CN101465791A - Document transmission method based on unidirection link - Google Patents

Abstract

The invention discloses a file transmission method based on a one-way link, which is used for transmitting the same file to multiple users in a one-way transmission network. This method uses the file attribute table to describe the file structure, file attributes, transmission segmentation parameters and other information of the data service, and generates data slices of uniform length by slicing the files to be transmitted. If the last piece is insufficient, it is supplemented with 0x00, and then encapsulated according to the data piece The syntax is packaged into a data slice package, and the data block is verified to form a check block next to the data block, and then the check block is segmented and packaged into a check slice package, followed by the corresponding data slice package for transmission. The terminal first receives and parses the file attribute table, and then completely restores locally the file and directory structure consistent with the originator according to the information indicated by the file attribute table. The invention simply and effectively realizes the transmission and reception of files in the one-way transmission network, and users can receive file data services conveniently and quickly, thereby greatly satisfying user needs.

Description

A File Transfer Method Based on Unidirectional Link

technical field

The invention belongs to the technical field of communication and broadcasting, and in particular relates to a method for file segmentation, encapsulation and transmission based on unidirectional link transmission.

Background technique

With the rapid development of communication technology and digital technology, users' demands for information resource acquisition and sharing are becoming more and more urgent and diverse. As an important carrier of information, various files, how to transmit them quickly and effectively in the network is an important issue before us.

At present, there are many ways of network transmission of files, such as the more commonly used File Transfer Protocol (File Transfer Protocol, abbreviated as FTP) service, which works in the seventh layer of the Open System Interconnection model (OSI model for short). Layer, on the fourth layer of the Transmission Control Protocol model (Transmission Control Protocol, referred to as the TCP model), that is, the application layer. In this way, the FTP client will go through a well-known "three-way handshake" process before establishing a connection with the server, which provides a reliable guarantee for data transmission. Now, the more widely used peer-to-peer (P2P) transmission, BT (BitTorrent protocol) is also a file transmission method.

However, for a one-way transmission network, such as a broadcast network, where the same file is transmitted to multiple users, there is currently no good solution for file transmission.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for encapsulating and transmitting files based on one-way links. This method divides and transmits the files to be transmitted, and can quickly and effectively realize the file data in the one-way transmission system. transmission.

In order to solve the problems of the technologies described above, the technical solution adopted in the present invention comprises the following steps:

In the first step, the file parameters of the file to be transferred are described as a file attribute table (File Attribute Table, abbreviated as FAT) file;

The second step is to fragment the FAT file according to the needs, and then pack it into a FAT packet for transmission according to the FAT encapsulation syntax;

The third step is to generate file slices of uniform length by fragmenting the files to be transmitted, fill in the last file slice if the length is insufficient, and then pack it into a file slice package according to the file slice encapsulation syntax;

In the fourth step, a plurality of file pieces are formed into a file block, and verified to form a check block following the file block;

The fifth step is to slice the check block according to the needs, and then pack it into a check slice package according to the check slice encapsulation syntax;

The sixth step is to transmit the file slice package and the verification slice package immediately thereafter.

The FAT file describes information such as the file composition, file attributes, and transmission segmentation parameters of the data service, and is described by the Extensible Markup Language (The Extensible Markup Language, abbreviated as XML). According to specific conditions, the present invention can divide a FAT file into n FAT slices, the length of each FAT slice is generally not more than 4095 bytes, and the value of n is usually in the range of 1 to 256. When n is equal to 1, it means no segmentation .

The FAT slice packet includes a FAT header, a FAT payload and CRC_32. Among them, the FAT header includes resource identification, current segment number, update sequence number, encoding type, last segment number and segment length, the FAT payload carries FAT segment data, and CRC_32 is a 32-bit cyclic check bit for verifying the FAT payload.

The file slice package is composed of a file slice header and a file slice payload. The file slice header includes resource identification, block serial number, slice serial number and update serial number; the file slice payload carries the actual file slice.

The syntax encapsulation structure of the verification slice package is the same as that of the file slice package, including the check slice header and the check slice payload. The check piece header includes resource identification, block number, piece number and update number; the check piece payload carries the actual check piece.

The present invention uses the FAT file to describe the file composition, file attributes, and transmission segmentation parameter information of the data service. By performing operations such as segmentation and error correction on the file, it is packaged to form a file package and a check package, thereby simply and effectively realizing the With the transmission and reception in the one-way transmission network, users can receive file data services conveniently and quickly, thereby greatly meeting user needs.

Description of drawings

Figure 1 is a schematic diagram of FAT segmentation;

Fig. 2 is a schematic diagram of the FAT chip packet structure;

Fig. 3 is a schematic diagram of file segmentation;

Fig. 4 is a schematic diagram of file block verification;

Fig. 5 is a schematic diagram of the structure of the file slice/verification slice package;

Fig. 6 is the pattern structural diagram of FAT file root element;

Fig. 7 is the model structural diagram of file path information element data type (abbreviation FDIType);

Fig. 8 is the pattern structural diagram of file attribute information element data type (abbreviation FAIType);

Fig. 9 is a schema structure diagram of a transfer information element data type (TransferInfoType for short);

FIG. 10 is a schema structure diagram of a content information element data type (ContentInfoType for short);

Fig. 11 is a pattern structure diagram of a segmented information element data type (SegmentInfoType for short);

Figure 12 is a schema structure diagram of the FEC information element data type (referred to as FECInfoType);

Fig. 13 is a schema structural diagram of the file information protection element data type (ProtectionInfoType for short);

FIG. 14 is a schema structure diagram of a life cycle element data type (LifePeriod for short).

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

First, define the data service as consisting of several files, the files can be in the same directory or in different directories, and the directory structure can be divided into multiple layers. The present invention uses a File Attribute Table (FAT for short) to describe the file composition, file attributes, and transmission segmentation parameter information of data services. The specific implementation can use the Extensible Markup Language (The Extensible Markup Language, abbreviated as XML) syntax to describe the file attribute table, and the file attribute table itself also forms a file. Before the file sending channel is established, the present invention first generates the FAT file. The terminal first receives and parses the FAT file, and locally restores the same file and directory structure as the source according to the information indicated by the FAT file.

Figure 1 shows a schematic diagram of FAT file segmentation. The present invention divides the FAT file into FAT slices according to the needs, and the serial numbers are 0, 1, ... n-1, n in total, and the value range of n is 1-256. When n is equal to 1, it means no division. FAT files and ordinary files use different encapsulation syntax for split transmission. The terminal can receive the FAT file without prior information.

FIG. 2 is a schematic diagram of the package structure of FAT chips. As shown in the figure, a FAT slice packet consists of a FAT header, a FAT payload, and a CRC_32.

The FAT header includes resource identification, current slice number, update number, encoding type, last slice number and slice length. Among them, the resource identification field is used to identify a FAT file data service; the current slice serial number field is used to indicate the serial number of the current FAT slice, if the FAT file is not fragmented, the value of this field is 0; the update serial number field is used to indicate the current resource If the FAT information changes, this field will be increased by 1 cyclically; the encoding type field is used to indicate the encoding type used by the FAT file; the last segment number field is used to identify the serial number of the last FAT segment, if the FAT file is not fragmented , the value of this field is 0; the slice length field is used to indicate the length of the current FAT slice.

The FAT payload field carries FAT slice data, and its length is indicated by the "slice length" field in the FAT header.

CRC_32 is a 32-bit cyclic check field for checking the FAT payload.

Figure 3 shows a schematic diagram of file segmentation. As shown in the figure, first divide the file into several file pieces of equal length. The length of each file piece generally does not exceed 65535 bytes. If the length of the last file piece is insufficient, it needs to be filled. In this embodiment, 0x00 is used for padding. Of course, Other filling methods can be used. Multiple file slices form a file block. Since the length of a file slice can be long or short, the number of file slices forming a file block is not uniquely determined, but generally it does not exceed 16383. According to the number of file pieces in the file block, it can be divided into two types: A and B. If the number of file pieces is equal, only type A exists. Distinguishing between type A file blocks and type B file blocks helps to achieve verification more easily. File error correction is performed by file block, and the error correction data obtained is called a check block. The check block is divided into several slices, called check slices, whose length is equal to the file slice, and the check slice and the file slice are serially numbered, as shown in Figure 4.

Figure 5 is a schematic diagram of the structure of the file slice/verification slice package. The file slices formed after the file is divided are combined into file blocks, and then the check operation is performed on the file blocks to generate check blocks. Finally, the file blocks and the checksum The blocks are divided and packaged into file slices/verification slice packages. The file slice and verification slice package adopts a unified syntax encapsulation structure, including the file slice/verification slice header and the file slice/verification slice payload.

The file slice/check slice header includes resource identification, block sequence number, slice sequence number and update sequence number. Among them, the resource identification field is used to uniquely identify a file; the block serial number field is used to indicate the serial number of the file block/check block to which the current file slice/check slice belongs; the slice serial number field is used to indicate the current file slice/check slice The sequence number in the file block/check block; the update sequence number field is used to indicate the update sequence number of the current resource.

The file slice/check slice payload carries the actual file slice or check slice, the length of which is specified by the FAT file, and the file slice and check slice are identified by the file slice serial number.

In the one-way link system, the transmitted file data is composed of a series of discrete files. In addition to the data information, each file also has some information describing the attributes of the file, such as file name, length, compression method, etc. The terminal not only It is necessary to receive the data correctly, and also receive the description information of the file attributes, so that the file consistent with the originator can be recovered. The terminal first receives and parses the FAT file, and according to the information indicated by the FAT file, completely restores the file and directory structure locally that is consistent with that of the originator, specifically including the following steps:

In the first step, the user first obtains a FAT file. If the FAT file is not fragmented, the FAT file is a complete FAT file. Fragment serial number" field information is spliced, and analyzed according to the "encoding type" field, and the complete FAT file is recovered;

In the second step, the user obtains the file slice/verification slice through data decapsulation;

In the third step, the user splices the obtained file pieces according to the parameters in the FAT file to obtain file data.

The terminal can receive the FAT file without a priori information, but for the data service file, the terminal must transmit the information according to the segmentation indicated by the FAT file to receive it correctly.

In this embodiment, XML is used to describe the data model of file attributes, and the file attribute data described in XML is an instance generated according to the model. The following is illustrated by the business parameter information example of the present invention:

FIG. 6 is a schema structure diagram of a FAT root element. See Table 1 for the semantic definition of the FAT root element.

Table 1 Root Element Semantics

field Semantics FDI File Path Information Element FAI File Attributes Information Element DefaultFECInfo Default FEC parameter information element MaxVersion The major version number attribute of FAT, if the major version number changes, the terminal needs to rebuild the resource

Correspondence between source identifiers and files. MinVersion For the minor version number attribute of FAT, if only the minor version number changes, the corresponding relationship between the resource identifier and the file remains unchanged.

The file path information element (FDI) describes the file path information, the data type of this element is defined by FDIType, its schema structure is shown in Figure 7, and the semantic definition of FDIType is shown in Table 2.

Table 2 FDIType Semantics

field Semantics DirName path element, describing the path of the file. DirID The path identification element, through which a corresponding relationship can be established with the path element. DirLevel The path level attribute, indicating the level of the file path.

The file attribute information element (FAI) describes file attribute information, and the data type of this element is defined by FAIType, and its schema structure is shown in FIG. 8 . See Table 3 for the semantic definition of FAIType.

Table 3 FAIType Semantics

field Semantics TransferInfo transmit information element ContentInfo content information element SegmentationInfo split information element FECInfo FEC information element ProtectionInfo Protect Information Elements resource_ID The resource identification attribute indicates the file resource corresponding to this FAI element. UpdateIndex The update serial number attribute indicates the update serial number of this FAI element.

The transfer information element (TransferInfo) describes some attribute information related to file transfer. The data type of this element is defined by TransferInfoType, and its schema structure is shown in FIG. 9 . See Table 4 for the semantic definition of TransferInfoType.

Table 4 TransferInfoType Semantics

field Semantics DirID The file path identifier corresponds to the DirID in the FDI element, and the file path relationship can be established according to the identifier. file_name file name life_period life cycle elements

The content information element (ContentInfo) describes some attribute information related to the content of the file. The data type of this element is defined by ContentInfoType, and its schema structure is shown in FIG. 10 . See Table 5 for the semantic definition of ContentInfoType.

Table 5 ContentInfoType Semantics

field Semantics container_file Indicates whether this document is a container

MIME_type File MIME type file_length file original length file_encoding file encoding file_encoding_length The total length of the encoded file MD5_code MD5 code, base64Binary type content_lingual_special Language-dependent content description elements title content title digest abstract keywords Content keywords, different keywords are separated by ';'. lang The attribute of the content description element, indicating language information. private_info Content private information, reserved.

The segmentation information element (SegmentationInfo) describes the segmentation information of the file, and the data type of this element is defined by SegmentationInfoType, and its schema structure diagram is shown in FIG. 11 . See Table 6 for the semantics of SegmentationInfoType.

Table 6 Semantics of SegmentationInfoType

field Semantics slice_length The size of the file slice, in bytes A_block_count Number of Type A file blocks B_block_count Number of Type B Blocks total_block_count The total number of file blocks, equal to the sum of A_block_count and B_block_count. slice_count_for_A Number of file slices in a type A file block slice_count_for_B Number of file slices in a type B file block fec_slice_count_for_A The number of type A file block check slices fec_slice_count_for_B The number of type B file block check slices

The FEC information element (FECInfo) describes the forward error correction information of the file, and FECInfoType is the data type definition of this element, and its schema structure is shown in FIG. 12 . See Table 7 for the semantics of FECInfoType.

Table 7 FECInfoType Semantics

field Semantics algorithm algorithm type

The file protection information element (ProtectionInfo) describes file protection information, and ProtectionInfoType is the data type definition of this element, and its schema structure diagram is shown in FIG. 13 . See Table 8 for the semantics of ProtectionInfoType.

Table 8 ProtectionInfoType Semantics

field Semantics protection_level Protection level, indicating the protection level of the file content. level_description Protection level description, a further description of the protection level of the file content.

The life cycle element (life_period) describes the file life cycle information, and LifePeriod is the data type definition of the element, and its schema structure diagram is shown in FIG. 14 . See Table 9 for the semantics of LifePeriod.

Table 9 LifePeriod Semantics

field Semantics time_unit_indic Time unit indication, indicating the limited time used by the file The time unit indication value is defined as follows: 0: hour 1: day 2: week 3: month show_time Indicates the limited time for file use, and the time period is determined according to the time unit indication. The display time limit is as follows: 0: no use time limit 1~60: 1 time unit to 60 time unit 61~63: reserved

To sum up, the present invention can divide files into equal-length file slices according to requirements and generate corresponding verification slices, so that they are suitable for unidirectional link transmission. Various modifications and variations of the present invention will occur to those skilled in the art. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (9)

1, a kind of document transmission method based on one way link is characterized in that comprising the steps:

The first step is described as file attribute table FAT file with the file parameters of the file of needs transmission;

Second step, as required the FAT file is carried out burst and handle, be packaged into the transmission of FAT sheet bag according to FAT encapsulation grammer again;

The 3rd step generated the file sheet of unified length with the file fragmentation of needs transmission, was filled when last file leaf length is not enough, was packaged into file sheet bag according to file sheet encapsulation grammer again;

In the 4th step,, and it is carried out verification form check block immediately following this blocks of files with some file sheet composing document pieces;

The 5th step, as required check block is carried out burst and handle, be packaged into verification sheet bag according to verification sheet encapsulation grammer again;

The 6th step, transfer files sheet bag and immediately following thereafter verification sheet bag.

2, document transmission method according to claim 1 is characterized in that, the root element semantical definition of described FAT file is as follows:

Field Semantic FDI The file path information element; FAI The file attribute information element; DefaultFECInfo Acquiescence FEC parameter information element; MaxVersion The major release attribute of FAT, if major release changes, terminal need rebuild the corresponding relation of resource identification and file; MinVersion The minor release/point release attribute of FAT, if only there is minor release/point release to change, the corresponding relation of resource identification and file remains unchanged.

3, document transmission method according to claim 2 is characterized in that, the routing information of described file path information element FDI description document, and its semantical definition is as follows:

Field Semantic DirName Path elements, the path of description document; DirID The ID of trace route path element, by this element can and path elements between set up corresponding relation; DirLevel The path-level attribute, the rank of expression file path.

4, document transmission method according to claim 3 is characterized in that, the attribute information of described file attribute information element FAI description document, and its semantical definition is as follows:

Field Semantic TransferInfo The transmission information element; ContentInfo The content information element; SegmentationInfo The carve information element; FECInfo The FEC information element;

ProtectionInfo The protection information element; Resource_ID The resource identification attribute is represented this FAI element corresponding file resource; UpdateIndex Upgrade the sequence number attribute, represent the renewal sequence number of this FAI element.

5, according to any described document transmission method in the claim 1 to 4, it is characterized in that, in described second step, as the case may be, a FAT file division is become n FAT sheet, and the n span is 1～256, and the length of each FAT sheet is no more than 4095 bytes.

6, document transmission method according to claim 5 is characterized in that, described FAT sheet bag comprises FAT packet header, FAT payload and CRC_32;

FAT packet header comprises resource identification, when the anter sequence number, upgrade sequence number, type of coding, rear panel sequence number and leaf length, the FAT payload carries FAT sheet data, CRC_32 is 32 cyclic check positions of the FAT payload being carried out verification.

7, document transmission method according to claim 6 is characterized in that, described file sheet bag is made up of file sheet packet header and file sheet payload; File sheet packet header comprises resource identification, piece sequence number, sheet sequence number and upgrades sequence number; File sheet payload carries actual file sheet;

Described verification sheet bag is made up of verification sheet packet header and verification sheet payload; Verification sheet packet header comprises resource identification, piece sequence number, sheet sequence number and upgrades sequence number; Verification sheet payload carries actual verification sheet.

8, document transmission method according to claim 7 is characterized in that, the equal in length of the length of described verification sheet and file sheet; The sheet sequence number serial number of the sheet sequence number of verification sheet and file sheet.

9, a kind of method that receives according to the file of the described method transmission of claim 8 is characterized in that comprising the steps:

The first step, the user at first obtains the FAT sheet, if the FAT file does not have burst, then this FAT sheet is complete FAT file, if the FAT file is by burst, then splice, and resolve, recover complete FAT file according to " type of coding " field according to " when the anter sequence number " in the FAT sheet packet header and " rear panel sequence number " field information;

In second step, the user obtains file sheet and verification sheet by the data decapsulation;

In the 3rd step, the user is spliced the acquisition file data by parameter in the FAT file to the file sheet that obtains.

Images