JP2005348262A - Data communication system, electronic conference system, data communication method, data communication program, and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a data communication method and an electronic conference system for performing data communication by switching between TCP and UDP.
A client 2 transmits to the server 1 by UDP (S1). When the server 1 permits sharing, the client 2 transmits a packet notifying permission to the client 2 and stores the network address of the client 2. (S2, S3). The client 2 stores the network address of the server and prepares to receive and display the screen data (S4). Initial screen data is transmitted from the server to the client by UDP (S5a), and screen data is transmitted by UDP every time the shared screen area of the server is updated (S5b, S5c, S5d). When the screen sharing is to be ended, a disconnection request is transmitted from the client to the server by UDP (S7), and the server that has received the disconnection request transmits a confirmation of disconnection to the client by UDP and sets transmission / reception to the client. Release (S8, S9). On the other hand, the client that has received the disconnect OK cancels the transmission / reception setting to the server (S10).
[Selection] Figure 2

Description

  The present invention is a server / client type data communication in which screen information displayed by a certain information device can be shared by another information device, or can be remotely operated from another information device. Regarding the method. The present invention also relates to an electronic conference system using the communication method. The present invention also relates to a data communication method, a data communication program, and a storage medium.

  In recent years, electronic conferencing systems that conduct conferences with distant users have become widespread due to the speeding up of computer system processing and network speedup. The following software is distributed in the electronic conference system.

1. Microsoft NetMeeting
View the entire server desktop screen or specified application screen from the client using the electronic conference application installed as standard in some Windows (registered trademark) operating systems sold by Microsoft Corporation in the United States, or Remote operation is possible.

2. VNC (Virtual Network Computing)
This is screen sharing software developed by AT & T in the United States, and basically shares the entire desktop screen of the server. An updated part of the screen area of the server is encoded using a protocol called RFB (Remote Frame Buffer) protocol and transmitted to the client. Some software developed based on this VNC has been improved so that only the specified application screen area can be shared, or only the specified rectangular area of the server desktop screen can be shared. A screen data encoding method with strong compression has been developed. As such improvements, software such as TightVNC, eSVNC, VDACC VNC is known, for example.

Other software that has screen sharing as its main function includes Symantec PC Anywhere, LapLink Gold, and PC remote management tools such as Danware NetOp Remote Control and Radmin Remote Administrator.
Software for educational use that uses the screen sharing function includes NetOp School of Danware and Remote Control Club for School developed by Cross Tech.

3. MulticastVNC
It is an improved version of the client software that operates on the Java (registered trademark) of the VNC, and has a function of relaying server screen data to a plurality of clients. Thereby, it is possible to reduce a decrease in the screen update speed due to a large number of clients connected to one server.

4). Windows RemoteDesktop
Windows Xp Professional, one of Microsoft's OSs, has a screen sharing function called RemoteDesktop. Similarly, the screen data of the RemoteDesktop server is received by the RemoteDesktop client and can be browsed or remotely operated from the client. However, since screen data is simply transmitted, it has been pointed out that when a video image is viewed on a client device with software such as Windows MediaPlayer, frames are dropped.

Patent Document 1 discloses a teleconference (by an electric communication means) between a conference participant connected via a connectionless network and a conference participant connected via a connection network having a bridge. A technology related to a teleconference device capable of performing a conference is disclosed.
Japanese Patent Laid-Open No. 10-270553

However, transmission of screen data uses a TCP packet that is a data stream type communication method. In TCP / IP communication, the certainty of communication is guaranteed, but it is necessary to respond to reception of a packet, that is, return an ACK packet.
On the other hand, in UDP / IP communication which is a datagram type communication method, it is not necessary to return ACK in response to packet reception. As a result, the reliability of communication is not guaranteed, but the communication speed is improved. The header of a UDP packet is 64 bits, whereas TCP has 182 bits, and the overhead of this header may cause a decrease in communication speed. In particular, when a plurality of clients browse a document displayed on a server by screen sharing or remotely edit a document from a client as in an electronic conference system, one client is used. Each time it is necessary to establish a TCP connection, the communication speed is lowered, the client screen is updated slowly, and the user is likely to feel stress or perform an erroneous remote operation. For example, when 10 or more clients are connected to a single server, the screen update speed is lowered with existing software, and it cannot be put into practical use.

  In order to solve this, it is possible to sandwich the relay device like MulticastVNC, but since the screen update is delayed due to processing in the relay device, the client connected via the relay device As the number increases, the screen update speed decreases accordingly.

  The present invention has been made in view of the above circumstances, and provides a data communication system, an electronic conference system, a data communication method, a data communication program, and a storage medium that perform data communication by switching between TCP and UDP as necessary. The purpose is to do.

  In order to solve the above-mentioned problem, the invention according to claim 1 includes an information device functioning as a server and an information device functioning as a client of the server, and the server relates to at least a part of a display screen thereof. Means for transmitting data to the client via a network that communicates using an IP protocol, and the client displays the screen data received from the server on a display device, whereby the display screen of the server A data communication method in a network system having means for sharing the screen, wherein the server is configured to transmit the screen data according to any one of the type of data or display condition of the screen area to be transmitted, the communication environment with the client, or an instruction given by the user. At least part of the screen data to be sent Or transmitted using TCP packets, or characterized by having a means for transmitting by switching or transmitted using UDP packets.

  The invention described in claim 2 is characterized in that the server has means for transmitting screen data to the plurality of clients by a broadcast communication method using a UDP multicast or a UDP broadcast packet.

  According to a third aspect of the present invention, the server has means for registering whether to transmit screen data in a TCP packet or a UDP packet for each application program, and is registered to transmit in a TCP packet. The screen data of the application program is transmitted by a TCP packet, and the screen data of an application program registered to be transmitted by a UDP packet is transmitted by a UDP packet.

  According to a fourth aspect of the present invention, the server has means for determining whether or not the window of the application program is displayed in the foreground, and transmits screen data of the window displayed in the foreground. Is transmitted with a TCP packet, and the window data not on the foreground or the screen data of the desktop screen is transmitted with a UDP packet.

  The invention according to claim 5 has a means for determining whether or not the server is active on the window of the application program. When transmitting the screen data of the active window, the server transmits it with a TCP packet. The screen data of the inactive window or the desktop screen is transmitted by a UDP packet.

  According to a sixth aspect of the present invention, the server includes means for a user to instruct whether to transmit screen data using a TCP packet or a UDP packet to a running application program. Screen data of an application program registered to be transmitted is transmitted by a TCP packet, and screen data of an application program registered to be transmitted by a UDP packet is transmitted by a UDP packet.

  According to a seventh aspect of the present invention, the server has means for the user to instruct whether to transmit screen data using a TCP packet or a UDP packet with respect to an arbitrary one of the shared screen regions. The screen data of the screen area registered to be transmitted by the TCP packet is transmitted by the TCP packet, and the screen data of the screen area registered to be transmitted by the UDP packet is transmitted by the UDP packet.

  The invention according to claim 8 is characterized in that the server has means for switching a protocol for transmitting screen data according to a user instruction, and when the user instructs to transmit the TCP protocol, transmits the screen data in a TCP packet, When the user instructs to send the UDP protocol, the screen data is sent by the UDP packet.

  The invention according to claim 9 is characterized in that the server has means for managing the number of connected clients, and means for switching between screen data transmission using the TCP protocol or UDP protocol depending on the number of connected clients. When the number of connected clients is smaller than a predetermined number, the screen data is transmitted by a TCP packet, and when the number of connected clients is larger than the predetermined number, the screen data is transmitted by a UDP packet.

  The invention according to claim 10 is characterized in that the server has means for managing whether the number of connected clients is connected via a wired LAN or is connected via a wireless LAN in the middle, and is connected via a wireless LAN. It is characterized in that screen data is transmitted with a TCP packet to a client that is connected, and screen data is transmitted with a UDP packet to a client connected only with a wired LAN.

  The invention according to claim 11 is characterized in that the server has means for managing whether the number of connected clients is connected via a LAN or via a WAN, and the client connected via the WAN On the other hand, the screen data is transmitted using a TCP packet, and when the client connected via the LAN is instructed to transmit the UDP protocol, the screen data is transmitted using a UD packet.

  The invention according to claim 12 is characterized in that the server has means for measuring the remaining amount of screen data to be transmitted or the transmission rate of screen data, and the remaining amount of screen data transmission or the transmission rate of screen data is a predetermined value. When the value is smaller than the value, the screen data is transmitted using a TCP packet, and when the remaining screen data transmission amount or the screen data transmission rate exceeds a predetermined value, the screen data is transmitted using a UDP packet.

  According to a thirteenth aspect of the present invention, the server includes means for measuring a network communication speed between the server and the connected client. When the communication speed is smaller than a predetermined value, the server uses a UDP packet. When screen data is transmitted and the communication speed exceeds a predetermined value, the screen data is transmitted by a TCP packet.

  The invention according to claim 14 is characterized in that the server has means for measuring a data capacity (MTU) that can be transmitted in one packet between the server and the connected client, and the MTU is smaller than a predetermined value. In this case, the screen data is transmitted by a UDP packet, and when the MTU exceeds a predetermined value, the screen data is transmitted by a TCP packet.

  According to a fifteenth aspect of the present invention, the server has means for measuring the QoS of the network between the server and the connection client, and when the QoS is smaller than a predetermined value, the screen data is transmitted with a TCP packet. When the QoS exceeds a predetermined value, the screen data is transmitted using a UDP packet.

  In the invention described in claim 16, the server has means for managing the priority of the connected client, and the screen data is transmitted to the client given the priority by a TCP packet. It is characterized in that screen data is transmitted by a UDP packet to a client not given.

  The invention according to claim 17 is characterized in that the server receives an input event from the client, forwards the received input event to the server, and whether the client has transmitted the input event to the server within a predetermined time. A client that transmits a screen data in a TCP packet to a client that has transmitted an input event to the server within a predetermined time, and has not transmitted the input event to the server within a predetermined time. Is characterized in that screen data is transmitted by a UDP packet.

  In the invention described in claim 18, when the server transmits the screen data, whether the screen data in the transmission area includes character data or not, and whether the OS performs the font drawing command or not. The screen data of the area including the character data is transmitted by a TCP packet, and the screen data of the area not including the character data is transmitted by a UDP packet.

  The invention according to claim 19 is characterized in that the server has means for determining whether or not the CPU load of the server exceeds a predetermined load amount. If the CPU load is equal to or less than the predetermined load amount, the server uses a TCP packet. When the screen data is transmitted and the CPU load exceeds a predetermined load amount, the screen data is transmitted using a UDP packet.

  An invention according to claim 20 is composed of an information device functioning as a server and an information device functioning as a client of the server, and the server transmits data relating to at least a part of the display screen to the client according to the IP protocol. A network system having means for transmitting via a network that communicates using the server, wherein the client displays the screen data received from the server on a display device, thereby sharing the display screen of the server The network system includes a relay device that relays the screen data received from the server to the client, and the relay device receives the screen data received from the server by a TCP packet as a UDP packet. To send to the client Characterized in that it.

  The invention according to claim 21 is characterized in that the relay device has means for transmitting screen data to the plurality of clients by a broadcast communication method using a UDP multicast or a UDP broadcast packet.

  The invention according to claim 22 is characterized in that the relay device has means for recording and reproducing the screen data received from the server.

  The invention according to claim 23 is composed of an information device functioning as a conference server and an information device functioning as a conference client of the conference server, and the conference server receives data relating to at least a part of the display screen, The conference server includes means for transmitting via a network that communicates using the IP protocol, and the conference client displays screen data received from the conference server on a display device, thereby displaying the display screen of the conference server. An electronic conference system having means for sharing the screen, wherein the conference server stores the screen data according to any of the type or display condition of the data of the screen area to be transmitted, the communication environment with the conference client, or an instruction given by the user. When sending, at least part of the screen data to be sent Or transmitted using Tsu bets, or characterized by having a means for transmitting by switching or transmitted using UDP packets.

  According to a twenty-fourth aspect of the present invention, an information device functioning as a conference server and an information device functioning as a conference client of the conference server are constituent elements, and the conference server stores data related to at least a part of the display screen. Means for transmitting to the conference client via a network that communicates using the IP protocol, and the conference client displays the screen data received from the conference server on a display device, thereby displaying the display screen of the server; An electronic conference system having means for sharing, wherein the network includes a conference relay device that relays screen data received from the conference server to the conference client, and the conference relay device receives a TCP packet from the conference server. The conference client receives the screen data received at the UDP packet. Characterized in that it comprises means to send to.

  According to a twenty-fifth aspect of the present invention, the conference server has means for managing the priority of the conference client to be connected, and transmits screen data in a TCP packet to the conference client to which the priority is given. The screen data is transmitted by a UDP packet to a conference client to which priority is not given.

  According to a twenty-sixth aspect of the present invention, the conference server receives an input event from the conference client, forwards the received input event to the conference server, and the connected conference client receives the input event within a predetermined time. It has means for managing whether it has been sent to the server, and for the conference client that has sent the input event to the conference server within a certain time, the screen data is transmitted with a TCP packet, and the input event is sent within the certain time to the conference server It is characterized in that the screen data is transmitted by a UDP packet to a client that has not transmitted to the client.

  The invention according to claim 27 is a data communication method in a network system including information equipment functioning as a server and information equipment functioning as a client of the server, and at least one of display screens of the server. A process for transmitting data relating to a section to the client via a network that communicates using an IP protocol, and displaying the screen data received from the server at the client on a display device, thereby displaying the display screen of the server The server transmits the screen data when the screen data is transmitted according to any one of the type or display condition of the screen area data to be transmitted, the communication environment with the client, or an instruction given by the user. At least part of the screen data Or transmitted using, or characterized by having a step of transmitting by switching or transmitted using UDP packets.

  According to a twenty-eighth aspect of the present invention, there is provided a network comprising information equipment functioning as a server, information equipment functioning as a client of the server, and relay equipment that relays screen data received from the server to the client. A method of data communication in a system, comprising: transmitting data related to at least a part of a display screen of the server via a network that performs communication using an IP protocol to the client; and Displaying the screen data received from the server on the display device to share the display screen of the server, and transmitting, in the relay device, the screen data received from the server in the form of a TCP packet to the client in the form of a UDP packet. It is characterized by having .

  A data communication program according to claim 29 causes a computer to execute the data communication method according to claim 27 or 28.

  A computer-readable storage medium according to a thirtieth aspect stores the data communication program according to the twenty-ninth aspect.

  According to the present invention, as will be apparent from the description of the embodiment below, it is a data stream type communication method that needs to return an ACK packet in response to normal reception of a packet to a transmission packet. It is high-speed because there is no need to send back an ACK as well as communication using a certain TCP packet, but it uses UDP packets, which are datagram-type communication methods that do not guarantee reliability or the order of receiving packets, Communication between the screen sharing server and the screen sharing client is possible.

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

FIG. 1 is a schematic diagram showing a network configuration of a data communication system according to an embodiment of the present invention.
In the data communication system, an information processing device functioning as a server (server 1) and an information processing device functioning as a client of the server 1 (clients 2a, 2b,..., 2n) are connected via an IP network 10. Has been. As an IP network, for example, there is an Ethernet (registered trademark) LAN defined by IEEE802.3.

The server 1 has a display device, and displays all or part of display contents displayed on the display device as a shared screen, and transmits shared screen data to the client 2 connected to the IP network 10. The client 2 can display the shared screen of the server 1 on the display device of the client by receiving the shared screen data.
Since the conventional technique can be used as it is for the method of sharing the screen, detailed description is omitted. As an outline, the server application detects an update portion of the screen data of the server, divides and encodes the screen update area by a certain algorithm, and transmits it to the client. The received client decodes the updated area screen data and updates the shared screen data.

In the conventional invention, the screen data is transmitted using TCP packets. TCP is a connection type (CO type) protocol and is a highly reliable protocol capable of covering the loss of IP packets in connectionless type (CL type) IP. However, there is a problem that the data transfer efficiency decreases.
On the other hand, the present invention has a function of transmitting screen data using a UDP packet. UDP is a CL type protocol and has an advantage that high-speed data transfer is possible although data reliability is inferior to TCP.

FIG. 2 is a diagram showing a processing flow of a method for sharing a screen by transmitting only a UDP packet.
As an initial state, the server 1 is in a state in which a UDP port is opened and a connection from a client is awaited by a UDP socket.
The client 2 transmits using a UDP packet to make a screen sharing request to the server 1 (step S1). When the server that has received the packet permits sharing, it transmits a packet notifying permission to the client that requested sharing, and stores the network address (IP address) of the client that permitted sharing (steps S2 and S3). . As a result, screen data can be transmitted with a UDP packet to a client that has requested sharing, and an input event from the client is received to enable remote operation.

The client that has received the permission from the server 1 stores the network address of the server, and prepares to receive and display the screen data from the server (step S4).
That is, the UDP port is opened, and a communication packet from the server 1 is waited at the UDP socket.

Note that authentication may be performed instead of requesting / permitting by one-way UDP packet communication in steps S1 and S2.
Although not shown in the figure, the client and server may include communication for adjusting mutual settings for the size of the screen to be shared and the encoding method.

Next, when preparation is completed, initial screen data is transmitted by UDP from the server 1 to the client 2 (step S5a). Thereafter, every time the shared screen area of the server 1 is updated, the screen data is transmitted as a UDP packet (steps S5b, S5c, S5d).
When the client performs a remote operation, an input event is transmitted to the server by a UDP packet (step S6).

  When the screen sharing is to be terminated, a disconnection request is transmitted from the client to the server as a UDP packet (step S7). Upon receiving the disconnection request, the server transmits a disconnection confirmation to the client using a UDP packet and cancels the transmission / reception setting for the client (steps S8 and S9). On the other hand, the client that has received the disconnect OK cancels the transmission / reception setting to the server (step S10).

Here, in the case of the communication method shown in FIG. 2, the server and the client are unilaterally transmitting data to each other using a UDP packet, so that communication is performed when the other party ends the screen sharing application or a network error occurs. It is impossible to detect whether the packet is disabled or the disconnection OK packet has not arrived.
Therefore, the other party is monitored by the algorithm shown in FIG.

  When the connection is established, the server and the client transmit a confirmation packet for confirming the connection of the other party at a predetermined time, for example, every minute using a timer (steps S11 and S12).

On the other hand, a timer is used to monitor whether any packet from the other party has been received.
For example, confirmation is performed with a 2-minute timer.
The packet reception is confirmed (step S21). When data or a confirmation packet is received (step S22 / Yes), the timer is started (step S23). If any packet is received within 2 minutes (step S24 / Yes), the timer is restarted (step S23). If it is not received within 2 minutes (step S24 / No, S25 / Yes), it is determined that the other party has disconnected and the transmission / reception setting with the other party is canceled (step S26).

In this embodiment, since transmission is performed using a UDP packet, packets such as screen data and input events may be lost on the network, and the communication is not reflected on the transmission destination. Further, the packet transmission order at the transmission side may be different from the packet reception order at the transmission destination.
Therefore, according to the present invention, when a server and a client are connected on a network line with a large amount of data communication in a short-distance network such as a LAN, the shared screen is updated more frequently than the certainty of the screen data. It is preferable to use in such a case.

In FIG. 1, a desktop PC provided with a large screen display device or a workstation is used as the server 1. Further, although a rack top type PC (notebook PC) is used as the client 2, it is not necessarily limited to such a configuration.
That is, in the present invention, a server is a computer having screen data shared in a network, and therefore, a large-screen display device may not be provided, and a desktop PC may be used as a client.

  Further, specific examples of the network are not limited to Ethernet (registered trademark) wired LAN, but are wireless LAN, IrDA, Apple Talk, ISDN, telephone exchange network, digital leased line, FR network,... For example, the connection may be performed by a combination of these methods.

The second embodiment is a modification of the method described in the first embodiment.
FIG. 4 is a diagram showing a processing flow of a system that uses a TCP / IP connection for connection between a server and a client and uses a UDP packet for transmission of screen data and input events.
Both the server 1 and the client 2 prepare two sockets, TCP and UDP.
When connected by a TCP packet (steps S31, S32, S33), screen data and input events are transmitted / received using a UDP socket having the same network address (steps S34a-d, S35).
When a request for disconnecting the TCP connection is made and the TCP connection is disconnected, the UDP socket is also ended, and waiting for screen data and input events is ended (steps S36, S37, S38). Since TCP is a connection-type communication protocol, management of connection with the other party is left to connection management of the TCP connection, and it is not particularly necessary to implement a monitoring function on the application side (upper layer).

The third embodiment is an example in which UDP multicast or UDP broadcast is further applied to the method of the second embodiment, and the processing flow is shown in FIG.
Table 1 is an example of a network address in the network configuration.

<1. For broadcast>
The server 1 is waiting for an input event from (133. 139. 100. 111) and (133. 139. 100. 222) via a UDP socket. The screen data is broadcast by broadcast address (255. 255. 255. 255) within the same subnet. The packet is a UDP packet.
The clients 2a and 2b are waiting for a screen data broadcast from (133. 139. 100. 100). Also, an input event is transmitted to (133. 139. 100. 100) by UDP unicast.
The client receives the screen data broadcast from the server and shares the screen.

<2. For multicast>
When establishing a connection between the server and the client, the server 1 notifies all clients of the multicast address.
The server 1 sets a multicast range so that the multicast reaches the client. That is, the value of TTL (Time To Live) is appropriately set.

The server 1 is waiting for an input event from (133. 139. 100. 111) and (133. 139. 100. 222) via a UDP socket. In addition, the screen data is multicast transmitted by the multicast address (233.233.233.233). The packet is a UDP packet.
The clients 2a and 2b are waiting for screen data from the multicast address (233.233.233.233) designated by the server 1. Also, an input event is transmitted to (133. 139. 100. 100) by UDP unicast.

The fourth embodiment is an example of a method of switching between TCP and UDP according to the type of server application, and FIG. 6 is an example of a server screen display.
When the server 1 transmits screen data 11 of an application that is set to be transmitted in advance using a TCP packet, the server 1 transmits the screen data using a TCP packet, and other screen areas (such as the UTD shared application screen 12) use a UDP packet. To send.

For example, consider a case in which only the software, Wordproc, which is word processor software, and Matrixcalc, which is spreadsheet software, are transmitted as TCP applications using TCP packets, and the client side that is sharing the screen wants to display the screen reliably.
In the screen sharing server program, register the path of the executable file of the application that you want to send by TCP packet. For example,
C: \ Program Files \ Wordproc \ Wordproc.exe
C: \ Program Files \ Matrixcalc \ Matrixcalc.exe
Register.

FIG. 7 is a diagram showing an algorithm for a method of transmitting by either TCP or UDP for each application of the server.
When the display screen of the server 1 is updated, the screen sharing program divides and encodes the area by a certain algorithm. Whether or not the divided screen area is a window area of the registered application. Is determined (step S51).
If it is the window area of the registered application (step S52 / Yes), it is instructed to transmit the TCP packet after encoding (step S53). On the other hand, if it is an area other than that (step S52 / No), an instruction is given to transmit by a UDP packet (step S54).

FIG. 8 exemplifies a processing flow for a method of switching and transmitting a TCP packet and a UDP packet in such a case.
Similar to the processing flow shown in the second embodiment, connection management is performed using TCP / IP (steps S61 to S63 and S68 to S70), and screen data is switched between a TCP packet and a UDP packet as necessary. (Steps S64 to S66).

The fifth embodiment is an example of a method of switching between TCP and UDP depending on whether or not the server window is positioned in the foreground, and FIG. 9 is an example of a server screen display.
In FIG. 9, when the screen data of the foreground window 13 is transmitted, it is transmitted using a TCP packet, and the other screen areas (such as the rear window 14) are transmitted using a UDP packet.

FIG. 10 is a diagram showing an algorithm for a method of switching between TCP and UDP depending on whether or not the server window is positioned in the foreground.
When the display screen of the server 1 is updated, the screen sharing program divides and encodes the area by a certain algorithm. Here, whether or not the divided screen area is the window area at the forefront. Is determined (step S71).
If it is the window area in the forefront (step S72 / Yes), it is instructed to transmit by TCP packet after encoding (step S73). On the other hand, in the case of other areas (step S72 / No), an instruction is given to transmit by a UDP packet (step S74).

Example 6 is an example of a method of switching between TCP and UDP depending on whether or not a server window is active, and FIG. 11 is an example of a server screen display.
For example, when the desktop area is clicked with the mouse, the frontmost window is not necessarily the active window, but even if it is inactive, TCP packets may be sent if it is in the foreground. Alternatively, in the case of inactivity, it is possible to transmit a UDP packet even in the foreground.

  In FIG. 11, when the screen data of the active window 15 is transmitted, it is transmitted using a TCP packet, and other screen areas (inactive windows 16a, 16b, etc.) are transmitted using a UDP packet.

FIG. 12 is a diagram showing an algorithm for a method of switching between TCP and UDP depending on whether or not the server window is active.
When the display screen of the server 1 is updated, the screen sharing program divides and encodes the area according to a certain algorithm, and determines whether the divided screen area is an active window area. (Step S81).
If the divided screen area is an active window area (step S82 / Yes), it is instructed to transmit a TCP packet after encoding (step S83). On the other hand, in the case of other areas (step S82 / No), an instruction is given to transmit by a UDP packet (step S84).

The seventh embodiment is an example of a method of switching between TCP and UDP depending on whether or not the server window is a document designated by the user, and FIG. 13 is a screen display example of the server.
In FIG. 13, when the screen data of the user-specified document window 17 is transmitted, it is transmitted using a TCP packet, and other areas (such as the non-user-specified document window 18) are transmitted using a UDP packet.

FIG. 14 is a diagram showing an algorithm for a method of switching between TCP and UDP depending on whether or not the server window is a document designated by the user.
When the display screen of the server 1 is updated, the screen sharing program divides and encodes the area by a certain algorithm. Whether the divided screen area is the window area of the document specified by the user. Is determined (step S91).
If the divided screen area is an active window area (step S92 / Yes), it is instructed to transmit in a TCP packet after encoding (step S93). On the other hand, in the case of other areas (step S93 / No), an instruction to send by a UDP packet is issued (step S94).

For example, a window to be transmitted by TCP is managed for each document, and the document path is registered in the screen sharing program. For example,
c: \ My Documents \ Statistics \ 2003Jan.pdf
And register. Then, in the window of an application (for example, Acrobat Reader (registered trademark)) that opens the document, the screen data of the window area in which the document is opened is transmitted by a TCP packet.

As a modified example of the seventh embodiment, it is possible to specify in units of windows instead of for each document.
For example,
c: \ My Documents \ Statistics \ 2003Jan.pdf
Specify the Acrobat Reader (registered trademark) window that opens the document. For example, in the screen sharing program, a function is provided to select a window for transmitting a screen using a TCP packet. When this function is executed, the window that is clicked with the mouse for the first time after execution is registered to transmit screen data using a TCP packet. Let the function end.

Example 8 is an example of a method of switching between TCP and UDP depending on whether or not the server window is a screen area designated by the user, and FIG. 15 is an example of a server screen display.
As shown in FIG. 15, when transmitting the screen data of the user designation area 19, it transmits using a TCP packet, and transmits the other area | region using a UDP packet.

FIG. 16 is a diagram showing an algorithm for a method of switching between TCP and UDP depending on whether or not the server window is a screen area designated by the user.
When the display screen of the server 1 is updated, the screen sharing program divides and encodes the area by a certain algorithm. Whether or not the divided screen area is the screen area specified by the user. Is determined (step S101).
If the screen area is specified by the user (step S102 / Yes), an instruction is given to transmit the packet as a TCP packet after encoding (step S103). On the other hand, in the case of other areas (step S102 / No), an instruction is given to transmit by a UDP packet (step S104).

A modification of the eighth embodiment is shown below.
In the screen sharing program, a function to select the screen area to send the screen by TCP packet is provided, and when this function is executed, the first window clicked with the mouse after execution is set as the upper left vertex, and the mouse is clicked and moved. A rectangular area having the position where the mouse click is released as a lower right vertex is registered so as to transmit screen data using a TCP packet, and the registration function is terminated. Acquire and register the first clicked coordinates and the last released coordinates. For example, when clicking is started at (100, 200), dragging to (400, 700) and the mouse is released, a rectangular area having these two points on the diagonal line as two vertices is set as the TCP transmission area.

  In the fourth to eighth embodiments, transmission using a TCP packet can be performed with priority over transmission using a UDP packet. This makes it possible to display the necessary screen data on the client screen quickly and reliably.

In the ninth embodiment, a means for the user to switch between the TCP packet and the UDP packet when transmitting screen data will be described.
FIG. 17 is a diagram exemplifying a screen for instructing switching of a communication protocol, and a function for instructing switching and selecting TCP / UDP is provided in the screen sharing program of the server.

FIG. 18 is a diagram showing a flow of the switching operation of the communication protocol.
As described above, in the initial default setting, it is assumed that the screen data is set to be transmitted by the TCP packet to the client that has established the TCP connection (step S111). If the communication means switching function of the screen sharing program as shown in FIG. 17 instructs to transmit the UDP packet (step S112 / Yes), the screen data is transmitted by the UDP packet (step S113). Conversely, it is also possible to return to a TCP packet (steps S114 / Yes, S111).
For example, when a video image is played on a server, or when a slide show of a presentation with a lot of animation effects is performed, the amount of screen data transmission increases, and the UDP packet is used when speed is required rather than certainty. Switch to the transmission mode with. On the other hand, when sharing only character data, it is troublesome if it is not displayed reliably, so switching to use TCP packets.

  Further, as a modification of the ninth embodiment, switching from TCP to UDP may be requested from the client side instead of switching from the server side program.

In the tenth embodiment, a means for selecting whether to use a TCP packet or a UDP packet for each user will be described.
FIG. 19 is a diagram illustrating a screen for instructing communication protocol switching for each user, and it is possible to select whether to use TCP or UDP for each client.
The screen sharing server has a function of changing the setting for each client using an IP address or a host name of the client or an arbitrary identification name (for example, a user name) exchanged by the screen sharing program. It has a function of managing and displaying whether the screen data is transmitted to the currently connected client using TCP or UDP, and changing the setting.

In FIG. 19, “Ai Ueio” and “Seisuke Suzue” who are checked are set as clients to send by TCP, and “Kukako Tsuji” that is not checked is UDP. It is set as a sending client.
Further, as shown in FIG. 19, it is possible to send all members in a TCP packet by pressing the “all TCP” button, or to send all members in a UDP packet by pressing the “all UDP” button. In the case where there are many clients participating in the network, such a means is also effective.

The eleventh embodiment is an example of a method of switching between TCP and UDP according to the number of connected clients, and FIG. 20 is a diagram showing the algorithm.
The screen sharing program of the server 1 monitors the number of connected clients on the network (step S121).
When it is detected that the number of connected devices exceeds the predetermined number (step S122 / Yes), the communication method used for transmitting the screen data is switched from TCP to UDP (step S124). As a result, when the number of clients is large, it is possible to reduce the occurrence of a delay in the screen display of each client due to an increase in communication amount.
Further, when performing communication by UDP, if the number of clients connected to the network is equal to or less than the predetermined number (step S122 / No), the communication method is switched from UDP to TCP (step S123). ). When the number of connected devices is small and the amount of data communication on the network is small, communication is performed by TCP with high reliability.

  Further, as a modification of the eleventh embodiment, when the number of connected devices exceeds a predetermined number, the dialog shown in FIG. 19 may be displayed, and a client to be switched to UDP may be designated, or all clients may be switched to UDP. May be.

The twelfth embodiment is an example of a method of switching between TCP and UDP by using a communication interface of a client, and FIG. 21 is a diagram showing the algorithm.
The screen sharing program on the server 1 has a function of acquiring whether the client is connected to the network via a wired LAN or via a wireless LAN.
The client can acquire information related to its own communication interface from the system information of the OS. The client screen sharing program transmits this communication interface information when connecting to the server 1.
On the other hand, the server 1 determines from the communication interface information sent from the client whether or not it is a wireless LAN. For example, in the case of an interface name or a wireless LAN, it is determined from information such as which standard of IEEE 802.11.

  As shown in FIG. 21, when the connection from the client is accepted, the communication interface information of the client is acquired, and it is determined whether it is a wired LAN or a wireless LAN (step S131). In the case of a wired LAN (step S132 / No), the screen data is set to be transmitted by a UDP packet (step S134). On the other hand, in the case of a wireless LAN (step S132 / Yes), the screen data is transmitted by a TCP packet. (Step S133).

Further, as a modification of the twelfth embodiment, when the server 1 is communicating with the wireless LAN interface, the screen data may be transmitted with the default setting using a TCP packet.
The target of the interface set to transmit by TCP may include not only a wireless LAN but also IrDA and Bluetooth (registered trademark).

As another modification, the screen sharing program of the server 1 and the client is provided with a function for exchanging information about the communication interface between the server 1 and the client, and this information is exchanged when the connection between the server 1 and the client is established. Also good.
When it is determined that the client is using the wireless interface, the screen data is set to be transmitted using a TCP packet as in the above example. When it is determined that the client is a wired LAN, the UDP packet is used.

The thirteenth embodiment is an example of a method of switching between TCP and UDP according to the connection path of the client, and FIG. 22 is a diagram showing the algorithm.
The screen sharing program on the server 1 has a function of acquiring whether the client is connected via a LAN or via a WAN.

There are the following methods for determining whether the client is a LAN connection or a WAN connection.
(Method 1)
The client can acquire information related to its own communication interface from the system information of the OS. The client screen sharing program transmits this communication interface information when connecting to the server 1.
On the other hand, the server 1 makes a first determination from information on the communication interface sent from the client. If the interface is a modem, it is determined that the connection is made by WAN.

(Method 2)
The network information of the server 1 itself is collated with the client IP address, and if the client IP address is a global IP, it is determined that the client is connected from the WAN.

(Method 3)
The client uses the traceroute command, which is one of the network commands, to inquire routing information. Therefore, when it is confirmed that the client is outside the LAN, it is determined that the client is connected from the WAN.

  As shown in FIG. 22, when a connection from a client is accepted, it is determined whether the client is a LAN connection or a WAN connection (step S141). When the client is a LAN connection (step S142 / No), screen data is displayed using a UDP packet. The transmission is set (step S144). On the other hand, in the case of WAN (step S142 / Yes), the screen data is set to be transmitted by a TCP packet (step S143).

Example 14 is an example of a method of switching between TCP and UDP according to the remaining amount of encoded data to be transmitted, and FIG. 23 is a diagram showing the algorithm.
The screen sharing program on the server 1 has means for measuring the amount of data necessary to encode and transmit the update area when the screen is updated. This amount is obtained from the portion of the screen sharing program that encodes the update area (step S151).

If the remaining amount of encoded data to be transmitted at a certain time is greater than a certain level, it is transmitted by a UDP packet. For example, it is set when the remaining amount exceeds 500 kilobytes.
As shown in FIG. 23, when the update amount exceeds a predetermined threshold (step S152 / Yes), the screen data is transmitted with priority given to the speed in the UDP packet (step S153), and otherwise (step S152). / No) is transmitted while confirming reception of the client by a TCP packet (step S154).
In addition, when UDP communication is performed, if the remaining amount becomes smaller than the threshold value, transmission is automatically returned to the TCP packet.

  As a modification of the fourteenth embodiment, the determination may be made based only on the amount of bitmap data that needs to be updated before encoding. For example, it is set when the remaining amount exceeds 1 megabyte.

The fifteenth embodiment is an example of a method of switching between TCP and UDP according to the transmission data rate, and FIG. 24 is a diagram showing the algorithm.
The screen sharing program on the server 1 has means for measuring the data transmission rate (the amount of transmission data per unit time) transmitted per unit time when the screen is updated. For example, it is acquired from the transmission bit rate of the OS system information (step S161).

When the data rate is smaller than the predetermined threshold value (step S162 / Yes), the screen data is transmitted with priority given to the speed by the UDP packet (step S163). Otherwise (step S162 / No), the TCP packet is transmitted. Then, transmission is performed while confirming reception of the client (step S164).
In addition, when the UDP communication is performed, when the data rate becomes larger than the threshold value, the transmission is automatically returned to the TCP packet.

The sixteenth embodiment is an example of a method of switching between TCP and UDP according to the communication speed between the server and the client, and FIG. 25 is a diagram showing the algorithm.
The screen sharing program activated on the server 1 and the client measures the communication speed between the server 1 and the client when the client connects to the server 1.
A conventional measurement method can be used as a method for measuring the communication speed between the server 1 and the client. For example, there is a method of measuring a required time by transmitting several megabytes of data, as is done in a website on the Internet.

As shown in FIG. 25, when the connection from the client is accepted, the server 1 measures the communication speed between the server 1 and the client (step S171), and the communication speed is equal to or higher than a predetermined value (step S172 / Yes) sets the screen data to be transmitted with a TCP packet (step S173), and if it is less than the predetermined value (step S172 / No), the screen data is set to be transmitted with a UDP packet (step S174).
Here, the reference value of this determination can be set to, for example, 1 megabyte / second (Mbps).

Example 17 is an example of a method of switching between TCP and UDP by MTU between a server and a client, and FIG. 26 is a diagram showing the algorithm.
The screen sharing program activated on the server 1 has means for measuring the MTU between the server 1 and the client when the client connects to the server 1.
A conventional measurement method can be used as a method of measuring the MTU between the server and the client. For example, there is a method of checking the maximum data capacity without fragmentation using a ping command which is one of network commands.
The principle is shown below.

ping -f -l <packet size><[destination host name] or [destination IP address]>
However,
-f ... Option to prohibit packet fragmentation
-l ... Option to specify the packet size

  By transmitting the ping command as described above, it is possible to confirm to the client how many bytes of packets are transmitted without being divided.

As shown in FIG. 26, when the connection from the client is accepted, the server 1 measures the MTU between the server and the client (step S181), and when the MTU is equal to or greater than a predetermined value (step S182 / Yes). The screen data is set to be transmitted by the TCP packet (step S183). If the screen data is less than the predetermined value (step S182 / No), the screen data is set to be transmitted by the UDP packet (step S184).
Here, the reference value for this determination can be, for example, 1 megabyte.

  In the above algorithm, when the MTU is small, the data capacity that can be transmitted in one packet is small. Therefore, if a TCP ACK response is made, the communication efficiency deteriorates.

The eighteenth embodiment is an example of a method of switching between TCP and UDP by QoS between the server and the client, and FIG. 27 is a diagram showing the algorithm.
The screen sharing program activated on the server 1 measures the QoS when the client connects to the server 1, and the bandwidth, the minimum guaranteed speed, the maximum delay time, the packet interval, the peak speed, the network delay and jitter, and the packet loss. Etc., and a means for evaluating communication quality.

As shown in FIG. 27, when the connection from the client is accepted, the server 1 measures the QoS between the server and the client (step S191), and the communication quality satisfies a certain standard (step S192 / Yes) is set to transmit screen data using a UDP packet (step S194). If it is determined that the screen data is not satisfied (step S192 / No), it is set to transmit screen data using a TCP packet (step S193). .
However, it is not always necessary to measure all parameters.

The nineteenth embodiment is an example of a method for switching between TCP and UDP according to the priority order of the client, and FIG. 28 is a diagram showing the algorithm.
The screen sharing program activated on the server 1 has a function of assigning priorities to clients in a screen sharing system in which a plurality of clients can connect and share screens simultaneously.
For example, when the screen of the server 1 is updated, first, the screen data is surely transmitted to the client given priority by a TCP packet (steps S201, S202 / Yes, S203), and the client without priority Then, the screen data is transmitted without confirmation of reception with a UDP packet (steps S201, S202 / No, S204).

In the twentieth embodiment, a method for registering a priority right and a control right for remote control on a shared screen in association with each other is described.
As shown in Fig. 29, only clients that have control rights (client "Ai Kazuo (192. 168. 0. 2)") can remotely control and have control rights. In this case, the screen data is transmitted by the TCP packet before the client that does not own it. On the other hand, the client without the control right only browses the shared screen, and the input event is not accepted by the server. In addition, after the screen data is transmitted to the client without the control right, the screen data is received with a UDP packet without confirmation of reception.

Embodiment 21 relates to a method for increasing the screen data transmission priority for a remotely operated client in a screen sharing system in which a plurality of clients can connect, share a screen at the same time, and can be operated remotely. Explains.
The server 1 has a function of determining whether the client is operating remotely.
As shown in FIG. 30, when the client performs a remote operation, the server 1 turns on the remote operation flag of the client (step S211). Therefore, a timer is started (step S212), and it is determined whether or not the client is operating based on whether or not the client has performed an operation within a certain time, for example, within one minute. For example, if there is no input event within 1 minute, the server 1 determines that the client is not performing remote operation (S213 / No, S214 / Yes), and turns off the remote operation flag (step S215). ).

When the screen data is updated, as shown in FIG. 31, the server 1 checks ON / OFF of the remote operation flag (step S221), and the client with the flag ON is more than the client with OFF. First, screen data is transmitted by a TCP packet (step S222). On the other hand, for the flag-OFF client, after the screen data is transmitted to the ON client, the screen data is transmitted without confirmation of reception using a UDP packet (step S223).
This makes it possible to give priority to quality and speed to the person performing the operation and transmit the screen data so as not to feel inconvenience in the remote operation.

  As a modified example of the twenty-first embodiment, for example, as in the twentieth embodiment, it is possible to combine management of control rights. In this case, the screen data is always transmitted as a UDP packet to a client without a control right and without a control right.

The twenty-second embodiment is an example of a method of switching between TCP and UDP depending on whether the shared screen data is font data or image data, and FIG. 32 is a diagram showing the algorithm.
When the screen has been updated, first, the image data of the part where the characters are displayed is reliably transmitted by the TCP packet, and then the image data of the other area is transmitted by the UDP packet. Make the part of the text easier to read.

When the shared screen is updated, the screen sharing program activated on the server 1 divides the update area, encodes it, and transmits the screen data to the client. Here, the OS is placed in the divided screen area. It is determined whether or not the font drawing command has been issued (step S231). If it is the area from which the font drawing command has been issued (step S232 / Yes), screen data is transmitted using a TCP packet (step S233). On the other hand, for the portion where the font drawing command is not issued (step S232 / No), the screen data is transmitted by the UDP packet (step S234). As a transmission order, it is desirable to transmit the font drawing portion first.
As a method for detecting a font drawing command, for example, there is a method in which a screen sharing program started on the server 1 checks a GDI (Graphic Device Interface) command in a divided area and executes it depending on whether or not a font drawing command is issued.

Example 23 is an example of a method of switching between TCP and UDP according to the load status of the CPU, and FIG. 33 is a diagram showing the algorithm.
The screen sharing program on the server 1 has means for measuring the load amount of the CPU when the screen is updated. For example, it is acquired from the CPU load information of the OS system information.

As shown in FIG. 33, the CPU load is measured (step S241), and if the CPU load exceeds a predetermined threshold (Yes in step S242), the screen data is prioritized for speed with a UDP packet. Transmit (step S244), otherwise (step S242 / No), the TCP packet is transmitted while confirming reception of the client (step S243). When the load amount of the CPU becomes smaller than the threshold value, the transmission is automatically returned to the TCP packet.
As the threshold setting, for example, when the CPU load exceeds 80% for 1 second or more, switching to a UDP packet is performed.

  When the load on the CPU is large, the amount of screen update is large, so it often takes time to encode the screen data of the updated portion. In addition, when the CPU load is large, the encoding process of the screen data in the update portion is slowed down, so it is necessary to reduce the CPU load in the communication processing portion, that is, increase the communication speed. Therefore, by switching from the TCP packet to the UDP packet, it is possible to reduce the CPU load and delay the screen display of the client.

Further, a high-speed screen sharing system can be realized by appropriately combining the above first to third embodiments. For example, for browsing-only clients that do not have control rights, screen data is sent unconditionally by UDP multicast, and broadcast data is transmitted. For clients with control rights, the active window in the foreground is The character drawing part of the data is preferentially transmitted by the TCP packet, and the other part is transmitted by the UDP packet.
Alternatively, screen data is unconditionally transmitted to the client connected via the wired LAN using a UDP packet, and only the designated application is prioritized using the TCP packet for a client connected via the wireless LAN. It is possible to combine such as transmitting to the other part and transmitting the other part by UDP packet.

In Examples 24 to 27, a case where a relay device (proxy) is provided in the network will be described.
FIG. 34 is a schematic diagram showing a network configuration of a data communication system according to an embodiment of the present invention.
The data communication system includes an information processing device (server 1) that functions as a server, an information processing device (clients 2a, 2b,..., 2n) that functions as a client of the server 1, and a server 1 and a client 2. The relay device 3 is included in between. The server 1, the client 2, and the repeater 3 are, for example, personal computers, which are connected via a network based on an Ethernet (registered trademark) LAN defined by, for example, IEEE 802.3.

The server 1 receives the entire desktop screen displayed on its display device or a part of the screen displayed on the screen as a shared screen and transmits the shared screen data to the connected client 2. The client can display the shared screen of the server 1 on the display device.
In this example, there is a relay device (hereinafter abbreviated as a proxy) between the server 1 and the client 2, receives the screen data received from the server 1, and transfers the screen data to the client connected to the proxy. To do. As a result, when a large number of clients are connected to the server 1, it is possible to reduce the load on the server and improve the communication efficiency.

  Similarly to the case of the first embodiment, by transmitting an event from an input device such as a mouse or a keyboard of the client to the server 1 in the shared screen displayed on the client 2, the client can remotely communicate with the server. Although operation is also possible, this may also be performed through a proxy, and a communication method may be employed in which an input event is transmitted directly to a server without passing through a proxy.

The principle will be described below.
Since the screen sharing method using the proxy can use conventional techniques such as Multicast VNC, VNC Proxy, and VNC Reflector as they are, details are omitted. As an outline, the server application detects an update portion of the server screen data, divides the screen update area by a certain algorithm, encodes it, and transmits it to the proxy. The proxy is activated as a kind of screen sharing client. The proxy also has a function as a server that forwards the received screen data to the connected client, and the received client decodes the screen data of the updated area and updates the data of the shared screen. Thus, the server screen can be displayed.

A processing flow of a method for sharing a screen via a proxy will be described with reference to FIG.
It is assumed that connection management between the server 1 and the proxy 3 and connection management between the proxy 3 and the client 2 are performed by TCP connection management as in the second embodiment. That is, the proxy 3 makes a TCP connection request to the server 1 (step S301), the server 1 responds, and a TCP connection between the server and the proxy is established (steps S302 and S303). Further, the client 2 makes a TCP connection request to the proxy 3 (step S304), and the proxy 3 responds to establish a TCP connection between the client and the proxy (steps S305 and S306).
When the proxy 3 receives screen data from the server 1 while confirming reception using a TCP packet (steps S307 and S308), the proxy 3 transmits the screen data to the client connected to the screen data using a UDP packet (step S309). .

As an example of a change in the processing flow of FIG. 35, for example, the proxy 3 may transfer screen data received from the server 1 using a UDP packet to the client 2 using a UDP packet.
Further, for example, screen data received from the server 1 using a UDP packet may be transferred to the client 2 using a TCP packet.
Alternatively, there is a method of transferring screen data received from the server 1 using a TCP packet to the client 2 using a TCP packet.

  As an example of a change in the configuration shown in FIG. 34, for example, as shown in FIG. 36, the client 2 does not necessarily need to receive screen data from the server 1 through the proxy 3, but is directly connected to the server 1. 2a, 2b,..., 2i and clients 2j,..., 2n connected via a proxy may be mixed. In this case, it is possible to improve the communication efficiency by connecting directly to the server 1 only with a client having priority to perform remote operation, and connecting the client that only browses the shared screen via the proxy 3. .

  The twenty-fifth embodiment is an example in which UDP multicast or UDP broadcast is applied at the proxy, and FIG. 37 shows the processing flow. Table 2 is an example of a network address in the network configuration.

<1. For broadcast>
The server 1 is waiting for input events from (133. 139. 100. 111) and (133. 139. 100. 222) through a UDP socket. The screen data is broadcast by broadcast address (255. 255. 255. 255) within the same subnet.
The clients 2j and 2n are waiting for a screen data broadcast from (133. 139. 100. 100). Also, an input event is transmitted to (133. 139. 100. 100) by UDP unicast.
The server 1 has a TCP connection with the proxy 3 and transmits screen data to the address of the proxy 3 (133. 139. 100.55) as a TCP packet. On the other hand, the TCP socket is waiting for input data from the proxy 3.
The proxy 3 is a TCP socket and is waiting for screen data from the address of the server 1 (133. 139. 100. 100).

When the proxy 3 receives the screen data from the server 1, the proxy 3 broadcasts the received screen data to the same subnet with a broadcast address (255.255.255.255). The packet is a UDP packet.
The proxy 3 is a UDP socket and is waiting for input events from the client addresses (133. 139. 100. 111) and (133. 139. 100. 222).
When the proxy 3 receives an input event from the client, the proxy 3 transfers the input event to the server 1 using a TCP packet.
The clients 2j and 2n are waiting for a screen data broadcast from (133. 139. 100.55). Also, the input event is transmitted to (133. 139. 100. 55) by UDP unicast.
The client receives screen data broadcast from the proxy 3 and performs screen sharing.

<2. For multicast>
When the connection between the proxy 3 and the client 2 is established, the server 1 notifies all clients of the multicast address.
The proxy 3 sets the multicast range so that the multicast reaches the client. That is, the value of TTL (Time To Live) is set appropriately.
The server 1 has a TCP connection with the proxy 3 and transmits screen data to the address of the proxy 3 (133. 139. 100.55) as a TCP packet. On the other hand, the TCP socket is waiting for input data from the proxy 3.

The proxy 3 is a TCP socket and is waiting for screen data from the address of the server 1 (133. 139. 100. 100).
When the proxy 3 receives the screen data from the server 1, the proxy 3 multicasts the received screen data using the multicast cast address (233.233.233.233). The packet is a UDP packet.
The proxy 3 is a UDP socket and is waiting for input events from the client addresses (133. 139. 100. 111) and (133. 139. 100. 222).
When the proxy 3 receives an input event from the client, the proxy 3 transfers the input event to the server 1 using a TCP packet.

  The clients 2j and 2n are waiting for screen data from the multicast cast address (233.233.233.233) designated by the proxy. Also, an input event is transmitted to (133. 139. 100. 100) by UDP unicast.

In the twenty-sixth embodiment, a session recording and reproduction function in the proxy will be described.
The proxy 3 sequentially adds and accumulates the screen data received from the server 1 to the file together with the time information in the order in which the server 1 has transmitted the TCP packet. For example, the time recording uses the recording start time as the origin.
When the client 2 connects to the proxy 3 and requests the reproduction of the recorded screen data of the server 1, the proxy 3 sequentially transmits the recorded screen data to the client according to the instruction of the elapsed time from the recording start time. Send with.
FIG. 38 shows such a state. After the connection between the server 1 and the proxy 3 is completed, the client 2 can connect to the proxy 3 to view the screen sharing state asynchronously. Note that during playback, the client 2 can only browse, and the proxy 3 does not accept input events from the client 2.

  In addition, while the proxy 3 is recording screen data from the server 1, the client 2 can connect to the proxy 3, and it is possible to view the screen data after the proxy 3 and the server 1 start connection with a time difference. is there.

Further, as a modification of the twenty-sixth embodiment, a screen data recorded in the proxy may be played back at a fast forward speed.
When the proxy 3 transmits screen data to the client 2 based on the recording time data, it is possible to shorten the transmission interval by setting the elapsed time to, for example, half of the recorded value.

In Examples 27 and 28, an electronic conference system to which the data communication system described in Examples 1 to 26 is applied will be described.
For example, in the network configuration shown in FIG. 1, an electronic conference system is constructed in which the server 1 is a conference server and the client 2 is a participant terminal used by a participant.
The conference server has a screen data transmission function using the UDP multicast of the screen sharing server 1 as described in the third embodiment.
The conference server sets the TTL so that the multicast packet reaches only the network in the conference room.
The conference server manages the control right, and basically transmits screen data to the participant terminals that do not have the control right by multicast UDP.
On the other hand, when sending screen data to a participant terminal that has the control right, the screen data in the character area of the active window in the foreground is preferentially used by the TCP terminal in the participant terminal having the control right. Send for quick and accurate display. Data other than the character area is transmitted in a UDP packet with a lower priority in the transmission order.

Also, for example, in the device configuration of FIG. 36, the server 1 is a conference server, the client 2 is a participant terminal used by a participant, the relay device (proxy) 3 is capable of recording / reproducing screen data, and multicast. A conference system is configured as a conference proxy capable of transferring screen data using a UDP packet.
The conference server sets the TTL so that the multicast packet reaches the directly connected participant terminal. The conference proxy sets TTL so that multicast packets reach the participant terminals connected to the proxy.

  As shown in FIG. 36, some participant terminals (2a, 2b,..., 2i) exist in the conference room, are directly connected to the conference server, and receive multicast UDP packets directly from the conference server. On the other hand, some other participant terminals (2j,..., 2n) are in other conference rooms, are connected via a conference proxy, and receive multicast UDP packets from the conference proxy.

By managing the communication in this way, the communication efficiency of the network is improved, and the screen can be shared smoothly when used for a remote conference.
Participants who want to join the conference from the middle connect to the proxy and play the screen data of the shared screen from the beginning of the conference, skipping unnecessary parts as appropriate, or fast-forward playback, If you want to follow the contents and share the screen of the conference server in real time, you can join the conference while switching the connection to the conference server and watching the synchronized shared screen or performing remote operation.

(effect)
As is clear from the above description, not only communication by a TCP packet that is a data stream type communication method that needs to return an ACK packet in response to the normal reception of the packet to the transmission packet, High-speed screen sharing that uses UDP packets, which are datagram-type communication methods that do not guarantee the reliability or the reception order of packets, because it does not require an ACK reply, but is fast. Communication between the screen sharing server and the screen sharing client can be performed.

  Also, a network that transmits screen data of a screen sharing server to a plurality of clients at a high speed by transmitting screen data to a plurality of clients at once by a broadcast packet using a UDP multicast or UDP broadcast packet. Highly efficient communication is possible.

In addition, by selecting the packet type dynamically manually or automatically, the screen data can be communicated with the packet type suitable for the case, so that the efficiency of the communication speed can be improved.
It is also possible to alleviate the sensory dissatisfaction caused by the time lag with the server, which is felt when the client user shares the screen data of the server by screen sharing.
Also, use TCP packets by sending screen data using UDP packets to less important screen data or clients in a good network client environment that need not be sent reliably using TCP. It is possible to relatively increase the transfer rate of screen data that needs to be reliably transmitted by a client user who needs it or by using a TCP packet.

In addition, when the screen area of the application is updated for each application in advance, the function of specifying whether to transmit the screen data as a TCP packet or a UDP packet is used to change the type of the screen data transmission packet. By selectively selecting and sharing the screen, the shared screen data displayed on the client can be adapted to the characteristics of the application.
In addition, it is possible to relatively increase the screen data transfer rate of an application registered to be transmitted using a TCP packet.
In addition, screen data of applications that prioritize the screen update speed over the certainty of TCP packets, such as video data playback applications, can be transmitted using UDP packets to reduce screen sharing frame drops on the client screen. It becomes.

  In addition, by sending the application window on the foreground with a TCP packet and sending the other window or desktop area on the other side with a UDP packet, important data is often displayed at that time. It is possible to improve the communication efficiency by transmitting the data of the window reliably, and transmitting the less important data of the other window area or desktop area by giving priority only to the speed rather than the certainty. Become. In addition, it is possible to relatively increase the screen data transfer rate of the frontmost window registered to be transmitted by TCP packets.

  Active window data is often displayed as important data at that time by sending active application windows using TCP packets and sending other inactive windows or desktop areas using UDP packets. It is possible to improve the communication efficiency by transmitting the non-critical data in the inactive window area or the desktop area other than that in the non-active window area or the desktop area by giving priority only to the speed over the certainty. In addition, it is possible to relatively increase the transfer rate of the screen data of the active window registered to be transmitted by the TCP packet.

In addition, when the screen area of the application that displays the document is updated in units of documents displayed by the application on the screen sharing server, the function of designating whether to transmit the screen data using a TCP packet or a UDP packet Thus, by dynamically selecting a screen data transmission packet type and performing screen sharing, the shared screen data displayed on the client can be adapted to the characteristics of the application.
Further, it is possible to select whether priority is given to certainty or priority is given to the communication speed depending on the importance of the document, and communication efficiency can be improved.
In addition, it is possible to relatively increase the screen data transfer speed of an application window that opens a document registered to be transmitted using a TCP packet.

  In addition, the screen sharing server has a function to specify whether screen data of a certain screen area in the desktop area is to be transmitted by TCP packet or UDP packet. It is possible to improve the communication efficiency by transmitting the screen data in the screen area in which the screen data giving priority to the speed is transmitted using the UDP packet. In addition, it is possible to relatively increase the transfer rate of screen data in an area registered to be transmitted by a TCP packet.

  In addition, by having a means for switching screen data to be transmitted in TCP packets or UDP packets in accordance with user instructions, it is possible to transmit screen data currently shared by users in different packet types. By making it possible to switch by packet type when it is determined that communication is better, it is possible to provide a communication method capable of performing screen data transmission suitable for the situation.

  In addition, when the number of clients connected to the screen sharing server is smaller than a certain number, the screen data is transmitted with a TCP packet, and when the number is larger than a certain number, the screen data is transmitted with a UDP packet. By having a function of automatically switching, it is possible to provide a communication method for performing screen sharing with high communication efficiency.

In addition, for clients using wireless communication means with many communication errors and poor communication quality, the screen data is automatically transmitted by TCP packets, thereby ensuring the certainty of the data, It is possible to give priority to speed and communication efficiency by selecting to send screen data with UDP packets to clients communicating with the server using only wired communication means with relatively low communication quality and communication quality. Become.
In addition, by sending screen data using a UDP packet to a client connected via a wired LAN, a screen for a client connected via a wireless LAN registered to send a TCP packet. It becomes possible to relatively increase the data transfer rate.

  In addition, select UDP for clients connected via LAN, and select TCP for clients connected from a network outside the LAN by WAN, and a communication method for screen sharing suitable for the network environment. Communication that is automatically selected can be performed. In addition, by transmitting screen data using UDP packets to clients connected via LAN, screen data can be transferred to clients connected via WANs registered for transmission using TCP packets. The speed can be relatively increased.

  In the screen sharing server, when the screen update data remaining amount to be transmitted or the screen data transmission rate is higher than a certain value, it is automatically switched so that it is transmitted with a UDP packet, and when it is small, it is reliably transmitted with a TCP packet. Accordingly, it is possible to provide a communication method in a screen sharing system with less stress on the client user.

  In addition, when the communication speed between the server and the client is slower than a certain value, the packet is transmitted by a UDP packet. When the communication speed is high, the TCP / IP packet is automatically switched so as to be surely transmitted. Communication in a screen sharing system with less user stress can be performed. In addition, by transmitting screen data using a UDP packet to a client having a high communication speed, the transfer speed of the screen data to a client having a low communication speed registered to transmit using a TCP packet is relatively set. It can be made faster.

  In addition, the screen sharing server measures the MTU of the network with the client, and when the MTU is smaller than a certain value, it is transmitted by a UDP packet, and when it is larger, it is automatically switched so as to be surely transmitted by a TCP packet. Depending on the network environment, it is possible to perform communication in a screen sharing system with less stress on client users.

  In addition, the screen sharing server measures the QoS with the client, and when the QoS is larger than a certain value, it is transmitted by a UDP packet, and when it is smaller, it is automatically switched so as to be surely transmitted by a TCP packet. Depending on the network environment, it is possible to perform a communication method in a screen sharing system with less stress on the client user. In addition, by sending screen data using UDP packets to clients with good communication quality, the transfer rate of screen data to clients with poor communication quality registered to send with TCP packets is relatively set. It can be made faster.

  In addition, by having a function to switch the type of packet used for screen data transmission between TCP and UDP according to the priority of the client, the screen data is reliably transmitted by TCP packet to clients with high priority. It is possible to improve communication efficiency by transmitting screen data with a UDP packet to a client having a low priority. In addition, by transmitting screen data using a UDP packet to a low-priority client, the transfer rate of the screen data to a high-priority client registered to be transmitted using a TCP packet is relatively set. It can be made faster.

  In addition, it is determined whether or not the remote operation from the client is in progress, and the type of packet used for transmission of the screen data is switched between TCP and UDP. It is possible to improve the communication efficiency by transmitting the screen data with a UDP packet to a client that reliably transmits the screen data and is not performing a remote operation. In addition, by transmitting screen data using a UDP packet to a client not performing remote operation, the screen data transfer rate to the client performing remote operation instructed to transmit using TCP packet Can be made relatively fast.

  Also, certainty is required by determining whether the OS is an area where a font rendering command is being issued or not, and switching the packet type used for screen data transmission between TCP and UDP. The screen data in the character area is transmitted with a TCP packet, and the screen data in the other area is transmitted with a UDP packet, so that the character part is reliably transmitted by the client and the communication speed is improved, and the character part is relatively It is possible to improve the screen data transfer speed. In addition, by transmitting screen data using an UDP packet to an area where data other than characters is drawn, the transfer speed of the screen data of the character area registered to be transmitted using a TCP packet is relatively high. It becomes possible to do.

  Also, according to the CPU load of the screen sharing server, by switching the type of packet used for screen data transmission between TCP and UDP, if the server has a large amount of processing, screen update data is generated by that processing, Considering that transmission processing is delayed, it is possible to prevent a decrease in the transmission speed of screen data when the load amount of the server is large by transmitting the screen data with a UDP packet.

  In addition, a relay information device is interposed between the screen sharing server and the client, and converts a screen data received as a TCP packet from the screen sharing server into a UDP packet, and sends it to the client. It is possible to reduce the load on the server that occurs when connected directly to the server. Further, by having a function of transmitting with a UDP packet, it is possible to improve the transfer rate of screen data.

  In addition, when multiple clients are connected to a relay information device by broadcast communication using UDP multicast or UDP broadcast, the screen data received by the TCP packet from the screen sharing server is displayed. It is possible to prevent a decrease in transfer speed.

  Furthermore, by recording the received screen sharing data, it becomes possible to view the screen of the server asynchronously. Further, by transmitting the recorded screen data using a UDP packet, it is possible to improve communication efficiency and realize high-speed screen reproduction that does not make the browsing client feel unnatural. Furthermore, it is possible to prevent a decrease in the screen reproduction speed due to an increase in the number of clients for a plurality of clients by broadcast communication using multicast or broadcast.

  In addition, it is not necessary to send back an ACK in response to a TCP packet that is a data stream type communication method that needs to send back an ACK packet that responds to the normal reception of the packet. Therefore, it is possible to perform high-speed screen sharing by transmitting screen data using a UDP packet, which is a datagram-type communication method that does not guarantee the reliability or the reception order of packets. A conference system can be provided.

  In addition, a relay device (proxy) is interposed between the screen sharing server and the client, converts the screen data received from the screen sharing server as a TCP packet into a UDP packet, and sends it to the client. It is possible to provide an electronic conference system that can reduce the load on the server that occurs when the server directly connects to the server.

It is the schematic which showed the network structure of the data communication system which is one Example of this invention. It is the figure which illustrated the processing flow of the system which performs screen sharing by transmitting only a UDP packet. It is the figure which showed the algorithm of the monitoring of a connection state in the screen sharing by UDP. It is the figure which illustrated the processing flow of the system which uses a TCP / IP connection for a connection of a server and a client, uses a UDP packet for transmission of screen data and an input event, and communicates by unicast. It is a figure which illustrated the processing flow of the system which uses a TCP / IP connection for a connection of a server and a client, uses a UDP packet for transmission of screen data and an input event, and performs broadcast communication by broadcast or multicast. It is the figure which illustrated the display screen of the server about the system which transmits in either TCP or UDP for every application of a server. It is the figure which showed the algorithm about the system transmitted by either TCP or UDP for every application of a server. It is the figure which illustrated the processing flow about the system transmitted by either TCP or UDP for every application of a server. It is the figure which illustrated the display screen of the server about the system which switches and transmits TCP and UDP according to whether the window of a server is located in the forefront. It is the figure which showed the algorithm about the system which switches and transmits TCP and UDP according to whether the window of a server is located in the foreground. It is the figure which illustrated the display screen of the server about the system which switches and transmits TCP and UDP according to whether the window of a server is active. It is the figure which showed the algorithm about the system which switches and transmits TCP and UDP depending on whether the window of a server is active. It is the figure which illustrated the display screen of the server about the system which switches and transmits TCP and UDP according to whether the window of a server is a document which the user specified. It is the figure which showed the algorithm about the system which switches and transmits TCP and UDP according to whether the window of a server is a document designated by the user. It is the figure which illustrated the screen display of the server about the system which switches and transmits TCP and UDP according to whether the window of a server is a screen area | region designated by the user. It is the figure which showed the algorithm about the system which switches and transmits TCP and UDP according to whether the window of a server is a screen area | region designated by the user. It is the figure which illustrated the screen which performs the switching instruction | indication of a communication protocol. It is the figure which showed the flow of switching operation | movement of a communication protocol. It is the figure which illustrated the screen which performs the switching instruction | indication of a communication protocol for every user. It is the figure which showed the algorithm about the system which switches and transmits TCP and UDP according to the number of clients connected. It is the figure which showed the algorithm about the system which switches and transmits TCP and UDP with the communication interface of a client. It is the figure which showed the algorithm about the system which switches and transmits TCP and UDP with the connection path | route of a client. It is the figure which showed the algorithm about the system which switches and transmits TCP and UDP according to the residual amount of the encoding data which should be transmitted. It is the figure which showed the algorithm about the system which switches and transmits TCP and UDP according to a transmission data rate. It is the figure which showed the algorithm about the system which switches and transmits TCP and UDP according to the communication speed between a server and a client. It is the figure which showed the algorithm about the system which switches and transmits TCP and UDP by MTU between a server and a client. It is the figure which showed the algorithm about the system which switches and transmits TCP and UDP by QoS between a server and a client. It is the figure which showed the algorithm about the system which switches and transmits TCP and UDP according to the priority of a client. It is the figure which illustrated the screen which sets the control authority of remote operation. It is the figure which showed the algorithm about the setting of a remote operation flag. It is the figure which showed the algorithm about the system which switches and transmits TCP and UDP by ON / OFF of a remote operation flag. It is the figure which showed the algorithm about the system which switches and transmits TCP and UDP depending on whether shared screen data is font data or image data. It is the figure which showed the algorithm about the system which switches and transmits TCP and UDP according to the load condition of CPU. It is the schematic which showed the network structure of the data communication system which is one Example of this invention (there is a proxy, the 1). It is the figure which illustrated the processing flow of the system which shares a screen via a proxy. It is the schematic which showed the network structure of the data communication system which is one Example of this invention (there is a proxy, the 2). It is the figure which showed the processing flow about the system which applied UDP multicast or UDP broadcast in the proxy. It is the figure which showed the processing flow about the reproduction | regeneration function in a proxy.

Explanation of symbols

1 server (screen sharing server)
2 Client 3 Relay device (proxy)
10 IP network 11 TCP shared application window 12 UDP shared application window 13 Frontmost window 14 Rear window 15 Active window 16 Inactive window 17 User specified document window 18 Non user specified document window

Claims (30)

An information device functioning as a server;
An information device functioning as a client of the server as a component,
The server includes means for transmitting data relating to at least a part of the display screen to the client via a network that performs communication using an IP protocol,
The client is a data communication method in a network system having means for sharing the display screen of the server by displaying the screen data received from the server on a display device,
When the server transmits the screen data according to any of the data type or display condition of the screen area to be transmitted, the communication environment with the client, or an instruction given by the user, at least a part of the screen data to be transmitted is: A data communication system comprising means for switching between transmission using a TCP packet or transmission using a UDP packet.   2. The data communication system according to claim 1, wherein the server includes means for transmitting screen data to the plurality of clients by a broadcast communication system using a UDP multicast or a UDP broadcast packet. The server has means for registering whether to transmit screen data in a TCP packet or a UDP packet for each application program,
Screen data of application programs registered to be transmitted by TCP packet is transmitted by TCP packet.
3. The data communication method according to claim 1, wherein screen data of an application program registered to be transmitted by a UDP packet is transmitted by a UDP packet. The server has means for determining whether or not an application program window is displayed in the foreground,
When sending screen data of the window displayed in the foreground, send it with a TCP packet,
The data communication method according to claim 1 or 2, wherein the screen data of a window not on the foreground or the desktop screen is transmitted by a UDP packet. The server has means for determining whether or not it is active on the window of the application program,
When sending screen data of the active window, send it with a TCP packet.
The data communication method according to claim 1 or 2, wherein the screen data of the inactive window or the desktop screen is transmitted by a UDP packet. The server has means for a user to instruct whether to transmit screen data using a TCP packet or a UDP packet to a running application program,
Screen data of application programs registered to be transmitted by TCP packet is transmitted by TCP packet.
3. The data communication system according to claim 1, wherein screen data of an application program registered to be transmitted by a UDP packet is transmitted by a UDP packet. The server has means for instructing whether to transmit screen data in a TCP packet or a UDP packet for an arbitrary area of the shared screen area,
Screen data of the screen area registered to be transmitted by TCP packet is transmitted by TCP packet.
3. The data communication system according to claim 1, wherein screen data of a screen area registered to be transmitted by a UDP packet is transmitted by a UDP packet. The server has means for switching a protocol for transmitting screen data according to a user instruction,
If the user instructs to send TCP protocol, send screen data with TCP packet,
The data communication system according to claim 1 or 2, wherein when the user instructs to transmit the UDP protocol, the screen data is transmitted by a UDP packet. The server has means for managing the number of connected clients;
According to the number of connected clients, there is means for switching between screen data transmission using the TCP protocol or UDP protocol,
When the number of connected clients is less than a predetermined number, screen data is transmitted with a TCP packet,
3. The data communication system according to claim 1, wherein when the number of connected clients is larger than a predetermined number, the screen data is transmitted by a UDP packet. The server has means for managing whether the number of connected clients is connected via a wired LAN or connected via a wireless LAN in the middle,
For clients connected via wireless LAN, send screen data in TCP packets,
3. The data communication method according to claim 1, wherein screen data is transmitted by a UDP packet to a client connected only by a wired LAN. The server has means for managing whether the number of connected clients is connected via a LAN or via a WAN,
Send screen data in TCP packets to clients connected via WAN,
The data communication method according to claim 1 or 2, wherein when the client connected via the LAN is instructed to transmit the UDP protocol, the screen data is transmitted by a UD packet. The server has means for measuring the remaining amount of screen data to be transmitted, or the transmission rate of screen data,
When the screen data transmission remaining amount or the screen data transmission rate is smaller than a predetermined value, the screen data is transmitted by a TCP packet,
The data communication method according to claim 1 or 2, wherein when the remaining amount of screen data transmission or the screen data transmission rate exceeds a predetermined value, the screen data is transmitted by a UDP packet. The server includes means for measuring a network communication speed between the server and the connection client;
When the communication speed is smaller than a predetermined value, screen data is transmitted with a UDP packet,
3. The data communication method according to claim 1, wherein when the communication speed exceeds a predetermined value, screen data is transmitted by a TCP packet. The server includes means for measuring a data capacity (MTU) that can be transmitted in one packet between the server and a connected client,
When the MTU is smaller than a predetermined value, screen data is transmitted with a UDP packet,
The data communication method according to claim 1 or 2, wherein when the MTU exceeds a predetermined value, screen data is transmitted by a TCP packet. The server comprises means for measuring the QoS of the network between the server and the connecting client;
When the QoS is smaller than a predetermined value, screen data is transmitted with a TCP packet,
The data communication method according to claim 1 or 2, wherein when the QoS exceeds a predetermined value, screen data is transmitted by a UDP packet. The server has means for managing priority of connected clients;
Send screen data in TCP packets to clients with priority.
3. The data communication method according to claim 1, wherein screen data is transmitted by a UDP packet to a client to which priority is not given. The server receives an input event from a client and forwards the received input event to the server;
Means for managing whether the client has sent an input event to the server within a certain period of time;
For the client that sent the input event to the server within a certain time, the screen data is sent with a TCP packet,
3. The data communication system according to claim 1, wherein screen data is transmitted by a UDP packet to a client that has not transmitted an input event to the server within a predetermined time. The server has means for determining whether or not the screen data in the transmission area includes character data when transmitting the screen data, based on whether or not the OS is a font rendering command.
The screen data of the area including the character data is transmitted by TCP packet,
3. The data communication system according to claim 1, wherein screen data in an area not including character data is transmitted by a UDP packet. The server includes means for determining whether the CPU load of the server exceeds a predetermined load amount;
If the CPU load is less than or equal to the predetermined load, send screen data with TCP packets,
3. The data communication system according to claim 2, wherein when the CPU load exceeds a predetermined load amount, the screen data is transmitted by a UDP packet. An information device functioning as a server;
An information device functioning as a client of the server as a component,
The server includes means for transmitting data relating to at least a part of the display screen to the client via a network that performs communication using an IP protocol,
The client is a data communication method in a network system having means for sharing the display screen of the server by displaying the screen data received from the server on a display device,
The network system includes a relay device that relays screen data received from the server to the client;
The data relay method according to claim 1, wherein the relay device includes means for transmitting screen data received from the server as a TCP packet to the client as a UDP packet.   21. The data communication system according to claim 20, wherein the relay device includes means for transmitting screen data to the plurality of clients by a broadcast communication system using a UDP multicast or a UDP broadcast packet.   The data communication system according to claim 20 or 21, wherein the relay device has means for recording and reproducing screen data received from the server. An information device functioning as a conference server;
An information device functioning as a conference client of the conference server is a component,
The conference server includes means for transmitting data relating to at least a part of the display screen to the conference client via a network that performs communication using an IP protocol,
The conference client is an electronic conference system having means for sharing the display screen of the conference server by displaying the screen data received from the conference server on a display device,
At least a part of the screen data to be transmitted when the conference server transmits the screen data according to any of the data type or display condition of the screen area to be transmitted, the communication environment with the conference client, or an instruction given by the user. Is transmitted using a TCP packet or using a UDP packet, and has a means for transmitting the electronic conference system. An information device functioning as a conference server;
An information device functioning as a conference client of the conference server is a component,
The conference server includes means for transmitting data relating to at least a part of the display screen to the conference client via a network that performs communication using an IP protocol,
The conference client is an electronic conference system having means for sharing the display screen of the server by displaying the screen data received from the conference server on a display device,
The network includes a conference relay device that relays screen data received from the conference server to the conference client;
The said conference relay apparatus has a means to transmit the screen data received with the TCP packet from the said conference server to the said conference client with a UDP packet, The electronic conference system characterized by the above-mentioned. The conference server has means for managing priority of a conference client to be connected,
For the conference client to which priority is given, the screen data is transmitted with a TCP packet,
25. The electronic conference system according to claim 23 or 24, wherein screen data is transmitted by a UDP packet to a conference client to which priority is not given. The conference server receives an input event from the conference client, and transfers the received input event to the conference server;
Means for managing whether the connected conference client has sent an input event to the server within a predetermined time;
For the conference client that has sent the input event to the conference server within a certain time, the screen data is sent by TCP packet,
25. The electronic conference system according to claim 23 or 24, wherein screen data is transmitted by a UDP packet to a client that has not transmitted an input event to the conference server within a predetermined time. A data communication method in a network system including information equipment functioning as a server and information equipment functioning as a client of the server,
In the server, transmitting data relating to at least a part of the display screen to the client via a network that communicates using an IP protocol;
In the client, the screen data received from the server is displayed on a display device, thereby sharing the display screen of the server,
When the server transmits the screen data according to any of the data type or display condition of the screen area to be transmitted, the communication environment with the client, or an instruction given by the user, at least a part of the screen data to be transmitted is: A data communication method comprising a step of switching between transmission using a TCP packet or transmission using a UDP packet. A data communication method in a network system comprising information equipment functioning as a server, information equipment functioning as a client of the server, and relay equipment that relays screen data received from the server to the client. ,
In the server, transmitting data relating to at least a part of the display screen to the client via a network that communicates using an IP protocol;
In the client, displaying the screen data received from the server on a display device, thereby sharing the display screen of the server;
A data communication method comprising the step of transmitting screen data received from the server as a TCP packet to the client as a UDP packet in the relay device.   A data communication program for causing a computer to execute the data communication method according to claim 27 or 28.   A computer-readable storage medium storing the data communication program according to claim 29.

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