AUTOMATED PROCEDURE FOR KERNEL CHANGE
A kernel provides a mechanism allowing various applications (e.g. CRM, logistics, procurement, etc.) hosted on a plurality of different application servers, to share access to a common underlying system (e.g. database). An automated process for implementing a kernel change (e.g. for upgrade or replacement) may employ a “Stop-the-World” approach involving suspension of application server instances, coordinated by the start service of the last application server whose kernel is to be changed. As used herein, suspending refers to halting any processing prior to calling a central service (CS) as long as a CS instance is unavailable, and then to resuming processing once the CS instance becomes available. This suspension of relevant clients avoids errors from arising during the downtime of the CS instance. Once the application server instances are in a stopped state, the CS instance is restarted. Then, the application server instances are resumed, and their kernels are changed.
1 . A computer-implemented method comprising:
causing a central services instance to receive a kernel change instruction from a first control engine of a first application server;
in response to the kernel change instruction, causing a second control engine of the central services instance to suspend operation of the first application server and to suspend operation of a second application server;
causing the central services instance to restart operation with a new kernel; and
causing the new kernel of the central services instance, to resume operation of the first application server and of the second application server such that the first control engine instructs,
the second application server to restart with the new kernel, and
the first application server to restart with the new kernel.
2 . The computer-implemented method of claim 1 wherein:
the second control engine instructs a message center of an old kernel of the central services instance to suspend operation, after suspension of operation of the first application server and of the second application server; and
the second control engine instructs a message center of the new kernel of the central services instance to resume operation prior to resuming operation of the first application server and of the second application server.
3 . The computer-implemented method of claim 1 further comprising:
prior to the central services instance receiving the kernel change instruction, causing the first control engine to trigger a queue services instance to change from an old kernel to the new kernel.
4 . The computer-implemented method of claim 3 wherein during restart of the central services instance, an existing queue table and a backup file are attached.
5 . The computer-implemented method of claim 4 wherein the second control engine attaches the existing queue table and the backup file by:
attaching to an existing queue lock table shared memory,
halting a queue server of the old kernel,
stopping remaining processes of the old kernel, and
restarting the central services instance by signaling a queue server of the new kernel to reattach to the existing queue lock table shared memory.
6 . The computer-implemented method of claim 1 wherein the new kernel of the first application server, and the new kernel of the second application server, are each in communication with a database.
7 . A non-transitory computer readable storage medium embodying a computer program for performing a method, said method comprising:
causing a central services instance to receive a kernel change instruction from a first control engine of a first application server;
in response to the kernel change instruction, causing a second control engine of the central services instance to suspend operation of the first application server and to suspend operation of a second application server;
causing the central services instance to restart operation with a new kernel; and
causing the new kernel of the central services instance, to resume operation of the first application server and of the second application server such that the first control engine instructs,
the second application server to restart with the new kernel, and
the first application server to restart with the new kernel.
8 . A non-transitory computer readable storage medium as in claim 7 wherein:
the second control engine instructs a message center of an old kernel of the central services instance to suspend operation, after suspension of operation of the first application server and of the second application server; and
the second control engine instructs a message center of the new kernel of the central services instance to resume operation prior to resuming operation of the first application server and of the second application server.
9 . A non-transitory computer readable storage medium as in claim 7 further comprising:
prior to the central services instance receiving the kernel change instruction, causing the first control engine to trigger a queue services instance to change from an old kernel to a new kernel.
10 . A non-transitory computer readable storage medium as in claim 9 wherein during restart of the central services instance, an existing queue table and a backup file are attached.
11 . A non-transitory computer readable storage medium as in claim 10 wherein the second control engine attaches the existing queue table and the backup file by:
attaching to an existing queue lock table shared memory,
halting a queue server of the old kernel,
stopping remaining processes of the old kernel, and
restarting the central services instance by signaling a queue server of the new kernel to reattach to the existing queue lock table shared memory.
12 . A non-transitory computer readable storage medium as in claim 7 wherein the new kernel of the first application server, and the new kernel of the second application server, are each in communication with a database.
13 . A computer system comprising:
one or more processors;
a software program, executable on said computer system, the software program configured to:
cause a central services instance to receive a kernel change instruction from a first control engine of a first application server;
in response to the kernel change instruction, cause a second control engine of the central services instance to suspend operation of the first application server and to suspend operation of a second application server;
cause the central services instance to restart operation with a new kernel; and
cause the new kernel of the central services instance, to resume operation of the first application server and of the second application server such that the first control engine instructs,
the second application server to restart with a new kernel, and
the first application server to restart with a new kernel.
14 . A computer system as in claim 13 wherein the computer program is configured to:
cause the second control engine to instruct a message center of an old kernel of the central services instance to suspend operation, after suspension of operation of the first application server and of the second application server; and
cause the second control engine to instruct a message center of the new kernel of the central services instance to resume operation prior to resuming operation of the first application server and of the second application server.
15 . A computer system as in claim 13 wherein prior to the central services instance receiving the kernel change instruction, the computer program is further configured to:
cause the first control engine to trigger a queue services instance to change from an old kernel to a new kernel.
16 . A computer system as in claim 15 wherein during restart of the central services instance, the computer program is configured to cause an existing queue table and a backup file to be attached.
17 . A computer system as in claim 16 wherein the computer program is configured to cause second control engine to attach the existing queue table and the backup file by:
attaching to an existing queue lock table shared memory,
halting a queue server of the old kernel,
stopping remaining processes of the old kernel, and
restarting the central services instance by signaling a queue server of the new kernel to reattach to the existing queue lock table shared memory.
18 . A computer system as in claim 13 wherein the new kernel of the first application server, and the new kernel of the second application server, are each in communication with a database.