System for dynamically switching logical sessions between terminal device and a processor which stops its operation to another working processor under control of communication control processor

A method for dynamically switching a logical session in an information processing system which includes a plurality of processing units, a plurality of terminal devices, and a communication control processor which controls communication between said processing units and said terminal devices, comprising the steps, executed by said communication control processor, of:

• establishing a first logical session between one of the terminal devices and a first one of the processing units, in response to a command for opening a logical session, issued by said one terminal device;
• transferring commands issued by said one terminal device after the establishing of said first logical session onto said first processing unit, and transferring messages issued by said first processing unit in relation to the commands onto said one terminal device;
• storing at least part of the commands;
• establishing a second logical session between the one terminal device and a second one of the processing units which should replace the first processing unit;
• switching a logical session related to the one terminal device from the first logical session to the second logical session;
• transferring the stored part of the commands to the second processing unit as commands issued by said one terminal device after the switching of the logical session;
• and
• transferring commands subsequently issued by said one terminal device after transferring of said part of the commands, onto said second processing unit, and transferring messages issued by said second processing unit in relation to said subsequently issued commands onto said one terminal device;
• wherein the part of the commands includes commands required to be executed by said second processing unit so as to continue communication between said first processing unit and said one terminal device, by said second processing unit and said one terminal device.

A method for dynamically switching a logical session in an information processing system which includes a plurality of processing units, a plurality of terminal devices, and a communication control processor which controls communication between said processing units and said terminal devices, comprising steps, executed by said communication control processor, of:

• establishing a first logical session between one of the terminal devices and a first one of the processing units, in response to a command for opening a logical session, issued by said one terminal device;
• transferring commands issued by said one terminal device after the establishing of said first logical session onto said first processing unit, and transferring messages issued by said first processing unit in relation to the commands onto said one terminal device;
• storing each of the commands at least until execution of each command has been completed;
• establishing a second logical session between the one terminal device and a second one of the processing units which should replace the first processing unit;
• switching a logical session related to the one terminal device from the first logical session to the second logical session;
• transferring a command stored in said communication control processor, if there is any, to said second processing unit after the switching of the logical session, so that the command is executed by said second processing unit, the command being a command which has been issued by said one terminal device but execution of which has not been completed by said first processing unit;
• and
• transferring commands subsequently issued by said one terminal device after the establishing of the second logical session, onto said second processing unit, and transferring messages issued by said second processing unit in relation to said subsequently issued commands onto said one terminal device.

A method for dynamically switching a logical session in a information processing system which includes a plurality of processing units, a plurality of terminal devices, and a communication control processor which controls communication between said processing units and said terminal devices, comprising steps, executed by said communication control processor, of:

• establishing a first logical session between one of the terminal devices and a first one of the processing units, in response to a command for opening a logical session, issued by said one terminal device;
• storing the command for opening of a logical session;
• transferring commands issued by said one terminal device after the establishing of said first logical session onto said first processing unit, and transferring messages issued by said first processing unit in relation to the commands onto said one terminal device;
• establishing a second logical session between the one terminal device and a second one of the processing units which should replace the first processing unit, by supplying said second processing unit with said stored command for opening of a logical session;
• switching a logical session related to the one terminal device from the first logical session to the second logical session;
• and
• transferring commands subsequently issued by said one terminal device after the switching of the logical session, onto said second processing unit, and transferring messages issued by said second processing unit in relation to said subsequently issued commands onto said one terminal device.

An information processing system, comprising:

• a plurality of processing units;
• a plurality of terminal devices;
• and
• a communication control processor connected to said processing units and said terminal devices for controlling communication between said processing units and said terminal devices;
• wherein said communication control processor includes:
• means for establishing a first logical session between one of the terminal devices and a first one of the processing units, in response to a command for opening a logical session, issued by said one terminal device,
• means for transferring commands issued by said one terminal device after the establishing of said first logical session onto said first processing unit, and for transferring messages issued by said first processor in relation to the commands onto said one terminal device,
• means for storing part of the commands transferred between said first processing unit and said one terminal device,
• means for establishing a second logical session between the one terminal device and a second one of the processing units which should replace the first processing unit,
• means for switching a logical session related to said one terminal device from the first logical session to the second logical session,
• means for transferring said stored part of the commands to said second processing unit as commands from said one terminal device, and
• means for transferring commands subsequently issued by said one terminal device after the switching of the logical session, onto said second processing unit, and for transferring messages issued by said second processing unit in relation to said subsequently issued commands onto said one terminal device,
• wherein the part of the commands includes commands required to be executed by said second processing unit so as to continue communication between said first processing unit and said one terminal device, by said second processing unit and said one terminal device.

An information processing system, comprising:

• a plurality of processing units;
• a plurality of terminal devices;
• and
• a communication control processor connected to said processing units and said terminal devices for controlling communication between said processing units and said terminal devices;
• wherein said communication control processor includes:
• means for establishing a first logical session between one of the terminal devices and a first one of the processing units, in response to a command for opening a logical session, issued by said one terminal device,
• means for transferring commands issued by said one terminal device after the establishing of said first logical session onto said first processing unit, and for transferring messages issued by said first processor in relation to the commands onto said one terminal device,
• means for storing each of the commands at least until execution of said each command has been completed,
• means for establishing a second logical session between the one terminal device and a second one of the processing units which should replace the first processing unit,
• means for switching a logical session related to the one terminal from the first logical session to the second logical session;
• means for transferring a command stored in said storing means, if there is any, to said second processing unit after the switching of the logical session by said switching means, so that the command is executed by said second processing unit, the command being a command which has been issued by said one terminal device but execution of which has not been completed by said first processing unit, and
• means for transferring commands subsequently issued by said one terminal device after the switching of the logical session, onto said second processing unit, and for transferring messages issued by said second processing unit in relation to said subsequently issued commands onto said one terminal device.

An information processing system, comprising:

• a plurality of processing units;
• a plurality of terminal devices;
• and
• a communication control processor connected to said processing units and said terminal devices for controlling communication between said processing units and said terminal devices;
• wherein said communication control processor includes;
• means for establishing a first logical session between one of the terminal devices and a first one of the processing units, in response to a command for opening a logical session, issued by said one terminal device,
• means for storing the command for opening of a logical session,
• means for transferring commands issued by said one terminal device after the establishing of said first logical session onto said first processing unit, and for transferring messages issued by said first processing unit in relation to the commands onto said one terminal device,
• means for establishing a second logical session between the one terminal device and a second one of the processing units which should replace the first processing unit,
• means for switching a logical session related to the one terminal device from the first logical session to the second logical session;
• and
• means for transferring commands subsequently issued by said one terminal device after the switching of the logical session, onto said second processing unit, and for transferring messages issued by said second processing unit in relation to said subsequently issued commands onto said one terminal device.

A control apparatus for dynamically switching a logical session in an information processing system in which a plurality of terminal devices are connected to a plurality of processing units via at least one communication control processor which controls communication between the terminal devices and the processing units, each of the processing units executes one or a plurality of programs, each of the one or plurality of programs being able to be used by the terminal devices, the communication control processor comprising:

• first storage means for storing at least part of histories of command data transactions corresponding to the respective terminal devices;
• second storage means for storing identification data of processing units currently connected to the respective terminal devices by logical sessions;
• and
• first control means for identifying based on the stored identification data, when one of the processing units is to be replaced by another of the processing units, one of said terminal devices that is logically connected to the one processing unit by a logical session and has used one program having been executed by the one processing unit, for automatically creating a first command data to cause the logical session between the one processing unit and the identified terminal device, for delivering the first command data to the one processing unit, for automatically establishing a logical session between said another processing unit replacing the one processing unit and the identified terminal device, for automatically creating a second command data which allows the identified terminal device to be used continuously, the creating being performed based on related to said identified terminal along the part histories of command data transactions stored in said first storage means and for delivering the second command data to the another processing unit.

A control method for dynamically switching a logical session in an information processing system comprising a plurality of processing units, a plurality of terminal devices, and at least one communication control processor which connects the plurality of terminal devices to the plurality of processing units, the communication control processor including first storage means for storing at least part of histories of command data transactions corresponding to the respective terminal devices and second storage means for storing identification data of processing unite currently connected to the respective terminal devices by logical sessions, the method comprising the steps, executed by the communication control processor, of:

• identifying on a basis of the stored identification data, when one of the processing units is to be replaced by another one of the processing units, one of said terminal devices that is logically connected to the one processing unit by a logical session and has used a program having been executed by the one processing unit:
• automatically creating a first command data to cause the logical session between the one processing unit and the identified terminal device and delivering the first command data to the one processing unit,
• automatically establishing a logical session between said another processing unit replacing the one processing unit and the identified terminal device;
• and
• automatically creating a second command data for allowing the identified terminal device to be used continuously, the creating being performed based on part related to the identified terminal device among histories of command data transactions stored in said first storage means and delivering the second command data to the another processing unit.