Title: Process, modules and switching center for identifying processes as well as their data and resources
Abstract: In a process for identifying a process (P1) and its resources, the process (P1) is provided with a first identifier (PID1) that unambiguously identifies the process (P1) and its resources. The process (P1) is further provided with a second identifier (RID1) that unambiguously identifies the process (P1) and its resources, and particularly after a premature termination of the process (P1), a new process (P2) which continues the functions of the terminated process (P1) is started. The new process (P2) retains the second identifier (RID1) of the terminated process (P1) as its second identifier. The new process (P2) which continues the terminated process (P1) can then, furthermore, access the resources of the terminated process (P1).
Patent Number: 6,938,255 Issued on 08/30/2005 to Willems, et al.
| Inventors:
|
Willems; Matthias (Leonberg, DE);
Ongena; Luc (Mechelen, BE);
Kunkel; Rolf (Freiberg, DE)
|
| Assignee:
|
Alcatel (Paris, FR)
|
| Appl. No.:
|
365784 |
| Filed:
|
August 3, 1999 |
Foreign Application Priority Data
| Aug 04, 1998[DE] | 198 35 177 |
| Current U.S. Class: |
718/104; 718/100; 718/102; 718/106 |
| Intern'l Class: |
G06F 009/46 |
| Field of Search: |
709/100,102-108
|
References Cited [Referenced By]
U.S. Patent Documents
| 5644719 | Jul., 1997 | Aridas et al.
| |
| 5802590 | Sep., 1998 | Draves.
| |
| 5894555 | Apr., 1999 | Harada et al.
| |
| 5974134 | Oct., 1999 | Park.
| |
| 6108715 | Aug., 2000 | Leach et al.
| |
| 6119145 | Sep., 2000 | Ikeda et al.
| |
| 6253225 | Jun., 2001 | Nakahara et al.
| |
| Foreign Patent Documents |
| 196 22 065 | Sep., 1997 | DE.
| |
| 197 34 320 | Feb., 1998 | DE.
| |
| 0 457 117 | Nov., 1991 | EP.
| |
| 0 750 257 | Dec., 1996 | EP.
| |
Primary Examiner: An; Meng-Al T.
Assistant Examiner: Ali; Syed J
Attorney, Agent or Firm: Sughrue Mion, PLLC
Claims
1. A method for identifying one or more processes and their resources, each process
having a first identifier unambiguously identifying the process and its resources,
wherein each process and its resources are provided with a second identifier unambiguously
identifying the process and its resources, and when premature termination of a
first process occurs, a second process is started to continue the functions of
the terminated first process, the second process retaining the second identifier
of the terminated first process as its second identifier.
2. The method according to claim 1, wherein the second identifier is protected
against at least one of restarting and reloading, which terminates the first process.
3. The method according to claim 1, wherein each second identifier is released
only when the functions of the process having this second identifier have been executed.
4. The method according to claim 1, wherein the second identifiers are managed
by the operating system.
5. The method according to claim 1, wherein the second identifier is transmitted
jointly with other data in a data word.
6. The method according to claim 1, wherein the second identifiers are stored
in one or more tables.
7. The method according to claim 1, wherein one or more of said one or more processes
are prematurely terminated when no longer required.
8. The method according to claim 1, wherein the processes are telecommunications processes.
9. A computer readable medium tangibly embodying a computer module, a program
module or a software module with means for implementing the method according to
claim 1.
10. A switching center having at least one computer module, program module or
software module according to claim 9.
11. A computer readable medium having a program recorded thereon, said computer
readable medium comprising a computer program code means adapted to perform the
method of claim 1.
12. A method for identifying a process and its allocated resources, comprising:
unambiguously identifying the process and its resources with a first identifier,
wherein the first identifier is dependent on the life of the process;
unambiguously identifying the process and its resources with a second identifier,
wherein the second identifier is independent of the life of the process; and
when a premature termination of the process occurs, starting a second process
to continue the functions of the terminated process, wherein the second process
retains the second identifier of the terminated process for accessing resources
or data of the terminated process.
Description
BACKGROUND OF THE INVENTION
The invention concerns a process for identifying processes, preferably telecommunications
processes, as well as their resources, each of which is provided with a (first)
identifier unambiguously identifying this process, and further concerns a suitable
computer, program or software module for implementing this process, as well as
a switching centre having such a module.
Such a process has been disclosed by U.S. Pat. No. 5,644,719, for example.
With quasi-simultaneous processing of several processes with a computer (multitasking)
the processing of processes in a computer is nested or interleaved chronologically
by an appropriate process controlled by an operating system, so that the processing
is effected in a quasi-simultaneous manner. To do this, each process receives a
so-called process identifier (PID), that is assigned only once in the system and
therefore unambiguously identifies the process. Resources such as, for example,
stacks or memory location, that are made available to a process by the operating
system, or even data, are provided with the respective process identifier in order
to identify their allocation to the respective process. If a process is terminated,
the memory location, for example, in which data of the terminated process are stored,
is freed by using the identifier.
If a process is aborted prematurely, that is to say not terminated normally,
because
an error has occurred, for example, a new process is started that is intended to
replace this abnormally terminated process. Of course, the new process which receives
a new process identifier cannot access the data of the aborted process, since these
are identified by the process identifier of the terminated process. If one of several
mutually coupled processes is prematurely terminated, the new process continuing
this process must be synchronised to the remaining processes in a complicated manner.
And if a process does not run for a prolonged period of time it cannot be terminated
since, otherwise, access to its data is no longer possible at a later time. This
leads to a high requirement for storage space and consequently for the resources
to be provided.
In the case of the nested computers described in U.S. Pat. No. 5,644,719, the
operating system also allocates process identifiers (PID) to application processes
that are handled by the computer, these process identifiers being used by the operating
system during the transmission of messages between the processes.
SUMMARY OF THE INVENTION
The object of the invention is therefore to develop a method of the type stated
above in such a way that a new process that is continuing a terminated process
is able to access the data and resources of the terminated process, and to create
suitable modules and a switching centre for this purpose.
This object is achieved according to the invention, in that a process and its
resources are provided with a further (second) identifier unambiguously identifying
the process and, particularly after premature termination of the process, a process
which continues the functions of the terminated process is started, which retains
the second identifier of the terminated process as the second identifier.
According to the invention, in addition to the first process identifier
that is dependent on the life of its process, resources, for example, data, are
identified by a second identifier-described in the following text as the reference
identifier (RID)-that is independent of the life of the process. The continuing
new process can thus access resources of the terminated process. The reference
identifier facilitates rapid and secure access to data of a terminated process.
If one of several chronologically coupled processes is prematurely terminated,
the continuing process takes the place of the terminated one without any time delay,
so that synchronisation with the remaining processes is not necessary.
Equipped with the newly assigned reference identifier of the terminated
process, the new process assumes the functions of the terminated process. Consequently,
the reference identifier enables communication on the basis of the function and
not on the basis of the process, as is the case when only the first process identifier
is used. The system gains flexibility.
In preferred developments of the invention, the reference identifiers (RID) are
protected against restarting and/or reloading of a control element, and particularly
those processes, data and resources that are dependent on the restarting and reloading
of their control unit, are identified by them. The process synchronisation that
is otherwise required after restarting or reloading of the control unit can be eliminated.
By enabling the reference identifier only when the functions of the first process
provided with this reference identifier have been executed, this ensures that the
functions are also successfully carried out.
The reference identifiers are preferably managed by the operating system, and
also assigned or requested by said operating system. The process continuing the
functions of the terminated process is also requested by the operating system.
In a further advantageous development of the process, provision is made for the
reference identifier to be transmitted jointly with other data in a (process-specific)
data word. This enables messages to be transmitted simultaneously with the reference
identifiers. If the reference identifier, composed for example, of 32 bits, that
identifies a process in a destination computer, is present, then with the 48-bit
data structure which is usual for such processes the remaining 16 bits can be used
for specifying the virtual path to this destination computer. The communications
software can then encrypt this two-part data word accordingly.
The reference identifiers can be stored in tables, preferably in a common table,
and allocated according to their chronological order of rank (priority). A reference
identifier is then only enabled from this table if its functions have been carried
out, if necessary by subsequent processes.
In a particularly preferred development of the process, if a process that is
not
required is terminated ("put to bed"), in particular by the operating system, it
is "brought back to life" on request in a new process that continues this put-to-bed
process with the aid of the reference identifier. As a result, resources are kept
free, so that with a constant number of operating system resources (process control
blocks) considerably more processes (e.g. a factor of 15) can be managed.
In a further aspect, the invention also concerns a suitable computer module,
program
module or software module for implementing the method as described, as well as
a switching centre having at least one such module. Such a switching centre can
be a node in a telecommunication network, for example.
BRIEF DESCRIPTION OF THE DRAWINGS
Further advantages of the invention are revealed in the description and the
drawing. According to the invention, the above-mentioned features and those to
be cited later on can be used individually or in any combination. The illustrated
and described embodiments should not be considered as a final list, but rather
have an exemplary character for the description of the invention.
FIG. 1 shows schematically two processes, one of which continues the other and
retains the same second identifier; and
FIG. 2 shows a flowchart for a computer module, program module or software module
implementing the process according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
In FIG. 1, an operating system with which the processing of multitasking processes
is controlled is denoted by BS. One such process P
1 receives from the operating
system BS a first (process) identifier PID
1 and a second (reference) identifier
RID
1, both of which are assigned only once, so that the process P
1
is unambiguously identified by each of these two identifiers. Resources such as
data D, to which the process P
1 has access or which were generated by it,
are identified in this manner.
The process identifier PID
1 is dependent on the life of its process P
1
and is used, for example, to manage the process resources and to control databank
transactions. Restarting and/or reloading terminate the process P
1 and the
life of this identifier.
The reference identifier RID
1 is independent of the life of the process
P
1 and exists until it functions are executed. This identifier is used to
manage process data dependent on restarting and/or reloading and offers user software
the possibility of operating with a process identification code independent of
a restart and/or reload.
If the process P
1 is terminated prematurely (shown by dashed lines), because
an error has occurred, for example, a new process P
2 having a first (process)
identifier PID
2 and continuing the functions of the terminated process P
1
is started. This new process P
2 retains the reference identifier RID
1
of the terminated process P
1 as its reference identifier. The new process
P
2 can also access the resources and data D of the terminated process P
1,
and thus continue its functions, via the reference identifier RID
1. A reference
identifier RID is deallocated only if a process comes to a normal end.
If, in the telecommunication field, the process P
1 has handled a telephone
call, for example, with premature termination of the process P
1 its data
D could still be used for ending the telephone call. The new process P
2
can read the data D associated with the telephone call in order to terminate the
call, or the new process P
2 is the receiver of messages which are still
to be sent to the terminated process P
1. The reference identifier RID simplifies
and accelerates the resynchronisation of associated, distributed processes following
restarting or reloading of a control unit participating in the control of a telephone
call. Moreover, as an operating system function, the reference identifier RID enables
application software to maintain stable telephone calls despite the restarting
and/or reloading of a control unit and to rapidly locate call-relevant data that
are stored in a databank. That is to say, fast and secure access to call-relevant
data is possible, even after restarting and/or reloading.
FIG. 2 shows by way of an example a flowchart of a computer program for the
process described above. In step
1, the process P
1 is provided with
the two identifiers PID
1 and RID
1. If it is established in step
2
that the process P
1 has ended, the system enquires in step
3 whether
the functions of this process are completed. If the answer is "yes", the program
is terminated (step
5). If otherwise (answer is "No"), a new process P
2
with identifier RID
1 is started in step
4. This process P
2
continues the process P
1 in order to execute its still outstanding functions.
If this process P
2 is also terminated without all functions of the process
P
1 being completed, the negative reply in step
3 causes a further
process to be started, which likewise retains RID
1 as the identifier. The
program jumps to the end (step
5) only if all functions of the process P
1
have been executed, that is to say if the reply in step
3 is positive.
*
