JPH11249950A - Communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication equipment which shortens the time required for data acquisition by securing display of the latest data on a Web browser and reducing the network traffic. SOLUTION: When a data change part 23 of a Web server 20 changes data in a data storage part 22, a change report message is generated by a change report generation part 24 and is transmitted to a change report processing part 44 of a proxy server 40, and the change report processing part 44 of the proxy server 40 receives the change report message to delete data before the change cached in a data cache part 42.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication device constructed using the Internet or an intranet, and more particularly, to guarantee that the latest data is displayed on a Web browser, reduce network traffic, and acquire data. The present invention relates to a communication device capable of reducing the time required for communication.

[0002]

2. Description of the Related Art With the spread of the Internet or intranet in recent years, an increase in network traffic when a Web browser acquires data in a Web server has become a problem.

FIG. 5 is a block diagram showing a conventional connection configuration between a Web browser and a Web server.

[0004] In FIG. 5, a plurality of Web browsers (W
The web browsers 1 to n) 10-1 to 10-n communicate with the web server 2 via the Internet / intranet 30.
0 to form a communication device.

Here, a plurality of Web browsers 10-1 to 10-1
10-n are mutually connected to form a private LAN (local area network).

The Web server 20 includes a request processing unit 21, a data storage unit 22, and a data change unit 23.
An external network is constructed by the intranet 30.

In the above configuration, the plurality of Web browsers 10-1 to 10-n each acquire data in the Web server 20 and display the data. Also, the Web server 20 transmits desired data to the Web browsers 10-1 to 10-n in response to requests from the Web browsers 10-1 to 10-n.
10-n.

[0008] The request processing unit 21 in the Web server 20 fetches data requested from the Web browsers 10-1 to 10-n from the data storage unit 22 and transmits the data to the Web browsers 10-1 to 10-n. .

Here, the data storage unit 22 is constituted by a hard disk or the like, and the Web browsers 10-1 to 10-n
The data to be transmitted is stored.

That is, the data storage unit 22 has a tree structure having nodes as nodes, as in a file system such as a personal computer, and each data is stored as one file in the tree structure. Further, the data change unit 23 changes the content of the data in the data storage unit 22.

Now, the Web browsers 10-1 to 10-n
Acquisition of data from the Web server 20 by
A request message transmitted from the b-browser 10-1 to 10-n to the Web server 20 via the Internet / intranet 30, and in response to the request message, the Web server 20 sends the Web browser 10-1 to 10-n via the Internet / intranet 30. This is done using the response message sent to -n.

FIG. 6 is a flowchart showing a process at the time of data acquisition in the configuration shown in FIG.

Web browsers 10-1 to 10-n (hereinafter described as Web browser 10) and Web browsers
When the processing of the server 20 is started (step 101,
201) First, the Web browser 10 transmits a request message to the Web server 20 via the Internet / intranet 30 (Step 102).

The Web server 20 is a Web browser 1
When the request message 202 from 0 is received (step 202), the request processing unit 21 retrieves the corresponding data from the data storage unit 22 (step 203).

The extracted data is included in a response message and transmitted to the Web browser 10 via the Internet / intranet 30 (step 20).
4), the processing of the Web server 20 ends (Step 205).

On the other hand, when the Web browser 10 receives the response message from the Web server 20 (Step 103), it displays the contents of the data contained in the response message (Step 104) and ends the processing (Step 105). ).

FIG. 7 is a diagram showing the Web processing in the processing shown in FIG.
FIG. 4 is a frame configuration diagram showing a frame configuration of a request message transmitted from a browser to a Web server.

In FIG. 7, "SP" indicates a space. That is, in the request message transmitted from the web browser 10 to the web browser 20 via the Internet / intranet 30, the URI (Universal Resource Id) of the data to be acquired is included.
entifier) in the URI field of the request message.

The URI is an identifier indicating the location of data. For example, in FIG. When executing html, the URI is "/data1.html".
Becomes Here, “/data1.html” means “a file named data1.html in the root directory”.

In addition, HTTP (Hyper Text)
The “Transfer Protocol” version field is a character string indicating a version number of a protocol “HTTP” used for transmission / reception of a request message / response message. For example, when using version 1.0 of HTTP, the HTTP version field includes “HTTP”.
P / 1.0 ".

[0021] The Web browser 10 transmits data1. ht
An example of a request message for obtaining ml is as follows.

GET / data1. html HTTP / 1.0 FIG. 8 is a frame configuration diagram showing a frame configuration of a response message transmitted from the Web server to the Web browser in the processing shown in FIG.

[0023] Web browser 20 to Web browser 1
In the header field of the response message transmitted to 0, a response code indicating the presence or absence of an error in the request processing unit 21 and information such as the transmission time of the response message are described. The details are omitted because they are not relevant.

The data field is the U of the request message.
This is the content of the data specified by the RI field, that is, the data itself extracted from the data storage unit 22.
For example, if the URI is “/data1.html”, data1.html is displayed in the data field. html content is included as it is.

When the Web browser 10 receives the response message, it extracts the contents of the data field from the response message and displays the contents on a display or the like.

However, in the above-mentioned conventional communication device, when a plurality of Web browsers 10 acquire the same information, the same data is repeatedly transmitted many times. For example, a plurality of Web browsers 10-1 to 10- n are all data1. html, data
1. The html is transmitted n times, causing a problem that unnecessary traffic occurs.

Therefore, a proxy server has been conventionally known as a technique for improving the problem of an increase in network traffic accompanying the spread of the Internet / intranet.

The proxy server is configured so that data once transferred from the web server is stored in the cache, and thereafter, the data stored in the cache is used instead of the data of the web server. Is obtained.

1) Useless traffic on the external network can be reduced.

2) When data is cached in the proxy server, the time required for data acquisition can be reduced.

FIG. 9 is a block diagram showing a connection configuration between a Web browser and a Web server when a conventional proxy server is used.

In FIG. 9, the proxy server 40
Is installed in the local LAN between the Web servers 10-1 to 10-n and the Web browser 20, and a request message,
All response messages are transmitted and received via the proxy server 40.

The proxy server 40 includes a request processing unit 41, a data cache unit 42, and a data cache management table 43.

Here, the data cache unit 42 is constituted by a hard disk or the like, and stores a copy of data included in the response message received from the Web server 20.

The data cache management table 43
Is composed of a RAM (random access memory) or the like,
UR of data stored in data cache unit 42
I, the last reference time, and the address of the data cache unit 42 where the data is stored.

Therefore, whether or not the data specified in the URI of the request message is stored in the data cache unit 42 can be determined by searching the data cache management table 43.

The request processing section 41 is a web browser 10-
If the request message is received from the Web browser 10-1 to 10-n and the data specified in the URI of the request message is not in the data cache unit 42, the request message received from the Web browsers 10-1 to 10-n is transferred to the Web server 20. Then, a response message received from the Web server 20 is transferred as a response to the Web browsers 10-1 to 10-n. At the same time, the data contained in the response message is stored in the data cache unit 42.

Further, the Web browsers 10-1 to 10-n
If there is data specified in the URI of the request message from the data cache unit 42, the data is included in the response message and transmitted to the Web browsers 10-1 to 10-n. At the same time, the last reference time of the data in the data cache management unit table 43 is updated.

Here, the Web browsers 10-1 to 10-
n transmits a request message in a predetermined format,
P so that the data in the data cache unit 42 is not used.
A command can be given to the proxy server 40.

FIG. 10 is a frame configuration diagram showing a frame configuration of a request message for instructing the proxy server not to use data in the data cache unit in the configuration of FIG.

That is, the Web browsers 10-1 to 10-10
If the request message from -n is in the format of FIG. 10, the proxy server 40
Even if the corresponding data exists in 2, the same processing as when there is no corresponding data in the data cache unit 42 is performed.

When the Web server 20 receives the request message in the format shown in FIG.
The processing of "a: no-cache" is ignored, and the same processing as when the request message having the configuration of FIG. 7 is received is performed.

FIG. 11 is a flowchart showing a process at the time of data acquisition in the configuration shown in FIG.

In FIG. 11, the Web browser 10-1
When the processing of the proxy server 40 and the processing of the Web server 20 are started (steps 111, 411, and 21).
1) First, the Web browser 10 transmits a request message to the proxy server 40 (step 1).
12). At this time, the Web browser 10 specifies the URI of the data to be obtained in the URI field of the request message.

Request processing unit 41 of proxy server 40
Receives this request message (step 41).
1), "if the request message has no-cache designation" (Y in step 413) or "if the data specified by the URI field of the request message (hereinafter, the corresponding data) does not exist in the data cache unit 42" (step 414) N) performs the processing of A, otherwise performs the processing of B. Whether or not the corresponding data exists in the data cache unit 42 is determined by the request processing unit 42 by searching whether or not the data cache management table 43 has the same entry (row) in the URI field as the URI field of the request message. Is determined.

First, the processing of A will be described.
The request processing unit 41 of the oxy server 40 transmits the request message received from the web browser 10 to the web server 2
0 (step 417). When a response message is received from the Web server 20 as the response (step 418), the data included in the data field of the response message is stored in the data cache unit 42.
Of the data, and the URI of the data,
The last reference time (response message reception time) and the address are registered in the data cache management table 43 (step 419).

If the free space in the data cache unit 42 or the data cache management table 43 is insufficient, the data with the oldest last reference time is deleted from the data cache unit 42 and the data cache management table 43. Create free space.

After storing the data in the data cache unit 42, the request processing unit 41 of the proxy server 40
The response message received from the web server 20 is
The data is transferred to the browser 10 (step 420).

As described above, "the request message is no-c
In the case of “acquisition specified” or “in the case where the data specified by the URI field of the request message does not exist in the data cache unit 42”, the data is transmitted from the Web server 20 to the Web browser 10 via the proxy server 40.

Next, the processing of B will be described.
The request processing unit 41 of the oxy server 40 extracts the relevant data from the data cache unit 42, transmits the data to the Web browser 10 in the response message (Step 41)
5). The location of the data in the data cache unit 42 is determined by the data cache management table 43.
Corresponding entry (the same URI as the URI of the request message)
) Can be known from the address recorded in the address column of the line having the).

After transmitting the response message, the last reference time of the corresponding entry in the data cache management table 43 is updated to the response message transmission time (step 416).

As described above, "the data is present in the data cache unit 42 and the request message is no-c
If there is no ache designation ", the corresponding data is prox
Sent from the y server 40 to the Web browser 10.

The use of the proxy server 40 has the following advantages.

1) Useless traffic on the external network can be reduced.

2) When data is cached in the proxy server 40, the time required for data acquisition can be reduced.

FIG. 12 is a diagram showing the flow of a request / response message when all Web browsers acquire the same data when there is no proxy server.

FIG. 13 is a diagram showing a flow of a request / response message when all the Web browsers obtain the same data when there is a proxy server.

When there is no proxy server shown in FIG. 12, each Web browser (1-n) sends a request message directly to the Web server, and the Web server sends a response message to each Web browser separately. Therefore, the same request message and the same response message are transmitted n times on the external network.

On the other hand, if there is a proxy server shown in FIG. 13, only the request message of the Web browser that first attempted to acquire the data, ie, the request message of Web browser 1, is transmitted to the Web server, and the data included in the response message to the request message is transmitted. Is stored in the proxy server, that is, in the data cache unit. For the subsequent request message from another Web browser, the proxy server, not the Web server, generates and sends a response message.

Here, in general, the external network is slower than the private LAN, and when data is stored in the data cache unit of the proxy server, the external network is not used and the time required for data acquisition is reduced. As a result, 1) useless traffic on the external network can be reduced. 2) When data is cached in the proxy server, the time required for data acquisition can be reduced.

[0061]

However, in the conventional configuration using such a proxy server, even if the data is changed in the Web server, this is not reflected in the data cached in the proxy server. In the Web browser, data before the change may be displayed.
(Factory Automation)
Considering the case where the proxy server is used, there is a problem in that although the production line has an abnormality, the Web browser may display data in a normal state.

FIG. 14 is a diagram showing a flow of a request / response message when the data change unit of the Web server changes the data after the Web browser acquires the data in FIG.

In this case, not the data changed by the data changing unit but the pr
The data before the change stored in the data cache unit of the oxy server is transmitted.

Here, each Web browser must be no-c
If the request message with the ahce designation is transmitted, this problem is solved, but in that case, all the request messages are transmitted to the Web server, and the advantage of the proxy server is lost.

For this reason, conventionally, a proxy server cannot be used as a communication device for production management in FA.

That is, when a Web server is installed in a factory or the like, and the production management information such as the number of defective products on the production line and the status information of the control device is stored as data in the Web server, the latest production management is performed by a Web browser in production management. You need to guarantee that the information is displayed,
If an xy server is used, this cannot be guaranteed, and despite the occurrence of an abnormality in the production line, the data at the normal time is displayed on the Web browser, and the occurrence of the abnormality may be overlooked. It is.

Accordingly, the present invention provides a communication apparatus which guarantees that the latest data is displayed on a Web browser, and which can reduce network traffic and shorten the time required for data acquisition. The purpose is to:

[0068]

In order to achieve the above object, the invention according to claim 1 is provided between a browser, a server having stored data, and the browser, and is provided between the browser and the server. A proxy server that caches stored data obtained from the server in response to the request, wherein the proxy server obtains the stored data from the server when the stored data related to the request from the browser is cached. A communication device that transmits the cached stored data to the browser without the cached data, and when the data is not cached, obtains the stored data from the server and transmits the obtained stored data to the browser. If the stored data is changed, the changed stored data is stored in the Characterized by comprising change notification means for notifying the server, the.

According to a second aspect of the present invention, in the first aspect of the present invention, when the changed stored data notified by the change notifying means is cached, the proxy server stores the cached data. And a deletion unit for deleting the stored data.

According to a third aspect of the present invention, in the first aspect of the present invention, the proxy server includes a data cache unit for storing stored data obtained from the server, and a storage unit stored in the data cache unit. Management table means for storing data management information, wherein the deletion means deletes the stored data stored in the data cache means and manages the stored data stored in the management table means. It is characterized in that information is deleted.

[0071]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the outline of the present invention will be described with reference to FIG. 1. As shown in FIG.
If the web server changes the data, it sends a change notification message to the proxy server, and the proxy server is configured to delete the cached (pre-change) data upon receiving the change notification message.

Hereinafter, an embodiment of the communication device according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an embodiment of a connection configuration between a Web browser and a Web server in the communication device according to the present invention.

The communication device shown in FIG. 1 has a configuration in which the conventional proxy server shown in FIG. 9 is used, and a change notification generating unit 24 is provided in the Web server 20 to provide a proxy.
The difference is that a change notification processing unit 44 is provided in the server 40.

Hereinafter, these components will be described in detail.

The change notification generation unit 24 provided in the Web server 20 is controlled by the data change unit 23, and outputs a change notification message from the URI of the change target data at the time of data change, to the change notification processing unit 44 of the proxy server 40.
Send to This allows the proxy server 40
Can know the change of data.

That is, the data change unit 23 notifies the URI of the data to be changed to the change notification generation unit 24 at the time of data change, and instructs the transmission of a change notification message, whereby the change notification generation unit 24 A change notification message related to the target data is generated and transmitted to the change notification processing unit 44 of the proxy server 40.

When the change notification processing unit 44 provided in the proxy server 40 receives the change notification message from the change notification generation unit 24 of the Web server 20,
The data specified in the URI field of the change notification message is deleted from the data cache unit 42, and an entry corresponding to the data is deleted from the data cache management table 4.
Delete from 3.

As a result, the data of the proxy server 40 corresponding to the data changed by the Web server 20 is deleted from the proxy server 40 immediately after the change.

FIG. 2 shows the change notification generation unit 24 shown in FIG.
FIG. 9 is a frame configuration diagram showing a frame configuration of a change notification message transmitted from to a proxy server to a change notification processing unit 44.

In FIG. 2, this change notification message is different from the request message shown in FIG. 7 in that the first field is “UPDATE”. In this change notification message, the URI field contains
The URI of the data changed by the data changing unit 23 of the Web server 20 is specified.

FIG. 3 is a flowchart showing a process when data is changed in the configuration shown in FIG.

In FIG. 3, the processing of the proxy server 40 and the Web server 20 is started (step 4).
31, 231), the data change unit 2 of the Web server 20
When the data stored in the data storage unit 22 is changed by the step 3 (step 232), the data change unit 23 notifies the change notification generation unit 24 of the URI of the changed data and instructs the change notification message to be transmitted. .

In response to this, the change notification generating unit 24 generates a change notification message and transmits it to the change notification processing unit 44 of the proxy server 40 (step 233). Here, the changed data URI is specified in the URI field of the change notification message.

When the change notification processing unit 44 of the proxy server 40 receives the change notification message from the Web server 20, the change notification processing unit 44 determines whether or not the data cache unit 42 has data specified by the URI field of the change notification message (hereinafter, applicable data). Is checked (step 433).
Here, whether or not the corresponding data exists in the data cache unit 42 is determined by the U
The determination is made by searching whether or not the same entry (line) as the URI field of the change notification message exists in the RI column.

If there is the corresponding data in the data cache unit 42 (Y in step 433), the change notification processing unit 44 deletes the corresponding data from the data cache unit 42 and deletes the entry corresponding to the corresponding data in the data cache management table 43. It is deleted (step 434).

If there is no corresponding data in the data cache unit 42 (N in step 433), nothing is performed.

According to the above processing, when data is changed in the Web server 20, the data is immediately deleted from the data cache unit 42 of the proxy server 40.

FIG. 4 is a diagram showing the flow of a request / response message when all the Web browsers acquire the same data in the configuration shown in FIG.

In FIG. 4, a request message from the Web browser 1 that has first attempted to acquire data is transmitted to the Web server 20, and a response message is transmitted from the Web server 20 to the Web browser 1 via the proxy server 40. .

At this time, the corresponding data included in the response message is cached in the proxy server 40 (stored in the data cache unit 42). After that, Web
When the corresponding data is changed in the server 20, a change notification message is transmitted from the Web server 20 to the proxy server 40.

When the proxy server 40 receives this change notification message, it deletes the corresponding data from the data cache unit 42.

Subsequently, when the Web browser 2 transmits the request message, the data has been deleted from the data cache unit 42 of the proxy server 40.
The request message is sent to the proxy server 40 via We
b is transmitted to the server 20. Then, a response message is transmitted from the Web server 20 to the Web browser 2 via the proxy server 40, and the corresponding data (changed data) is stored in the data cache unit 42 of the proxy server 40.

Thereafter, unless the data is changed in the Web server 20, the request message of another Web browser is sent to the proxy instead of the Web server 20.
The server 40 generates and sends a response message.

As described above, when data is changed in the Web server 20, the data is deleted from the data cache unit 42 of the proxy server 40.
The request message from the web browser is web server 2
0, and the latest data reflecting the changed content is always transmitted to the Web browser.

In the present invention, as described above, when the Web server changes data, the UR of the changed data is changed.
Since the proxy server sends a change notification message specifying I to the proxy server, and upon receiving the change notification message, the proxy server deletes the data corresponding to the URI (data before the change) from the data cache unit. Can guarantee that the latest data is displayed, and at the same time, reduce network traffic and shorten the time required for data acquisition.

[0097]

As described above, according to the present invention, when a Web server changes data, a change notification message designating the URI of the changed data is transmitted to the pr.
When the proxy server receives the change notification message, the proxy server deletes the data (data before the change) from the data cache unit, so that the latest data is displayed on the Web browser. While at the same time reducing network traffic and reducing the time required to acquire data.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a connection configuration between a Web browser and a Web server in a communication device according to the present invention.

FIG. 2 is a frame configuration diagram showing a frame configuration of a change notification message transmitted from a change notification generation unit shown in FIG. 1 to a change notification processing unit of a proxy server.

FIG. 3 is a flowchart showing processing when data is changed in the configuration shown in FIG. 1;

FIG. 4 is a diagram showing a flow of a request / response message when all Web browsers acquire the same data in the configuration shown in FIG. 1;

FIG. 5 is a block diagram showing a conventional connection configuration between a Web browser and a Web server.

FIG. 6 is a flowchart showing processing at the time of data acquisition in the configuration shown in FIG. 5;

FIG. 7 is a frame configuration diagram showing a frame configuration of a request message transmitted from the Web browser to the Web server in the processing shown in FIG. 6;

FIG. 8 is a frame configuration diagram showing a frame configuration of a response message transmitted from the Web server to the Web browser in the processing shown in FIG. 6;

FIG. 9 shows a Web using a conventional proxy server.
FIG. 2 is a block diagram showing a connection configuration between a browser and a Web server.

FIG. 10 is a frame configuration diagram showing a frame configuration of a request message instructing the proxy server not to use data in the data cache unit in the configuration of FIG. 9;

FIG. 11 is a flowchart showing processing at the time of data acquisition in the configuration shown in FIG. 9;

FIG. 12 is a diagram showing a flow of a request / response message when all Web browsers acquire the same data when there is no proxy server.

FIG. 13 is a diagram showing a flow of a request / response message when all Web browsers acquire the same data when there is a proxy server.

FIG. 14 is a diagram showing a flow of a request / response message when the data change unit of the Web server changes data after the Web browser acquires data in FIG. 13;

[Explanation of symbols]

 10-1 to 10-n Web browser 20 Web server 21 Request processing unit 22 Data storage unit 23 Data change unit 24 Change notification generation unit 30 Internet / intranet 40 Proxy server 41 Request processing unit 42 Data cache unit 43 Data cache management table 44 Change notification processing unit

Claims (3)

[Claims] 1. A browser, a server having stored data, and a proxy server provided between the browser and the server, for caching stored data obtained from the server in response to a request from the browser. If the stored data relating to the request from the browser is cached, the proxy server transmits the cached stored data to the browser without obtaining the stored data from the server, and the cached data is not cached. A communication device that obtains the stored data from the server and transmits the obtained stored data to the browser. If the stored data is changed, the server transmits the changed stored data to the proxy. Change notification means for notifying the server, That communication device. 2. The proxy server according to claim 1, further comprising a deletion unit for deleting the cached stored data when the changed storage data notified by the change notification unit is cached. The communication device according to claim 1. 3. The proxy server comprises: data cache means for storing accumulated data obtained from the server; and management table means for storing management information of the accumulated data stored in the data cache means. 2. The communication apparatus according to claim 1, wherein the deletion unit deletes the stored data stored in the data cache unit and deletes management information of the stored data stored in the management table unit. .