JP2003348152A - Information transmission apparatus and information transmission method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information transmission apparatus and a method thereof capable of resuming downloading from the data corresponding to the point of time when data interruption takes place. <P>SOLUTION: A server 1 divides data whose downloading is requested into packets with the number of transmitted packets, generates packets: having a header provided with a data number indicative of the total division number of the divided data and what order number of the data in the total number of data divisions is stored; and containing the data corresponding to the data number, and transmits the packets to a terminal 2. Upon the receipt of a request signal of retransmission transmitted from the terminal 2 for detecting packet missing, the server 1 generates packets provided with a header after the data number of missing packets included in the request signal and retransmits the packets to the terminal. Thus, on the occurrence of data missing such as interrupted downloading of data due to a communication error or the like, the information transmission apparatus can resume downloading from data corresponding to a point of time when data interruption takes place. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information transmission apparatus and an information transmission method capable of restarting download from the data at the time of interruption when data download is interrupted due to, for example, a communication error.

[0002]

2. Description of the Related Art Information which is composed of a server / client system and which sends data from a server to a client in response to a download request from the client accessing the server via a communication network such as the Internet using TCP / IP. Delivery devices are known. Specifically, for example, when the client side is configured by a portable information terminal having a wireless communication function, when a dial-up connection is made to a server (service provider) by wireless communication, the portable information terminal is negotiated during the dial-up connection. An IP address is assigned. When the IP address of the destination (mobile information terminal) is determined, the server responds to the download request from the mobile information terminal,
Data to be transmitted is stored in an IP packet having a header formed from the own IP address of the transmission source and the IP address of the transmission destination, and the packet is transmitted. The IP packet sent from the server is routed on the network based on the IP address and downloaded to the portable information terminal.

[0003]

By the way, in the above-mentioned conventional information transmitting apparatus, the communication quality is improved by, for example, re-transferring an IP packet lost during network transfer by using TCP which is a protocol of a transport layer. However, if the data download is interrupted due to a communication error or the like, the download must be restarted from the beginning, and there is a problem that the download cannot be restarted from the data at the time of the interruption.
The present invention has been made in view of such circumstances, and it is an object of the present invention to provide an information transmission apparatus and an information transmission method capable of restarting download from the data at the time of interruption.

[0004]

According to the first aspect of the present invention, there is provided an apparatus for downloading data to a terminal in response to a request from a terminal accessing the terminal via a network. Dividing means for dividing the data requested to be downloaded from the terminal into the number of transmission packets, the total number of data divided by the dividing means, and the number of data stored in the total number of divisions Sending means for forming a packet containing data corresponding to the data number and sending it to the terminal, and a request signal sent by the terminal to detect a packet loss and send the packet to the terminal. Retransmission means for forming and retransmitting the packet having a header subsequent to the data number of the missing packet included in the request signal when receiving Characterized by comprising.

According to a second aspect of the present invention, there is provided a method of downloading data to a terminal in response to a request from a terminal accessing the terminal via a network, and transmitting the data requested to be downloaded from the terminal. It has a header provided with a dividing step of dividing the number of packets, a total number of data divided in the dividing step, and a data number indicating the number of data in the total number of divisions. A transmission step of forming a packet containing data corresponding to the data number and transmitting the packet to the terminal, and a request signal transmitted from the terminal when the terminal detects a packet loss and included in the request signal. And a retransmission step of forming and retransmitting the packet having a header subsequent to the data number of the missing packet.

According to a third aspect of the present invention, there is provided an apparatus for downloading data from a server to a terminal in response to a request from a terminal accessing the server via a network, wherein the server requests the terminal to download the data. Dividing means for dividing the divided data into the number of transmission packets, a total number of data divided by the dividing means, and a data number indicating the number of data in the total number of divisions is stored. Sending means for forming a packet containing data corresponding to the data number and sending the data to the terminal; and when the terminal receives a request signal for detecting and transmitting a packet loss, the requesting means sends the request to the terminal. Retransmission means for forming and retransmitting the packet having a header subsequent to the data number of the missing packet included in the signal, The end receives the packet, secures a storage area corresponding to the total number of divisions in the header, and stores data contained in the packet in an address area corresponding to the data number in the header in this storage area. A storage means for determining whether or not the data stored by the storage means is equal to the total number of divisions, detecting the presence or absence of a packet loss, and detecting a packet loss; And retransmission request means for transmitting a request signal for requesting retransmission.

According to a fourth aspect of the present invention, there is provided a method of downloading data from a server to a terminal in response to a request from a terminal accessing the server via a network, wherein the server requests download from the terminal. Dividing the divided data into the number of transmission packets, the total number of divided data in the dividing process,
A transmission step of forming a packet containing data corresponding to the data number and having the header provided with a data number indicating the number of data in the total number of divisions, and transmitting the packet to the terminal; A retransmission step of, when the terminal receives a request signal to detect and transmit a packet loss and forming the packet with a header subsequent to the data number of the missing packet included in the request signal, and retransmitting the packet. The terminal receives the packet, secures a storage area corresponding to the total number of divisions in the header, and stores the packet in the address area corresponding to the data number in the header in the storage area. A storage step of storing data to be stored, and determining whether or not the data stored in the storage step is equal to the total number of divisions to determine whether there is a packet loss. And, characterized by comprising a re-transmission request process for transmitting a request signal for requesting re-transmission of packets with missing data number after the header if it detects a packet loss.

[0008] In the invention according to claim 5 which depends on claim 3, when the storage means receives a packet retransmitted from the server, the storage means sequentially starts from the address area corresponding to the data number in the header. Data stored in the packet is stored.

[0009] In the invention according to claim 6 dependent on claim 4, when the packet retransmitted from the server is received, the storing step sequentially starts from the address area corresponding to the data number in the header. Data stored in the packet is stored.

According to a seventh aspect of the present invention, there is provided an apparatus for downloading data to a terminal in response to a request from a terminal accessing the terminal via a network, and transmitting the data requested to be downloaded from the terminal. A dividing unit for dividing the packet into the number of packets, a header provided with a total number of data divided by the dividing unit, and a data number indicating the number of data in the total number of divisions, Sending means for forming a packet containing data corresponding to the data number and sending the packet to the terminal;
When the terminal detects a packet loss and receives a request signal to be transmitted, the terminal includes a packet having a header of the data number of the missing packet included in the request signal and retransmits the packet. It is characterized by doing.

[0011] The invention according to claim 8 is a method for downloading data to a terminal in response to a request from a terminal accessing the terminal via a network, and transmitting the data requested to be downloaded from the terminal. It has a header provided with a dividing step of dividing the number of packets, a total number of data divided in the dividing step, and a data number indicating the number of data in the total number of divisions. A transmission step of forming a packet containing data corresponding to the data number and transmitting the packet to the terminal, and a request signal transmitted from the terminal when the terminal detects a packet loss and included in the request signal. Retransmitting the packet with the header of the data number of the missing packet and retransmitting the packet.

In the present invention, the data requested to be downloaded from the terminal is divided into the number of packets to be transmitted, and the total number of the divided data and the data number indicating the number of data in the total number of divisions are stored. And a packet containing data corresponding to the data number is formed and transmitted to the terminal. Then, upon detecting a packet loss and receiving a request signal transmitted by the terminal side,
The packet including a header subsequent to the data number of the missing packet included in the request signal is formed and retransmitted to the terminal. Therefore, when the data download is interrupted due to a communication error or the like, the download can be restarted from the data at the time of the interruption, and the problem of restarting the download from the beginning as in the related art can be solved.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. (1) Configuration FIG. 1 is a diagram showing a schematic configuration of an information transmitting apparatus according to an embodiment. The information transmission device shown in this figure is constituted by a so-called server-client system, and comprises a server 1 and a terminal 2 connected to each other via a network NT such as the Internet.

The server 1 downloads data of the designated content to the terminal 2 in response to a download request from the terminal 2 whose access has been authenticated. Upon downloading, the server 1 forms a packet having the structure shown in FIG. The packet shown in this figure is composed of a header HD and a data body DATA. The header HD is characterized in that it has a source IP address, a destination IP address, and the like, as well as a data number IP and a total number of divisions TOTAL, similarly to the above-described conventional IP packet. Here, the total number of divisions TOTAL represents the total number of divisions (the total number of packets) when dividing the data to be downloaded to the terminal 2 into packets. The data number IP is such that the data body DATA stored in each packet is the total number of divisions TOTAL.
Represents the number of data in the total number of divisions represented by.

The terminal 2 is composed of a personal computer equipped with a well-known Web browser.
It accesses the server 2 via T and sends out a download request. Further, when the data download is interrupted due to a communication error or the like, the terminal 2 refers to the data number IP and the total number TOTAL in the packet received immediately before the interruption, and requests the server 1 to redownload the packet after the interruption. Thereby, the server 1 can resume the download from the data at the time of the interruption. Note that the terminal 2 is not limited to a personal computer, and may be, for example, a mobile phone or a wireless mobile terminal having a browser function. In this case, the terminal 2 is connected to the network NT via a wireless connection company 3. Become.

(2) Operation Next, the operation of the information transmitting apparatus will be described with reference to FIGS. In the following, first, an outline of the overall operation will be described with reference to a sequence flow, and then each operation of a “data transmission process” executed by the server 1, a “data storage process” and a “data confirmation process” executed by the terminal 2 Will be described in detail.

Overall Operation First, it is assumed that the terminal 2 issues a connection request to access the server 1 via the network NT (step SA1 in FIG. 3). Then, the server 1 establishes a connection with the terminal 2 (step SA2). When communication between the two is established, the terminal 2 transmits access authentication data including a user ID and a password to the server 1 (step SA3). . Thus, the server 1 proceeds to step SA4 to perform access authentication, and when authenticated as an authorized user, proceeds to the next step SA5, creates a menu screen corresponding to a Web page, and requests connection thereof. And sends it to the terminal 2.

Then, the terminal 2 advances the process to step SA6, and displays the received menu screen on the screen. The menu screen includes, for example, an icon for displaying a list of downloadable content data, selecting data to be downloaded from the list, and generating a download request. Then, data to be downloaded is selected on this menu screen (step SA7), and when an icon for generating a download request is clicked, the result of the determination in step SA8 becomes "YES" and the flow proceeds to step SA9. At step SA9, a download request signal is generated and transmitted to the server 1. Then, in step SA10, the server 1 specifies data to be downloaded, for example, by extracting data of the content requested to be downloaded from the database.

Next, the server 1 proceeds to step SA11 shown in FIG. 4, and executes a data transmission process (described later) for dividing the data to be downloaded into packets having the structure shown in FIG. When the server 1 starts the download, the result of the determination in step SA12 for determining whether or not there is a download in the terminal 2 is "YES", the process proceeds to step SA13, and the data storage process for receiving the downloaded data and storing it in the memory. (Described later)
Execute Thereafter, the terminal 2 proceeds to step SA14, and determines whether the download has been completed. If downloading is in progress, the determination result is “NO”, and the process returns to step SA12.

Thereafter, the terminal 2 repeats steps SA12 to SA13 until the download is completed. When the download is completed, the determination result of step SA14 becomes "YES", and the process proceeds to step SA15.
After executing data confirmation processing (described later) for confirming whether data for all packets has been stored in the memory, the processing shifts to other processing. Note that the other processing here refers to, for example, when the downloaded data is music data such as MIDI data, a process of reproducing the downloaded music data.

In the data confirmation process executed in step SA15, as described later, it is determined whether or not data for all packets has been downloaded with reference to the data number IP and the total number TOTAL in the received packet. If the data download for all packets has been confirmed, an OK signal is sent to the server 1 side. On the other hand, if the data download is interrupted due to, for example, a communication error and the packet is lost, a request signal requesting retransmission of the packet after the lost packet is transmitted to the server 1 side.

In the server 1, the above described step SA11
When all the packets are transmitted and the download is completed in the data transmission process, the process proceeds to step SA16, and the response from the terminal 2 side, that is, the OK signal or the request signal generated in the data confirmation process (step SA15) Is received in step SA16. Then, step SA
At 17, it is determined whether the received signal is an OK signal or a request signal. Here, when the OK signal is received, it is determined that the download has been normally performed, and the process proceeds to another process. On the other hand, when the request signal is received,
The process returns to step SA11, and retransmits the packet after the missing packet in response to the request signal. Therefore, when the data download is interrupted due to a communication error or the like, the download can be restarted from the data at the time of the interruption, and the adverse effect of restarting the download from the beginning as in the related art can be solved. ing.

Next, the operation of the data transmission process will be described with reference to FIG. When the data transmission processing is executed via the above-described step SA11 (see FIG. 4), the server 1 advances the processing to step SB1 shown in FIG. In step SB1, the data specified by the download request from the terminal 2 is divided into the number of transmission packets. Then, step S
In B2, the division number is stored in the register TOTAL, and in the next step SB3, the initial value “1” is stored in the register IP. Next, in step SB4, of the data divided into the number of packets to be transmitted in step SB1, the IP-th data corresponding to the value of the register IP is used as the data body DATA, and the IP address of the source and the destination HD with IP address etc.
Is added.

Then, in step SB5, the header HD
The value of the register IP and the value of the register TOTAL are copied to the data number IP and the total number TOTAL, respectively, to form a packet having the structure shown in FIG. When the packet formation is performed in this way, the server 1 advances the process to step SB6, and sends out the formed packet. After completing the transmission of the packet, the server 1 proceeds to step SB7,
The value of the register IP (data number IP) is incremented to advance. Next, in step SB8, it is determined whether or not the incremented value of the register IP has exceeded the value of the register TOTAL, that is, whether or not all packets have been transmitted. If the transmission has not been completed, the judgment result is “N
O ", and the above-described steps SB4 to SB7 are repeatedly executed to sequentially form and transmit packets corresponding to the incremented data number IP. When all the packets have been transmitted, the result of the determination in step SB8 is “YE
S ”, the process proceeds to step SA16 (see FIG. 4) described above, and the present process is completed.

If the download is interrupted due to, for example, a communication error while the data is being downloaded to the terminal 2 in the data transmission processing, the terminal 2 retransmits the data after the packet lost in the data confirmation processing described later. An outgoing request signal is sent to the server 1 side.
Upon receiving this request signal, the server 1 proceeds to step SB9 of the data transmission process, extracts the data number of the missing packet from the received request signal, and stores it in the register IP. Thereafter, steps SB4 to SB4 described above are performed.
SB8 is executed to form the packet after the missing packet and download it to the terminal 2 again.

Next, the operation of the data storage process will be described with reference to FIG. When the data storage processing is executed through step SA13 (see FIG. 4) described above, terminal 2 advances the processing to step SC1 shown in FIG. In step SC1,
It is determined whether or not there is an error in the data body DATA based on the checksum included in the header HD in the received packet. If there is an error, the determination result is “NO”, and this processing is completed without doing anything. However, if there is no error, the determination result is “YES”, and the flow advances to next Step SC2.

In step SC2, it is determined whether or not the data is the first received data, that is, whether the value of the data number IP included in the header HD of the received packet is "1". If it is the first received data, the determination result is "YES", and the process proceeds to the next step SC3. If it is not the first received data, the determination result is "NO", and a later-described step SC5 Proceed to. In step SC3, the total number TOTAL is read from the header HD of the received packet. In subsequent step SC4,
A storage area corresponding to the total number TOTAL is secured in the memory. Next, at step SC5, the data number IP is read from the header HD. Then, Step SC6
Then, in the storage area secured in the memory, the data body DATA extracted from the received packet is stored in the address area corresponding to the data number IP, and this processing is completed.

Next, the operation of the data confirmation process will be described with reference to FIG. When the data confirmation processing is executed via the above-described step SA15 (see FIG. 4), the terminal 2 advances the processing to step SD1 shown in FIG. In step SD1,
An initial value "1" is stored in a register m (hereinafter, referred to as a pointer m) for temporarily storing a pointer corresponding to the data number IP. In step SD2, it is determined whether or not data is stored in the address area corresponding to the pointer m.
That is, it is determined whether or not the data body DATA of the data number IP corresponding to the pointer m has been downloaded to the memory. If it has been downloaded to the memory, the result of the determination is "YES" and the operation proceeds to step SD3 to increment the pointer m.

In step SD4, it is determined whether or not the incremented pointer m has exceeded the total number TOTAL. If the pointer m does not exceed the total number TOTAL, the determination result is “NO”, and the above-described step S
The process returns to D2. Thereafter, the pointer m indicates the total number of divisions TOT.
Each time the pointer m is incremented until it exceeds AL, the data body DATA of the data number IP corresponding to the pointer m
To determine if has been downloaded to memory. When it is confirmed that the data body DATA for all the packets has been downloaded to the memory, step SD
The result of the determination at step 4 is "YES", the process proceeds to step SD5, and an OK signal indicating that the download has been completed normally is sent to the server 1 to complete this processing.

On the other hand, if there is no data in the address area corresponding to the pointer m before the pointer m exceeds the total number TOTAL, that is, if a packet loss is detected, the determination result in step SD2 becomes "NO",
The process proceeds to Step SD6. In step SD6,
A request signal is sent to the server 1 requesting retransmission of the packet with the data number IP corresponding to the pointer m. Thereby, the server 1 forms the packet after the packet lost in the data transmission processing (see FIG. 5) described above and re-downloads it to the terminal 2 side. The re-downloaded data is sequentially stored from the address area corresponding to the data number IP in the above-described data storage processing (see FIG. 6).

(3) Modified Example Next, a modified example of the above-described embodiment will be described with reference to FIGS. In the flowcharts shown in these drawings, steps (processes) common to the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted. The difference of the modified example from the above-described embodiment is that when the server 1 receives the request signal from the terminal 2 side, the server 1 forms only the packet which is lost in steps SA18 to SA21 shown in FIG. Side to re-download.

That is, when the server 1 executes the data transmission process shown in FIG. 9 through the step SA11 in FIG. 8 in accordance with the download request from the terminal 2, the data to be downloaded in steps SB1 to SB8 described above The packet is divided into packets having the structure shown in FIG. As a result, the terminal 2 executes the data storage process of receiving the downloaded data and storing it in the memory (step SA13).
A data confirmation process for confirming whether data for all packets has been downloaded is executed (step SA1).
5). For example, when a packet is lost due to a communication error or the like, a request signal requesting retransmission of the lost packet is transmitted to the server 1 side.

Upon receiving the request signal, the server 1 proceeds to step SA18 shown in FIG. 8, extracts the data number of the missing packet from the received request signal, and stores it in the register IP. Next, in step SA19, the IP-th data corresponding to the value of the register IP is used as the data body DATA, and a header HD including a source IP address and a destination IP address is added thereto. Next, in step SA20, the data number IP in the header HD and the total number TOTAL are set in the register I, respectively.
P and the values of the register TOTAL are copied to form a packet having the structure shown in FIG. And step SA
Proceed to 21 and send the formed packet to the terminal 2 side.
As described above, in the modified example, when the terminal 2 detects a packet loss and generates a request signal requesting retransmission of the lost packet, the server 1 redownloads only the corresponding packet according to the request signal. Therefore, it is possible to re-download in packet units.

As described above, according to the present embodiment, the server 1 divides the data requested to be downloaded from the terminal 2 into the number of packets to be transmitted, the total number TOTAL representing the total number of divisions, and the total number TOTAL. When a packet in which the data number IP indicating the number of data in the TOTAL is stored is provided in the header HD and the packet is transmitted to the terminal 2 that has requested the download, the terminal 2 that has received the packet, Total number of divisions T extracted from header HD
A memory area corresponding to the OTAL is secured in the memory, and the data body DAT in the packet is stored in the address area corresponding to the data number IP extracted from the header HD.
A is stored.

Then, the data body DA stored in the memory
It is determined whether or not TA is equal to the total number TOTAL, and if a packet loss is detected, the lost data number IP
A request signal for requesting retransmission of the packet after is transmitted to the server 1 side. Then, the server 1 forms the packet after the missing packet in response to the request signal and re-downloads it to the terminal 2 side. As a result, when data download is interrupted due to a communication error or the like, the download can be restarted from the data at the time of the interrupt, and the adverse effect of restarting the download from the beginning as in the related art can be solved.

In this embodiment, the data re-downloaded from the server 1 to the terminal 2 has the data number IP
Is stored in order from the address area corresponding to the data, so that the data after the lost packet can be stored in the memory continuously with the data before the loss. Further, according to the above-described modified example, when the terminal 2 detects a packet loss and generates a request signal for requesting retransmission of the lost packet, the server 1 repeats only the packet corresponding to the request signal. Since downloading is performed, it can be re-downloaded in packet units.

[0037]

According to the first and second aspects of the present invention, the data requested to be downloaded from the terminal is divided into the number of transmission packets, the total number of the divided data and the number of the divided total. Has a header provided with a data number indicating whether the data is stored, forms a packet containing data corresponding to the data number, and sends it to the terminal side. Then, upon detecting a packet loss and receiving a request signal transmitted by the terminal side, the terminal forms the packet having a header subsequent to the data number of the lost packet included in the request signal and retransmits the packet to the terminal side. If the data download is interrupted due to an error or the like, there is no need to restart the download from the beginning as in the past,
Download can be resumed from the data at the time of interruption. According to the third and fourth aspects of the present invention, in response to a download request from the terminal, the server divides the requested data into the number of packets to be transmitted, the total number of the divided data, and the number of the divided data. When a packet containing data corresponding to the data number is formed and transmitted to the terminal side, the terminal provides the header in the received packet. In addition to securing a storage area corresponding to the divided total number, data stored in the packet is stored in an address area corresponding to the data number in the header in this storage area, and there is stored data for the divided total number. Then, the presence or absence of a packet loss is detected. When the packet loss is detected, a request signal for requesting retransmission of a packet having a header subsequent to the missing data number is transmitted to the server. Then, the server receives the request signal, forms the packet having a header subsequent to the data number of the missing packet included in the request signal, and retransmits the packet. As a result, if the data download is interrupted due to a communication error or the like, Thus, it is not necessary to restart the download from the beginning unlike the conventional technique, and the download can be restarted from the data at the time of the interruption. According to the fifth and sixth aspects of the present invention, when a packet retransmitted from the server is received, data stored in the packet is stored in order from the address area corresponding to the data number in the header. Data downloaded before the interruption and data after the interruption to be re-downloaded can be continuously stored in the memory. According to the seventh and eighth aspects of the present invention, when the terminal detects a packet loss and generates a request signal requesting retransmission of the lost packet, only the corresponding packet is re-downloaded in response to the request signal. Can be re-downloaded in packet units.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of an information transmission device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a structure of a packet transmitted by a server 1;

FIG. 3 is a sequence flow showing an overall operation.

FIG. 4 is a sequence flow showing an overall operation.

FIG. 5 is a flowchart illustrating an operation of a data transmission process executed in the server 1.

FIG. 6 is a flowchart showing an operation of a data storage process executed in the terminal 2.

FIG. 7 is a flowchart illustrating an operation of a data confirmation process executed in the terminal 2.

FIG. 8 is a sequence flow showing an overall operation of a modification.

FIG. 9 is a flowchart illustrating an operation of a data transmission process according to a modification.

[Explanation of symbols]

1 server 2 terminal 3 connection companies HD header IP data number TOTAL DATA data body

Claims (8)

[Claims] An apparatus for downloading data to a terminal in response to a request from a terminal accessing the terminal via a network, wherein the division is performed by dividing the data requested to be downloaded from the terminal into the number of transmission packets. Means, the total number of data divided by the dividing means,
Sending means for forming a packet containing the data corresponding to the data number, having a header provided with a data number indicating the number of data in the total number of divisions, and sending the packet to the terminal; Retransmission means for, when the terminal receives a request signal for detecting and transmitting a packet loss, forming the packet having a header subsequent to the data number of the missing packet included in the request signal and retransmitting the packet; An information sending device comprising: 2. A method for downloading data to a terminal in response to a request from a terminal accessed via a network, the method comprising: dividing data requested to be downloaded from the terminal into a number of transmission packets. Process, and a header provided with a total number of data divided in the division process and a data number indicating the number of data stored in the total number of divisions. A transmitting step of forming a packet for storing data and transmitting the packet to the terminal; and when the terminal detects a packet loss and receives a request signal to be transmitted, the terminal receives a request signal transmitted after the data number of the missing packet included in the request signal. Retransmitting the packet with a header and retransmitting the packet. 3. An apparatus for downloading data from a server to a terminal in response to a request from a terminal accessing the server via a network, wherein the server sends data requested to be downloaded from the terminal to a transmission packet. Dividing means for dividing the data into several minutes, the total number of data divided by the dividing means,
Sending means for forming a packet containing the data corresponding to the data number, having a header provided with a data number indicating the number of data in the total number of divisions, and sending the packet to the terminal; Retransmission means for, when the terminal receives a request signal for detecting and transmitting a packet loss, forming the packet having a header subsequent to the data number of the missing packet included in the request signal and retransmitting the packet; The terminal receives the packet, secures a storage area corresponding to the total number of divisions in the header, and stores the packet in the address area corresponding to the data number in the header in the storage area. Storage means for storing data to be divided, and determining whether or not the data stored by the storage means is equal to the total number of divisions, and determining whether or not a packet is lost. Retransmission request means for transmitting a request signal for requesting retransmission of a packet having a header subsequent to the missing data number when detecting absence and detecting packet loss. . 4. A method for downloading data from a server to a terminal in response to a request from a terminal accessing the server via a network, wherein the server transmits data requested to be downloaded from the terminal to a transmission packet. A dividing step of dividing the data into several minutes, a header having a total number of data divided in the dividing step, and a data number indicating the number of data in the total number of divisions, A transmitting step of forming a packet containing the data corresponding to the data number and transmitting the packet to the terminal; and, when the terminal receives a request signal to detect and transmit the packet loss, the loss included in the request signal. A retransmission step of forming and retransmitting the packet having a header subsequent to the data number of the packet, and retransmitting the packet. Receiving and securing a storage area corresponding to the total number of divisions in the header, and storing data contained in the packet in an address area corresponding to the data number in the header in the storage area; It is determined whether or not the data stored in the storage process is equal to the total number of divisions to detect the presence / absence of packet loss. When the packet loss is detected, retransmission of a packet having a header subsequent to the lost data number is performed. And a retransmission requesting step of transmitting a request signal. 5. The storage means, when receiving a packet retransmitted from the server, stores the data contained in the packet in order from the address area corresponding to the data number in the header. The information sending device according to claim 3, wherein 6. The storage step wherein, when a packet retransmitted from the server is received, data contained in the packet is stored in order from an address area corresponding to a data number in the header. The information sending method according to claim 4, wherein 7. An apparatus for downloading data to a terminal in response to a request from a terminal accessing the terminal via a network, the apparatus dividing data requested to be downloaded from the terminal into the number of packets to be transmitted. Means, the total number of data divided by the dividing means,
Sending means for forming a packet containing the data corresponding to the data number, having a header provided with a data number indicating the number of data in the total number of divisions, and sending the packet to the terminal; When the terminal detects a packet loss and receives a request signal to be transmitted, retransmitting means for forming and retransmitting the packet having the header of the data number of the lost packet included in the request signal. An information transmission device, comprising: 8. A method for downloading data to a terminal in response to a request from a terminal accessing the terminal via a network, comprising: dividing data requested to be downloaded from the terminal into a number of packets to be transmitted. Process, and a header provided with a total number of data divided in the division process and a data number indicating the number of data stored in the total number of divisions. A transmission step of forming a packet containing data and transmitting the packet to the terminal; and a header for a data number of the missing packet included in the request signal when the terminal detects a packet loss and receives a request signal to be transmitted. Retransmitting the packet and retransmitting the packet.