JPH11149405A - WWW cache system and method of prefetching WWW data - Google Patents

Abstract

(57) [Summary] In WWW data access on the Internet, a technique of placing a copy of frequently accessed data in an intranet (referred to as cache)
Conventionally, in order to increase the recall rate of a cache, all pages referred to by a requested page in a hyperlink structure are read ahead.
Such a method is effective for increasing the recall, but has a problem of increasing the data transfer load at the same time. A mechanism is provided for totalizing and analyzing the history of WWW data access of a proxy server, and a priority is given to data cached in a cache server based on the analysis result. According to the priority, a condition is set as to whether or not to perform prefetch for each requested data. [Effect] It is possible to provide a look-ahead method for improving the cache recall rate by the look-ahead while suppressing an increase in load on the network due to the look-ahead. At the same time, it is possible to differentiate customer services in prefetching.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a WWW cache system capable of improving the cache recall while suppressing an increase in network load by efficiently prefetching WWW data in a computer network.

[0002]

2. Description of the Related Art Conventionally, one of information services widely used on the Internet is WWW (World Wi-Fi).
de Web). A WWW server connected to the Internet provides information to a user in units called pages, and the pages have a reference relationship structure to another page called a hyperlink.

On the other hand, such a method of prefetching WWW data in page units is described in "Possibility of speeding up WWW access by prefetching" published at Internet Conference '96 (Japan Society for Software Science and Technology, JUS, WIDE). Proposed. This is a technique for increasing the recall of the cache by pre-reading and storing in a cache all referenced pages by hyperlinks in the page requested by the client.

[0004]

However, the above-mentioned prior art realizes a high-speed access, but has a problem that a traffic load increases as a side effect thereof.
This is because, at a stage where it is unclear which reference destination page is to be selected by the user, all the reference destination pages are read ahead.

SUMMARY OF THE INVENTION It is an object of the present invention to minimize the increase in traffic by performing efficient selection of prefetching and non-prefetching when performing prefetching to increase the cache recall rate.

[0006]

According to one aspect of the present invention, there is provided a WWW cache system, comprising: cache means for caching accessed WWW data in a cache area; and WWW data cached in the cache area. Priority judgment means for judging the priority of the WWW data based on the result of the judgment of the priority, and prefetch judgment means for judging whether to prefetch the WWW data referred to by the requested WWW data, A read-ahead operation means for performing a pre-read operation based on a result of determination as to whether or not to perform pre-read by the means.

According to a second aspect of the present invention, there is provided a WWW cache including a proxy server for processing access to WWW data in response to a request from a client, and a cache server for caching the accessed WWW data in a cache area. In the system, the cache server device includes a priority determination unit configured to determine a priority of the WWW data cached in the cache area, and based on the determination result of the priority, the WWW data referred to by the requested WWW data. The proxy server device includes a prefetch operation unit that performs a prefetch operation based on a result of the prefetch operation performed by the prefetch determination unit. It is characterized by.

The invention according to claim 3 is the invention according to claim 1 or 2
A means for acquiring an access history of WWW data, a means for calculating a request frequency of WWW data cached in the cache area based on the acquired access history, and information on the obtained request frequency. Means for determining the priority of the WWW data cached in the cache area.

The invention according to claim 4 is the invention according to claim 1 or 2
In, further comprising an importance determination means for determining the importance of the user of the system, the look-ahead determination means, in addition to the determination result of the priority, based on the determination result of the importance of the user, It is characterized in that it is determined whether or not to prefetch the WWW data referred to by the requested WWW data.

[0010] The invention according to claim 5 is the invention according to claim 1 or 2.
, Further comprising: means for acquiring a current access status to WWW data; and prefetch permission determining means for determining permission / non-permission of execution of prefetch based on the acquired access status.

A method of prefetching WWW data according to claim 6, wherein the step of caching the accessed WWW data in a cache area; the step of determining the priority of the WWW data cached in the cache area; Based on the priority determination result, a prefetch determination step of determining whether to perform prefetching of the WWW data referred to by the requested WWW data, and based on the determination result of whether to perform the prefetching by the prefetch determination step. A prefetch operation step of performing a prefetch operation.

According to a seventh aspect of the present invention, there is provided a WWW cache comprising: a proxy server for processing access to WWW data in response to a request from a client; and a cache server for caching the accessed WWW data in a cache area. WW in the system
A method of prefetching W data, comprising: a priority determining step of determining a priority of WWW data cached in a cache area by the cache server device; and a requesting WWW data based on the determination result of the priority. A look-ahead determination step of determining whether to perform look-ahead of the reference destination WWW data; and a look-ahead operation step of performing a look-ahead operation based on the determination result of whether the look-ahead is performed by the look-ahead determination unit, by the proxy server device. It is characterized by having.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a W connected to the Internet.
It is an example showing how data on a WW server is provided to a user (client). Usually the Internet
Data on the WWW server 102 connected to 101 is provided to the user 104 in units called pages 103. The page 103 is uniquely specified by an identifier indicating a position of the page 103 on the Internet 101 called a URL (Uniform Resource Locator) 105. User 104 has URL1
WWW server 102 by specifying page 103 at 05
Makes a data use request 106, and the WWW server 102 responds to the
Provide to 104. In the following, the first to third embodiments will be described.
Data shall be handled in page units.

A page on the Internet has a reference relationship structure to another page called a hyperlink as shown in the example of FIG. In FIG. 2, page 201 is
The hyperlink 202 and the hyperlink 203 have a reference relationship to a page 204 and a page 205, respectively.

A first embodiment will be described. FIG. 3 is a block diagram of the WWW cache system according to the first embodiment of the present invention. User client 301, proxy server device 302, and cache server device 303
Are connected to each other in one LAN 304. The LAN 304 is connected to the Internet 305 via the proxy server device 302.

The user client 301 has a WWW browser 306. The WWW browser 306 sends a request 307 to the proxy server device 302 and receives a response 308 from the request 307 from the proxy server device 302 to access a page on the Internet 305. I do.

The proxy server device 302 receives a request 307 from the user client 301 to the page specified by the URL. The proxy server device 302 that has received the request 307 performs a cache search 311 as to whether or not the requested page is cached in the cache area 310 with reference to the cache entry table 309 of the cache server device 303. If not cached, access is made to a page on the Internet 305 specified by the URL, and the obtained page is returned to the user client 301 as a response 308. If cached, a copy of the page in cache area 310 is returned as response 308.

Further, if the requested page is cached, the prefetch mechanism 312 makes a prefetch judgment 314 as to whether or not to perform a prefetch operation 313. When the prefetch operation 313 is to be performed as a result of the prefetch determination 314, the proxy server device 302 makes a request 315 to the page to be prefetched and caches the page obtained by the response 316 to the cache server device 303. Also, the proxy server device 302 records the series of access processes as an access history 317.

The cache server device 303 manages information of pages cached in the cache area 310 by using a cache entry table 309. FIG. 4 shows the data structure of each entry registered in the cache entry table 309. As shown in the figure, one entry 401 in the cache entry table 309 includes the URL 402 of the cached page, the priority 403, and the position 4 of the page body copied to the cache area 310.
04 information is retained. The priority 403 is determined by the priority determination mechanism 323 performing a priority determination 325 for each entry based on the access history 317 of the proxy server device 302, and by performing the priority registration 324. It is given to an entry in the cache entry table 309.

It is assumed that the URL of the page requested by the user client 301 matches the URL 319 of an entry 318 in the cache entry table 309. In this case, the look-ahead mechanism 312 determines whether the cache area 310 indicated by the position 322 of the page body of the entry 318 is present.
The URL 326 of the page referred to by the hyperlink is extracted from the page body 321 in the URL. Then, the prefetching mechanism 312, based on the priority 320 of the requested page, the URL 326 of the page referred to by the hyperlink, and the information held in the cache entry table 309,
A look-ahead determination 314 for determining a page to be pre-read according to a predetermined determination flow is performed. In addition, the look-ahead mechanism 312
A prefetch operation 313 is performed on the page selected by the prefetch judgment 314. An example of the pre-read determination flow will be described later in detail. The information on the page body and the page obtained by the response 316 by the prefetch operation 313 are stored in the cache area 310 and the cache entry table 3 respectively.
Managed by 09.

FIG. 3 shows an example of the system configuration, and the proxy server device 302 and the cache server device 303 may be on the same machine. Of course, there may be a plurality of user clients 301.

FIG. 5 shows an example of a processing flow by the priority determination mechanism 323. In this example, priority 403 is set to high, medium,
It is expressed in three stages of low. However, the example here shows an example of how to give the priority 403, and another way of giving the priority (for example, expressing the priority in two levels of high or low or more levels) may be used. The processing in FIG. 5 may be executed at an appropriate timing such as every predetermined period. For example, the processing of FIG. 5 may be performed at a predetermined time every night, and the priority of each entry may be obtained from the access history for one week before that.

In the processing by the priority determination mechanism 323 in FIG. 5, first, the access history 317 of the proxy server device 302 is analyzed, and the number of requests to the proxy server device 302 for each page in a certain period is counted ( Step 501). Next, a priority determination 325 is performed for each entry registered in the cache entry table 309 using the obtained request count result (step 502), and the cache entry table 309 is determined according to the obtained priority value. Priority registration for each entry in 324
Is performed (step 503).

The specific procedure of the priority determination 325 and the priority registration 324 is as follows. Two values of m and n (n <m) are given in advance as thresholds for priority determination, and the number of requests for each page is compared with the thresholds m and n (step 504). If the number of requests is m or more (step 505), a high priority is given to the page (step 506). If the number of requests is at least n and less than m (step 507), medium is given as the priority (step 508). If the number of requests is less than n (step 509), a low priority is given (step 510). Then, the obtained priority value is registered in the entry of the page in the cache entry table 309 (step 503). Step 504, 505, 50
The steps 6, 507, 508, 509, 510, and 503 are repeated for all the pages registered in the cache entry table 309.

FIG. 6 shows an example of a processing flow by the prefetch mechanism 312. This flow is a detailed processing flow of the look-ahead mechanism 312 outlined in the description of the cache server device 303 described above. In this example, the priority is expressed in three levels of high, medium, and low as in the example of FIG.
Although described in the description of the cache server device 303, the U of the page requested by the user client 301
RL is entry 3 in cache entry table 309
When the URL matches the URL 319 of 18, the processing by the look-ahead mechanism 312 in FIG. 6 is executed.

First, referring to the entry 318, the priority 320 of the requested page and the position 322 of the page body in the cache area 310 are extracted (step 601). Next, the page main body 321 in the cache area 310 is called based on the obtained page main body position 322, and the URLs 326 of all the reference pages by the hyperlink are extracted from the page main body 321 (step 602). Next, the cache entry table 309 is searched based on the obtained URL 326,
Each of the referenced pages already has a cache server device 30
It is checked whether it is cached in 2 and if so, its priority is taken out (step 60).
3). Next, the priority 320 of the requested page obtained in steps 601 to 603, and the U of the reference page by the hyperlink in the requested page
A prefetch determination 314 and a prefetch operation 313 are performed based on the RL 326 and the priorities of the reference pages already cached in the cache server device 302 (step 604).

The specific procedure of the prefetch judgment 314 and the prefetch operation 313 is as follows. First, the priority 320 of the requested page is determined (step 605). If the priority 320 of the requested page is high (step 606), all pages referred to by the hyperlink are prefetched (prefetch) or reloaded (step 607). If the priority 320 of the requested page is medium (step 608), all of the hyperlinked reference pages 326 already cached in the cache server device 302 are reloaded (step 609). If the priority 320 of the requested page is low (step 610), the hyperlinked reference page 326 that has already been cached in the cache server device 302 and has a high priority is selected. All are reloaded (step 611). Here, the term “reload” means that the page body already copied in the cache area 310 is replaced with the latest original page on the Internet 305, and the prefetch (pr
“efetch” means that a page not yet cached in the cache server device 303 is retrieved from the Internet 305 and cached in the cache server device 303. Reloading is performed in the cache area
The version and date of creation of the page on 310 are sent to the WWW server on the Internet 305 for inquiry,
Only when the version and the creation date and time of the page have been changed, the latest data of the page is downloaded. In addition, “read ahead” in the present application includes both reloading and prefetching.

FIG. 7 shows the prefetching process for the reference page by the hyperlink in the prefetch determination and the prefetch operation (step 604) based on the priority 320 of the requested page and the priority of the reference page by the hyperlink. Here is an organized table. In the leftmost column of FIG.
The priority of the requested page is high, medium,
The heading "Low" was added. When the priority of the requested page is “high”, “medium”, or “low”, the priority of the reference page referred to by the page is “high”, “medium, low”, Or, the reference page was divided into "not cached" and showed how to handle each case.

Next, the flow of FIG. 6 will be described with reference to FIGS.
0, FIG. 11, and FIG.

FIG. 8 shows an example of an entry in the cache entry table 309 of the cache server device 303 and a page body in the cache area 310. In the example in this figure,
Four pages specified by URLs 802, 803, 804, and 805 are cached in the cache server device 801, and entries 807, 808, 809, and 810 of the four pages are registered in the cache entry table 806 accordingly. Have been. Each entry has a priority of 812, 813, 814, and 815, respectively, and has a cache area.
811 has 816, 817, 818 and 819 as the position of the body of each page. In addition, in the cache area 811, there are four pages designated by the positions 816, 817, 818 and 819 of the page body.
The body of one page has been copied.

FIG. 9 is an example showing a state where a certain page refers to another page by a hyperlink on the Internet. The WWW server 901, the WWW server 902, and the WWW server 903 are connected to the Internet 90.
Connected through four. Then, the page 905 on the WWW server 901 is replaced with the pages 906, 907 and WW on the same server.
A page 908 on the W server 902 and a page 909 on the WWW server 903 are referred to by hyperlinks. The URLs of pages 905, 906, 907, 908 and 909 are
Provided at 802, 803, 910, 804 and 805, respectively. The URLs 802, 803, 804, and 805 are registered in the entries 807, 808, 809, and 810 in the cache entry table 806 of FIG. 8, but the URL 910 is not registered. That is, pages 905, 906, 908, and 909 are cached in cache server device 801, but page 907 is not.

Now, the cache status of the cache server device 303 is as shown in the cache server device 801 in FIG.
It is assumed that the reference structure by the hyperlink of the page cached in the cache server device 801 is as shown in FIG. Then, it is assumed that a request for the page 905 is made from the user client 301 to the proxy server device 302. At that time, the cases are classified into three cases, case 1, case 2 and case 3, according to the values of the priorities 812, 813, 814 and 815 of the entries 807, 808, 809 and 810. The following describes how the mechanism 312 performs the prefetch determination 314 and the prefetch operation 313.

As Case 1, let us consider a case where priorities are given as shown in FIG. This is because the priority 812 of the entry 807 of the page 905 specified by the URL 802 is high,
Priority 813 of entry 808 of page 906 specified by L803
Is high, entry 809 of page 908 specified by URL 804
Priority 814 is medium, and the priority 815 of the entry 810 of the page 909 specified by the URL 805 is low. In this case, since page 905 has a high priority 812,
All pages 90 to which 905 refers by hyperlink
6, 907, 908 and 909 are prefetched or reloaded. That is, the pages 906, 908 and 909 cached in the cache server device 801 are reloaded, and the uncached page 907 is prefetched.

As Case 2, consider the case where the priorities are given as shown in FIG. This is because the priority 812 of the entry 807 of the page 905 specified by the URL 802 is medium,
Priority 813 of entry 808 of page 906 specified by L803
Is high, entry 809 of page 908 specified by URL 804
Priority 814 is medium, and the priority 815 of the entry 810 of the page 909 specified by the URL 805 is low. In this case, since page 905 has medium as priority 812,
Page 9 cached in cache server device 801 among pages referenced by hyperlink 905
06, 908 and 909 are reloaded. Page 907 is not cached and will not be read ahead.

As a case 3, consider a case where the priorities are given as shown in FIG. This is because the priority 812 of the entry 807 of the page 905 specified by the URL 802 is low,
Priority 813 of entry 808 of page 906 specified by L803
Is high, entry 809 of page 908 specified by URL 804
Priority 814 is medium, and the priority 815 of the entry 810 of the page 909 specified by the URL 805 is low. In this case, since page 905 has a low priority 812,
Of the pages referred to by the hyperlink 905, the page 906 that is cached in the cache server device 801 and has a high priority is reloaded.
Pages 908 and 909 are cached but do not look ahead because they have medium or low priority. Since the page 907 is not cached, it is not read ahead.

According to the first embodiment, a page presumed to be likely to be selected next by the user is prefetched based on the criterion as shown in FIG. 7, so that an increase in the load on the network is suppressed. However, it is possible to improve the recall rate of the cache by prefetching.

Next, a second embodiment of the present invention will be described. FIG. 13 shows a WWW according to the second embodiment of the present invention.
It is a block diagram of a cache system. 13, the same reference numerals as those in FIG. 3 denote the same parts, and a description thereof will be omitted. The user client 301 and the proxy server device 302 behave in the same manner as the corresponding parts 301 and 302 in the system of FIG.

The cache server 1301 stores a user importance management table 1302, an importance determination mechanism 1303, and a customer information list 1304 in addition to the cache entry table 309, the cache area 310, the priority determination mechanism 323, and the look-ahead mechanism 1317. Have. Cache entry table 30
9, cache area 310, and priority determination mechanism 323
Correspond to the corresponding parts 309, 310, 32 in the system of FIG.
It behaves the same as 3. The user importance management table 1302 manages the importance of users who access the proxy server device 302 through the user client 301.

FIG. 14 shows a user importance management table 1302.
Shows the data structure of each entry registered in. As shown in the figure, one entry 1401 holds two pieces of information, ie, a user ID 1402 and a degree of importance 1403 of a user who is allowed to access the proxy server device 302. This importance 1403 is a user importance determination mechanism 1303
However, the customer information list 1304 and the proxy server device 30
The user importance management table 1302 is determined by performing importance determination 1305 for each user based on the access history 317 of 2 and performing the importance registration 1306.
Is assigned to each entry.

Assume that the URL of the page requested by the user having the user ID 1313 through the user client 301 matches the URL 1308 of the entry 1307 in the cache entry table 309. In this case, the prefetching mechanism 1317 extracts the URL 1311 of the reference destination page by the hyperlink from the page body 1310 indicated by the page body position 1309 of the entry 1307. The read-ahead mechanism 1317 performs a predetermined determination based on the priority 1312 of the requested page, the URL 1311 of the reference page referred to by the hyperlink, information held in the cache entry table 309, and the importance 1314 of the user who made the request. A prefetch determination 1315 for deciding a page to prefetch according to the flow is performed. Furthermore, look-ahead mechanism
A step 1317 performs a look-ahead operation 1316 on the page selected by the look-ahead determination 1315. An example of the pre-read determination flow will be described later in detail. Information about the page body and the page obtained by the response 316 by the prefetch operation 1316 is managed in the cache area 310 and the cache entry table 309, respectively.

FIG. 13 shows an example of the system configuration, and the proxy server device 302 and the cache server device 1301 may be on the same machine. Of course, there may be a plurality of user clients 301.

Two examples of the importance determination mechanism 1303 and the look-ahead mechanism 1317 in the system of this embodiment will be described.

The importance determination mechanism in this embodiment
The first example of 1303 and the look-ahead mechanism 1317 is an example in which the present invention is applied to a corporate intranet. It is assumed that the job system of a certain company applying the present invention to the intranet is as shown in FIG. In this diagram, an employee in one position controls an employee in a lower position,
In addition, the area occupied by each position in the pyramid-shaped diagram indicates a rough ratio of the number of employees who take that position. FIG. 16 is an example of the flow of processing by the importance determination mechanism 1303 in this case. In this example, the importance level 1403 is expressed in three stages: upper, middle, and lower. However, the example here is an example of how to assign the importance 1403, and the importance may be divided into two or more stages. First, it is assumed that a user who is permitted to access the proxy server device 302 has the user ID 1402 and has one of the positions in the job system shown in FIG. 1304.

In the processing of the importance determination mechanism 1303 in FIG. 16, first, an importance determination 1305 is performed on the user who satisfies the preconditions (step 1601), and the user importance is determined based on the user ID 1402 and the obtained importance 1403. Management table
An importance registration 1306 to 1302 is performed (step 1602). An example of a specific procedure of the importance determination 1305 and the importance registration 1306 is as follows. First, it is determined what the position of the user registered in the customer information list 1304 is. If the position of the user is chairman, president, or officer (step 1603), the user is given an upper degree of importance 1403 (step 1604). If the job title of the user is headquarters, office manager, office manager or office manager (step
1605), giving medium as importance 1403 (step 160)
6). If the position of the user is an office employee (step 1607), the following is given as the importance 1403 (step 160).
8). Then, the obtained value of the importance 1403 is stored in the user ID 140
The user is registered as an entry 1401 of the user in the user importance management table 1302 together with 2 (step 1602). Steps 1603, 1604, 1605, 1606, 1607, 1608 and 1602
Is repeated for all users who satisfy the above preconditions.

FIG. 17 shows an example of the flow of processing by the look-ahead mechanism 1317. This flow is based on the look-ahead mechanism 13 outlined in the description of the cache server device 1301 described above.
17 is a detailed processing flow of 17. In this example, the importance 1403 is expressed in three levels of upper, middle, and lower as in the example of FIG. 16, and the priority 403 is expressed in three levels of high, medium, and low as in the example of FIG. It is expressed by Now, the user ID of the user who made the request 307 is the user importance management table.
Assume that the user ID 1313 of the entry 1318 of the entry 1302 matches the URL of the requested page matches the URL 1308 of the entry 1307 in the cache entry table 309. At this time, processing by the look-ahead mechanism 1317 in FIG. 17 is executed.

First, referring to the user importance management table 1302, the importance 1314 of the user who made the request 307 is extracted (step 1701). Next, referring to the cache entry table 309, the priority 1312 of the requested page and the position 130 in the cache area 310 of the page body are read.
9 is taken out (step 1702). Next, the page body 1310 in the cache area 310 is called based on the obtained page body position 1309, and the URLs 1311 of all the referenced pages by the hyperlink are extracted from the page body 1310 (step 1703). Next, the cache entry table 309 is searched based on the obtained URL 1311 to check whether each of the referenced pages has already been cached in the cache server device 1301. If cached, the priority is taken out. (Step 1704). next,
User importance 1314 obtained in steps 1701, 1702, 1703 and 1704, requested page priority 1312,
A prefetch determination 1315 and a prefetch operation 1316 are performed based on the URL 1311 of the reference page and the priority of the page already cached in the cache server device 1301 (step 1705).

The specific procedure of the prefetch determination 1315 and the prefetch operation 1316 is as follows. First, it is determined what the importance 1314 of the user who issued the request is (step 1706). If the user's importance 1314 is higher (step 1707), all pages referred to by hyperlinks are prefetched or reloaded (step 170).
8). If the user importance 1314 is medium (step 170
9), based on the priority 1312 of the requested page, the URL 1311 of the reference page by the hyperlink, and the priority of the reference page that has already been cached in the cache server device 1301, and
The same pre-reading determination and pre-reading operation as in step 604 of this embodiment are performed (step 1710). If the importance of the user is lower (step 1711), the prefetch operation is not performed (step 1712).

Next, a second example of the importance determination mechanism 1303 and the look-ahead mechanism 1317 in this embodiment will be described.
This example is an example in which the present invention is applied to a provider business. FIG. 18 shows a processing flow of the importance determination mechanism 1303 in this example. By this processing, the importance of each user who subscribes to the provider service and uses the service is determined based on the service usage amount of the user, and registered in the user importance management table 1302. Also in this example, the importance 1403 is expressed in three stages of upper, middle and lower. However, the example here is an example of how to assign the importance 1403, and the importance may be divided into two or more stages. First, it is assumed that a user who is permitted to access the proxy server device 302 is a user registered in the customer list 1304. Customer list 1304
It is assumed that the user ID 1402 of each user and the monthly average service usage time of the user calculated from the access history 317 stored in the proxy server device 302 are stored and managed.

In the processing of the importance determination mechanism 1303 shown in FIG. 18, first, an importance determination 1305 is performed for a user who satisfies the prerequisites (step 1801). Management table
An importance registration 1306 to 1302 is performed (step 1802). The specific procedure of importance determination 1305 and importance registration 1306 is as follows. In advance, two values of m and n (n <m) are given as appropriate thresholds for judging importance. First, the user refers to the average service usage time per month of the user from the customer information list 1304, and compares the value with the threshold values m and n (step 1803). If the monthly average service usage time is m hours or more (step 1804), the importance of the user
Give the top as 1403 (step 1805). If the monthly average service usage time is n hours or more and less than m hours (step
1806), giving medium as importance 1403 (step 180)
7). If the monthly average service use time is less than n hours (step 1808), the lower level is given as the importance 1403 (step 1809). Then, the obtained value of the importance 1403 is registered as an entry 1401 of the user in the user importance management table 1302 together with the user ID 1402 (step 180).
2). The procedures of steps 1803, 1804, 1805, 1806, 1807, 1808 and 1802 are repeated for all users who satisfy the above preconditions.

The look-ahead mechanism 1317 in this example may be performed in the same procedure as in FIG.

According to the second embodiment, in addition to the effects of the first embodiment, the prefetch effect is made different according to the importance of the user (a user having a high importance determines the prefetch range). In other words, a user of low importance can narrow the range of prefetching).

Next, a third embodiment of the present invention will be described. FIG. 19 shows a WWW according to the third embodiment of the present invention.
It is a block diagram of a cache system. In FIG. 19, the same reference numerals as those in FIGS. 3 and 13 denote the same components, and a description thereof will be omitted. The user client 301 and the cache server device 1301 have the same behavior as the corresponding parts 301 and 1301 in the system of FIG.

The proxy server device 1901 has an access amount measuring mechanism 1902 in addition to the components and functions of the proxy server device 302 in FIG. The access amount measurement mechanism 1902 measures the access amount per unit time 1903 from the proxy server device 1901 to the Internet 305, and records the access status 1904. Therefore, by referring to the access status 1904, the access amount per unit time at the present time can be known. Also,
The look-ahead mechanism 1905 makes a look-ahead determination 1315 in the same manner as in the above-described second embodiment, and then makes a look-ahead permission determination 1906 based on the current access status 1904, and the result of the look-ahead determination 1315 and the look-ahead permission A prefetch operation 1907 is performed based on the result of the determination 1906.

FIG. 19 shows an example of the system configuration, and the proxy server device 1901 and the cache server device 1301 may be on the same machine. Of course, there may be a plurality of user clients 301.

FIG. 20 shows an example of the flow of the prefetch permission determination 1906. This process is executed at predetermined short intervals, irrespective of the user's request for WWW data. First, the current access amount per unit time is obtained from the access status 1904 (step 2001). M is given in advance as a threshold value for determination, and the current access amount per unit time is compared with the threshold value m (step 2002). If the current access amount per unit time is equal to or less than m (step 2003), a prefetch permission is given (step 2004). If the current access amount per unit time is larger than m (step 2005), the prefetch permission is not given (step 2006). As described above, the prefetching permission is not given when the access amount is large (when it is crowded), and the prefetching permission is given when the access amount is small (when it is crowded). Further, since this processing is repeatedly executed at predetermined time intervals, it is always set as a flag as to whether the prefetch permission has been given or not given according to the access amount at the present time.

FIG. 21 shows an example of the flow of the prefetch operation 1907. First, the result of the prefetch permission determination 1906 is compared (step 2101). When the prefetch permission is given by the prefetch permission determination 1906 (step 2102), the prefetch is performed on the prefetch target page selected by the prefetch determination 1315 (step 2103). The process of the prefetch determination 1315 may be performed in the same manner as in FIG. If the prefetch permission is not given by the prefetch permission determination 1906 (step 2104), the prefetch is not performed (step 2105).

According to the third embodiment, in addition to the effect of the second embodiment, when the access amount at that time exceeds a certain amount, read-ahead is not permitted. Flexible prefetching according to the degree of crowding can be realized.

In the first to third embodiments, the proxy server device and the cache server device are:
Each of them may be realized in a form in which functions are distributed to a plurality of computers. Further, even when a proxy server device or a cache server device is not provided, the prefetching and caching functions described in the first to third embodiments may be implemented in the user client. For example, the present invention may be applied to a browser executed on a user client. Further, in the first to third embodiments, examples in which the present invention is applied to prefetching WWW data on the Internet have been described. However, the present invention can be applied to prefetching WWW data not on the Internet but on an intranet. .

[0060]

As described above, according to the present invention,
It is possible to provide a look-ahead method for improving the cache recall rate by the look-ahead while suppressing an increase in the load on the network due to the look-ahead. At the same time, it is possible to differentiate customer services in prefetching.

[Brief description of the drawings]

FIG. 1 is a diagram showing a form of providing data on a WWW server on the Internet.

FIG. 2 is a diagram showing a reference relation structure by hyperlink of a page on the Internet.

FIG. 3 is a block diagram illustrating a system configuration according to the first embodiment;

FIG. 4 is a diagram showing a data structure of an entry registered in a cache entry table.

FIG. 5 is a diagram showing a flow of processing by a priority determination mechanism;

FIG. 6 is a diagram showing a flow of processing by a prefetch mechanism.

FIG. 7 is a diagram showing a table in which prefetch processing operations are arranged based on the priority of a request page and the priority of a reference page;

FIG. 8 is a diagram showing an example of a cache entry table and a cache area in a cache server device;

FIG. 9 is a diagram showing an example of a reference relationship structure based on a hyperlink of a page on the Internet.

FIG. 10 is a diagram showing an example (part 1) of an entry in a cache entry table;

FIG. 11 is a diagram showing an example (part 2) of an entry in a cache entry table;

FIG. 12 is a diagram illustrating an example (part 3) of an entry in a cache entry table;

FIG. 13 is a block diagram illustrating a system configuration according to a second embodiment;

FIG. 14 is a diagram showing a data structure of an entry registered in a user importance management table.

FIG. 15 is a diagram showing an example of a job system of a certain company;

FIG. 16 is a diagram showing a processing flow by an importance determination mechanism;

FIG. 17 is a diagram showing a flow of processing by a prefetching mechanism;

FIG. 18 is a diagram showing a processing flow according to an importance determination mechanism.

FIG. 19 is a block diagram illustrating a system configuration according to a third embodiment;

FIG. 20 is a diagram showing a flow of a prefetch permission determination.

FIG. 21 is a diagram showing a flow of a prefetch operation.

[Explanation of symbols]

301: user client, 302: proxy server device, 303: cache server device, 304: LA
N, 305: Internet, 306: Browser, 30
7 Request, 308 Response, 309 Cache entry table, 310 Cache area, 31
1: Cache search, 312: Look-ahead mechanism, 313 ...
Pre-reading operation, 314: Pre-read judgment, 315: Request, 316: Response, 317: Access history, 31
8 entry, 319 URL, 320 priority, 32
1 ... Page body, 322 ... Page body position, 323 ...
Priority determination mechanism, 324: priority registration, 325: priority determination, 326: URL of the reference page.

Claims (7)

[Claims] A cache unit that caches the accessed WWW data in a cache area; a priority determination unit that determines a priority of the WWW data cached in the cache area; and a priority determination result based on the priority determination result. Requested W
It is provided with a pre-reading determining means for determining whether to perform pre-reading of WWW data as a reference destination of the WW data, and a pre-reading operation means for performing a pre-reading operation based on a result of the pre-reading determination performed by the pre-reading determining means. WWW cache system characterized by the above-mentioned. 2. The method according to claim 2, wherein W
In a WWW cache system including a proxy server device that processes access to WWW data and a cache server device that caches the accessed WWW data in a cache area, the cache server device stores the WWW data cached in the cache area. A priority determination unit configured to determine a priority; and a prefetch determination unit configured to determine, based on a result of the priority determination, whether to prefetch the WWW data referred to by the requested WWW data, The proxy server device further includes a prefetch operation unit that performs a prefetch operation based on a determination result of whether to perform prefetch by the prefetch determination unit.
WW cache system. 3. A means for acquiring an access history of WWW data; a means for calculating a request frequency of WWW data cached in the cache area based on the acquired access history; 3. The WWW cache system according to claim 1, further comprising: means for using information to determine a priority of WWW data cached in the cache area. 4. An apparatus according to claim 1, further comprising an importance determination unit configured to determine importance of a user who uses the system, wherein the prefetch determination unit determines the importance of the user in addition to the determination result of the priority. 3. The WWW cache system according to claim 1, wherein it is determined whether to prefetch the WWW data referred to by the requested WWW data based on the request. 4. 5. A system according to claim 1, further comprising: means for acquiring a current access status to WWW data; and prefetch permission determining means for judging permission / non-permission of execution of prefetch based on the acquired access status. Or WWW cache system according to any one of 2. 6. A step of caching the accessed WWW data in a cache area, a priority determining step of determining the priority of the WWW data cached in the cache area, and a request based on the priority determination result. Done W
A read-ahead determining step of determining whether to perform read-ahead of WWW data as a reference destination of the WW data; and a read-ahead operation step of performing a read-ahead operation based on a determination result of whether to perform read-ahead in the read-ahead determining step. A method of prefetching WWW data, characterized in that: 7. A method according to claim 1, wherein W
A method of prefetching WWW data in a WWW cache system including a proxy server device for processing access to WWW data and a cache server device for caching the accessed WWW data in a cache area, wherein the cache server device uses a cache area. Priority determining step of determining the priority of the WWW data cached in the server; and requesting WW based on the priority determination result.
A look-ahead determination step of determining whether to perform look-ahead of WWW data to be referred to by the W data; and a look-ahead operation of performing a look-ahead operation by the proxy server device based on a determination result of whether the look-ahead is performed by the look-ahead determination means. And a prefetching method for WWW data.