JP2008219264A - Data compression and transfer device, data compression and transfer system, data compressing and transferring method, and data compression and transfer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To compress data of a format with a tag of about 1KB into about 1/10 and to establish each of divided data as one piece of completed data. <P>SOLUTION: A data converting part 22 of this data compression and transfer device 2 performs first stage compression that converts a keyword used in a data tag into a code on the basis of a conversion list of a dictionary 23, and subsequently performs second stage compression that applies a data structure of ASN. 1 encode rule to eliminate a start tag symbol, an end tag symbol and a line feed symbol. Thus, a high compression rate is achieved. Further, in the case of having to divide the data, a slot preparing part 26 inserts the start tag symbol and the end tag symbol into a division position determined so as not to separate relevant data. Consequently, each divided data can be established as one piece of completed data, and a receiving side can process the dats even if all of the divided data are not collected. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique for improving transfer efficiency when transferring data.

  By using a satellite link as a communication infrastructure, information communication with a wide range of disaster resistance is possible over a wide area, and application to a service for monitoring disaster information and environmental information is being studied. As a system for monitoring disasters and the environment, it is assumed that a large number of various sensors are used. For example, various sensors and information (sensor information) obtained by the sensors are received and a satellite line is received. It is conceivable to include a gateway device (GW device) that transfers data via the server and a server device that manages sensor information received from the GW device.

  In such a system, the data sent from each sensor is analog numerical type, logical value type, two-dimensional vector type, three-dimensional vector type, average value of a plurality of sampling measurement values, maximum value, maximum change amount, etc. There are various output formats. In order to send and receive such various types of data between the GW device and the server device, the XML format is a highly extensible format that can handle data easily and can accommodate new data structures. It is required to use the tagged format.

There are many algorithms and software (compression tools) for compressing files, and there are also compression techniques specialized for XML files. However, if the file size is not large to some extent, there will be no compression effect, and it will be a huge file The compression takes a considerable amount of time. As shown in the graph of Non-Patent Document 1, the compression efficiency is at a level that can be compressed to about 30% when the XML data size is about 100 KB (Kilo-Byte).
Internet, <http://www-06.ibm.com/jp/developerworks/xml/020705/j_x-matters19.html/>

  In the system in which the sensor information is centrally managed by the server device as described above, it is necessary to collect the sensor information in a timely and efficient manner due to its urgency.

  In order to efficiently transmit a huge amount of sensor information on a fixed-length slot using a satellite line with a small amount of sensor information, how to compress a small XML file How to allocate the compressed data to the fixed-length slots is important.

  With the conventional compression technology, even an XML file of about 100 KB can only be compressed to about 30%, and sensor information of a small size of about 100-several KB (simple information storing sensor ID, type, measurement value, etc.) If this is an XML file, the compression rate will be further reduced. Although it is conceivable to compress the sensor information together to some extent, a huge file requires time for compression. For example, in order to achieve a high compression ratio of 1/10, a size of about several MB is necessary. Since only 1 KB can be processed per second, it is necessary to accumulate about 17 minutes of data, which cannot fulfill the purpose of collecting sensor information in a timely manner.

  In an environment where about 100 sensors are attached to an observation station on a satellite line, each sensor transmits data once a minute, and the XML data of one sensor information is as simple as described above and is about 600 bytes. Then, when all the sensors under the observation station are totaled, data of about 1 KB (100 × 1/60 × 600 bytes) per second is generated.

  On the other hand, in the satellite line, the band of the satellite line is about 1 Kbps because it is necessary to divide the band finely so that thousands of GW apparatuses arranged in the whole country can be used. Therefore, it is necessary for the GW apparatus to compress an XML file of about 1 KB generated in one second to about 1/10 and transmit it through a 1 Kbps satellite line.

  Further, if data having a size larger than the slot size is divided and transmitted in accordance with the slot size, the receiving side cannot process the data until all the divided data are collected. The satellite line is not always communicable, the communication time is allocated to each GW device, and it may be tens of minutes before the GW device transmits one data until the next data is transmitted. As a result, it is necessary that each of the divided data is established as one completed data, and can be read and processed immediately on the receiving side.

  The present invention has been made in view of the above, and an object thereof is to compress data of a small-sized tagged format to about 1/10.

  Another object of the present invention is to establish each of the divided data as completed data.

  The data compression transfer apparatus according to the first aspect of the present invention stores storage means for storing data in a tagged format, and a dictionary in which keywords used for the data tags are associated with corresponding codes. An information structure definition rule that reads out the data from the storage means and converts the keyword in the data into a code based on the dictionary, and defines a data structure that does not require symbols and codes in the converted data And a data conversion unit that deletes the start tag symbol, the end tag symbol, and the line feed code to obtain binary data, and a transmission unit that transmits the binary data to the server device via a network.

  In the present invention, after compression of the first step of converting a keyword used for a data tag into a code, an information structure definition rule is further applied to delete a start tag symbol, an end tag symbol, and a line feed code. A high compression ratio is achieved by performing the second stage compression.

  Here, the information structure definition rule is a rule that defines a data structure that does not require symbols and codes. For example, it is possible to identify each information by size, associate the information and the size, and grasp the entire information in a hierarchical structure so that codes such as tag symbols and line feed codes can be eliminated.

  The data compression and transfer apparatus according to the second aspect of the present invention includes a compression tool for compressing binary data and storage means for storing the compression ratio, and when the size of the binary data is larger than the slot size of the network, When the value obtained by multiplying the size of the binary data by the compression rate is smaller than the size of the slot, the binary data is compressed by the compression tool, and the value obtained by multiplying the size of the binary data by the compression rate is the value of the slot. When the size is larger than the size, with respect to the original data of the binary data, a dividing means for dividing the data by inserting a start tag symbol or an end tag symbol at a division position determined so as not to leave the related data, and the division Repeat the process by the data conversion means and the dividing means for subsequent data. That the repeating unit has, the transmission unit, and transmits the binary data processed by the repeating unit.

  In the present invention, even when binary data is compressed using a compression tool, the data is not smaller than the slot size of the network, and when it is necessary to divide the data, the related data is determined not to be separated. By inserting a start tag symbol or an end tag symbol at the division position, each divided data is established as one tag-formatted data.

  A data compression / transfer system according to a third aspect of the present invention includes a data compression / transfer apparatus and a server apparatus which can communicate with each other via a network, and the data compression / transfer apparatus stores tagged format data. 1 storage means, a first storage means for storing a dictionary that associates a code corresponding to a keyword used for the tag of the data, and the data is read from the first storage means, and the keyword in the data is Convert to code based on dictionary, apply information structure definition rule that defines data structure that does not need symbols and codes to the converted data, delete start tag symbol, end tag symbol, and line feed code to make binary data Data conversion means, and transmission means for transmitting the binary data to a server device via a network, and the server A second storage means for storing a dictionary in which a keyword used for the tag of the data and a code corresponding thereto are stored; and binary data is received from the data compression transfer device and stored in the second storage means Reading the binary data from the second storage means, applying an information structure definition rule to the binary data, inserting a start tag symbol, an end tag symbol, and a line feed code, and converting the code in the data into the dictionary And restoring means for restoring the original data by converting into keywords based on the above.

  In the present invention, binary data compressed by the data compression / transfer apparatus is collected by a server device, and an information tag definition rule is applied to the binary data to insert a start tag symbol, an end tag symbol, and a line feed code. Then, the original data is restored by converting the code in the data into a keyword based on the dictionary.

  In the data compression transfer system according to the fourth aspect of the present invention, the server device extracts a keyword from the data, records the number of appearances for each keyword in the recording means, and ranks them in descending order of the number of appearances. It is characterized by having a dictionary creation means for creating the dictionary by expressing keywords up to 64th by a 1-byte code and expressing keywords by 65th or lower by a 2-byte code.

  In the present invention, the keywords are ranked in descending order of the number of appearances, the keywords up to the top 64 are expressed by a 1-byte code, and the keywords below the 65th are expressed by a 2-byte code. Thus, codes can be assigned in order from keywords with the highest appearance frequency, and even when new keywords are added, the codes corresponding to the keywords can be automatically registered in the dictionary.

  According to a fifth aspect of the present invention, there is provided a data compression / transfer system, wherein the server device converts the keyword of the data into a code using the keyword added / changed by the dictionary creation unit and the code corresponding thereto, Transmission means for collectively transmitting the converted data and the keyword and code used for the conversion to the data compression / transfer apparatus, and the data compression / transfer apparatus receives the keyword received from the server apparatus And updating means for updating the dictionary using the code, and restoring means for restoring the data received from the server device using the updated dictionary.

  In the present invention, the server device transmits the converted data using the added / changed keyword and the corresponding code, and the keyword and the code together to the data compression and transfer device, In the compression transfer device, the latest dictionary can be shared with the server device by updating the dictionary using the received keyword and code. Further, in the data compression / transfer apparatus, various data such as control commands and communication schedules can be used by restoring the data received from the server apparatus using the updated dictionary.

  In a data compression transfer method according to a sixth aspect of the present invention, the data compression transfer device stores the data in the tagged format in storage means, reads the data from the storage means, An information structure definition rule for converting a keyword in the data into a code based on a dictionary that associates a keyword used for a tag with a code corresponding to the keyword, and defining a data structure that does not require a symbol and a code in the converted data. Applying and deleting a start tag symbol, an end tag symbol, and a line feed code to form binary data, and transmitting the binary data to a server device via a network.

  According to a seventh aspect of the present invention, there is provided a data compression / transfer program for causing a data compression / transfer apparatus to store data in a tagged format in a storage means, reading the data from the storage means, and Based on a dictionary that associates keywords used with their corresponding codes, the keywords in the data are converted into codes, and information structure definition rules that define data structures that do not require symbols and codes in the converted data are applied. And deleting the start tag symbol, the end tag symbol, and the line feed code into binary data, and transmitting the binary data to the server device via a network.

  According to the first aspect of the present invention, data of a tagged format having a small size of about 1 KB can be compressed to about 1/10.

  According to the second aspect of the present invention, each of the divided data can be established as one completed data.

  FIG. 1 is a block diagram showing a configuration of a data compression / transfer system according to the present embodiment. As shown in the figure, this system includes a data compression / transfer apparatus 2 that can communicate with the sensor apparatus 1 and a server apparatus 3 that can communicate with the data compression / transfer apparatus 2 via a network. Here, a satellite line 4 is used as an example of this network.

  About 100 sensors 1a, 1b, 1c... Are attached to the sensor device 1, and each sensor transmits data in a tagged format once a minute. As an example, XML format data is handled here.

  A data compression transfer device 2 includes a sensor connection unit 21 that receives data from the sensor device 1 via a network, a data conversion unit that encodes a keyword in the received data, and deletes a tag symbol to convert it into binary data. 22, a dictionary 23 used for keyword code conversion, a dictionary management unit 24 for managing the dictionary 23, a binary data compression unit 25 for further compressing the converted binary data using a compression tool, encoded and binarized and compressed A slot creation unit 26 that packs data into the slot of the satellite line 4, a data transmission / reception unit 27 that transmits data to the server device 3 via the satellite line 4 or receives data from the server device 3, and the server device 3, a compressed data restoration unit 28 that restores the compressed data received from 3 using the dictionary 23 Having a control command processing unit 29 that performs processing such as control commands indicated by the data.

  The data compression transfer device 2 may be a dedicated device, or may be configured using a general-purpose computer, and the processing of each unit may be executed by a program. The data compression / transfer apparatus 2 includes an arithmetic processing device, a storage device, and the like for executing processing of each unit. In the processing in each unit, the necessary information is read from the storage device, and the processed information is stored in the storage device. Remember.

  When this system is applied to a system for monitoring disasters and the environment, the data compression / transfer apparatus 2 can be used as a gateway apparatus that can be installed at thousands of locations nationwide. In this case, a satellite channel band of about 1 Kbps is assigned to each gateway device.

  The server device 3 includes a data transmission / reception unit 31 that transmits / receives compressed binary data to / from the data compression / transfer device 2, a binary data restoration unit 32 that restores compressed binary data, a dictionary 33 that restores a code to a keyword, a dictionary 33, a dictionary management unit 34 that manages the data 33, a compressed data restoration unit 35 that restores the binary data code to the corresponding keyword using the dictionary 33, a data generation / analysis unit 36 that generates and analyzes data, and data that is generated and analyzed Is compressed to transmit data to the data compression transfer device 2, and a dictionary creation unit 38 that learns the correspondence between keywords and codes in data and registers them in the dictionary 33.

  The server device 3 may also be a dedicated device, may be configured using a general-purpose computer, and the processing of each unit may be executed by a program. The server device 3 includes an arithmetic processing device, a storage device, and the like for executing processing of each unit. In the processing of each unit, the server device 3 reads necessary information from the storage device and stores the processed information in the storage device.

  Next, the flow of processing in the data compression / transfer apparatus 2 will be described with reference to the flowchart of FIG.

  First, in the sensor device 1, the measurement information acquired from each sensor is transmitted to the data compression transfer device 2. This measurement information is described in, for example, the XML format shown in FIG.

  In step 1 (shown as “S1” in FIG. 2; the same applies hereinafter), the data compression transfer device 2 receives the XML data from the sensor device 1 through the sensor connection unit 21 and stores it in the storage device.

  In step 2, the data conversion unit 22 encodes the keywords included in the XML data using the dictionary 23, and further applies the data structure of the information structure definition rule to delete the start tag symbol, end tag symbol, and line feed code. To convert to binary data.

  An information structure definition rule defines a data structure that eliminates the need for symbols and codes. For example, each information is specified by size, and the information and size are associated with each other and the entire information is hierarchically structured. Can eliminate the need for tag symbols, line feed codes, and the like. Information structure definition rules include, for example, ASN.1 rules and EBML (Extensible Binary Meta-Language). Here, an ASN.1 rule is used as an example, and in step 2 above, XML data is converted to binary data by applying the ASN.1 encoding rule.

  In order to perform the encoding process in step 2, the dictionary 23 associates the keyword used for the XML tag and the code of the corresponding hexadecimal code on the conversion list as shown in FIG. . The code is 1 byte or 2 bytes, and the conversion list of the dictionary 23 is the same as that of the dictionary 33 in the server device 3.

  The data conversion unit 22 checks whether or not the keyword used for the tag is present in the list of the dictionary 23 against the XML data as shown in FIG. 3A. Replace the keyword with the corresponding code. In the example of FIG. 3A, the keyword “? Xml version =" 1.0 "encoding =" UTF-8 "?" That appears at the beginning of the XML data is searched from the conversion list of FIG. 4 and corresponds to it. Replace with “80”.

  Similarly, other keywords are also replaced with codes to obtain XML data in which keywords as shown in FIG. 3B are all replaced with codes. In the figure, “&” indicates hexadecimal. Through the above encoding process, 382 bytes of data are converted to 163 bytes, and the compression ratio is about 40%.

  The data converter 22 further converts the encoded XML data from the XML structure into a data structure based on the ASN.1 encoding rule, and deletes the start tag symbol, end tag symbol, and line feed code. For reference, FIG. 5 shows a data structure conversion example based on the ASN.1 encoding rule. In this rule, XML data as shown in FIG. 5A is represented by three sets of a tag code, a data size (Length) in the tag, and data (data), as shown in FIG. 5B. The tag code is represented by 1 byte or 2 bytes, and the data size is also represented by 1 byte or 2 bytes. The data size is the size of data after ASN.1 encoding.

  A specific example of ASN.1 encoding is shown in FIG. When the encoded XML data as shown in FIG. 6A is converted based on the ASN.1 encoding rule, binary data as shown in FIG. 6B is obtained. In FIG. 9A, the start tag symbol is indicated by “<>”, the end tag symbol is indicated by “</>”, and these are omitted in FIG. In addition, a line feed code (not shown) is inserted in the part where the line is broken in FIG. 10A, and this is also omitted in FIG.

  In this conversion, for example, the tag “<& 80>” in the first line in FIG. 6A becomes “& 80” in the first byte and “& 18” in the second byte in FIG. 6B. Here, “& 80” is a code code corresponding to the tag character, and “& 18” corresponds to decimal number 24, which means that the data size after conversion by ASN.1 is 24 bytes. As shown in the figure, after converting 163 bytes of XML data, the data becomes 26 bytes in total. In this way, the encoded / binary data is referred to as binary data here.

  In order to distinguish between a code and a non-code, the most significant bit is used as a flag for distinguishing both. Here, if the most significant bit is 0, it is determined that the subsequent character string is a non-binary character string or a data portion other than a tag character. If the most significant bit is 1, since it is not a readable character, it is determined to be a code. At this time, if the code is expressed by the remaining 7 bits, only 128 corresponding keywords can be handled, so that the code can be expressed even by 2 bytes. Therefore, the upper 2 bits are used as a flag for distinguishing whether the Length part is 1 byte or 2 bytes. Specifically, the identification between the 1-byte code and the 2-byte code is performed based on whether the upper 2 bits of the first byte are “10” or “11” as shown in FIG. As a result, a total of 64 codes represented by 1 byte start with “10”, and a total of 16384 codes represented by 2 bytes start with “11”. Details of the identification algorithm are shown in FIG. In FIG. 8, if the data after the Length part is data, it will always be a character. Therefore, if the part is a character, the first bit will never be 1, so the first bit is 1 if it is a tag. It may be recognized as a code, and since the Length part always comes after the tag code, it is assumed that the position of the Length part is also determined.

  Next, XML data division processing will be described.

  FIG. 9 shows a table showing examples of measurement contents and transmission intervals performed by the sensor in Step 1 of FIG. 2, and FIG. 10 shows the timing of the measurement. As shown in FIGS. 9 and 10, each sensor performs a plurality of measurements on a single measurement target data at a sampling period of 10 msec, and the average value, maximum value, minimum value, and change amount average value. Measure the maximum change amount, minimum change amount, and number of zero crossings. These measured values are recorded in a storage device inside the sensor. This process is performed at measurement timings of several seconds. Thereby, the measurement result is sequentially recorded on the sensor at intervals of several seconds. Further, the transmission interval is set at a time interval longer than the measurement timing, and the measurement values recorded in each sensor are collectively transmitted to the sensor device 1 at every transmission interval. The sensor device 1 expresses each received measurement value in the XML format and transmits it to the data compression transfer device 2.

  An example of XML data created by the sensor device 1 is shown in FIG. In this XML data, division positions are determined so that related data does not leave. Specifically, the sensor device 1 adds a “<EOF />” tag as a severable mark at the end of a group of measured values (average, maximum, minimun, zero_cross, etc.). In addition, “<Split>” is inserted at the start portion of the data indicating the measurement result accumulated during the transmission interval, and “</ Split>” is inserted at the end portion thereof. These “<EOF />”, “<Split>”, and “</ Split>” are special tags for dividing XML data.

  Here, each sensor performs the above-described advanced processing. However, it is assumed that the sensor has a function of notifying a measured value for each measurement, and the sensor device 1 performs the above calculation function and accumulation. It is good also as providing a function.

  Subsequently, in step 3 of FIG. 2, the slot creating unit 26 of the data compression / transfer apparatus 2 compares the size of the binary data after encoding / binarization with the size of the slot of the satellite line 4. If it is smaller than the latter, the process proceeds to step 9 to pack binary data into the slot. On the other hand, if the former is larger than the latter, the process proceeds to step 4.

  In step 4, the slot creating unit 26 compares the value obtained by multiplying the size of the binary data by the compression rate by the compression tool with the size of the slot. This compression tool is compression software represented by GZIP, for example, and is stored and managed in a storage device by the binary data compression unit 25. The compression rate is assumed to be 80% -90% and is registered in advance by the user. As a result of comparison, if the value obtained by multiplying the size of binary data by the compression ratio is smaller than the size of the slot, the process proceeds to step 5, and after the binary data is compressed by the compression tool, the process proceeds to step 6. On the other hand, if the value obtained by multiplying the size of the binary data by the compression ratio is larger than the size of the slot, the process proceeds to Steps 7 and 8, and the original XML data of the binary data is divided.

  In step 6, the slot creating unit 26 compares the compressed binary data with the slot size, and if the former is smaller, the process proceeds to step 9 to pack the binary data into the slot. On the other hand, if the former is larger, the process proceeds to steps 7 and 8, and the original XML data of the binary data is divided.

  In step 8, the slot creation unit 26 divides the data by inserting a start tag symbol or an end tag symbol at a division position determined so that related data is not separated from the original XML data of binary data. And the process of the said steps 1-9 is repeated.

  More specifically, it is assumed that the size of the original XML data is 1165 bytes as shown in FIG. 12A and has become 100 bytes by encoding / binarization. Here, if the compression rate of the compression tool registered in advance is 80%, the predicted size of the compressed data is 80 bytes, and if the slot size is 70 bytes, the original data size to be divided is It is obtained by a calculation formula of uncompressed data size × slot size / (compression rate × binary data size), and it can be calculated that the original XML data needs to be 1165 × 70/80 = 1019 bytes or less by dividing.

  In the XML data of FIG. 12A, the division mark “<EOF />” is at the 543rd and 824th bytes. From the viewpoint of reducing the number of divisions as much as possible by dividing at the maximum mark position whose size does not exceed 1019 bytes, here, division is performed at the 824th byte. After this, “</ GetRes>”, “</ KVPTransac>”, “</ Frame>” indicating the end tags displayed after “</ Split>” of the XML data in the latter part of the first half of the divided XML data. Is granted. As a result, the divided data in the first half is as shown in FIG. In addition, a start tag displayed before “<Split>” of the XML data is added to the former stage of the latter half of the divided data. As a result, the divided data in the latter half is as shown in FIG.

  Note that the compression rate of the compression tool may be updated as needed in addition to registering in advance as described above. As a method of updating as needed, the binary data compression unit 25 holds an old value (here, α) as compression rate information in a storage device, and the size of binary data × α ≦ slot size is satisfied. As a result of actual compression, when the size of binary data × α> slot size is satisfied, the value of α is updated to the value of the actual compression rate. Thereafter, in step 7 and subsequent steps in FIG. 2, the division process is performed using the updated compression rate.

  In the server device 3, the data transmission / reception unit 31 receives the compressed binary data sent from the data compression / transfer device 2 and temporarily stores it in the storage device, and then the binary data restoration unit 32 uses a restoration tool. Restore the binary data. The compressed data decompression unit 35 applies the ASN.1 decoding rule to the binary data and inserts a start tag symbol, an end tag symbol, and a line feed code, and then converts the code in the data based on the conversion list of the dictionary 33. Restore original data by converting to keywords.

  Next, the learning function of the dictionary will be described. This is a function of the dictionary creation unit 38 of the server device 3. As a premise, as described with reference to FIG. 7, a keyword used for a tag is represented by a 1-byte or 2-byte code. Since the number that can be expressed by 1 byte is up to 64, the main process of learning is to determine which keyword is expressed by 1 byte and which keyword is expressed by 2 bytes.

  In the server device 3, the compressed data is restored by the binary data restoration unit 32 and the compressed data restoration unit 35 and then transmitted to the dictionary creation unit 38, and the uncompressed data is transmitted to the dictionary creation unit 38 as it is. That is, the original XML data is transmitted to the dictionary creation unit 38. Note that the compressed data restoration unit 35 determines whether received data is compressed data or non-compressed data by using a flag at a predetermined position of the data.

  The dictionary creation unit 38 extracts keywords from the received data, and temporarily stores the number of appearances for each keyword in the storage device. Then, the ranking is performed in descending order of the number of appearances, and the keywords up to the top 64 are represented by 1-byte codes, and the keywords below 65th are represented by 2-byte codes, and these keywords are associated with the codes. Thus, the dictionary 33 is created.

  For example, as shown in FIG. 13, the number of appearances is recorded every 24 hours for the extracted specific keywords, and the number of applications within 24 hours from the present time and the number of appearances that occurred every 24 hours before that are counted. Then, each weight is weighted, and the sum is obtained to obtain an evaluation value. In FIG. 13, the number of appearances is 3, 2, 3, 4 and 4 in order from the present, and the evaluation is made when the weights are 1.0, 0.8, 0.4, 0.2 and 0.1 in order. Indicates that the value is 6.0. The ranking is given in descending order of the evaluation value, and the upper 64 positions are expressed by 1 byte, and the 65th and lower positions are expressed by 2 bytes.

  FIG. 14 shows an example of a conversion list that summarizes the correspondence between keywords, the number of appearances, and codes. In the figure, the keyword “attribData xsi: type =“ java: java.lang.String ”” is 64th and assigned a 1-byte code, and the keyword “MagnetSensorAttribute” is 65th and assigned a 2-byte code. ing. Then, when learning is performed at the stage where the number of appearances shown in the figure is counted, the evaluation value of the keyword “attribData xsi: type =“ java: java.lang.String ”” is 5 × 1.0 + 5 × 0.8 + 5 × 0.6 + 20 × 0.4 + 20 × 0.2 = 24, and the evaluation value of the keyword “MagnetSensorAttribute” is 10 × 1.0 + 10 × 0.8 + 10 × 0.6 + 5 × 0.4 + 5 × 0.2 = 27 Become. As a result, “attribData xsi: type =“ java: java.lang.String ”” is 65th, so it is associated with “& C000” which is a 2-byte code, while “MagnetSensorAttribute” is 64th, so it is a 1-byte code. Corresponds to "& BF". Through the above processing, the rankings of both keywords are reversed, and the dictionary creation unit 38 updates the conversion list of the dictionary 33 with this information.

  Also, as shown in FIG. 14, when a new keyword “AAABBBCCCDDD” appears, if the number of codes after registration has not reached 64 (1 byte) +16384 (2 bytes), the end Is assigned. In the example of the figure, “& C002” is assigned. When the number of registrations is less than 64, allocation to a 1-byte code is performed. Such an evaluation value is calculated every 24 hours, for example. If a new tag is to be compressed from the beginning, the code may be manually registered in advance in the conversion list.

  The dictionary creation unit 38 notifies the dictionary management unit 34 of the conversion list change result and the new assignment result, and the dictionary management unit 34 manages the correspondence between the keyword and the code. Further, the dictionary management unit 34 notifies the latest conversion list to all the data compression / transfer apparatuses 2 via the data transmission / reception unit 31, and each data compression / transfer apparatus 2 updates its own dictionary 23 with the received conversion list. . Thereby, the same dictionary can be used in each data compression transfer device 2 and server device 3. Note that the dictionary management unit 34 may store not only the newly updated dictionary but also the pre-update dictionary without deleting it.

  Next, a process for transmitting data from the server apparatus 3 to the data compression / transfer apparatus 2 will be specifically described.

  The data compression unit 37 of the server device 3 uses the conversion list indicating the correspondence relationship between the keyword and the code added / changed to the dictionary 33 by the dictionary creation unit 38, and performs the same compression method as the data compression / transfer device 2. The XML data keyword is converted into a code. Then, the data transmission / reception unit 31 collects the converted data and the keywords and codes used for the conversion together and transmits them to the data compression / transfer apparatus 2.

  When the server device 3 distributes a control command to the data compression / transfer device 2 and the sensor device 1 under the data compression / transfer device 2, the data compression unit 37 expresses the control command in the XML format as well as the sensor information, and the dictionary 33 Is used to convert a keyword into a code. Then, the data compression unit 37 assigns the keyword and code referred to at this time to the tail of the data, and transmits them to the data transmission / reception unit 31 together.

  In the transmission process in the server device 3, the data to be transmitted is binarized by applying the data structure of the ASN.1 encoding rule, and compressed using a compression tool.

  FIG. 15A shows data indicating an example of keyword code conversion applied at this time, and FIG. 15B shows an example of the structure of the data collectively. The data is in XML format as shown in FIG. 15A, and a compressed control command is inserted between the XML tags “<XMLbody>” and “</ XMLbody>” as shown in FIG. Then, the difference between the referenced conversion list or the previously transmitted dictionary content is inserted between the XML tags “<KeywordRule>” and “</ KeywordRule>”. FIG. 15C shows a specific example of dictionary information inserted between “<KeywordRule>” and “</ KeywordRule>”.

  In FIG. 1, when the data transmitting / receiving unit 31 of the server device 3 transmits data, the data transmitting / receiving unit 27 of the data compression / transfer device 2 receives the data and temporarily stores it in the storage device. Then, the received data is transmitted to the compressed data decompression unit 28. When the data is first compressed by the compression tool, the compressed data restoration unit 28 restores the data using the restoration tool. Then, information inserted between “<KeywordRule>” and “</ KeywordRule>” in the data shown in FIG. 15C is transmitted to the dictionary management unit 24.

  The dictionary management unit 24 uses the code indicated in the “<key>” tag described in the “<record>” tag indicated in the received data, and the character string of the keyword indicated in the “<char>” tag. Are extracted and recorded in the dictionary 23. With this process, the conversion list of the dictionary 23 is updated.

  After the dictionary update processing is completed, the compressed data decompression unit 28 refers to the dictionary 23 and converts the data inserted between “<XMLbody>” and “</ XMLbody>” of the received data into the original XML. Restore to data. FIG. 16C shows an example of the compressed control command, and FIG. 16D shows an example of the restored control command. FIG. 16A is a diagram showing an example of the structure of data to be restored, and FIG. 16B is a diagram showing information in the dictionary portion.

  Therefore, according to the present embodiment, the data compression / transfer apparatus 2 applies the data structure of the ASN.1 encoding rule after the first-stage compression of converting the keyword used for the data tag into the code. Then, by performing the second-stage compression of deleting the start tag symbol, end tag symbol, and line feed code, a high compression rate can be realized. By applying this to a system for monitoring disaster information and environmental information using satellite links, gateway devices are installed in thousands of locations nationwide, and about 100 different sensors are attached to each gateway device. Even if the satellite line bandwidth assigned to 1 is about 1 kbps, it is possible to compress data of a tagged format with a small size such as sensor information to about 1/10.

  According to the present embodiment, in the data compression transfer device 2, when it is necessary to divide data, the start tag symbol and the end tag symbol are inserted at the division positions determined so as not to leave the related data. Thus, each divided data can be established as one completed data, and the receiving side can process the data without collecting all the divided data.

  According to the present embodiment, the dictionary creation unit 38 of the server device 3 ranks the keywords in descending order of appearance, and expresses the keywords up to the top 64 with 1-byte codes. The keyword is expressed by a 2-byte code. Thus, codes can be assigned in order from keywords with the highest appearance frequency, and when new keywords are added, codes corresponding to the keywords can be automatically registered in the dictionary.

  According to the present embodiment, the server device 3 transmits the converted data using the added / changed keyword and code, and the keyword and code together to the data compression / transfer device 2, By updating the dictionary using the received keyword and code in the compression transfer device 2, the data compression transfer device 2 can use the latest dictionary identical to that of the server device 3. In the data compression / transfer apparatus 2, various information such as control commands and communication schedules can be used by restoring the data received from the server apparatus 3 using the updated dictionary.

  In particular, by transmitting the keywords and codes used in the dictionary together at the transmission timing of the control command, it is possible to reduce the number of communications and avoid inconsistencies when compressing / decompressing the control command. .

It is a block diagram which shows the structure of the data compression transfer system in one embodiment. It is a flowchart which shows the flow of a process in a data compression transfer apparatus. FIG. 4A shows an example of XML data before encoding, and FIG. 4B shows an example of data obtained by encoding a keyword of XML data using a dictionary. It is a figure which shows the example of the conversion list which linked | related the keyword and code | symbol used for an XML tag. It is a figure which shows the example of a conversion which converts an XML structure into the data structure based on an ASN.1 encoding rule. 2A shows an example of encoded XML data, and FIG. 2B shows an example of data further compressed by applying the ASN.1 encoding rule to the encoded XML data. It is a figure which shows the flag for identifying 1 byte code | symbol and 2 byte code | symbol. It is a figure which shows the algorithm for identifying 1 byte code and 2 byte code. It is a table | surface which shows the measurement content by a sensor, a transmission interval, etc. It is a figure which shows the timing of the measurement by a sensor. It is a figure which shows the example of the data which expressed the value which the sensor measured in the XML format. It is a figure which shows the example which divides | segments XML data, The figure (a) shows the XML data before a division | segmentation, The figure (b), (c) shows the XML data after a division | segmentation. It is a figure which shows the example of calculation of the evaluation value in dictionary learning. It is a figure which shows the example of the conversion list which put together the correspondence of the keyword used for a dictionary, the frequency | count of appearance, and a code | symbol. FIG. 4A shows an example of keyword code conversion for data transmitted from the server device, FIG. 4B shows an example of the structure of the data grouped together, and FIG. An example of the dictionary information part is shown. FIG. 4A shows an example of the structure of data to be restored, FIG. 4B shows an example of the dictionary portion thereof, FIG. 4C shows an example of a compressed control command, and FIG. 4D shows restored control. It is a figure which shows the example of a command, respectively.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Sensor apparatus 1a, 1b, 1c ... Sensor 2 ... Data compression transfer apparatus 3 ... Server apparatus 4 ... Satellite line 21 ... Sensor connection part 22 ... Data conversion part 23 ... Dictionary 24 ... Dictionary management part 25 ... Binary data compression part 26 ... Slot creation unit 27 ... Data transmission / reception unit 28 ... Compressed data restoration unit 29 ... Control command processing unit 31 ... Data transmission / reception unit 32 ... Binary data restoration unit 33 ... Dictionary 34 ... Dictionary management unit 35 ... Compressed data restoration unit 36 ... Data generation・ Analysis unit 37 ... Data compression unit 38 ... Dictionary creation unit

Claims (7)

Storage means for storing tagged data,
Storage means for storing a dictionary in which a keyword used for the tag of the data is associated with a code corresponding to the keyword;
Start by applying the information structure definition rule that reads the data from the storage means, converts the keyword in the data into a code based on the dictionary, and defines a data structure that does not require symbols and codes in the converted data Data conversion means that deletes the tag symbol, end tag symbol, and line feed code to make binary data,
Transmitting means for transmitting the binary data to a server device via a network;
A data compression transfer apparatus characterized by comprising: A compression tool for compressing binary data and storage means for storing the compression ratio;
When the size of the binary data is larger than the size of the slot of the network, when the value obtained by multiplying the size of the binary data by the compression rate is smaller than the size of the slot, the binary data is compressed by the compression tool; When the value obtained by multiplying the size of the binary data by the compression rate is larger than the size of the slot, the original tag data of the binary data is set to a start tag symbol or a division position determined so as not to leave the related data. A dividing means for dividing the data by inserting an end tag symbol;
Repetitive means for repeating the processing by the data conversion means and the dividing means for the divided data,
2. The data compression transfer apparatus according to claim 1, wherein the transmission unit transmits the binary data processed by the repetition unit. A data compression and transfer system comprising a data compression and transfer device and a server device that can communicate with each other via a network,
The data compression transfer device
First storage means for storing tagged format data;
First storage means for storing a dictionary in which a keyword used for a tag of the data is associated with a corresponding code;
Read the data from the first storage means, convert a keyword in the data into a code based on the dictionary, and start applying an information structure definition rule that defines a data structure that does not require symbols and codes in the converted data Data conversion means that deletes the tag symbol, end tag symbol, and line feed code to make binary data,
Transmission means for transmitting the binary data to a server device via a network,
The server device
Second storage means for storing a dictionary in which a keyword used for the tag of the data is associated with a code corresponding to the keyword;
Receiving means for receiving binary data from the data compression transfer device and storing it in a second storage means;
Reading the binary data from the second storage means, applying an information structure definition rule to the binary data, inserting a start tag symbol, an end tag symbol, and a line feed code, and using the code in the data as a keyword based on the dictionary A restoration means for restoring the original data by converting,
A data compression and transfer system comprising: The server device
The keywords are extracted from the data, the number of appearances is recorded in the recording means for each keyword, and the ranking is performed in descending order of the number of appearances. 4. The data compression and transfer system according to claim 3, further comprising dictionary creation means for creating the dictionary by expressing the keyword by a 2-byte code. The server device
Conversion means for converting the keyword of the data into a code using the keyword added / changed by the dictionary creation means and the code corresponding thereto;
Transmission means for collectively sending the converted data and the keywords and codes used for the conversion to the data compression transfer device,
The data compression transfer device
Updating means for updating the dictionary using the keyword and code received from the server device;
Restoring means for restoring the data received from the server device using the updated dictionary;
5. The data compression transfer system according to claim 4, further comprising: By the data compression transfer device,
Storing the data in the tagged format in a storage means;
The data is read from the storage means, the keyword in the data is converted into a code based on a dictionary that associates the keyword used for the tag of the data and the code corresponding thereto, and the converted data is converted to a symbol and code. Applying an information structure definition rule that defines data structures that do not need to be deleted and removing the start tag symbol, end tag symbol, and line feed code to make binary data,
Transmitting the binary data to a server device via a network;
A data compression transfer method characterized by comprising: For data compression transfer equipment
Storing data in a tagged format in a storage means;
The data is read from the storage means, the keyword in the data is converted into a code based on a dictionary that associates the keyword used for the tag of the data and the code corresponding thereto, and the converted data is converted to a symbol and code. Applying an information structure definition rule that defines a data structure that does not need to delete the start tag symbol, end tag symbol, and line feed code to make binary data,
Transmitting the binary data to a server device via a network;
A data compression and transfer program characterized in that

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