International Business Machines Corporation

Marsha E Ferree

James P Gray

John E Drake, Jr

Mark Pozefsky

Andrew P Citron

Zvonimir Ordanic

John E Fetvedt

John F Wilder

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.

System for establishing and performing multiple conversations

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.

Full duplex conversation between transaction programs

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.

Method of controlling limited resource sessions in a data communications

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Marsha E Ferree