Classifications

• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
  • H03M7/00—Conversion of a code where information is represented by a given sequence or number of digits to a code where the same, similar or subset of information is represented by a different sequence or number of digits
  • H03M7/30—Compression; Expansion; Suppression of unnecessary data, e.g. redundancy reduction

Definitions

• Compression method decompression method, compression unit, decompression unit and compressed document
• the invention relates to the compression and decompression of structured documents, in particular a compression method, a decompression method, a compression unit and a decompression unit and a compressed document, for example in binary form.
• structured documents For several years, information has been presented using structured documents.
• a well-known standard for presenting structured documents is XML (XML-En- rich Markup Language) from W3C (W3C - World Wide Web Consortium).
• XML XML-En- rich Markup Language
• W3C W3C - World Wide Web Consortium
• This provides information in many applications and devices.
• configuration data for initializing terminals such as e.g. Mobile telephones or plant modules are provided with structured documents.
• structured documents for the description of multimedia content, as used for example in the standard SVG (SVG - Scalable Vector Graphic).
• Structured documents have the disadvantage that a data volume required for storage or transmission is large. Therefore, compression methods have been developed that can reduce the data volume of structured documents.
• GZIP GZIP - GNU ZIP
• BIM BIM MPEG MPEG
• EXI Efficient XML Interchange
• Invention to provide an associated decompression method and a decompression unit.
• the invention relates to a compression method for compressing a structured document, wherein the structured document has at least one information unit that instantiates at least one information unit of one type of a predetermined structure rule, the structural rule comprises a first base type and a second base type, the first base type for Representation of at least one character, the type has a data field represented by the at least one first base type, and a structure of the data field is determined by a regular expression, a predetermined compression method can compress the structured document into a compressed document in which the following steps are performed:
• the inventors have recognized that compression of data represented by the first base type string results in a poor compression rate. This is based on the recognition that the first base type only achieves a poor compression rate due to a large number of characters that it can represent.
• the information element generated by instantiation of a type based on the first base type has a character string in the data field defined by the first base type.
• An improvement in the compression rate can be achieved by dividing the character string into at least one section that can be compressed with a second base type different from the first base type.
• the structure of the data field is based on a regular expression, for example in BNF (BNF - Backus-Naur form), whereby, by analyzing the regular expression, at least part of this regular expression can be assigned to one or more non-first base types.
• BNF BNF - Backus-Naur form
• the regular expression explicitly specifies the structure and the possible contents of the data field or the at least one section, so that the at least one part can be assigned to one of the non-first base types without running the risk of possible contents of the section can not be represented by the selected second base types.
• Another advantage of the compression method is that decompression of the structured document makes it possible to use the predetermined decompression method, since the compression of the sections is carried out exclusively on predetermined base types of the structural specification by means of the predetermined compression method.
• the first and second base types are different base types.
• the predetermined compression method can take into account the structural rule when performing the compression.
• two parts of the regular section and two sections of the at least one information unit are determined, wherein the two sections are based on the respective part of the regular expression, the two sections are combined into a new section, and the new section of the predetermined compression method is compressed on the basis of the predetermined compression rule for the second base type. This achieves a further increase in the compression rate by combining two or more sections into a new section.
• a new type based on the basic types may be formed instead of the at least one information unit forming a first number of new information units, this first number corresponding to a second number of parts and the new information units based on the corresponding new types are instantiated and assigned the sections corresponding to the parts.
• each of the parts of the regular expression is assigned its own type based on predefined base types of the structure rule.
• a content assignment such as the date of the day, the month or the year, is possible.
• the compression rate can be increased further, because due to the content assignment a value range of a respective part and thus an associated section is known.
• this value range can only include the natural numbers 1 to 31.
• the basic type when assigning basic types, the basic type must be selected which encompasses both the entire range of values and achieves the highest compression rate for the range of values to be covered.
• At least one of the sections can be attached (before its compression, an identifier which compresses the code to be compressed). identified section.
• the identifier may be formed on the basis of the portion of the regular section underlying the respective section.
• the formation of the identifier is advantageously feasible by the evaluation of the parts of the regular expression.
• the regular expression has a so-called "day,” such as day, month, or year, that can be directly adopted as an identifier, which simplifies the process of creating the identifier.
• the structure rule is defined by the standard XML, where
• the at least one information unit is an XML element or XML attribute
• the structured document is an XML document
• the base types are formed from a set of XML types built-in primitive types and built-in derived types.
• the present method can also be used when using an XML-based structured document. Especially the XML standard is very widespread, so that in particular for this purpose, a great economic benefit in using the invention comes to light.
• a compression unit for compressing a structured document is part of the invention, wherein the structured document has at least one information unit that instantiates at least one information unit of one type of a predetermined structure rule, the structural rule specifies a first base type and a second basic types, the first basic type is used to represent at least one character, the type has a data field represented by the at least one first basic type, and a structure of the data field is determined by a regular expression, a predetermined compression method incorporates the structured document compressed compressed document, where the compression unit has the following center:
• second means for determining a respective portion of the at least one information unit based on the respective part of the regular expression;
• the compression unit has the same advantages as the compression method.
• the compression unit further comprises a fourth means adapted to carry out the above-mentioned method steps of the compression method.
• the compression unit has the same advantages as the developments of the compression method.
• a decompression method for decompressing a compressed document is part of the invention, wherein a structured document has been compressed into the compressed document according to one of the above-mentioned method steps of the compression method, the structured document comprises at least one information unit comprising at least one information unit of one type of a predetermined structure specification instantiated, the structural specification comprises a first base type and a second base type, the first basic type is used to represent at least one character, the type has a data field represented by the at least one first base type and a structure of the data field is determined by a regular expression, a predetermined decompression method can decompress the compressed document, in the following Steps to be performed:
• the decompression method takes advantage of the compression method in decompressing the compressed document.
• the respective section is assigned to the at least one information unit, the respective section being based on the respective part of the regular expression. This can be used to create a reconstructed structured document.
• the decompression method two parts of the regular expression can be determined, the new portion obtained by decompressing is divided into two sections based on the two parts so that each of the sections is assigned one of the parts.
• an increased compression rate can be achieved.
• a new type is formed for each of the parts on the basis of the basic types, instead of the at least one information unit a first number of new information units on the basis of Decompression is formed, this first number corresponds to a second number of parts and the new information units are instantiated on the basis of the new types corresponding to the respective parts and occupied with the sections corresponding to the parts, which are reconstructed by decompression.
• the advantage here is analogous to the description of the corresponding compression method.
• Improving the legibility of sections can be achieved in the context of the decompression method by assigning at least one of the sections an identifier which identifies the at least one section. This can be accomplished, in particular, by forming the identifier on the basis of the part of the regular expression underlying the respective section.
• the structure rule is defined by the standard XML, where
• the at least one information unit is an XML element or XML attribute
• the structured document is an XML document
• the base types are formed from a set of XML types built-in primitive types and built-in derived types.
• the decompression method can also be used in one of the most common XML standards.
• the decompression method can be developed in such a way that, before the decompression step, it is decided based on the at least one part of the regular expression whether the section corresponding to the at least one part is based on the respective predetermined decompression rule for the first base type or for the first second basic types.
• This variant allows a simple implementation of the decompression method, since the structural rule is not to change.
• the decompression method takes advantage of the compression method in decompressing the compressed document. It should be noted that, depending on an implementation, the assignment of a section obtained by decompression to the respective information unit represents a development, since the section can be directly taken over by a further processing unit, for example, to display information on a screen.
• a further advantage of the decompression method is that the decompression of the compressed document can be carried out using the predefined decompression method, since the compression of the sections has been carried out exclusively on predefined base types of the structural rule by means of the predetermined compression method. Furthermore, the predetermined decompression method can be carried out on the basis of the structural rule and / or the parts of the regular expression, whereby an adaptation of the specified decompression rule to the specific circumstances of the structural rule and / or the parts of the regular expression can be taken into account.
• the invention relates to a decompression unit for decompressing a compressed document, wherein a structured document is compressed into the compressed document with the aid of the compression unit, the structured document having at least one information unit that instantiates at least one information unit of a type of a predetermined structure rule Structural rule comprises a first base type and a second base type, the first base type is used to represent at least one character, the type has a data field represented by the at least one first base type and a structure of the data field is determined by a regular expression by predetermined decompression method decompresses the compressed document in which the decompression unit has the following means:
• the decompression unit has the same advantages as the decompression method.
• the compression unit further comprises a sixth means, which is designed such that at least one of the method steps is executable according to the decompression method.
• the decompression unit has the same advantages as the developments of the decompression method.
• a compressed document also forms part of the invention, being able to be generated according to one of the method steps of the compression method.
• the compressed document for example in the form of a binary file or a data stream, has a higher compression rate than known compression methods.
• a further advantage of the compressed document is that the decompression of the compressed document can be carried out using the given decompression method, since the compression of the sections was carried out exclusively on predetermined base types of the structural specification by means of the predetermined compression method. Thus, a cost effective implementation of the invention is made possible.
• Figure IA An XML element with a string based on the SVG language
• Figure IB Visual representation of the XML element with a string based on the SVG language, according to
• FIG. 2 Comparison of Compression Rates of the EXI
• FIG. 3 Structure of a compression unit for performing the compression method
• Figure 4 Structure of a system comprising the compression unit, a decompression unit for performing a decompression method and a storage unit for storing a compressed document.
• a date can be defined using a regular expression RA [1] as follows:
• a character string generated from the above regular expression for a date is "23.03.2009”.
• a structured document DOC [2] has one or more information units ELE, ATT.
• XML [3], standardized by W3C, is one of the most well-known representatives for the definition of structured documents.
• information units formed by elements and attributes.
• the structure of the structured document is specified by a structure rule SYN, which specifies TYP types in addition to the syntax.
• the structure rule is known, for example, as a schema or DTD (Document Type Definition).
• the information units are generated by instantiation of the types.
• the structure rule specifies several basic types for different functions. Thus, a first base type (BTSTR) is provided for recording or displaying one or more characters.
• BTSTR first base type
• base types are referred to as built-in primitive types and built-in derived types, where the first base type in XML is defined as "string.”
• a second base type, BTINT may be given to hold non-negative integers XML this is, for example, the base type "nonNegativelnteger”.
• type TYP typeDate in the form of a string as
• Table 2 Type typeDate defined in XML using the first base type String
• CM structured document compression method
• CM such as MPEG-MPEG (Motion Picture Expert Group) or W3C's EXI (Efficient XML Interchange) standard BIM (BIM)
• a first part ETA of the regular expression RA is determined such that this first part can be represented by the second base type BTINT.
• the regular expression two digits are found at the beginning, each with a number between 0 and 9 ([0-9] ⁇ 2, 2 ⁇ ). This gives a number between 0 and 99. If it were known that this number represents the day of a date, the number could be restricted to a value range between 1 and 31.
• the second base type "nonNegativelnteger" allows a representation of non-negative numbers of 0, 1, etc.
• the first part ETA [0-9] ⁇ 2,2 ⁇
• parts of the regular expression as a number, [0-9] ⁇ 2,2 ⁇ and [0-9] ⁇ 4,4 ⁇ , and it can be seen that there is one character between each of the number-recognizable parts of the regular expression "Colon" occurs.
• the predetermined compression method CM based on a predetermined compression rule CMBTINT for the second base type BTINT can at least partially compress the datum instead of as a string in several sections. This is done from the structured Document the information unit present there, so the XML element date, according to the above determined parts analyzed whereby corresponding parts EAS, EAT, EAU are found to the parts.
• the following table shows the corresponding parts and sections as well as the basic types underlying each section:
• the regular expression still has additional information that can be taken into account during compression.
• Table 8 Document definition in XML for the extended regular expression date
• the information units to be intoned are given a respective name day, month, year as identification.
• This respective identifier is the extended regular expression according to Table 6 removable. In English, the technical term for identifier is "day”.
• Table 9 Part to Section and Base Type Assignment This enhancement has the advantage that each section and every part of the regular expression can be assigned a content-related meaning.
• the XML type "positive integer” can also be assigned to the new types, because it is known that a value for the day, month and year is due to the assignment of the meaning of content greater than zero.
• the XML type "PositiveInterger” can achieve a higher compression rate than the "nonNegativelnteger” XML type.
• the information unit ⁇ date> 23.03.2009 ⁇ / date> of the structured document can be modified as follows before compression in three information units corresponding to a number of new types formed, see table 8:
• the compression of the two points contained in the regular expression RA can be dispensed with, since the position of the two points is known by the sequence of the element names day, month and year in conjunction with the respectively associated regular expression.
• SVG Scalable Vector Graphic
• W3C W3C Scalable Vector Graphic
• SVC describes two-dimensional vector graphics.
• the specification defines the structure and functions of SVG using XML. It defines 14 important functional areas, such as basic body shapes, text and color.
• a very important feature is paths (path). Within a path, defined straight or curved lines of a body to be described, which may for example also be filled.
• the path is generated by the XML attribute d, which initializes the shape of the body starting from a pair of coordinates (x, y) with the aid of a connoisseur M, defines subsequent pairs of coordinates (x, y) of the form with the aid of a connoisseur L and finally with help of the connoisseur Z the path is completed.
• FIG. 1a shows a textual description of such an SVG path
• FIG. 1b a pictorial representation of the body indicated by the textual path.
• EXI a compression method provided by EXI
• the original size is 100%
• the size after compression using the EXI compression method is approximately 87%
• the size of the compressed structured document is approximately 57% using the EXI + COD compression method.
• FIG. 2 shows a portion of the path d in percent of the file size of the respective uncompressed or compressed document in the respective layered column.
• the path comprises 82% of the data, EXI compression 83% in the compressed document, and 50% using the EXI + COD compression method.
• the aforementioned two structured documents do not include any path information, so that no improvement can be achieved by the method according to the invention when applied to the path data. However, an improvement can be achieved even if the method of the present invention is applied to other structural elements of the structured document, in this example according to SVG standard.
• the combination of the sections EAS, EAT into the new section EAN forms a section which can also be represented with the second basic type and can be compressed with the associated prescribed compression rule CMBTINT.
• This can already be done by analysis of the two parts ETA, ETB and the rule for combining the two sections, since the rule for summarizing the two parts is also applicable.
• This gives a new part to [0-9] ⁇ 2, 2 ⁇ [0-9] ⁇ 2, 2 ⁇ .
• a number from 0 to 9999 can be described by the new part.
• the second base type can be used to represent the new part, and later the default compression rule can be used.
• FIG. 3 shows a compression unit CE for compressing the structured document DOC.
• the compression unit has the predetermined structure specification SYN, which comprises the first base type BTSTR for representing at least the one character CH and the second base type BTINT.
• the structure rule defines type TYP, which has a data field represented by at least a first base type and the structure of the data field is determined by the regular expression RA.
• the dependencies of the type TYP on the first basic type BTSTR and its dependency on the regular expression RA are symbolically represented by an arrow in FIG.
• FIG. 3 the structured document with at least one information unit ELE, ATT, which is instantiated by the type, can be seen.
• the instantiation is symbolized by an arrow on the structured document DOC.
• a first means M1 determines at least a part ETA of the regular expression RA such that this respective part ETA can be represented by the second base type BTINT.
• the first means Ml reads the regular Expression RA at least partially and then, after performing this step, at least the part ETA to a second means M2 on.
• the second means M2 is then configured in a second step such that it determines the respective section EAS of the at least one information unit ELE, ATT, which is based on the respective part ETA of the regular expression RA.
• the at least one part ETA and the information unit are at least partially read in by the second means, processed and passed on at one of its outputs the determined respective section EAS the predetermined compression method CM.
• the predetermined compression method CM is designed in such a way that it can compress structured documents that are formed on the basis of the predefined structural rule SYN.
• the predetermined compression method for example for the second base type BTINT, has a predefinable compression regulation CMBTINT.
• the section EAS of the at least one information unit ELE is compressed.
• Compressing means a reduction of the storage volume required to store the respective section EAS.
• the structured document DOC is output in compressed form as a compressed document BDOC.
• the predetermined compression method CM is based, for example, on BIM or EXI.
• the compression of the respective section by means of the predetermined compression method CM is performed by a third means M3. It should also be noted that one or more further method steps according to the above exemplary embodiments can be carried out with the aid of a fourth means M4.
• the decompression unit has the predetermined structure specification SYN comprising the first base type BTSTR for representing at least the one character CH and the second base type BTINT.
• the structure rule defines type TYP, which has a data field represented by at least a first base type and the structure of the data field is determined by the regular expression RA.
• the dependencies of the type TYP on the first basic type BTSTR and its dependency on the regular expression RA are symbolically represented by an arrow in FIG.
• the first means provides the at least part ETA of the regular expression RA.
• the at least one part ETA and the compressed document are at least partially read in.
• the fifth means is designed such that it can decompress at least part of the compressed document BDOC into the at least one section EAS.
• a predetermined decompression method DM is used, which can decompress the compressed document generated with the corresponding predetermined compression method CM.
• the default decompression method DM is based, for example, on the standard BIM or EXI. It should be noted here that the predetermined decompression method has at least for the second base type BTINT an associated predefined decompression rule DMBTINT with the aid of which a section EAS compressed with the predetermined compression rule CMBTINT corresponding thereto is decompressable.
• the at least one section EAS is transferred to a sixth means M6.
• the sixth resource can do two things:
• the sixth means M6 enters the section EAS obtained by decompression at that position in the reconstructed structured document DOC which is predetermined by the part of the regular section corresponding to the section EAS obtained by decompression.
• the sixth means M6 may pass the section EAS to another processing unit (not shown), for example passing the connoisseur indicating which part of the regular expression is in the pass passed section EAS trades.
• the connoisseur can be determined as shown in one of the above exemplary embodiments.
• the fifth means may also decide prior to performing the decompression on the basis of the at least one part of the regular expression whether the respective predefined decompression provision DMBTSTR, DMBTINT for the first basic type BTSTR or the second one for obtaining the section corresponding to the at least one part BTINT is used.
• Each base type has its own predefined compression and corresponding decompression rule.
• the structure rule SYN can be changed on the basis of the changes of the information unit, for example, into new information units, wherein this changed structure rule can be transmitted from the compression unit to the decompression unit or the modified structural rule analogously in the compression unit and in the Decompression unit is generated.
• An extension takes at least two parts of the regular expression into compression and decompression.
• the procedure for Considering three parts in practice, at least two parts are taken into account.
• the first means both on the part of the compression method and the decompression method or in the context of the compression unit or decompression unit, determines the parts ETA, ETB, ETC.
• the parts ETA, ETB, ETC are generated such that the corresponding parts EAS, EAT, EAU of the information unit are compressible in a later subsequent compression step in a summarized form by the second base types.
• the parts ETA, ETB, ETC exclusively describe numbers, so that a combination of the corresponding sections EAS, EAT, EAU results in a longer number chain which in the present example is compressible by the second base type.
• the sections EAS, EAT, EAU corresponding to the parts ETA, ETB, ETC are obtained by the second means.
• the second means summarizes the sections into a new section EAN. In the present example, this is done by stringing together the sections EAS, EAT, EAU. This is followed by the compression of the new EAN section by the third means.
• the fifth means obtains the new section EAN from the compressed document BDOC.
• the fifth means gives the new section EAN to the sixth means M6, which first performs a division of the new section into the sections corresponding to the new section, i. H. into the sections EAS, EAT and EAU. These can be transferred to the reconstructed structured document DOC or to a processing unit as described above.
• the compression unit CE and the decompression unit DE are shown by way of example in the form of a system.
• the compressed document BDOC is transferred to a storage unit STOR at the output of the compression unit CE.
• the storage unit is, for example, a server for caching compressed documents.
• the compressed document BDOC may be transmitted to the decompression unit for further processing.
• a direct transmission of the compressed document BDOC from the compression unit to the decompression unit see dotted arrow in FIG. 4, is possible.
• a transmission over a network such as GSM (Global System for Mobile GSM) or over the Internet, for example by means of LAN and IP / TCP (local area network LAN, IP - Internet Protocol, TCP - Transport Control Protocol) performed become .
• GSM Global System for Mobile GSM
• IP / TCP local area network LAN, IP - Internet Protocol, TCP - Transport Control Protocol
• the compression unit and the decompression unit can be implemented in hardware, software or a mixture of hardware and software. For example, individual process steps are provided in a program code and executed by a microcontroller. In this case, individual intermediate steps are buffered in a memory coupled to the microcontroller. In addition, this memory can store information for describing the prescribed structure specification SYN, as well as the structured document and, at least in part, the compressed document.
• the compression unit CE may be part of a terminal, such as a video-on-demand server for providing multimedia content.
• the decompression unit may also be part of a terminal, such as a navigation system.

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