U.S. patent number 4,934,823 [Application Number 07/117,525] was granted by the patent office on 1990-06-19 for staging method and system in electronic file apparatus.
This patent grant is currently assigned to Hitachi, Ltd.. Invention is credited to Yoshinori Okami.
United States Patent |
4,934,823 |
Okami |
June 19, 1990 |
Staging method and system in electronic file apparatus
Abstract
In a staging method and system for an unrewritable storage
medium such as an optical disk in which the updating or deletion of
stored information is possible only by annotatively recording
information concerning the updating or deletion, information stored
in the medium before any alteration or charge including addition,
updating and deletion is made to the medium is staged on a staging
file while positions of the read or staged information are stored
on a management file. Thereafter, the last end of the information
staged on the staging file is detected by referring to the
information positions stored on the management file. Then,
information concerning the addition is additionally recorded at a
location on the staging file after the previously staged
information while information concerning the updating or deletion
is used to update or delete the information on the staging file at
a location indicated by the information concerning the updating or
deletion.
Inventors: |
Okami; Yoshinori
(Minamiashigara, JP) |
Assignee: |
Hitachi, Ltd. (Tokyo,
JP)
|
Family
ID: |
17417861 |
Appl.
No.: |
07/117,525 |
Filed: |
November 6, 1987 |
Foreign Application Priority Data
|
|
|
|
|
Nov 10, 1986 [JP] |
|
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61-265487 |
|
Current U.S.
Class: |
345/530;
707/E17.005 |
Current CPC
Class: |
G06F
16/10 (20190101) |
Current International
Class: |
G06F
17/30 (20060101); G06F 009/46 (); G06F
007/38 () |
Field of
Search: |
;364/9MSFile,2MSFile
;358/296 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Zache; Raulfe B.
Assistant Examiner: Richman; Glenn
Attorney, Agent or Firm: Antonelli, Terry & Wands
Claims
I claim:
1. A staging method for an unrewritable medium in which alteration
including addition, updating and deletion of stored information is
made by additionally recording information of the addition and
annotatively recording information of the updating or deletion on
said medium, said method comprising the steps of:
(a) staging, on a staging file, key information of retrieval key
words or key codes which are stored on said medium before an
alteration including addition, updating or deletion is performed on
said medium, and storing on a management file location information
representing storage positions of said key information staged in
said medium;
(b) detecting a last end of said key information stored in said
staging file before alteration thereof; and
(c) transferring only alteration information of addition, updating
or deletion of said key information from said medium to said
staging file to make a processing depending upon the alteration
information and updating the location information stored in the
management file.
2. A staging method according to claim 1, wherein in said step (c),
upon detection of the last end of the information, information of
the addition is additionally recorded on said staging file at a
location next to the information previously staged thereon while
information of the updating or deletion is used to update or delete
the corresponding information previously staged on said staging
file.
3. A staging method according to claim 1, wherein said medium is
removable and has many picture image data units stored thereon, and
said medium includes an area which stores an identification number
identifying said medium, an area which stores retrieval key words
or key codes for the picture image data units, and an area which
stores the picture image data units.
4. A staging method according to claim 3, wherein each of said
retrieval key words or key codes includes a type of treatment to be
made to the associated picture image data unit, an identification
number identifying the associated picture image data unit, and data
representative of a title of the associated picture image data
unit, and wherein in said step (c), the retrieval key words or key
codes are successively read in accordance with the information
positions indicated by said management file so that when the type
included in the keyword or key code indicates the addition, the
title data included in the key word or key code is written after
the information staged on said staging file while when the type
indicates the updating or deletion, said staging file is searched
in accordance with the picture image data unit identification
number included in the key word or key code to update or delete a
location on said staging file corresponding to said identification
number and thereafter the position information in said management
file is updated.
5. A staging system for an unrewritable medium of the type which an
alteration including addition, updating or deletion of stored
information is made by additionally recording information of the
addition and annotatively recording information of the updating or
deletion thereon, said system comprising:
a storage device for detachably mounting thereon an unrewritable
medium and for retrieving information stored on said medium, said
information including at least title information which is used for
retrieval of said information;
a retrieval device connected to said storage device, said retrieval
device including an input/output device, staging file means
connected to said input/output device for staging title information
retrieved from said medium, management file means connected to said
input/output device for managing information of storage locations
of title information stored in said medium and a controller
connected to said input/output device, said staging file means, and
said management file means and said storage device means for
controlling said staging file means, said management file means,
said input/output device and said storage device;
said controller, via said storage device, retrieves and
transferring said title information stored on said medium from said
medium to said staging file means and said management file means
respectively to stage title information on said staging file means
and to store location information of the title information on said
management file means, refers to said management file means to
detect a last end of the title information staged on said staging
file means and in response to the detection of the last end of the
title information, retrieves via said storage device only
alteration information of addition, updating or deletion of title
information from said medium and transfers said alteration
information to said staging file means so that title information of
the addition is written on said staging file means at a location
next to the information staged before the alteration while title
information of the updating or deletion is used to update or delete
the title information on said staging file means at locations
indicated by the title information.
6. Information retrieval network system for performing a staging
function for an unrewritable medium in which alteration including
addition, updating and deletion of stored information is made by
additionally recording information of the addition and annotatively
recording information of the updating or deletion thereon, said
system comprising:
an electronic file device including an unrewritable medium mounted
detachably thereto, information concerning retrieval key words or
key codes being stored in said medium;
a plurality of retrieval devices connected to said electronic file
device, each of said retrieval devices including an input/output
device; a staging file, a management file and a controller for
controlling the input/output device, staging file and management
file;
an interface for interconnecting said plurality of retrieval
devices with said electronic file device;
said controller transfers, via said electronic file device the
information stored in said medium before alteration, inclusive of
the addition, updating and/or deletion, to the staging file and
management file of each of said retrieval devices to stage said
information on the staging file and store positions of the
information on the management file;
said controller refers to the management file of each of said
retrieval devices to detect a last end of the information staged on
the staging file of each of said retrieval devices before the
alteration; and
said controller in response to the detection of the last end of the
information before the alteration, reads, via said electronic file
device, only alteration information concerning the addition,
updating and deletion from said medium to the staging file of each
of said retrieval devices so that information of the addition is
written on the staging file at a location next to the information
staged before the alteration while information of the updating or
deletion is used to update or delete the information on the staging
file at a location indicated by the information of the updating or
deletion.
7. A staging system according to claim 6, wherein said interface
for interconnecting between said electronic file device and said
retrieval devices comprises a large area communication network.
8. A staging apparatus comprising:
a storage device for storing data to be retrieved, said data each
having a retrieving key code added thereto;
first file means for storing key codes stored in said storage
device;
second file means for managing information representing the storage
location of the key codes stored in said first file means on said
storage device; and
a controller for comparing the storage location of a key code
stored in said storage device with the information of storage
location of key codes managed by said second file means to
determine a key code which is stored in said storage device but is
not stored in said first file means, reading out said determined
key code from said storage device, transferring the same to said
first file means, and updating the information of the storage
location of key codes in said second file means, on the determined
key code.
9. A staging apparatus according to claim 8, wherein said storage
device includes a write-once, read-many recording medium.
10. A staging apparatus according to claim 9, wherein said
recording medium is exchangeable and is available for
annotation.
11. A staging apparatus for use with a storage device for storing a
multiplicity of data to be retrieved, each data having key
information for retrieval added hereto, comprising:
staging file means for storing key information
stored in said file device;
managing file means for managing information representing the
storage location of the key information stored in said staging file
means on said storage device; and
controller means coupled to said staging file means and said
managing file means and adapted to connected to said storage
device, for comparing the storage location of key information
stored in said storage device with the information representing the
storage location of key information managed by said managing file
means to determine key information which is stored in said storage
device but is not stored in said staging file means, reading out
said determined key information from said storage device,
transferring the same to said staging file means, and updating the
information of the storage location of key information in said
managing file means, on the determined key information.
12. A staging apparatus according to claim 11, wherein said storage
device includes a recording medium recording data on a write-once,
read-many, annotatable record basis.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a staging (or data rereading)
method and system, and more particularly to a staging method and
system capable of shortening a search time when data are read and
retrieved or searched from an unrewritable and removal medium such
as an optical disk.
As the conventional staging method is known a reading method
disclosed in No. JP-A-57-13546. According to this method in which
data are read from a sequential file having keyed records, the
reading of blocks is carried out by recording the positions of the
first and last records in each block and referring to the position
information. Namely, node numbers (i.e., key information of
records) of the first block to the last block are first written in
a staging designation range setting device. Thereafter, all the
records 1 to n are read so that the position information is written
in a record position register while the reading of the first block
is performed. Since the position numbers of the first and last
records in each block are thus written in the record position
register, the reading of the second block and the subsequent blocks
is made referring to those position numbers. In this method, the
number of times of reading equal to the total number of records
plus the number of records in the second and subsequent blocks is
required.
In the above-mentioned conventional method, only the reading from a
medium such as a magnetic tape or magnetic disk to which the
writing has been made, is taken into consideration. No
consideration is taken to a removal and unrewritable medium such as
an optical disk. For such a medium, therefore, in the case where
the medium subjected to any alteration or modification such as
addition, updating and/or deletion by another device is again
processed, it is necessary to read over the entire file again from
the beginning to the end.
In an electronic file device using an optical disk, alteration such
as addition, updating and/or deletion is effected by additionally
or annotatively recording alteration information on a blank region
of the optical disk.
In the electronic file device, when a plurality of optical disks
are searched at once, titles on the optical disks, for example,
names added to picture images are preliminarily staged on a staging
file including a non-volatile memory such as a magnetic disk, a
desired title is searched from the titles staged on the staging
file, and a picture image data corresponding to the searched or
located title is read from one of the optical disks. In that case,
if any alteration such as addition, updating and/or deletion is to
be made, data of both the optical disks and the staging file should
be simultaneously altered, thereby preventing any deviation or
anti-coincidence of data between the optical disks and the staging
file. However, if the optical disk is removed after the staging and
the alteration such as addition, updating and/or deletion is made
to the optical disk in another electronic file device, the optical
disk would have information of the alteration additionally or
annotatively recorded thereon. Therefore, a deviation or
discrepancy exists between the information on the optical disk and
the data in the staging file on which the data were previously
staged. Accordingly, staging must be carried out again for
searching of picture image data. As a result, a time required for
reading of data is remarkably elongated.
Further, in the case where an electronic file (device) is used in
common by a plurality of terminals or retrieval devices, the fact
that the time necessary for the staging for each terminal is long,
obstructs the access from the other terminals, thereby lowering the
availability and operation rate of the electronic file
(device).
SUMMARY OF THE INVENTION
An object of the present invention is to improve the transfer rate
in staging upon data retrieval from a medium such as optical disk.
Namely, the present invention aims at providing a staging method
and system capable of minimizing the staging time, i.e. a time
necessary for rereading data written on the medium such as optical
disk.
Another object of the present invention is to provide a staging
method and system capable of improving the operation rate of an
electronic file device commonly accessable from a plurality of data
retrieval devices by shortening the staging time.
To that end, in a staging method and system according to the
present invention, after information concerning retrieval key word
or key code stored on an electronic file medium such as an optical
disk before addition, updating and/or deletion is staged on a
staging file while storing positions (or pointers) of the read key
word or key code information on a management file, the last end of
information stored in the staging file is detected so that addition
information additionally recorded on the medium by the alteration
is read from the medium to record it at a predetermined location on
the staging file having the staged information while information
concerning the updating and/or deletion annotatively recorded on
the medium by the alteration is used to update and/or delete the
corresponding information location on the staging file having the
staged information.
For an unrewritable medium such as an optical disk, only
information to be added can be additionally recorded on the medium.
When it is desired to update or delete the recorded information,
only information concerning the updating or deletion (i.e.
information indicative of the updating or deletion and information
indicative of the position of data to be updated or deleted) is
annotatively recorded after consecutive data which have already
been recorded. This scheme of recording is utilized in the present
invention. In the present invention, since it is not necessary to
read the previously staged data again from a master file such as an
optical disk onto a staging file, only data following the data
previously read on the staging file are read from the master file
to alter the previously staged data. More especially, the last
position of information stored in the title/index storage areas of
the medium is detected by means of a well-known blank block
searching function, and only information concerning addition,
updating and/or deletion recorded on a blank block following the
last position of the previously read data is read from the medium
and transferred to the staging file including a non-volatile memory
such as a magnetic disk so that a necessary treatment concerning
the addition, updating and/or deletion is made to the staging file.
With such a construction, a need to read the previously staged data
again is eliminated and hence the number of times of reading and
the amount of data to be processed can be greatly reduced, thereby
shortening the staging time the present invention is suitably
applied to a stand-alone multi-cabinet retrieval system, type
"HITFILE 650" fabricated by Hitachi, Ltd.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows the states of storage in a management file, a staging
file and a title storage area of an optical disk in a staging
process according to an embodiment of the present invention;
FIG. 2 is a block diagram of an electronic file system according to
the embodiment of the present invention;
FIG. 3 is a diagram showing the state of storage in an optical disk
shown in FIG. 2;
FIG. 4 illustrates a title data format for one title shown in FIG.
3;
FIG. 5 is a flow chart of the staging process explained with
reference to FIG. 1;
FIG. 6 is a block diagram of an electronic file system according to
another embodiment of the present invention; and
FIG. 7 is a flow chart of the staging process carried out in the
system of FIG. 6.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiments of the present invention will now be explained in
detail referring to the accompanying drawings.
FIG. 2 shows a block diagram of an electronic file system to which
the present invention is applied and in which an electronic file
device using a removable and unrewritable optical disk is employed.
The electronic file system includes a retrieval device R and an
electronic file device F. The retrieval device R is composed of a
system controller 1, a memory 7, a magnetic disk input/output
controller 4, a staging file memory 5, a management file memory 6,
a picture image input unit 8, a picture image printer 9, an
operation console 10 including a keyboard or the like, and a
display unit 11. The electronic file device F includes an optical
disk input/output controller 2 and has a disk read/write mechanism
for mounting detachably an optical disk 3 in which document titles,
page data and picture image data are stored.
The optical disk 3 is a medium containing recorded data a process
for reading of which the present embodiment concerns. The staging
file 5 is a file for storing reread data and the management file 6
is a file for storing pointers of the previously read (pre-read)
data (or title positions). In the operation console 10, inputting
of titles to be prefixed to picture images or the other operations
are made by an operator. The display unit 11 is provided for
displaying picture image data read from the optical disk 3 so that
it can be monitored by the operator. The picture image input unit 8
is a device for reading a picture image on a document in order to
store it into the optical disk 3. The picture image printer 9 is
provided for printing out the picture image data read from the
optical disk 3. The memory 7 is provided for temporarily storing
data before the data is stored into the optical disk 3 or before
the data read from the optical disk 3 is outputted. The system
controller 1 controls the entire electronic file system.
In accordance with a command from the operation console 10 by the
operator, picture image data on a document is read by the picture
image input unit 8 and the read picture image data is stored into
the optical disk 3 through the optical disk input/output controller
2 together with titles (or names prefixed to the picture images)
inputted from the operation console 10 by the operator. The optical
disk 3 is a removable medium. In the case where search to a
plurality (for example, several thousands) of optical disks is
desired, the titles stored on the optical disk 3 is preliminarily
read from the optical disk 3 and stored in the staging file 5
through the magnetic disk input/output controller 4. When the
search is made, the titles stored in the staging file 5 are read to
determine the present or absence of a desired document, and the
picture image data on the optical disk 3 is thereafter read, as
required, for delivery to the display unit 11 and/or the picture
image printer 9.
FIG. 3 shows the state of storage in the optical disk 3, and FIG. 4
shows a title data format of one title shown in FIG. 3.
As is shown in FIG. 3, the optical disk 3 includes an optical disk
identification (ID) area 30, a title storage area 31 and a picture
image data storage area 32. The optical disk ID area 30 is an area
for storing an identification number which identifies one of a
plurality of optical disks 3. The title storage area 31 stores a
plurality of titles T-1 to T-n. As is shown in FIG. 4, each title
is composed of a type field 311 which represents the type of
treatment to be made to the title, a title ID field 312 which
represents a unique number (block number) of the title, and a data
field 313 which represents information concerning a document title
and the storage position of picture image data. In the type field
311, "A" (addition), "U" (update) or "D" (delete) is recorded for
addition, updating or deletion. In the title ID field 312, a new
title number is recorded in the case of addition. In the case of
updating or deletion, the title number corresponding to the title
to be updated or deleted is recorded. Namely, even in the case of
updating or deletion, the updating or deletion is realized by such
recording.
FIG. 1 shows the states of storage in the management file 6, the
staging file 5 and the title storage area 31 of the optical disk 3
when the staging process according to the embodiment of the present
invention is made. The shown example illustrates a relation between
the management file 6 and the title storage area 31 of the optical
disk 3 in the case where the optical disk 3 having titles T-13 to
T-17, as well as the titles T-1 to T-12 which have already been
staged on the staging file 5 are to be staged on the staging file
5. The management file 6 includes optical disk ID fields which
store disk ID information recorded in the disk ID areas 30 of the
optical disks 3 and pointer fields each of which stores the
positions of titles previously read and indicates the position of a
title to be next read. The disk ID information identifying each of
optical disks having a possibility that they are subjected to
staging, is stored in the disk ID field of the management file 6.
In the shown example, 0-1 to 0-4 identifying four optical disks 3
are stored. Pointers P-1 to P-4 corresponding to the respective
optical disks are stored in the pointer fields. Each pointer
indicates the position of a title to be read. In the shown example,
the pointer P-3 corresponding to the disk ID 0-3 indicates the
title T-13 next to the titles which have already been staged.
The staging file 5 includes title ID fields which store title ID's
recorded in the title ID fields 312 of the title storage area 31 of
the optical disk 3, and data fields which store data such as
document titles recorded in the data fields 313 of the title
storage area 31 of the optical disk 3. In FIG. 1, the title ID's
stored in the ID fields of the staging file 5 are indicated by I-1
to I-12 and the data stored in the data fields thereof are
indicated by D-1 to D-12. Thus, all the contents of the titles
excepting the types are stored in the staging file 5.
FIG. 5 is a flow chart for explaining the staging method in FIG. 1.
In the staging process, an optical disk ID 30 (0-3) is first read
from the optical disk 3 (step 51). Next, the disk ID fields on the
management file 6 are searched to obtain a pointer (P-3)
corresponding to the read disk ID (0-3), thereby recognizing the
last position (T-12) of previously read titles (steps 52 and 53).
Since the pointer P-3 indicates the title T-13 following
immediately after the previously read titles, the title T-13 in the
title storage area 31 on the optical disk 3 is read (step 55). When
the type field 311 of the title T-13 represents "A" (addition), the
corresponding title ID 312 and data 313 are recorded at an end
portion of staging file 5 or after the data previously staged (step
56). On the other hand, when the type represents "U" (update) or
"D" (delete), the corresponding title ID 312 is used as a key word
or key code to search one of the title ID fields (I-1 to I-12) on
the staging file 5 (step 57) and to update or delete one of the
data fields (D-1 to D-12) on the staging file 5 corresponding to
the located title ID (step 58 or 59). Thereafter, the pointer is
positioned to the next title (step 60) and the step is returned to
the step 55. If a blank block is detected by means of a well-known
blank block searching function or mechanism, there results in the
detection of the completion of staging of the last title T-17 and
the pointer P-3 on the management file 6 is updated so as to
indicate T-18 (step 61).
In the above-mentioned staging process, when no disk ID field
exists as a result of search of the disk ID fields on the
management file 6 at the step 52, it is recognized that the optical
disk 3 being read is one which was previously subjected to no
staging. In newly staging such an optical disk 3, the staging is
started from the heading title (step 54). Upon completion of this
staging, a disk ID 30 (0-5) identifying that optical disk 3 and a
pointer (P-5) indicative of the position of a blank are added to
the disk ID and pointer fields of the management file 6,
respectively (step 62).
Thus, when the optical disk previously subjected to staging is
again staged, only information concerning the block(s) including
any alteration is read, thereby shortening the staging time.
For example, assume that an optical disk having about ten thousands
of picture image data unit stored in document units of 4 to 5 pages
was previously subjected to staging and the staging time required
was 6 milliseconds per one document unit and totally 60 seconds.
When staging is again made to the optical disk after addition,
updating and deletion have been made to one thousand of picture
image data units; the conventional staging method would require 66
seconds but the present embodiment requires only 6 seconds since it
is not necessary to read the previously read data again and it is
sufficient to read only data concerning the addition, updating and
deletion.
Accordingly, when the present embodiment is applied to an
electronic file system which handles a great amount of picture
image data, the staging time can be greatly saved.
In the embodiment, the staging information is stored in the staging
file memory 5 using the magnetic disk. However, the staging
information may be stored in any memory which has a large capacity
like the magnetic disk.
FIG. 6 shows a composite electronic file system according to
another embodiment of the present invention which includes a
plurality of retrieval devices R1 to R4 and an electronic file
device F which is interconnected with the retrieval devices through
a communication network such as a local area network (LAN) for
common use. Keyword or title information stored on an optical disk
included in the electronic file device F is staged at high speed
onto a staging file provided in each of the retrieval devices R1 to
R4.
More especially, each of the retrieval devices R1 to R4 has the
same function as shown by the dotted chain line R of FIG. 2. The
optical disk 3 mounted to the electronic file device F can be
commonly accessed by the retrieval devices R1 to R4. Titles
recorded on the optical disk 3 of the electronic file device F are
staged through the LAN onto respective staging files 5 of the
retrieval devices R1 to R4. Upon searching, each of the staging
files 5 is searched and data on the optical disk 3 of the
electronic file device F is read through the LAN. With such a
construction, a load imposed on the electronic file device F can be
distributed.
However, the retrieval devices R1 to R4 are independent devices
from one another. Therefore, for example, when any alteration is
made in conjunction with the retrieval device R1 and the alteration
is not communicated to the other retrieval devices R2 to R4, a
deviation or non-coincidence takes place between the contents of
the staging files 5 of the respective retrieval devices and the
titles on the optical disk of the electronic file device F.
In order to recover or prevent the staging files involving the
deviation, staging must be made again, normally for each retrieval
operation. The present invention is applied for performing this
staging in such a manner that only information concerning the
alteration is transferred to the staging file through the LAN. The
staging operation steps required are as illustrated in FIG. 7. The
flow chart of FIG. 7 will be apparent from the explanations made in
conjunction with FIG. 5.
In operation, in the retrieval device R, a disk ID of an optical
disk to be retrieved is read from the management file 6, and
thereby a pointer RP indicating the position of disk information
already read on its staging file 5 is obtained (step 71).
Subsequently, in order to obtain a pointer FP indicating the
position of the read disk information in the electronic file device
a command for request of FP and the optical disk ID are transferred
from the retrieval device to the electronic file device (step 72).
On the other hand, in the electronic file device, a data is
received to receive a request and the associated information from
the retrieval device (step 80). If the received data is an FP
request in a step 81, an optical disk ID on a management file which
may be provided in the electronic file device (not shown) is read
out to obtain an FP data (step 84). Alternatively, the FP data may
be taken out directly from the loaded optical disk using the known
search-for-blank block function. The FP data thus obtained is
transferred to the retrieval device (step 85). In the retrieval
device, the FP data is received (step 73) and collated with the RP.
If RP is equal to FP, the retrieval processing is terminated. If RP
is not equal to FP, a command for a title request and a pointer
indicating the position of a title to be read (which equals RP) are
transferred to the electronic file device F (step 74).
The electronic file device F receives a data for requests thereto
again when the processing of one request command received from the
retrieval device is completed (step 80). When the command is a
title request, a title is read based on the received pointer
information (step 82) and is transferred to the retrieval device
(step 83). The retrieval device performs a processing for
alteration as indicated in the flow chart of FIG. 5 including steps
56 to 60, when the title is received from the electronic file
device F (steps 75 and 76). The processing is repeated until an
updated RP coincides with the FP (step 78). When RP=FP is reached,
the pointer FP in the retrieval device is updated (step 79). In
such a manner, a staging operation of the electronic file device is
completed by the retrieval device.
As an example, assume that a transfer capacity of the LAN is 10
kB/s and the length of one title is 100 bytes, 10 milliseconds are
required for transfer per one title or document unit. When this
example is applied to the example which has been explained in
conjunction with the system shown in FIG. 2, 16 milliseconds
(staging time of 6 milliseconds plus transfer time of 10
milliseconds) will be required per one document unit. If the
conventional staging method through the LAN is employed, a staging
time would require totally 176 seconds. On the other hand, in the
case where the present embodiment is applied, a staging process can
be completed with 16 seconds. In this case, the staging is started
at a point of time at which any deviation is detected. Namely, when
the deviation between titles on the optical disk 3 of the
electronic file device F and the contents of the staging files 5 of
the retrieval devices R1 to R4 is detected at the retrieval
devices, the staging can be performed at high speed automatically
or through actuation by the operator.
As has been explained, according the present embodiment, a high
speed staging through LAN is possible and the load imposed on the
electronic file device can be greatly and efficiently reduced by
the provision of the respective staging files in the retrieval
devices.
* * * * *