JP3990395B2 - Communication method and communication system - Google Patents

Description

  The present invention relates to a communication method and communication system for performing real-time communication between a client and a server on a network limited to HTTP (Hypertext Transfer Protocol) communication.

  With the development of computer networks in recent years, security that protects against unauthorized access such as computer worms, viruses, and hacking is regarded as important. In this security measure, for example, a firewall or proxy server is installed at the boundary between a communication network to which unspecified client devices such as the Internet are connected and a communication network to which a protection target device such as an in-house LAN server is connected. Thus, by passing only packets of a specific protocol, the terminal to be protected is protected from unauthorized access. This firewall or HTTP proxy server adopts a method of allowing only HTTP communication to pass and blocking packets of other protocols. The HTTP proxy server and the firewall are gateway devices that perform processing while interpreting HTTP, which is an application layer protocol, and perform processing while holding the HTTP state on the storage device.

  When such a firewall or proxy server that allows only HTTP communication is provided, an HTTP tunneling server is installed between the firewall or proxy server and the protection target device, and any packet is transmitted by HTTP by the HTTP tunneling server. Encapsulated to enable communication through firewalls and proxy servers.

  Specifically, the processing is performed as shown in FIG. In the example shown in FIG. 10, the case where the function of the HTTP tunneling server is provided in the interface on the server side of the gateway will be described. When a packet encapsulated by HTTP is transmitted from the client to the gateway, the packet received by the gateway is accumulated and the encapsulated data is combined and transmitted to the server. When a packet encapsulated by HTTP is transmitted from the server to the gateway, the packet received by the gateway is accumulated and the encapsulated data is combined and transmitted to the client device. As described above, in the conventional method, since the process of combining the divided and transmitted data is performed by the function of the HTTP tunneling server, real-time communication has not been realized.

  Since such an HTTP tunneling server uses a process for combining data transmitted in a divided manner, it is inappropriate for real-time communication such as a remote GUI. Based on such a situation, there is a bidirectional communication system using a communication network via a communication path in which a proxy exists (for example, Patent Document 1). In the communication system described in Patent Document 1, before data transmission / reception is performed between the server device and each client device, data transmission from the client device to the server device can be performed in real time. A total of two lines, that is, an uplink using the HTTP POST method and a downlink using the HTTP GET method to enable real-time data transmission from the server apparatus to the client apparatus are created. There is a two-way communication system between a server and a plurality of clients, which is characterized by the above.

In the system described in Patent Document 1, as shown in FIG. 11, first, the POST method is transmitted from the client device to the server device, and the POST data is continuously transmitted from the client device without terminating the POST request. Open. On the other hand, a GET method is transmitted from the client device to the server device, and a downlink that continues to send GET data from the server device without terminating the GET request is established. In this way, by providing respective lines for uplink and downlink, real-time communication is realized by transmitting data cells at a timing when an application requests data transmission.
Japanese Patent No. 3478200

  However, the communication system described in Patent Document 1 described above must maintain bidirectional communication between the uplink and downlink, and requires processing resources for two lines in one bidirectional communication. There is a problem that the load on the gateway device increases. In addition, the number of lines processed by the gateway device may be limited so that gateway devices that concentrate access to the protection target device do not fall into an overload state, and real-time communication is realized with low load on the HTTP tunneling server. It is expected to provide a communication method and a communication system.

  Accordingly, an object of the present invention is to provide a communication method and a communication system for realizing real-time communication with low load in an HTTP tunneling server.

A first feature of the present invention is that a server device, a client device that requests processing to the server device and communicates by HTTP, a gateway that is connected to the client device and allows only HTTP communication, and a gateway and the server device The present invention relates to a communication method used in a communication system including an HTTP tunneling server that is connected and implements HTTP communication. That is, the communication method according to the first aspect of the present invention includes a step of generating server connection information including a host identifier and a port number of a server device that is a connection destination of a communication connection by a client device, An HTTP request in which POST is specified in the HTTP method field, the maximum content length that the gateway can communicate in is specified in the content length field, server connection information is specified in the request body field, and the HTTP request is transmitted to the HTTP tunneling server. A request body field of the HTTP request is read by the HTTP tunneling server, a communication connection is established with the server device included in the connection information, and an HTTP tunneling server. The connection ID for identifying the connected communication is numbered by the server, and the connection ID and the connection information are stored in association with each other in the server side setting data storage unit of the storage device that can be read by the HTTP tunneling server. When the HTTP response is received from the server device by the HTTP tunneling server, the HTTP response and the connection ID are transmitted to the client device, and the client device determines the HTTP request body field of the HTTP request from the maximum content length. The step of calculating the transmittable content length from which the data length is subtracted and the transmittable content length and connection information are associated with the client side setting data storage unit of the storage device readable by the client device by the client device Is provided with a step to be stored, when transmitting a packet to the server device from the client device, the client device checks whether the communication connection with the server is established, if it is not connected, communication connection is re If the header length of the packet is larger than the transmittable content length, the communication connection is disconnected and the communication connection is reestablished. The maximum packet length, which is the maximum data length that can be encapsulated in one packet, is greater than the packet data length, and the transmittable content length is the packet header length. Packet data if greater than the sum of the data length A packet of long data is transmitted to the HTTP tunneling server, and a transmittable content length obtained by subtracting the packet header length and the data length from the transmittable content length is stored in the client side setting data storage unit; When the maximum packet length is the packet data length is small and the transmittable content length is smaller than the sum of the packet header length and the data length, the maximum packet length data packet is transmitted to the HTTP tunneling server, The transmittable content length obtained by subtracting the packet header length and the maximum packet length from the transmittable content length, and the data length obtained by subtracting the maximum packet length from the packet data length are stored in the client side setting data storage unit. Step and the maximum packet length is greater than the packet data length When the transmittable content length is large and smaller than the sum of the packet header length and the data length, or the maximum packet length is the packet data length is small and the transmittable content length is the sum of the packet header length and the data length. Data packet having a size obtained by subtracting the header length of the packet from the transmittable content length is transmitted to the HTTP tunneling server, and data obtained by subtracting the transmittable content length from the data length and adding the header length long it is Ru and a step to be stored in the client-side setting data storage unit.

  According to the present invention, a real-time bidirectional communication between a client and a server can be performed by creating a line using the HTTP POST method. At this time, in the HTTP request, the maximum content length allowed in the communication system is specified in the content length field, and the data to be transmitted is divided into packets that do not exceed the maximum content length, thereby performing real-time communication. be able to. At this time, as long as the maximum content length is not exceeded, communication can be performed by one HTTP request.

A second feature of the present invention is that a server device, a client device that requests processing to the server device and communicates by HTTP, a gateway that is connected to the client device and passes only HTTP communication, and the gateway and server device The present invention relates to a communication system including an HTTP tunneling server that is connected and implements HTTP communication. That is, the communication system according to the second aspect of the present invention generates server connection information including a host identifier and a port number of a server device that is a connection destination of a communication connection, specifies POST in the HTTP method field, and a content length field. Specify the maximum content length that the gateway can communicate with, generate an HTTP request specifying the server connection information in the request body field, send the HTTP request to the HTTP tunneling server, and the HTTP response and connection ID from the HTTP tunneling server. When transmitted, the data length of the HTTP request body field of the HTTP request is subtracted from the maximum content length to calculate the transmittable content length, and the readable content length is connected to the client side setting data storage unit of the readable storage device. When an HTTP request is received from a client device that stores information in association with the client device, the request body field of the HTTP request is read, a communication connection is established with the server device included in the connection information, and the connected communication is identified. The connection ID and the connection information are stored in the server-side setting data storage unit of the readable storage device in association with each other, and when the HTTP response is received from the server device, the HTTP response and the connection ID are stored. When the client device transmits a packet from the client device to the server device, the client device checks whether a communication connection with the server device is established. Re-establish communication connection, If it is confirmed that the communication connection is established, if the packet header length is larger than the transmittable content length, the communication connection is disconnected, the communication connection is reestablished, and the packet header length is the transmittable content. When the maximum packet length, which is the maximum data length that can be encapsulated in one packet, is greater than the packet data length and the transmittable content length is greater than the sum of the packet header length and the data length , The packet of the data length of the packet is transmitted to the HTTP tunneling server, and the transmittable content length obtained by subtracting the packet header length and the data length from the transmittable content length is stored in the client side setting data storage unit, The maximum packet length is small and the packet data length is small. When the content length is smaller than the sum of the packet header length and the data length, the packet of the maximum packet length data is transmitted to the HTTP tunneling server, and the packet header length and the maximum packet length are subtracted from the transmittable content length. The transmittable content length and the data length obtained by subtracting the maximum packet length from the packet data length are stored in the client side setting data storage unit, and the maximum packet length is larger than the packet data length and the transmittable content length is If the packet header length and data length are less than the sum, or if the maximum packet length is the packet data length is small and the transmittable content length is greater than the packet header length and data length, send A packet of data whose size is obtained by subtracting the packet header length from the possible content length. The transmits the HTTP tunneling server, the data length obtained by adding the header length by subtracting a transmittable content length from the data length and stores in the client-side setting data storage unit.

  ADVANTAGE OF THE INVENTION According to this invention, the communication method and communication system which implement | achieve real-time communication with the low load in an HTTP tunneling server can be provided.

  Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

(Best Embodiment)
(Communications system)
As shown in FIG. 1, the communication system according to the preferred embodiment of the present invention includes a server device 2, a client device 7 that requests processing from the server device 2 and communicates by HTTP, and is connected to the client device 7 and is HTTP. A proxy server 4 and a firewall 3 that allow only communication to pass through, and an HTTP tunneling server 1 that is connected between the gateway and the server device 2 and that realizes HTTP communication are provided. The server device 2 and the HTTP tunneling server 1, the HTTP tunneling server 1 and the firewall 3, the firewall 3 and the proxy server 4, and the proxy server 4 and the client device 7 are connected by a communication network and can communicate with each other.

  The server device 2 is a device that provides services such as contents to the client device 7.

  The HTTP tunneling server 1 is installed between the proxy server 4 and the firewall 3 and the server device 2, receives an HTTP packet encapsulated from the client device 7, extracts data from the HTTP packet, and transmits it to the server device 2. Then, the data received from the server device 2 is encapsulated and transmitted to the client device 7.

  The client device 7 is a device that receives a service provided from the server device 2. The client device 7 includes a client application 6 such as a browser, and an HTTP tunnel client 5 that performs HTTP tunneling processing.

  The HTTP tunnel client 5 receives the HTTP packet encapsulated from the HTTP tunneling server 1, extracts data from the HTTP packet, transmits it to the client application 6, encapsulates the data received from the client application 6, and encapsulates the HTTP tunneling server 1 to send.

  In the example shown in FIG. 1, the server device 2, the HTTP tunneling server 1, the proxy server 4, and the firewall 3 are configured on different hardware, but the function of the HTTP tunneling server 1 is the server device 2, The proxy server 4 and the firewall 3 may be mounted on one or more hardware. In the example illustrated in FIG. 1, the client device 7 includes the client application 6 and the HTTP tunnel client 5, but the HTTP tunnel client 5 may be configured on hardware different from the client device 7. good.

  As shown in FIG. 2, the communication system according to the preferred embodiment of the present invention does not wait for the completion of the POST request transmitted from the client device 7 and returns a POST reply, so that both of them can be connected with one line. Communication. For this reason, a sufficiently large value is specified in the header of the number of transmission bytes of the POST request transmitted from the client device 7. Unless the data of the number of bytes specified here is transmitted, the HTTP tunneling server 1 recognizes that the POST request is continued. Further, the client device 7 divides the data to be transmitted into packets so as not to transmit data exceeding the designated number of transmission bytes, and transmits the packets.

  In FIG. 2, when a response header is transmitted from the HTTP tunneling server 1 in response to transmission of a request header from the client device, request body 1, request body 2,..., POST request data. Then, an HTTP packet is transmitted.

  Specifically, the client device 7 transmits an HTTP request as a request body 1 to the HTTP tunneling server 1. Next, the HTTP tunneling server 1 transmits, as the response body 1, an HTTP response and a connection ID for identifying this connection to the client device 7. At this time, the HTTP tunneling server 1 transmits the data to be transmitted from the server device 2 to the client device 7 as a response body 2 in HTTP encapsulation. On the other hand, the client device 7 transmits the data to be transmitted to the server device 2 as the request body 2 after HTTP encapsulation.

(HTTP tunneling server)
As shown in FIG. 3, the HTTP tunneling server 1 according to the preferred embodiment of the present invention includes a central processing control device 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, and an input / output interface 109. Are connected via a bus 110. An input device 104, a display device 105, a communication control device 106, a storage device 107, and a removable disk 108 are connected to the input / output interface 109.

  The central processing control device 101 reads out and executes a boot program for starting the HTTP tunneling server 1 from the ROM 102 based on an input signal from the input device 104, and further reads an operating system stored in the storage device 107. Further, the central processing control device 101 controls various devices based on input signals from the input device 104, the communication control device 106, etc., and reads programs and data stored in the RAM 103, the storage device 107, etc., into the RAM 103. A processing device that loads and implements a series of processing described later, such as data calculation or processing, based on a program command read from the RAM 103.

  The input device 104 is configured by an input device such as a keyboard and a mouse through which an operator inputs various operations. The input device 104 generates an input signal based on the operation of the operator, and inputs via the input / output interface 109 and the bus 110. It is transmitted to the central processing control apparatus 101. The display device 105 is a CRT (Cathode Ray Tube) display, a liquid crystal display, or the like, and receives an output signal to be displayed on the display device 105 from the central processing control device 101 via the bus 110 and the input / output interface 109. It is a device that displays the processing result of the control device 101 and the like. The communication control device 106 is a device such as a LAN card or a modem, and is a device that connects the HTTP tunneling server 1 to a communication network such as the Internet or a LAN. Data transmitted / received to / from the communication network via the communication control device 106 is transmitted / received to / from the central processing control device 101 via the input / output interface and the bus 110 as an input signal or an output signal.

  The storage device 107 is a semiconductor disk device, a magnetic disk device, or the like, and stores programs and data executed by the central processing control device 101. The removable disk 108 is an optical disk or a flexible disk, and signals read / written by the disk drive are transmitted / received to / from the central processing control apparatus 101 via the input / output interface 109 and the bus 110.

  The storage device 107 of the HTTP tunneling server 1 according to the first embodiment of the present invention stores an HTTP tunneling program and includes a server side setting data storage unit 210 and a server side packet storage unit 211. Further, the HTTP tunneling program is read and executed by the central processing control device 101 of the HTTP tunneling server 1 so that the server side data transmission unit 201, the server side retransmission management unit 202, the server side data reception unit 203, and the server side packet reception. Means 204, server-side packet transmission means 205, server-side communication path management means 206, and server-side connection start means 207 are mounted on the HTTP tunneling server 1.

  Here, in the communication system according to the preferred embodiment of the present invention, data is information transmitted / received between the server apparatus 2 or the client application 6. The packet is information transmitted / received between the HTTP tunnel client 5 of the client device 7 and the HTTP tunneling server 1. As described above, when receiving data from the client application 6, the HTTP tunnel client 5 divides the data into HTTP packets and transmits them to the HTTP tunneling server 1 via the proxy server 4 and the firewall 3. Accordingly, when receiving the HTTP packet from the HTTP tunnel client 5, the HTTP tunneling server 1 extracts data from the HTTP packet and transmits it to the server device 2. On the other hand, when receiving data from the server device 2, the HTTP tunneling server 1 divides the data into HTTP packets, and transmits them to the HTTP tunnel client 5 via the firewall 3 and the proxy server 4. Accordingly, when receiving the HTTP packet from the HTTP tunneling server 1, the HTTP tunnel client 5 extracts data from the HTTP packet and transmits it to the client application 6.

  When an HTTP request is received from the client device 7, the HTTP tunneling server 1 reads the request body field of the HTTP request, establishes a communication connection with the server device included in the connection information, and identifies the connected communication When the ID is assigned, the connection ID and the connection information are stored in the server-side setting data storage unit 210 of the readable storage device in association with each other, and when the HTTP response is received from the server device 2, the HTTP response and the connection are connected. The ID is transmitted to the client device 7.

  The server-side setting data storage unit 210 uses, as a key, a connection ID that identifies a connection connection with the client device 7, server connection information that is a combination of a host identifier that is an identifier of the connection destination server device 2 and a port number, SENDABLE_LEN (transmittable content length) that is a variable indicating the length of data that can be transmitted on this communication path, the second sequence number that is the sequence number of the packet to be transmitted next to the client device 7, and the client device 7 And a second acknowledgment number which is a sequence number of the packet received from. Further, the maximum packet length (MAX_PACKET_LEN), which is the maximum value of the data length that can be encapsulated in one packet, may also be stored in the server-side setting data storage unit 210.

  The server-side packet storage unit 211 stores a packet that has been transmitted by the HTTP tunneling server 1 and has not been acknowledged by the client device 7 and a packet received from the HTTP tunnel client 5.

  When receiving an HTTP request from the client device 7, the server-side connection start unit 207 establishes a communication connection with the server device 2 based on the connection information included in the HTTP request. Further, the server side connection start unit 207 causes the server side communication path management unit 206 to number the connection ID and transmits the connection ID to the client side connection start unit 503.

  The server-side communication path management means 206 assigns a connection ID for identifying this communication connection and stores it in the server-side setting data storage unit 210. Further, the server-side communication path management unit 206 receives an HTTP request for requesting reconnection of the communication connection from the HTTP tunnel client, searches for a connection ID included in the HTTP request, and transmits the client-side communication path management unit 502 and the server-side retransmission. The management unit 202 is notified.

  The server-side data receiving unit 203 is a unit that receives data to be transmitted from the server device 2 to the client device 7, divides the data into packets of a predetermined size, and inputs the packets to the server-side packet transmitting unit 205.

  When a packet to be transmitted is generated, the server-side packet transmission unit 205 transmits the packet to the client device 7 and inputs the packet identifier to the server-side retransmission management unit 202.

  When a packet is input from the client-side packet transmission unit 501, the server-side packet reception unit 204 stores the packet in the server-side packet storage unit 211 and inputs the identifier of this packet to the server-side retransmission management unit 202. .

  When the intra-packet data is input from the server-side packet receiving unit 204, the server-side data transmitting unit 201 transmits the data to the server device 2.

  When the identifier of the packet received from the client device 7 is input, the server-side retransmission management unit 202 reads the first sequence number of this packet and sets the first sequence number as the second acknowledgment number. While storing in the server side setting data storage unit 210, the server side packet storage unit 211 deletes a packet associated with a number lower than the first acknowledgment number of the packet. In addition, when the identifier of the packet to be transmitted is input from the server-side packet transmission unit 205, the server-side retransmission management unit 202 reads the server-side setting data storage unit 210 and adds the second sequence number and the 2, and the second sequence number is incremented and stored in the server-side setting data storage unit 210.

(Client device)
The client device 7 has a hardware configuration diagram similar to that of the HTTP tunneling server 1 shown in FIG. The storage device of the client device 7 stores a client application program and an HTTP tunnel client program, and includes a client side setting data storage unit 510 and a client side packet storage unit 511. Further, the HTTP tunnel client program is read and executed by the central processing control unit of the client device 7, so that the client side packet transmission unit 501, the client side communication path management unit 502, the client side connection start unit 503, and the client side packet reception Means 504, client-side data transmission means 505, client-side retransmission management means 506, and client-side data reception means 507 are mounted on the client device 7.

  The client device 7 generates server connection information including the host identifier and port number of the server device 2 that is the connection destination of the communication connection, specifies POST in the HTTP method field, and the maximum content that the gateway can communicate in the content length field When a length is specified, an HTTP request in which server connection information is specified in the request body field is generated, an HTTP request is transmitted to the HTTP tunneling server 1, and an HTTP response and a connection ID are transmitted from the HTTP tunneling server 1. The transmittable content length is calculated by subtracting the data length of the HTTP request body field of the HTTP request from the maximum content length, and the transmittable content length and connection information are stored in the client side setting data storage unit 510 of the readable storage device. In association with the memory.

  The client-side setting data storage unit 510 uses, as a key, a connection ID that identifies a connection connection with the server device 2, and server connection information that is a combination of a host identifier that is an identifier of the connection destination server device 2 and a port number; SENDABLE_LEN (transmittable content length) that is a variable indicating the length of data that can be transmitted on this communication path, a first sequence number that is a sequence number of a packet to be transmitted next to the HTTP tunneling server 1, and HTTP tunneling A first acknowledgment number that is a sequence number of a packet received from the server 1 is stored. Further, the maximum packet length (MAX_PACKET_LEN) that is the maximum value of the data length that can be encapsulated in one packet may also be stored in the client side setting data storage unit 510.

  The client-side packet storage unit 511 stores a packet that has been transmitted by the client device 7 and has not been acknowledged by the HTTP tunneling server 1 and a packet received from the HTTP tunneling server 1.

  When the server connection information is input, the client side connection start unit 503 specifies POST in the HTTP method field, specifies the maximum content length that the gateway can communicate in the content length (CONTENT-LENGTH) field, and requests body field. An HTTP request specifying the server connection information is generated, and the HTTP request is transmitted to the server side connection start means 207 of the HTTP tunneling server 1. Further, upon receiving the HTTP response and the connection ID, the client side connection start unit 503 calculates a transmittable content length obtained by subtracting the data length of the HTTP request body field of the HTTP request from the maximum content length, and transmits the transmittable content length and the connection ID. Is input to the client side communication path management means 502.

  When the client-side communication path management unit 502 receives the transmittable content length and the connection ID, the client-side communication path management unit 502 associates the transmittable content length with the connection information in the client-side setting data storage unit 510. Remember. Further, the client-side communication path management unit 502 inputs a response indicating registration completion to the client-side connection start unit 503. When reestablishing the connection with the server apparatus 2, the client side communication path management unit 502 designates POST in the HTTP method field, designates the maximum content length that the gateway can communicate in the content length field, and designates in the request body field. An HTTP request designating a connection ID is generated, and this HTTP request is input to the server side communication path management means 206 of the HTTP tunneling server 1.

  When the client side packet receiving unit 504 receives a packet from the HTTP tunneling server 1, the client side packet receiving unit 504 inputs the identifier of the packet to the client side retransmission management unit 506 and inputs the in-packet data to the client side data receiving unit 507.

  When the client-side data receiving unit 507 receives the in-packet data from the client-side packet receiving unit 504, the client-side data receiving unit 507 stores the data and inputs the data to the client application based on a request from the client application 6.

  Upon reception of data to be sent from the client application 6 to the server device 2, the client-side data transmission unit 505 causes the client-side communication path management unit 502 to read out the transmittable content length and the maximum content length, and to transmit the transmittable content length and the maximum Data is divided into packets based on the content length and input to the client-side packet transmission means 501.

  The client side packet transmission unit 501 inputs the packet identifier to the client side retransmission management unit 506 and also inputs the packet to the server side packet reception unit 204.

  When the identifier of the packet received from the HTTP tunneling server 1 is input, the client-side retransmission management unit 506 reads the second sequence number of the packet and sets the second sequence number as the first acknowledgment number. The packet stored in the client side setting data storage unit 510 is deleted, and the packet associated with a lower number than the second acknowledgment number of the packet is deleted from the client side packet storage unit 511. When the identifier of the packet to be transmitted to the HTTP tunneling server 1 is input, the client-side retransmission management unit 506 receives the first sequence number from the client-side setting data storage unit 510 and the packet transmitted from the server device 2. The first acknowledgment number that is the sequence number is read out, and the first sequence number and the first acknowledgment number are written into the packet and stored in the client-side packet storage unit 511. At this time, the client-side retransmission management unit 506 increments the first sequence number stored in the client-side setting data storage unit 510.

(Connection start processing)
Next, connection start processing in the communication system according to the preferred embodiment of the present invention will be described with reference to FIG.

  First, in step S <b> 101, the client application 6 generates server connection information including the host identifier and port number of the connection destination server apparatus 2, and inputs the server connection information to the client side connection start unit 503. When the server connection information is input, the client side connection start unit 503 specifies POST in the HTTP method field, specifies the maximum content length that the gateway can communicate in the content length (CONTENT-LENGTH) field, and requests body field. An HTTP request specifying the server connection information is generated, and the HTTP request is transmitted to the server side connection start means 207 of the HTTP tunneling server 1. Here, the maximum content length is determined by a gateway such as the proxy server 4 or the firewall 3 or a communication device provided in a communication network between the client device 7 and the server device 2.

  When the server side connection start means 207 receives the HTTP request, in step S103, the request body field of the HTTP request is read, and a connection request is transmitted to the server apparatus 2 included in the connection information to establish a communication connection. In step S104, when the server apparatus 2 receives the connection request, the server apparatus 2 transmits a response corresponding to the request to the server-side connection start unit 207. When the server side connection start unit 207 receives the response from the server device 2, in step S105, the server side connection start unit 207 transmits a request for numbering the connection ID for identifying the communication connection to the server side communication path management unit 206. In step S106, the server side connection start unit 207 When the connection ID is received from the side communication path management unit 206, the connection ID and the connection information are stored in the server side setting data storage unit 210 in association with each other.

  Upon receiving the connection ID, the server-side connection start unit 207 transmits an HTTP response corresponding to the HTTP request transmitted in step S102 and the connection ID to the client-side connection start unit 503 in step S107.

  When the client side connection start means 503 receives the HTTP response and the connection ID, it calculates a transmittable content length by subtracting the data length of the HTTP request body field of the HTTP request from the maximum content length, and sets the transmittable content length and the connection ID to the client. To the side communication path management means 502.

  When the transmittable content length and the connection ID are input, the client-side communication path management unit 502 stores the transmittable content length and connection information in the client-side setting data storage unit 510 in association with each other. Further, the client-side communication path management unit 502 inputs a response indicating registration completion to the client-side connection start unit 503.

  When the response is input, the client side connection start unit 503 inputs the HTTP response received in step S107 to the client application 6 in step S110.

(Data transmission from client application to server device)
When data is transmitted from the client application to the server device, the client application 6 inputs the data transmitted to the server device 2 to the client-side data transmission unit 505. The client-side data transmission unit 505 inputs a packet to the client-side packet transmission unit 501 according to the flowchart shown in FIG. Here, the header length of the packet (HEADER_LEN) is the header length of the packet transmitted from the HTTP tunnel client 5 to the HTTP tunneling server 1. The packet data length (DATA_LEN) is a variable representing the length of data transmitted by the client application 6.

  First, in step S1, the client-side packet transmission unit 501 checks whether a communication connection with the server apparatus 2 is established. If not, the client-side packet transmission unit 501 reestablishes the communication connection in step S2. This re-establishment of the communication connection will be described in detail later.

  When it is confirmed that the communication connection is established, the client-side packet transmission unit 501 compares the packet header length with the transmittable content length in step S3. If the header length of the packet is larger than the transmittable content length, the communication connection is disconnected in step S4, and the communication connection is reestablished in step S2. On the other hand, if it is determined in step S3 that the length of the packet header is smaller than the transmittable content length, the process proceeds to step S5.

  In step S5, it is determined that the maximum packet length, which is the maximum data length that can be encapsulated in one packet, is greater than the data length of the packet, and in step S6, the transmittable content length is greater than the sum of the packet header length and the data length. If determined to be larger, the client side packet transmission means 501 transmits a data packet having the data length of the packet to the HTTP tunneling server in step S7. Further, in step S8, the client-side packet transmission unit 501 stores the transmittable content length obtained by subtracting the packet header length and the data length from the transmittable content length in the client-side setting data storage unit 510.

  On the other hand, if it is determined in step S5 that the maximum packet length is smaller than the data length of the packet, and it is determined in step S11 that the transmittable content length is smaller than the sum of the packet header length and the data length, then in step S12 the client The side packet transmitting means 501 transmits a packet of data having the maximum packet length to the HTTP tunneling server. Further, in step S13, the client-side packet transmission unit 501 obtains the transmittable content length obtained by subtracting the packet header length and the maximum packet length from the transmittable content length, and the data length obtained by subtracting the maximum packet length from the packet data length. The data is stored in the client side setting data storage unit 510. Next, the client-side packet transmission unit 501 proceeds to step S1, confirms whether the communication path is established, and transmits the next data.

  If it is determined in step S5 that the maximum packet length is larger than the data length of the packet and it is determined in step S6 that the transmittable content length is smaller than the sum of the packet header length and the data length, or in step S5 the maximum packet length If it is determined that the length of the packet is smaller than the data length of the packet and it is determined in step S11 that the transmittable content length is greater than the sum of the header length of the packet and the data length, then in step S9, the client side packet transmission means 501 A packet of data having a size obtained by subtracting the header length of the packet from the possible content length is transmitted to the HTTP tunneling server. Further, in step S10, the client side packet transmission unit 501 stores the data length obtained by subtracting the transmittable content length from the data length and adding the header length in the client side setting data storage unit 510. Thereafter, the process proceeds to step S4, where the client side packet transmission means 501 disconnects the communication path and re-establishes the communication path.

  The packet transmitted in steps S7, S9, and S12 in FIG. 5 has fields as shown in FIG. Specifically, this packet includes a sequence number of a packet transmitted from the HTTP tunnel client, an acknowledgment number that is a sequence number of the packet transmitted from the HTTP tunnel client, a data length of the packet, and data.

(Packet transmission from HTTP tunnel client to HTTP tunneling server)
Next, referring to FIG. 7, the packet transmission processing in steps S7, S9 and S12 of FIG. 5 will be described in detail. Specifically, any one of the data packet of the data length of the packet from the client application 6, the data packet of the maximum packet length, and the data packet of a size obtained by subtracting the header length of the packet from the transmittable content length is received. A case of being transmitted to the HTTP tunneling server 1 will be described.

  First, in step S201, the client-side data transmission unit 505 creates a packet and inputs the packet to the client-side packet transmission unit 501. The client-side packet transmission means 501 stores the packet in association with the first sequence number in the client-side packet storage unit 511 of the storage device that can be read by the client device 7. The first sequence number is a sequence number of a packet transmitted from the HTTP tunnel client 5.

  Next, in step S 202, the packet identifier (the packet storage location identifier stored in the client-side packet storage unit 511, the packet pointer, the packet identifier such as the packet name) is input to the client-side retransmission management unit 506. , Wait for a response.

  When the packet identifier is input, the client-side retransmission management unit 506 receives from the client-side setting data storage unit 510 the first sequence number and the first confirmation response that is the sequence number of the packet transmitted from the server device. The first sequence number and the first acknowledgment number are written in the packet and stored in the client side packet storage unit 511. At this time, the client-side retransmission management unit 506 increments the first sequence number stored in the client-side setting data storage unit 510. Further, the client side communication path management unit 502 inputs a response to step S202 to the client side packet transmission unit 501 in step S203.

  Next, the client-side packet transmission unit 501 reads the packet from the client-side packet storage unit 511 in step S204, transmits the packet to the server-side packet reception unit 204 of the HTTP tunneling server 1, and in step S205, the step S201. To the client side data transmission means 505.

  When the packet is received from the client side packet transmitting unit 501 of the HTTP tunnel client 5 in step S204, the server side packet receiving unit 204 stores the packet in the server side packet storage unit 211, and in step S206, the identifier of the packet is stored on the server side. Input to the retransmission management means 202.

  When the packet identifier is input, the server-side retransmission management unit 202 reads the first sequence number of the packet, sets the first sequence number to the second confirmation response number, and stores it in the server-side setting data storage unit 210. In addition to storing the packet, the server-side packet storage unit 211 deletes the packet associated with a number lower than the first acknowledgment number of the packet. Further, the server side retransmission management unit 202 inputs a response to step S206 to the server side packet receiving unit 204 in step S207.

  When a response is input, the server-side packet receiving unit 204 extracts data from the packet, and in step S208, inputs data to the server-side data transmitting unit 201 and waits for a response.

  When data is input, the server-side data transmission unit 201 transmits this data to the server apparatus 2 in step S209 and inputs a response to step S208 to the server-side packet reception unit 204 in step S210.

(Communication connection re-establishment process)
Next, with reference to FIG. 8, the communication path re-establishment process in step S2 of FIG. 5 will be described in detail.

  First, in step S301, the client-side communication path management unit 502 designates POST in the HTTP method field, designates the maximum content length that the gateway can communicate in the content length field, and designates the connection ID in the request body field. A request is generated, and this HTTP request is input to the server side communication path management means 206 of the HTTP tunneling server 1. When an HTTP request is input, the server-side communication path management unit 206 searches the server-side setting data storage unit 210 to search for connection information using the connection ID as a key. In step S302, an HTTP response to step S301 is sent to the HTTP tunnel. Input to the client-side communication path management means 502 of the client 5.

  When the HTTP response is input, the client side channel management unit 502 notifies that the client side retransmission management unit 506 is reconnected in step S303, and in step S304, the client side retransmission management unit 506 Therefore, all the packets stored in the client side packet storage unit 511 are input to the client side packet transmission unit 501. The client side packet transmission unit 501 transmits the input packet to the server side packet reception unit 204 of the HTTP tunneling server 1.

  On the other hand, when the connection information is retrieved, the server-side communication path management unit 206 notifies the server-side retransmission management unit 202 that the connection has been reconnected in step S305, and in step S306, the server-side retransmission management unit 202 All packets stored in the server-side packet storage unit 211 are input to the server-side packet transmission unit 205 for retransmission. The server side packet transmission unit 205 transmits the input packet to the client side packet reception unit 504 of the HTTP tunnel client 5.

(Data transmission from server device to client device)
Next, a data transmission process from the server apparatus 2 to the client apparatus 7 will be described with reference to FIG.

  In step S401, when data to be sent from the server apparatus 2 to the client apparatus 7 is input to the server-side data receiving means 203 of the HTTP tunneling server 1, the server-side data receiving means 203 stores the server-side setting data storage in step S203. When the maximum packet length is read from the unit 210 and the data is larger than the maximum packet length, data having the maximum packet length is read from the data and written to the packet. This process is repeated until all the data to be sent is sent, and the packets created here are processed in the following steps S402 to S408.

  When the packet is generated, the server side data receiving unit 203 inputs this packet to the server side packet transmitting unit 205 in step S402, and the server side packet transmitting unit 205 associates the server side packet with the second sequence number. Store in the storage unit 211. The second sequence number is a sequence number of a packet transmitted from the HTTP tunneling server 1. Further, the server-side packet transmission unit 205 inputs the packet identifier to the server-side retransmission management unit 202 in step S403.

  The server-side retransmission management unit 202 reads the second sequence number and the second acknowledgment number that is the sequence number of the packet transmitted from the client device from the server-side setting data storage unit 210, and the second sequence number The number and the second confirmation response number are written in the packet and stored in the server-side packet storage unit 211. Further, the server side retransmission management unit 202 inputs a response to step S403 to the server side packet transmission unit 205 in step S404. At this time, the server-side retransmission management unit 202 increments the second sequence number and stores it in the server-side setting data storage unit 210.

  When the response is input, the server-side packet transmission unit 205 reads the server-side packet storage unit 211 and transmits the packet to the client-side packet reception unit 504 of the HTTP tunnel client 5 in step S405.

  When the packet is received, the client side packet receiving unit 504 stores the received packet in the client side packet storage unit 511 and inputs the packet identifier to the client side retransmission management unit 506 in step S406.

  When the packet identifier is input, the client-side retransmission management unit 506 reads the second sequence number of the packet, sets the second sequence number to the first acknowledgment number, and stores it in the client-side setting data storage unit 510. At the same time, the packet associated with a lower number than the second acknowledgment number of the packet is deleted from the client side packet storage unit 511. Further, the client side retransmission management unit 506 inputs a response to step S406 to the client side packet receiving unit 504.

  When the response is input, the client side packet receiving unit 504 extracts data from the packet, and inputs the data to the client side data receiving unit 507 in step S408. The client-side data receiving unit 507 stores data until the client application 6 receives the data.

  As described above, according to the communication system according to the preferred embodiment of the present invention, in a network in which only HTTP communication is permitted by a firewall or an HTTP proxy server, a line using the HTTP POST method is created. And real-time bi-directional communication between servers. At this time, in the HTTP request, the maximum content length allowed in the communication system is specified in the content length field, and the data to be transmitted is divided into packets that do not exceed the maximum content length, thereby performing real-time communication. be able to. At this time, as long as the maximum content length is not exceeded, communication can be performed by one HTTP request.

  Furthermore, according to the communication system according to the preferred embodiment of the present invention, when the maximum content length is exceeded by the HTTP POST method, the line is connected by a new POST method including a connection ID for identifying this communication connection. Thus, communication can be continued.

(Other embodiments)
As described above, the present invention has been described according to the best mode for carrying out the invention. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples, and operational techniques will be apparent to those skilled in the art.

  It goes without saying that the present invention includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

1 is a system configuration diagram of a communication system according to a best embodiment of the present invention. It is a sequence diagram explaining the outline of the communication method which concerns on the best embodiment of this invention. It is a hardware block diagram of the HTTP tunneling server which concerns on the best embodiment of this invention. It is a figure explaining the connection start process in the communication system which concerns on the best embodiment of this invention. It is a flowchart explaining the process which transmits data from a client in the communication system which concerns on the best embodiment of this invention. It is a figure explaining the packet transmitted / received between an HTTP tunnel client and an HTTP tunneling server in the communication system which concerns on the best embodiment of this invention. It is a sequence diagram explaining the process which transmits a packet to an HTTP tunneling server from an HTTP tunnel client in the communication system which concerns on the best embodiment of this invention. It is a sequence diagram explaining the process which reconnects a communication connection in the communication system which concerns on the best embodiment of this invention. It is a sequence diagram explaining the process which transmits a packet from an HTTP tunneling server to an HTTP tunnel client in the communication system which concerns on the best embodiment of this invention. It is a sequence diagram explaining the conventional communication system. (Part 1) It is a sequence diagram explaining the conventional communication system. (Part 2)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... HTTP tunneling server 2 ... Server apparatus 3 ... Firewall 4 ... Proxy server 5 ... HTTP tunnel client 6 ... Client application 7 ... Client apparatus 101 ... Central processing control apparatus 102 ... ROM
103 ... RAM
DESCRIPTION OF SYMBOLS 104 ... Input device 105 ... Display device 106 ... Communication control device 107 ... Storage device 108 ... Removable disk 109 ... Input / output interface 110 ... Bus 201 ... Server side data transmission means 202 ... Server side retransmission management means 203 ... Server side data reception means 204: Server side packet reception means 205 ... Server side packet transmission means 206 ... Server side communication path management means 207 ... Server side connection start means 210 ... Server side setting data storage section 211 ... Server side packet storage section 501 ... Client side packet transmission Means 502 ... Client side communication path management means 503 ... Client side connection start means 504 ... Client side packet reception means 505 ... Client side data transmission means 506 ... Client side retransmission management means 507 ... Client side data Receiving means 510 ... client side setting data storage unit 511 ... client side packet storage unit

Claims (8)

A server device, a client device that requests processing to the server device and communicates by HTTP, a gateway that is connected to the client device and allows only HTTP communication, and is connected between the gateway and the server device to perform HTTP communication. In a communication method used for a communication system including an HTTP tunneling server to be realized,
A step of generating server connection information including a host identifier and a port number of a server device that is a connection destination of a communication connection by the client device;
The client device generates an HTTP request in which POST is specified in the HTTP method field, the maximum content length that the gateway can communicate in is specified in the content length field, and the server connection information is specified in the request body field. An HTTP request is sent to the HTTP tunneling server;
The HTTP tunneling server reads the request body field of the HTTP request and establishes a communication connection with the server device included in the connection information;
A connection ID for identifying the connected communication is numbered by the HTTP tunneling server, and the connection ID and the connection information are stored in a server-side setting data storage unit of a storage device readable by the HTTP tunneling server. Associated and stored steps;
When an HTTP response is received from the server device by the HTTP tunneling server, the HTTP response and the connection ID are transmitted to the client device;
Calculating a transmittable content length obtained by subtracting a data length of the HTTP request body field of the HTTP request from the maximum content length by the client device;
The client device includes the step of storing the transmittable content length and the connection information in association with each other in a client-side setting data storage unit of a storage device readable by the client device ,
When transmitting a packet from the client device to the server device, the client device
Checking whether a communication connection with the server device is established, and if not, the step of re-establishing the communication connection;
When it is confirmed that the communication connection is established, if the header length of the packet is larger than the transmittable content length, the communication connection is disconnected and the communication connection is re-established.
It is determined that the length of the packet header is smaller than the transmittable content length,
When the maximum packet length, which is the maximum data length that can be encapsulated in one packet, is larger than the data length of the packet, and the transmittable content length is larger than the sum of the header length and the data length of the packet, The data packet of the data length of the packet is transmitted to the HTTP tunneling server, and the transmittable content length obtained by subtracting the header length and the data length of the packet from the transmittable content length is the client side Steps stored in the setting data storage unit;
When the maximum packet length is the data length of the packet is small and the transmittable content length is smaller than the sum of the header length and the data length of the packet, the data packet of the maximum packet length is the HTTP The packet is transmitted to a tunneling server, and the transmittable content length obtained by subtracting the header length and the maximum packet length of the packet from the transmittable content length, and the maximum packet length is subtracted from the data length of the packet. Storing the data length in the client-side setting data storage unit;
When the maximum packet length is larger than the data length of the packet and the transmittable content length is smaller than the sum of the packet header length and the data length, or the maximum packet length is smaller than the packet data length, When the transmittable content length is larger than the sum of the header length and the data length of the packet, a packet of data having a size obtained by subtracting the header length of the packet from the transmittable content length is the HTTP tunneling. The data length that is transmitted to the server and subtracts the transmittable content length from the data length and adds the header length is stored in the client-side setting data storage unit
The communication method according to claim 1, further comprising: Confirming that a communication connection with the server device has been established, if not, the step of re-establishing the communication connection,
The client device designates POST in the HTTP method field, designates the maximum content length that the gateway can communicate in the content length field, and designates an HTTP request in which the connection ID is designated in the request body field. Steps sent to the tunneling server;
The HTTP tunneling server retrieves the connection information from the server-side setting data storage unit using the connection ID as a key;
When the connection information is retrieved, a communication connection with the client device is reestablished by transmitting an HTTP response to the client device by the HTTP tunneling server. The communication method according to claim 1 . When the HTTP response is transmitted to the client device, a packet stored for retransmission by the client device is transmitted to the HTTP tunneling server;
The communication method according to claim 2 , further comprising: when the communication connection is re-established, the HTTP tunneling server transmits a packet stored for retransmission to the client device. . Any one of the data packet of the data length of the packet, the data packet of the maximum packet length, and the data packet of a size obtained by subtracting the header length of the packet from the transmittable content length is the HTTP tunneling. When sent to the server,
The packet is generated by the client device and the packet generated for retransmission is stored in association with a first sequence number in a client-side packet storage unit of a storage device readable by the client device. Steps,
The client device reads out the first sequence number and a first acknowledgment number that is a sequence number of a packet transmitted from the server device from the client side setting data storage unit, and The sequence number and the first acknowledgment number are written to the packet;
The client apparatus further includes the step of incrementing the first sequence number and storing the incremented first sequence number in the client-side setting data storage unit, and transmitting the packet to the HTTP tunneling server. Item 4. The communication method according to Item 3 . When the packet is received by the HTTP tunneling server, the HTTP tunneling server reads the first sequence number of the packet, and a second acknowledgment number in which the first sequence number is set is obtained. And further comprising the step of deleting a packet associated with a number lower than the first acknowledgment number of the packet from the server-side packet storage unit while being stored in the server-side setting data storage unit. The communication method according to claim 4 . When data is transmitted from the server device to the HTTP tunneling server, the HTTP tunneling server reads the maximum packet length from the server side setting data storage unit, and the data is larger than the maximum packet length, the data The maximum packet length data is read from, written to the packet, and stored in the server-side packet storage unit in association with the second sequence number;
The HTTP tunneling server reads the second sequence number and a second acknowledgment number that is a sequence number of a packet transmitted from the client device from the server-side setting data storage unit, and A sequence number of 2 and the second acknowledgment number are written to the packet;
The second tunnel number is incremented by the HTTP tunneling server and stored in the server-side setting data storage unit, and the packet is transmitted to the client device. The communication method according to 1. When the packet is received by the client device, the second sequence number of the packet is read by the client device, and the first acknowledgment number in which the second sequence number is set is the client. The method further comprises: deleting a packet stored in the side setting data storage unit and associated with a number lower than the second acknowledgment number of the packet from the client side packet storage unit. 6. The communication method according to 6 . A server device, a client device that requests processing to the server device and communicates by HTTP, a gateway that is connected to the client device and allows only HTTP communication, and is connected between the gateway and the server device to perform HTTP communication. In a communication system comprising an HTTP tunneling server to be realized,
Generate server connection information including the host identifier and port number of the server device that is the connection destination of the communication connection,
Specify HTTP in the HTTP method field, specify the maximum content length that the gateway can communicate in the content length field, generate an HTTP request specifying the server connection information in the request body field, and send the HTTP request to the HTTP tunneling To the server,
When an HTTP response and a connection ID are transmitted from the HTTP tunneling server, a transmittable content length is calculated by subtracting the data length of the HTTP request body field of the HTTP request from the maximum content length,
A client device that stores the transmittable content length and the connection information in association with each other in a client-side setting data storage unit of the readable storage device;
When the HTTP request is received from the client device, the request body field of the HTTP request is read, a communication connection is established with the server device included in the connection information,
Numbering a connection ID for identifying the connected communication, and storing the connection ID and the connection information in association with each other in a server-side setting data storage unit of a readable storage device,
An HTTP tunneling server that transmits the HTTP response and the connection ID to the client device when an HTTP response is received from the server device ;
When transmitting a packet from the client device to the server device, the client device
Check if the communication connection with the server device is established, if not, re-establish the communication connection,
When it is confirmed that the communication connection is established, if the header length of the packet is larger than the transmittable content length, the communication connection is disconnected and the communication connection is re-established.
Determining that the packet header length is less than the transmittable content length;
When the maximum packet length, which is the maximum data length that can be encapsulated in one packet, is larger than the data length of the packet, and the transmittable content length is larger than the sum of the header length and the data length of the packet, The client sets the transmittable content length obtained by subtracting the header length and the data length of the packet from the transmittable content length while transmitting the data packet of the data length to the HTTP tunneling server. Store in the data storage unit,
When the maximum packet length is the data length of the packet is small and the transmittable content length is smaller than the sum of the header length and the data length of the packet, the packet of the data with the maximum packet length is the HTTP packet And transmitting to the tunneling server, the transmittable content length obtained by subtracting the header length and the maximum packet length of the packet from the transmittable content length, and the maximum packet length subtracted from the data length of the packet. The data length is stored in the client side setting data storage unit,
When the maximum packet length is larger than the data length of the packet and the transmittable content length is smaller than the sum of the packet header length and the data length, or the maximum packet length is smaller than the packet data length, When the transmittable content length is larger than the sum of the header length and the data length of the packet, a packet of data having a size obtained by subtracting the header length of the packet from the transmittable content length is the HTTP tunneling. The communication is transmitted to the server, and the data length obtained by subtracting the transmittable content length from the data length and adding the header length is stored in the client side setting data storage unit. system.

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