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Claims  |
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We claim:
1. A control method 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
processing units and the terminal devices, each of the processing units
executes one or a plurality of programs, each of said one or plurality of
programs being used by one of the terminal devices, comprising the steps
of:
identifying, by said communication control processor, a terminal device
which has used at least one of said one or said plurality of programs
having been executed by a first one of said plurality of processing units
when operation of said first processing unit is stopped; and
establishing, by said communication control processor, a logical connection
between said identified terminal device and a second one of said plurality
of processing units which replaces said first processing unit.
2. A control method according to claim 1, further including a step of:
storing, by said communication control processor, information identifying
relations among said one or said plurality of programs being executed by
the respective processing units and the terminal devices using the
respective programs, wherein said identifying step is performed on the
basis of said stored information.
3. A control method according to claim 1, further comprising the steps of:
storing, by said communication control processor, histories of command data
transactions corresponding to respective terminal devices; and
after establishing the logical connection between the identified terminal
device and the second processing unit, selecting by said communication
control processor, part of the histories of command data transactions
corresponding to the identified terminal device and delivering, by said
communication control processor, the selected part of the histories of
command data to the second processing unit, said selected part of the
histories of command data comprises command data required in order to
enable the identified terminal device to continue use of a program which
has been used by the identified terminal device prior to the stop of the
operation of the first processing unit.
4. A control method according to claim 1, further comprising a step of:
establishing, by the communication control processor, the logical
connection between the identified terminal device and the second
processing unit after disconnecting the logical connection between the
identified terminal device and the first processing unit.
5. 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.
6. A method according to claim 5, wherein the part of commands includes a
command which requires allocation of a file.
7. A method according to claim 5, wherein the system further includes a
storage shared by said first and second processing units, further
comprising the steps of:
storing by said first processing unit, results of execution of commands
issued by said one terminal device before said first processing unit is
replaced by said second processing unit; and
accessing by said second processing unit, at least part of the results
stored in said shared storage for execution of the subsequently issued
commands, after said first processing unit has been replaced by said
second processing unit.
8. A method according to claim 5, wherein the establishing of the second
logical session is executed at a timing when the first processing unit is
to be replaced by said second processing unit.
9. A method according to claim 5, further comprising the steps of:
executing by said second processing unit, communication with another of
said terminal devices by said communication control processor, in parallel
to execution of communication by said first processing unit with said one
terminal device, before said first processing unit is replaced by said
second processing unit; and
executing by said second processing unit, both the communication with said
another terminal device and communication with said one terminal device.
10. A method according to claim 5, wherein said first processing unit is
replaced when said first processing unit is in a normal operation state.
11. A method according to claim 10, further comprising the step of:
stopping an operation of said first processing unit after the establishing
of the second logical session.
12. A method according to claim 5, wherein said first processing unit is
replaced at a timing when a fault has been found in an operation of said
first processing unit.
13. 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.
14. A method according to claim 13, wherein said system further includes a
storage shared by said first and second processing units, the method
further comprising the steps of:
storing by said first processing unit, results of execution of commands
issued by said one terminal device into said shared storage; and
executing by said second processing unit, commands issued by said one
terminal device after the establishing of the second logical session by
using at least part of the results stored in said shared storage.
15. A method according to claim 13, wherein the storing step comprises the
steps of:
storing by said communication control processor, a command issued by said
one terminal device, in response to issuing of the command thereby; and
erasing the stored command by said communication control processor, in
response to a message issued by said first processing unit and indicative
of completion of execution of the command.
16. A method according to claim 13, further comprising the steps:
storing by said communication control command, the command issued by said
one terminal device for opening of a logical session; and
wherein the establishing step of the second logical session includes the
step of transferring the stored command for opening of a logical session
to said second processing unit from said communication control processor.
17. A method according to claim 13, wherein the establishing step of the
second logical session is executed at a timing when the first processing
unit actually needs to be replaced by one of said plurality of processing
units.
18. A method according to claim 13, further comprising the step of:
supplying said communication control processor with a command for
replacement of said first processing unit by another of the plurality of
processing units, when the first processing unit is in a normal operating
condition.
19. A method according to claim 18, wherein the transferring step of the
command which has not been executed by said first processing unit is
executed in response to said supplied command for replacement of said
first processing unit.
20. A method according to claim 18, wherein the establishing step of the
second logical session is executed in response to said supplied command
for replacement of said first processing unit and before execution of the
transferring step of the command execution which has not been executed by
said first processing unit.
21. A method according to claim 18, further comprising the step of:
supplying by said communication control processor, said first processing
unit with a command for closing the first logical session, in response to
said command for replacement.
22. A method according to claim 13, further comprising the step of:
detecting occurrence of a fault with said first processing unit;
wherein the transferring step of the command execution which has not been
executed by said first processing unit is executed in response to
detection of the occurrence of a fault with said first processing unit.
23. A method according to claim 22, wherein the establishing step of the
second logical session is executed in response to the detection of the
occurrence of a fault and before execution of the transferring step of the
command execution which has not been executed by said first processing
unit.
24. 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.
25. A method according to claim 24, wherein said system further includes a
storage shared by said first and second processing units, the method
further comprises the steps of:
storing by said first processing unit, results of execution of commands
issued by said one terminal device into said shared storage; and
executing by said second processing unit, commands issued by said one
terminal device after the establishing of the second logical session by
using at least part of the results stored in said shared storage.
26. A method according to claim 24, wherein the establishing step of the
second logical session is executed at a timing when the first processing
unit actually needs to be replaced by one of said plurality of processing
units.
27. A method according to claim 24, further comprising the step of:
supplying said communication control processor with a command for
replacement of said first processing unit by another of the plurality of
processing units, when the first processing unit is in a normal operating
condition.
28. A method according to claim 27, wherein the transferring step of the
subsequently issued commands is executed in response to said supplied
command for replacement of said first processing unit.
29. A method according to claim 28, wherein the establishing step of the
second logical session is executed in response to said supplied command
for replacement of said first processing unit and before execution of the
transferring step of the subsequently issued commands.
30. A method according to claim 24, further comprising the step of:
detecting occurrence of a fault with said first processing unit;
wherein the transferring step of the subsequently issued commands is
executed in response to detection of the occurrence of a fault with said
first processing unit.
31. A method according to claim 30, wherein the establishing step of the
second logical session is executed in response to the detection of the
occurrence of a fault and before execution of the transferring step of the
subsequently issued commands.
32. 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.
33. A system according to claim 32, further comprising:
a storage shared by said first and second processing units for storing
results of execution of commands provided by said first processing unit
for commands issued by said one terminal device so that at least part of
the results stored in said shared storage is used by said second
processing unit for execution of commands issued by said one terminal
device after the establishing of the second logical session.
34. A system according to claim 32, further comprising:
means for supplying said communication control processor with a command for
replacement of said first processing unit by another of the plurality of
processing units, when the first processing unit is in a normal operating
condition.
35. A system according to claim 34, wherein the transferring means of the
stored part of the commands includes means for transferring the stored
part of the commands in response to said supplied command for replacement
of said first processing unit.
36. A system according to claim 35, further comprising:
means responsive to said supplied command for stopping an operation of said
first processing unit.
37. A system according to claim 32, further comprising:
means for detecting occurrence of a fault with said first processing unit;
wherein the transferring means of the stored part of the commands includes
means for transferring the stored part of the commands in response to
detection of the occurrence of a fault with said first processing unit.
38. 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.
39. A system according to claim 38, further comprising:
a storage shared by said first and second processing units for storing
results of execution of commands provided by said first processing unit
for commands issued by said one terminal device so that at least part of
the results stored in said shared storage is used by said second
processing unit for execution of commands issued by said one terminal
device after the establishing of the second logical session.
40. A system according to claim 38, further comprising:
means for storing the command issued by said one terminal device for
opening of a logical session; and
wherein said means for establishing the second logical session includes
means for transferring the stored command for opening of a logical session
to said second processing unit.
41. A system according to claim 38, further comprising:
means for supplying said communication control processor with a command for
replacement of said first processing unit by another of the plurality of
processing units, when the first processing unit is in a normal operating
condition.
42. A system according to claim 41, wherein the transferring means of the
command execution which has not been executed by said first processing
unit includes means for transferring the command in response to said
supplied command for replacement of said first processing unit.
43. A system according to claim 38, further comprising:
means for detecting occurrence of a fault with said first processing unit;
wherein the transferring means of the command execution of which has not
been executed by said first processing unit includes means for
transferring the command in response to detection of the occurrence of a
fault with said first processing unit.
44. 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.
45. A system according to claim 44, further comprising:
a storage shared by said first and second processing units for storing
results of execution of commands provided by said first processing unit
for commands issued by said one terminal devices so that at least part of
the results stored in said shared storage is used by said second
processing unit for execution of commands issued by said one terminal
device after the establishing of the second logical session.
46. A system according to claim 44, further comprising:
means for supplying said communication control processor with a command for
replacement of said first processing unit by another of the plurality of
processing units, when the first processing unit is in a normal operating
condition.
47. A system according to claim 46, wherein the transferring means of the
stored command for opening a logical session includes means for
transferring the command in response to said supplied command for
replacement of said first processing unit.
48. A system according to claim 44, further comprising:
means for detecting occurrence of a fault with said first processing unit;
wherein the transferring means of the command for opening of a logical
session includes means for transferring the command in response to
detection of the occurrence of a fault with said first processing unit.
49. 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.
50. 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
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