JP4709060B2 - COMMUNICATION DEVICE, COMMUNICATION DEVICE CONTROL METHOD, AND PROGRAM - Google Patents

Description

The present invention relates to a communication apparatus that communicate via a network stream data such as packetized video and audio information, about the control method and program of the communication device.

  In the communication system using the Internet protocol (IP), two communication protocols generally known as RFC (Transmission Control Protocol) known as RFC793 and UDP (User Datagram Protocol) known as RFC768 are used. (For example, refer to Patent Document 1). Since this communication protocol is usually used on the IP layer and operates in close cooperation with the IP layer, it is generally called TCP / IP or UDP / IP.

TCP / IP is a connection-oriented protocol. In other words, this is a protocol that performs data communication after establishing a connection between a client and a server, and performs communication while performing retransmission when a transmission error occurs based on a sequence number. Therefore, it is possible to transmit without error. On the other hand, UDP / IP is a connectionless protocol. In other words, it is a protocol with a small overhead that is used for the purpose of efficiently transferring data and does not define a retransmission procedure. When multimedia data such as voice and images is transmitted in real time, UDP / IP is used. When non-real time transmission is performed, it is desirable that error-free data is transmitted. Therefore, TCP / IP is generally used.
JP 2004-80145 A

  However, the data communication system found in the above-mentioned conventional example has a problem that twice the bandwidth is required to communicate the same data contents with respect to the two protocols TCP / IP and UDP / IP.

  That is, for example, when recording while monitoring video data in real time, it is desirable to transmit using UDP / IP that minimizes delay for real-time image display on the monitor, and error-free for information to be recorded. For this reason, there is a case of transmission using TCP / IP. In such a case, since each piece of information is transmitted through a separate connection, twice the bandwidth of the information source is required.

In view of the above-described conventional problems, an object of the present invention is to efficiently use a transmission band by transmitting data used for different processing in one packet. Another object of the present invention is to enable data retransmission while transmitting data that prioritizes data arrival time .

The communication device according to claim 1 includes: a first generation unit configured to generate a data arrival time priority type packet in which a data arrival time priority type protocol header is added to data; and a data accuracy priority type protocol header as data. Second generation means for generating a given data accuracy priority type packet; and third generation means for generating a encapsulation packet in which a header of the data arrival time priority type protocol is added to the data accuracy priority type packet; A transmission unit that transmits the encapsulation packet generated by the third generation unit to a communication partner, and the transmission unit retransmits the data included in the encapsulation packet transmitted by the transmission unit, and transmitting the data arrival time-priority packet and the data accuracy-priority packets separately

A communication apparatus according to claim 3 includes: a first processing means for processing data included in a data arrival time priority type packet in which a header of a data arrival time priority type protocol is attached to data; and a data accuracy priority type protocol. Second processing means for processing data included in a data accuracy priority type packet in which the header of the data is attached to the data, and a encapsulation packet in which the header of the data arrival time priority type protocol is added to the data accuracy priority type packet. Receiving means for receiving, and generating means for generating the data arrival time priority packet and the data accuracy priority packet based on data included in the encapsulation packet received by the receiving means, 1 processing means is included in the data arrival time priority type packet generated by the generation means Processes over data, the second processing means, characterized in that processing the data contained in the data accuracy-priority packet generated by the generating means.

According to the present invention, when data transmitted once included in a capsuling packet is retransmitted, the data arrival time is prioritized by separately transmitting the data arrival time priority packet and the accuracy priority packet. Data can be retransmitted while transmitting data. In addition, the transmission band can be used efficiently by receiving data used in both the processing giving priority to the data accuracy and the processing giving priority to the data arrival time in one packet .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
<System configuration>
FIG. 1 is a block diagram showing a configuration example of a data communication system according to the first embodiment of the present invention.

  In this data communication system, a station A as a receiving device and a station B as a transmitting device are connected to a network using the transmission path 113 as a medium. It is assumed that communication of stream data is executed between these stations using a data arrival time priority type protocol (UDP / IP) and a data accuracy priority type protocol (TCP / IP).

  Station A includes a video recorder 104 that is a recording device, a recording application processing device 106 that is a recording application thereof, a monitor 103 that is an image receiving device, and a display application processing device 105 that is an image receiving application processing device. In addition, the station B includes an imaging apparatus 101 and a camera application processing apparatus 102 that is the imaging application processing apparatus.

  More specifically, in the station A, the monitor 103 displays the image information (stream data) obtained by the imaging device 101 of the communication partner in real time. Furthermore, the video recorder 104 records the image information of the imaging device of the communication partner. In the station B, the imaging apparatus 101 converts an image captured using the imaging element into a digital image and passes it to the application processing apparatus. In addition, the camera application processing apparatus 102 performs communication destination designation, imaging apparatus control, transport layer control, and the like on the digitized image data through a user interface.

  Also, reference numeral 105 in FIG. 1 denotes a display application processing apparatus that controls the monitor 103 and the UDP layer. A recording application processing apparatus 106 controls the video recorder 104 and the TCP layer. Reference numeral 107A denotes a UDP protocol apparatus that generates and analyzes a UDP layer, and reference numeral 108A denotes a TCP protocol apparatus that generates and analyzes a TCP layer. 109A is a UDP-TCP protocol device that receives the output of the protocol devices 107A and 108A and encapsulates the TCP packet by UDP. 110A is an IP protocol device that generates and analyzes an IP layer, 111A is a MAC device that generates and analyzes an Ethernet (registered trademark) frame, and 112A is a PHY device that performs modulation and demodulation to the physical layer. Stations B are provided with apparatuses 107B to 112B having the same functions as the apparatuses 107A to 112A.

<System communication procedure>
Next, a communication procedure of the data communication system configured as described above will be described with reference to FIGS.

  FIG. 2 is a sequence diagram showing a communication procedure of stations A and B configured as shown in FIG. 1, and FIG. 3 shows a reception process of stream data composed of packets of station A which is a receiving apparatus according to the present embodiment. It is a flowchart.

  In FIG. 2, first, in the station B, in order to transmit image information (stream data) captured by the image capturing apparatus 101 to the station A using UDP / IP, a transmission instruction such as a port number and an IP address is captured by the imaging application process. To device 102. This transmission instruction information is given from station A. Then, the stream data generated by the imaging apparatus 101 is sent to the imaging application processing apparatus 102, and the generated information is sent to the UDP protocol apparatus 107B together with the instructed port number and IP address (S401 in FIG. 2).

  During transmission, the UDP protocol device 107B generates a UDP header. Since the UDP port number is designated from the imaging application processing apparatus 102, the generated UDP packet is subsequently sent to the IP protocol apparatus 110B. Then, an IP header is added, and a UDP / IP packet having a format as shown in FIG. 4 is generated. At this time, “Source IP Address” describes “IP Address” of station A, and “Destination IP Address” describes “IP Address” of station B. The MAC device 111B further adds an Ether header (not shown) to the UDP / IP packet, and after modulation by the PHY device 112B, the packet is output to the transmission path 113.

  On the other hand, a packet that is stream data received by the station A is demodulated and the Ether header is removed from the MAC layer by the PHY device 112A and the MAC device 111A. Then, the IP protocol device 110A confirms that “Destination IP Address” is the own station in the IP layer. Further, the IP protocol device 110A determines whether a protocol other than UDP is operating based on the protocol type written in the protocol field of the IP header (S701 in FIG. 3). For example, if TCP is operating, TCP layer processing is performed by the TCP protocol device 108A (S707). If UDP is operating, the UDP layer processing by the UDP protocol device 107A and the UDP-TCP layer processing by the UDP-TCP protocol device 109A are performed. At this time, if the port number addressed to the station A is a UDP packet defined by UDP, the UDP protocol device A107 performs processing in the UDP layer (S708). On the other hand, if the port number is defined by UDP-TCP, the UDP-TCP protocol device 109A performs processing in the UDP-TCP layer (S703).

  The UDP protocol device 107A removes the UDP header of the packet, and sends the data from which the header has been removed to the display application device 105. Thereby, the stream data generated by the imaging apparatus 101 is sent to the monitor 103 (S402). On the other hand, when the UDP-TCP port is designated, the UDP-TCP protocol device 109A decomposes the packet into two packets of a UDP packet and a TCP packet (S703). Then, the UDP-TCP protocol device 109A reconstructs the header of the UDP packet by re-adjusting the UDP packet length and the checksum (S704). Then, the UDP-TCP protocol device 109A adds a payload to make a UDP packet (S705), and sends the UDP packet to the UDP protocol device 107A. Further, the UDP-TCP protocol device 109A reconstructs a TCP packet with the TCP header and payload (S706), and sends the TCP packet to the TCP protocol device 108A.

  In this way, one UDP-TCP packet is disassembled into two ports, sent to each protocol processing layer, and processing of each application is performed.

<Detailed operation of stations A and B in each protocol processing>
Next, detailed operations of the stations A and B in each protocol processing of TCP / IP, UDP / IP, and UDP-TCP / IP will be described.

  It is assumed that a connection request is generated from the TCP protocol device 108B in a state where image information (stream data) is transferred from the station B to A using UDP / IP (S403). Then, in order to establish a connection between the stations A and B, a so-called three-way handshake is performed. The three-way handshake procedure is as follows.

  (1) S403: A TCP packet (hereinafter referred to as a SYN packet) in which the SYN flag is set to “1” is transmitted from the station B.

  (2) S404: As a response when the station A receives the SYN packet, S405: transmits a TCP packet (hereinafter, SYN-ACK packet) with the SYN flag and the ACK flag set to the station B.

  (3) S406 and S407: Upon reception of the SYN-ACK packet, a TCP packet (hereinafter referred to as an ACK packet) with an ACK flag set is sent from station B to station A.

  Through the above steps, the connection between the stations A and B is established (S408). The connection establishment by TCP is also notified to the application processing apparatuses of stations A and B, so that transmission of image information (stream data) that has been performed only by UDP / IP is also started by TCP / IP. (S413).

  Next, the operation when the same stream data is transmitted by TCP / IP and UDP / IP will be described with reference to FIG.

  FIG. 5 is an operation process flowchart of the station B, which is a transmission apparatus, showing an operation when the same stream data is transmitted by TCP / IP and UDP / IP.

  In the previous S408, a three-way handshake is established and a TCP connection is established. In this state, it is assumed that the camera application processing apparatus 102 requests the UDP protocol apparatus 107B and the TCP protocol apparatus 108B to transmit UDP / IP and TCP / IP (S409). Then, each packet created by the UDP protocol device 107B and the TCP protocol device 108B is given a unique value indicating UDP-TCP as a port number and sent to the UDP-TCP protocol device 109B.

  In S603 and S605, the UDP-TCP protocol device 109B determines whether the packet generated by the TCP protocol device 108B is the latest and can be transmitted. If the packet generated by the TCP protocol device 108B is the latest and cannot be transmitted, the packet generated by the UDP protocol device is output to the IP protocol device 110B and transmitted by UDP / IP (S604). Since the datagram that could not be transmitted via the UDP-TCP protocol device 109B could not be transmitted by TCP / IP, the data is accumulated in the memory of the TCP protocol device 108B and queued (S608). Then, when the TCP / IP connection can be transmitted, the queued data is transmitted (S609).

  On the other hand, when it is determined in S603 and S605 that the packet generated by the TCP protocol device 108B can be transmitted, the UDP-TCP protocol device 109B reconstructs the packet as a UDP-TCP packet. The format of the UDP-TCP packet is shown in FIG. As shown in FIG. 6, the UDP-TCP packet has a structure in which a TCP packet is encapsulated with a UDP header. Since the UDP header is newly included in the datagram as the UDP packet, the UDP-TCP protocol device 109B recalculates the checksum and the UDP data length, and reconstructs the header (S606). Then, the IP protocol device 110B adds an IP header and sends a UDP-TCP / IP packet (S607).

  As described above, the UDP-TCP packet sent to the transmission path 113 is in a state in which only the UDP packet or the UDP-TCP packet is recognized by the result of the analysis of the IP header in the station A as the receiving apparatus. Therefore, the packet excluding the IP header is transmitted to the UDP-TCP protocol device 109A and the UDP protocol device 107A via the IP protocol device 110A. Since the UDP-TCP packet has a predetermined port number, the UDP-TCP packet sent to the UDP protocol device 107A is discarded.

  The UDP-TCP packet sent to the UDP-TCP protocol device 109A analyzes the UDP header and the port number of the TCP header, confirms that it is a UDP-TCP packet, and reconstructs the UDP packet and the TCP packet. In the reconstruction of the TCP packet, the UDP-TCP protocol device 109A removes the UDP header from the UDP-TCP packet to form a TCP packet, which is then sent to the TCP protocol device 108A (S411 in FIG. 2). In the reconstruction of the UDP packet, the UDP-TCP protocol device 109A removes the TCP header, changes the checksum and the UDP data length, and creates a new UDP header. Then, it is sent to the UDP protocol device 107A (S410).

  The TCP protocol device 108A sends an ACK packet to the station B, which is a transmission device, for confirmation of reception, and the station B completes a series of transmission upon receipt of the ACK packet. Thereafter, each time transmission data is generated, the UDP packet and the TCP packet are transmitted as a UDP-TCP packet, thereby halving the data transmission band.

  Next, an operation in a problem such as retransmission due to a transmission error will be described with reference to FIG.

  FIG. 7 is a sequence diagram when a UDP-TCP packet is retransmitted.

  First, in step S901, a UDP-TCP packet is transmitted, and an ACK packet corresponding to the TCP packet has also arrived. That is, the stream data is transmitted without any problem. Next, it is assumed that the UDP-TCP packet is lost before it reaches the station A due to a network problem (S902).

  Next, the transmitted UDP-TCP packet arrives at station A which is a receiving apparatus. Then, the TCP protocol device 108A knows that the packet has arrived discontinuously because the “Sequence Number” in the TCP header is discontinuous (S903). Then, the station A immediately transmits an ACK packet and notifies the station B that there is a lost packet (S904). Then, the station B immediately retransmits the lost packet by TCP / IP (S905).

  In S906, when sending of stream data is instructed from the camera application processing apparatus 102, transmission may not be possible with TCP / IP. In that case, the stream data is transmitted by UDP / IP (S906). When the station B completes the retransmission and confirms the reception of the ACK packet (S907), the station B can send it again as a UDP-TCP packet in the next data transmission instruction (S908).

  Transmission of TCP packets is also suppressed when an ACK packet is not transmitted due to some state of the network or station. In this case, the stream data is transmitted as a UDP packet instead of UDP-TCP. A sequence of this processing is shown in FIG. FIG. 8 is a sequence diagram when TCP congestion control by UDP-TCP operates.

  In FIG. 8, in S1001, since station B has not received an ACK packet, stream data is transmitted as a UDP packet. In S1002, the station B transmits the stream data by TCP / IP in response to the reception of the ACK packet. In S1003, the station B confirms that the transmission of the untransmitted TCP packet is completed by receiving the ACK packet. In S1004, transmission is performed using UDP-TCP.

<Advantages of the first embodiment>
According to the present embodiment, the station B which is a transmitting apparatus transmits and transmits the TCP by UDP, and the station A which is a receiving apparatus is provided with a distribution unit block which distributes to sockets suitable for each purpose. did. That is, prior to UDP-TCP / IP communication, a TCP / IP connection is first established between station A and station B. In the station B, when the same stream data is sent by UDP / IP and TCP / IP, packet information corresponding to each protocol is sent to the UDP-TCP protocol device 109B. Then, the UDP-TCP protocol device 109B encapsulates the TCP packet with the UDP packet and transmits it. In the station A, the UDP-TCP protocol device 109A serving as a UDP-TCP distribution unit sends the data to the protocol devices 107A and 108A, and outputs them to 105 and 106 which are output to the application processing device. Since transmission / retransmission of ACK packets necessary only for TCP / IP is not necessary for UDP / IP, transmission / reception is performed using normal TCP / IP packets. Further, when TCP transmission is restricted on the transmission side for TCP / IP bandwidth control, transmission is performed only with UDP / IP.

  In this way, in the case where the same stream data is transmitted using UDP / IP and TCP / IP having different properties, a packet format called UDP-TCP obtained by encapsulating TCP with UDP is defined and processed. Thus, conventionally, data divided and sent twice can be transmitted as a single UDP-TCP packet, and the transmission band can be used efficiently. In addition, compatibility with conventional protocols can be maintained while performing data communication with a minimum amount of traffic.

[Second Embodiment]
FIG. 9 is a block diagram showing a configuration example of a data communication system including a data communication apparatus according to the second embodiment of the present invention.

  In this data communication system, a station A including a recording application processing apparatus 106, a station B including a display application processing apparatus 105, and a station C including an imaging application processing apparatus 102 are respectively connected to a network using the transmission path 113 as a medium. It is connected.

  In order to operate in the same manner as in the first embodiment, the packet generated and transmitted by the imaging application processing apparatus 102 of the station C is imaged on the monitor 103 at the station B while being recorded in an error-free manner at the station A. It is necessary to display an image. For this reason, normal UDP-TCP packets cannot be transmitted simultaneously.

  Therefore, simultaneous transmission is performed to a plurality of destinations by using multicast. Multicast uses an IP address called class D, and only allows transmission and reception of UDP packets. As shown in FIG. 10, the IP address of class D is an IP address starting with 1101..., And is in the range of 224, 0, 0, 0 to 239, 255, 255, 255 in decimal notation. It is an IP address. A set of stations belonging to these classes D is called a host group and can be distributed and arranged in a plurality of networks. It is possible to belong to a member of a host group who has acquired a class D IP address in addition to an IP address indicating itself to each station, or to leave the station. IGMP (Internet Group Management Protocol) is used as a protocol for managing such multicast host groups.

  Using this protocol reveals the client of the multicast datagram, so this protocol is used to determine whether the datagram belongs to the host group to which the station belongs, and the router uses the interface for routing. Used to judge. By transferring only to necessary interfaces, unnecessary traffic can be reduced.

  The multicast transmission side can transmit a message to a specific host group by transmitting the acquired class D IP address (host group) using UDP / IP. The receiving side can receive a multicast datagram by joining the host group, and can leave the host group by leaving.

  In IGMP, a message called a membership query, in which a router inquires a multicast member to the network, can be output, and in response to this, a message that a host joins or leaves a host group can be output as a membership report.

  A router that controls multicast using these membership queries and membership reports maintains and manages the host groups of stations participating in the multicast. When UDP-TCP is transferred using this class D multicast address, a UDP / IP host is allowed to participate in multiple units using multicast, but a host using UDP / IP establishes a connection. Only one vehicle is allowed to participate.

  Therefore, TCP / IP is encapsulated with UDP / IP as shown in the UDP-TCP packet format in FIG. 11 to establish a TCP connection for a specific unicast IP address, and multiple TCP / IP clients participate. The configuration is not possible. This is to prevent error retransmission type communication from being allowed to occur over a plurality of connections, so that when the state of the transmission path deteriorates, retransmissions increase and the network is likely to be congested.

  By configuring as described above, it is possible to simultaneously transmit from the station C including one imaging application 102 to the station A including one recording application and the station B including a plurality of display applications.

  Note that an object of the present invention is to supply a storage medium recording program codes for realizing the functions of the embodiments to the stations A and B, and to read and execute the program codes by the system or the computer of the apparatus. Is also achieved.

  In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the program code and the storage medium storing the program code constitute the present invention.

  As a storage medium for supplying the program code, for example, a hard disk, a magneto-optical disk, a CD-ROM, a CD-R, or a CD-RW can be used. Further, a DVD-ROM, a DVD-RAM, a DVD-RW, a DVD + RW, a magnetic tape, a non-volatile memory card, a ROM, or the like can be used. Alternatively, the program code may be downloaded via a network.

  The present invention not only realizes the functions of the above-described embodiments by executing the program code read by the computer, but also includes the following cases. That is, an OS (operating system) running on a computer performs part or all of the actual processing based on an instruction of the program code, and the functions of the above-described embodiments may be realized by the processing. included.

  Further, after the program code read from the storage medium is written to the function expansion unit, the CPU of the function expansion unit performs actual processing based on the instruction of the program code, and the above-described implementation is performed by the processing. The case where the function of the form is realized is also included.

  In this case, the program is supplied by downloading directly from a storage medium storing the program or from another computer or database (not shown) connected to the Internet, a commercial network, a local area network, or the like.

It is a block diagram which shows the structural example of the data communication system containing the data communication apparatus which concerns on 1st Embodiment. It is a sequence diagram which shows the communication procedure of the data communication system of a structure of FIG. It is a flowchart which shows a packet reception process. It is a format diagram of a UDP / IP packet. It is a flowchart which shows the operation | movement in the case of transmitting the same data by TCP / IP and UDP / IP. It is a format figure of a UDP-TCP packet. It is a sequence diagram when packet retransmission by UDP-TCP occurs. It is a sequence diagram when TCP congestion control by UDP-TCP operates. It is a block diagram which shows the structural example of the data communication system containing the data communication apparatus which concerns on 2nd Embodiment. It is a format diagram of an IGMP message. This is a UDP-TCP packet format using multicast.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Imaging device 102 Camera application 103 Monitor 104 Video recorder 105 Display application 106 Recording application 107 UDP protocol apparatus 108 TCP protocol apparatus 109 UDP-TCP protocol apparatus 110 IP protocol apparatus 111 MAC apparatus 112 PHY apparatus 113 Transmission path

Claims (10)

A communication device,
First generation means for generating a data arrival time priority type packet in which a header of a data arrival time priority type protocol is attached to data;
Second generation means for generating a data accuracy priority type packet in which a data accuracy priority type protocol header is added to the data;
Third generation means for generating a encapsulation packet in which a header of the data arrival time priority type protocol is added to the data accuracy priority type packet;
Transmission means for transmitting the encapsulation packet generated by the third generation means to a communication partner;
The transmission means transmits the data arrival time priority type packet and the data accuracy priority type packet separately when retransmitting the data included in the encapsulation packet transmitted by the transmission means. . When the transmission unit retransmits the data included in the encapsulation packet transmitted by the transmission unit, the data arrival priority packet including the data accuracy priority packet including the data and the data arrival including other data different from the data The communication apparatus according to claim 1, wherein the time-priority packet is transmitted separately. A communication device,
First processing means for processing data included in a data arrival time priority type packet in which a data arrival time priority type protocol header is attached to the data;
A second processing means for processing data included in a data accuracy priority type packet in which a header of a data accuracy priority type protocol is attached to the data;
Receiving means for receiving a encapsulation packet in which a header of the data arrival time priority type protocol is added to the data accuracy priority type packet;
Generating means for generating the data arrival time priority packet and the data accuracy priority packet based on the data included in the encapsulation packet received by the reception means;
The first processing means processes data included in the data arrival time priority type packet generated by the generation means, and the second processing means is the data accuracy priority type generated by the generation means. A communication apparatus that processes data included in a packet. When the transmission source of the encapsulation packet resends the data included in the encapsulation packet, the reception unit receives the data arrival time priority type packet and the data accuracy priority type packet from the transmission source separately. The communication apparatus according to claim 3. The encapsulated packet is a communication device according to any one of claims 1 to 4, characterized in that a packet encapsulates a TCP packet with UDP. Wherein the data arrival time-priority protocol of the communication device according to any one of claims 1 to 5, characterized in that a UDP protocol. The data accuracy-priority protocol of the communication apparatus according to item 1 or claims 1 to 6 noise, characterized in that it is a TC P protocols. A communication device control method executed by a communication device, comprising:
A first generation step of generating a data arrival time priority type packet in which a data arrival time priority type protocol header is added to data;
A second generation step of generating a data accuracy priority type packet in which a data accuracy priority type protocol header is added to the data;
A third generation step of generating a encapsulation packet in which a header of the data arrival time priority type protocol is added to the data accuracy priority type packet;
A transmission step of transmitting the encapsulation packet generated in the third generation step to a communication partner;
A retransmission step of separately transmitting the data arrival time priority packet and the data accuracy priority packet when retransmitting data included in the encapsulation packet transmitted in the transmission step. A method for controlling a communication device. A communication device control method executed by a communication device, comprising:
A receiving step of receiving a encapsulation packet in which a header of a data arrival time priority type protocol is attached to a data accuracy priority type packet in which a header of a data accuracy priority type protocol is attached to data;
Based on the data included in the encapsulation packet received in the reception step, the data accuracy priority type packet and the data arrival time priority type packet in which the header of the data arrival time priority type protocol is attached to the data are generated. Generating step to
A first processing step of processing data included in the data arrival time priority type packet generated by the generation step;
And a second processing step of processing data included in the data accuracy priority type packet generated by the generation step. The program for operating a computer as a communication apparatus of any one of Claims 1 thru | or 7.

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