not known by the server node, it searchers all resources that reside in its associated end nodes. If the resource does not reside in the associated end nodes, either a request is sent to a central directory if one exists or a search of all resources in the network is made.