JPH0823353A - Data transfer method using packet exchange - Google Patents

Abstract

PURPOSE:To reduce the time required for data transfer and the communication charge by minimizing the umber of packets with respect to the data transfer method employing inter-computer packet exchange among computers being components of a network via a packet exchange network. CONSTITUTION:A data transmitter side computer compresses plural consecutive records in which data to be sent are stored in the unit of records to generate a data aggregate and a packet of a length most efficient to send the entire data aggregate is generated and sent to the packet exchange network. A data receiver computer receives the packet from the packet exchange network and expands the compressed data aggregate as to each record being a component of the packet to decode it into a regular record for reading data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transfer method using packet switching, and more particularly to a data transfer method using packet switching between computers constituting a network via a packet switching network.

In recent years, in a computer network system, a data transfer method using packet switching via a packet switching network such as ISDN-P has been adopted as a data transfer method between computers constituting a network.

The present invention provides a method capable of efficiently performing data transfer using packet switching in a computer network system.

[0004]

2. Description of the Related Art FIG. 4 is a diagram showing a conventional example, which is used for packet switching when a terminal computer accesses data to a host computer having a file server function via a network (packet switching network). The conventional conventional data transfer method is shown.

In the example shown in FIG. 4, when a READ command is executed for an A file stored in the host computer in an operation program started by the terminal computer, transmission / reception is performed between the terminal computer and the host computer. It shows the movement of a packet that is dropped. This will be specifically described below.

The terminal computer creates one packet containing the transfer request for the A file and sends it to the network (packet switching network). The host computer that receives the packet from the network (packet switching network) cuts out one record (128 bytes) from the A file, creates one packet, and sends it to the network (packet switching network).

The terminal computer receives a packet from the network (packet switching network) and acquires data for one record (128 bytes) in the A file. Then, one response packet having the content of data acquisition completion is created and sent to the network (packet switching network).

For example, the A file has 10 records (12
If it consists of 80 bytes), the packet exchanges 1 to 3 above are repeated 10 times. As a result, a total of 30 packets will be exchanged.

In packet switching, charges are charged according to the number of packets sent and received. Therefore, if 1 packet = 0.5 yen, 15 yen will be charged when 30 packets are exchanged.

In packet switching, a delay occurs when passing through a network (packet switching network). Assuming that the delay time per packet is 0.5 seconds, when 30 packets are exchanged, a delay of 15 seconds will occur.

[0011]

In a data transfer method using packet switching between a host computer and a terminal computer, when executing a file open instruction and a file close instruction, two round trips are performed per instruction.
Sending and receiving packets. When executing a read command, a write command, and a rewrite command, three packets are sent and received in a round trip for each data transfer.

In the conventional data transfer method using packet switching, when executing a read command, a write command, and a rewrite command, the packet length is determined by the record length of the file to be accessed. It is not sent or received in packets of packet length. That is, in the conventional example shown in FIG. 4, the record length of the file is 128 bytes, and the packet length is determined to be 128 bytes, which is not the most efficient packet length of 4096 bytes.

Therefore, in the conventional data transfer method using packet switching, if a large amount of data is accessed by executing a read command, a write command, and a rewrite command,
There was a problem that it was inefficient and the communication charge increased.

Regarding the response (response performance), since there is a storage delay of about 0.5 seconds per packet in the network (packet switching network), the delay time increases as the number of packets to be exchanged increases. There was also the problem of poor response.

The present invention solves the above-mentioned problems and minimizes the number of packets, thereby shortening the time required for data transfer and reducing the communication charge, and data using packet switching. It is an object of the present invention to provide a transfer method, particularly a data transfer method using packet switching between computers forming a network via a packet switching network.

[0016]

In order to achieve the above object, the present invention is configured as follows. (1) A data transfer method using packet switching between computers forming a network via a packet switching network, in which a computer transmitting data has a plurality of consecutive records in which the data to be transmitted is stored. Is compressed in record units to create a data set, and a packet with the most efficient packet length for sending the entire data set is created and sent to the packet switching network to receive data. The computer is configured to, after receiving the packet from the packet switching network, decompress the compressed data aggregate for each record forming the packet to restore the regular record and read the data.

(2) In (1), the computer on the data transmitting side compresses the data in each record in which the data to be transmitted is stored, and then collects a plurality of consecutive records in record units. Data is compressed into a data aggregate, a packet with the most efficient packet length for transmitting the entire data aggregate is created, and the computer receiving the data configures the received packet. After decompressing the compressed data set for each record to restore it to a plurality of data-compressed records, decompress the data that composes each record, restore it to regular data, and read the data. Configure.

(3) A data transfer method using packet switching between computers constituting a network via a packet switching network, in which a terminal computer reads a plurality of files stored in a host computer at one time. In the data transfer method, the terminal computer decodes the program logic, creates a packet containing information of points at which data can be continuously transferred, and sends the packet to the packet switching network. Upon receiving this packet from the network and knowing in advance the points at which data can be transferred continuously, the terminal computer creates a packet containing data access to the host computer and sends it to the packet switching network. Receive this packet from the packet switching network The most efficient packet for reading records across multiple files, compressing records across multiple files in record units to create a data aggregate, and transmitting the entire data aggregate. After creating a long packet and sending it to the packet switching network, the terminal computer receives this packet from the packet switching network, and then decompresses the data aggregate that has been data-compressed in units of records that make up the received packet to generate multiple packets. After being restored to each regular record, the multiple regular records are decomposed into multiple files and the file is read.

(4) In (3) above, the host computer compresses the data in the records constituting each file and then compresses the records of a plurality of files in record units to create a data aggregate. Then, a packet having the most efficient packet length for transmitting the entire data aggregate is created, and the terminal computer decompresses the data aggregate that is data-compressed for each record constituting the received packet, After decompressing each data compressed record, decompress the data that composes each record and decompress it to regular data to create multiple regular records. Configure to read the file by decomposing it into a file.

[0020]

1 is a diagram showing the basic configuration of the present invention. The operation of the present invention will be described below with reference to FIG.

The host computer and the terminal computer constitute a computer network via a packet switching network (for example, ISDN-P). The search program (1) is always executed by the host computer. On the other hand, the terminal computer transfers the desired file among the files held in the immediate update database in the host computer by executing the reference program.

At this time, the search request segment (2) in the reference program creates a packet containing the search information and sends it to the packet switching network (ISDN-P). In the host computer that receives this packet, the search program (1) refers to the search file VLD and extracts the corresponding file from the immediate update database.

The extracted file is subjected to data compression (3) for each record (128 bytes) that constitutes the file. Data compression is performed on a record-by-record basis for each data-compressed record. The data aggregate, which has been compressed in record units, is divided into 4096 bytes, which is the most efficient for transmission.
A packet is created with a packet length of 6 bytes.

Then, the created packet having a packet length of 4096 bytes is sequentially transferred to the packet switching network (I
SDN-P). After receiving a packet having a packet length of 4096 bytes from the packet switching network (ISDN-P), the terminal computer decompresses the data aggregate forming the received packet in record units by using the search result segment (4). After restoring to multiple records, decompressing the data that constitutes each restored record to make a regular record (128 bytes)
Restore to and load the desired file.

As described above, in the data transfer method using packet switching according to the present invention, particularly in the data transfer method using packet switching between computers forming a network via a packet switching network, the number of packets Since it can be minimized, the time required for data transfer and the communication charge can be reduced.

[0026]

FIG. 2 is a diagram showing an embodiment of the present invention,
1 shows a data transfer method using packet switching according to the present invention when a terminal computer accesses data to a host computer having a file server function via a network (packet switching network).

In the example shown in FIG. 2, when the READ command for the A file stored in the host computer in the operation program started by the terminal computer is executed, transmission / reception between the terminal computer and the host computer is performed. It shows the movement of a packet that is dropped. This will be specifically described below.

The terminal computer creates one packet containing the transfer request for the A file and sends it to the network (packet switching network). The host computer that received the packet from the network (packet switching network) receives 12 from the A file.
Create a data aggregate by compressing multiple consecutive records having a record length of 8 bytes in record units, and change the packet length according to the data amount of this data aggregate to create a packet with an optimum packet length. To do.

That is, a packet having a packet length of, for example, 4096 bytes, which is the most efficient for transmission, is created. At this time, as shown in the figure, the A file has 10
If the record is 1280 bytes, the data amount of the data aggregate compressed in record units is 4096.
Since it is less than bytes, it creates a packet with a packet length of 1280 bytes. On the contrary, if the data amount of the data aggregate compressed in record units is larger than 4096 bytes, a plurality of packets having a packet length of 4096 bytes are created.

The created packet is sent to the network (packet switching network). After receiving the packet from the network (packet switching network), the terminal computer reads the A file by decompressing the data aggregate forming the packet and restoring the record with a regular record length of 128 bytes. .

Then, one response packet having the content of the completion of reading the A file is created and sent to the network (packet switching network). As described above, according to the present invention, for example, when the A file is composed of 10 records (1280 bytes), the packet exchanges 1 to 3 above need only be performed once. That is, it becomes possible to exchange 3 packets. Compared with the case where the conventional example shown in FIG. 4 requires the exchange of 30 packets, it can be seen that the data transfer method using the packet exchange according to the present invention significantly improves the transfer efficiency.

In packet switching, the amount of packets sent and received is charged. Therefore, 1 packet = 0.5
If yen and 1 long packet = 8.7 yen, 8.7 yen will be charged when 3 packets are exchanged.

Further, in packet switching, a delay occurs when passing through a network (packet switching network). Assuming that the delay time per packet is 0.5 seconds, when 3 packets are exchanged, a delay of 1.5 seconds will occur.

Incidentally, in the conventional example shown in FIG. 4, 30 packets are exchanged even though the A file consists of 10 records (1280 bytes) as in the case of the present embodiment, so that 15 yen is charged and the delay time is increased. Was for 15 seconds. Compared with this, the data transfer method using packet switching according to the present invention achieves a significant reduction in communication charges and a significant reduction in delay time (that is, a significant improvement in data transfer rate). Recognize.

The data transfer method using packet switching according to the present invention has been described above by using the example of executing the READ (read) command from the terminal computer to the file in the host computer, but is not limited to the read command. Even if a large amount of data is accessed by executing a write command and a rewrite command, the communication charge and the delay time are significantly reduced (that is, the data transfer speed is significantly improved). Of course, you can

In the above-described embodiment, a data set is created by compressing a plurality of continuous records in record units, and the packet length is changed according to the data amount of this data set. Although described as an example of creating, the present invention also provides a method of creating a packet having the most efficient packet length for transmission.

That is, a plurality of continuous records are data-compressed in record units to form a data set, and each data set is transmitted before the packet having the optimum packet length for transmitting the entire data set is created. This is a method of compressing the data that constitutes a record. Specifically, the same data in which four characters (words) or more are consecutive in each record is compressed.

For example, when there is a data string of 40 40 40 40 40 40 40 40 in hexadecimal notation, by compressing like FE 00 07 40, data of 7 characters (word) is 4 characters (word). Can be compressed into. Although there are various other data compression methods, the most suitable method may be selected for practical application of the present invention.

Since it is possible to further shorten the packet length by compressing the data in each record before compressing the data of consecutive records in record units,
The efficiency of data transfer is further improved.

Next, an embodiment in which the terminal computer reads a plurality of files in the host computer at a time,
This will be described using the operation flow of the present invention shown in FIG. (S1) The terminal computer decodes the program logic, creates a packet containing the points at which data can be continuously transferred and the usage items of the file, and sends it to the host computer. The point at which data can be transferred consecutively is to create a data aggregate by compressing multiple consecutive records in record units, and to create the optimum packet for transmitting the entire data aggregate. It is a break. The file usage item is an item used by the program being executed by the terminal computer, among the items in the plurality of files in the host computer.

(S2) The host computer is (S1)
When the packet is received, the terminal computer accumulates information obtained by decoding the program being executed. That is, the points at which data can be continuously transferred and the usage items (usage items used by the program executed by the terminal computer, the same applies hereinafter) of the items in the file being used are grasped in advance.

(S3) The terminal computer creates a packet containing data access to the host computer and sends it to the host computer. (S4) The host computer selects an effective (most efficient) data transfer method. Specifically, the procedure is as follows.

Read a record. This record is read by simultaneously reading records from different files.

Of the records read above,
Extract only records that have used items. For each file, multiple records that make up the file are compressed in record units to create a data aggregate.

Each file that has been data-compressed in record units is data-compressed in file units. A data collection that is data compressed in file units,
A packet having the most efficient packet length of 128 to 4096 bytes for transmission is created and sequentially sent to the terminal computer.

(S5) The terminal computer restores the packet sequence received from the host computer to the original data and reads a plurality of files. Specifically, the procedure is as follows.

A data aggregate, which is data-compressed in record units, is expanded into individual records. Each decompressed individual record is decomposed into regular records.

Unused items not specified as the usage items in (S1) are added to adjust the form of each file to a regular one. Multiple files are read by fetching different records (each record belonging to a unique record group that constitutes each file) for each file.

In the above embodiment as well, similar to the above-described embodiment, if data compression of each record is performed before data compression is performed in record units to create a data aggregate,
Since the packet length can be further shortened, the data transfer efficiency can be further improved.

[0050]

According to the present invention, the number of packets is minimized in a data transfer method using packet switching, and particularly in a data transfer method using packet switching between computers forming a network via a packet switching network. It becomes possible to do.

As a result, the time required for data transfer is shortened, and the data transfer speed is improved. Also,
Since the number of packets sent and received is reduced, the communication charge is reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic configuration of the present invention.

FIG. 2 is a diagram showing an embodiment of the present invention.

FIG. 3 is a diagram showing an operation flow of the present invention.

FIG. 4 is a diagram showing a conventional example.

[Explanation of symbols]

 1 Search program 2 Search request segment 3 Data compression 4 Search result segment

Claims (4)

[Claims] 1. A data transfer method using packet switching between computers constituting a network via a packet switching network, wherein a computer transmitting data has a plurality of continuous data storing data to be transmitted. Create a data aggregate by compressing the records of
A computer having a packet length most efficient for transmitting the entire data aggregate and transmitting the packet to the packet switching network, and the computer receiving the data, after receiving the packet from the packet switching network, A data transfer method using packet switching, which comprises decompressing a compressed data set for each record forming the packet to restore a regular record and reading the data. 2. The computer according to claim 1, wherein the computer on the data transmitting side compresses the data in each record in which the data to be transmitted is stored, and then collects a plurality of continuous records in record units. A data aggregate is created by compression, a packet with the most efficient packet length for transmitting the entire data aggregate is created, and the computer receiving the data uses the records that make up the received packet. The compressed data set is decompressed and restored to a plurality of data-compressed records, and then the data that composes each record is decompressed and restored to regular data, and the data is read. Data transfer method using packet switching. 3. A data transfer method using packet switching between computers composing a network via a packet switching network, wherein a terminal computer reads a plurality of files stored in a host computer at one time. In the data transfer method, the terminal computer decodes the program logic, creates a packet containing the information of points at which data can be transferred continuously, and sends the packet to the packet switching network.
Upon receiving this packet from the packet switching network and grasping in advance the points at which data can be continuously transferred, the terminal computer creates a packet having data access to the host computer and sends it to the packet switching network. When this packet is received from the packet switching network, it reads records across multiple files, compresses the records across multiple files in record units, and creates a data aggregate. To create a packet of the most efficient packet length for transmission to the packet switching network, and the terminal computer receives this packet from the packet switching network, and then compresses the data in record units that compose the received packet. The expanded data set is expanded and After restoring the de data transfer method using packet switching, characterized in that to read the file by decomposing a record of the plurality of regular in multiple files. 4. The host computer according to claim 3, after compressing the data in the records making up each file, compressing the records in a plurality of files in record units to create a data aggregate, A packet having the most efficient packet length for transmitting the entire data aggregate is created, and the terminal computer decompresses the data aggregate, which is data-compressed in the record unit forming the received packet, to obtain a plurality of packets. After decompressing the data into compressed records, decompressing the data that composes each record and decompressing it into regular data to create multiple regular records, and writing these multiple regular records into multiple files. A data transfer method using packet switching characterized by disassembling and reading a file.