Schema, syntactic analysis method and method of generating a bit stream based on a schema

• US 20030177341A1
• Filed: 10/28/2002
• Published: 09/18/2003
• Est. Priority Date: 02/28/2001
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Devillers, Sylvain
• Granted Patent: US 7,080,318 B2
• Time in Patent Office: Days
• US Class Current: 712/227
• CPC Class Codes: G06F 40/143 Markup, e.g. Standard Generalized Markup Language [SGML] or Document Type Definition [DTD]
• CPC Class Codes: G06F 40/149 Adaptation of the text data for streaming purposes, e.g. Efficient XML Interchange [EXI] format
• CPC Class Codes: G06F 40/221 Parsing markup language streams streaming G06F40/149

Abstract

The invention proposes a new type of schema derived from the XML schema which permits to describe a coding format in a generic fashion. Such a schema is used to carry out the syntactic analysis of a bit stream to produce a document that represents the bit stream which is an instance of said schema, or to generate a bit stream from a document representing the bit stream.

Claims

1. A method of syntactically analyzing a bit stream containing data which have a structure and contents according to a certain format, said method being ntended to generate a tree-like representation of said stream, characterized in that said method comprises:

A) reading a schema which, for generically describing said format;

a) defines one or more types of data which may contain one or more facets, notably;

when said format uses binary words of predefined length or lengths;

, one or more types of data corresponding to said binary words of predefined length or lengths, said types of data having at least one facet relating to said length and, when said binary words of predefined lengths may contain one or more padding bits, said types of data having a facet relating to said padding bits,

when said format uses binary segments of indefinite length which have contents intended to be imported in said representation by using a certain import mode;

a type of data corresponding to said binary segments, said type of data having at least one facet relating to said import mode and, when said binary segments are defined by a stop flag, said type of data having one facet relating to said stop flag,

b) comprises a plurality of elements for which it describes a name, a type of data, an interleaving, a predefined or random order and number of occurrences, the occurrence of an element being mandatory or optional,

c) when said format provides that data situated at the front of said bit stream give information about the structure or the contents of the rest of said bit stream,

defines one or various variables constituted by an access path in said tree-like representation to said data situated at the front,

and comprises one or more conditional branches for describing various possible structures or contents as a function of the value of said variable or variables,

B) searching in said bit stream for the data that correspond to the elements contained in said schema,

C) generating an instance of said schema which contains the data found in said bit stream and which constitutes said tree-like representation.

2. A computer program comprising instructions for implementing a syntactic analysis method as claimed in claim 1.

3. A method of generating a bit stream according to a certain format, from a document which is a tree-like representation of said bit stream and which contains data, notably data imported by the use of a certain import mode, characterized in that it comprises:

A) reading said document

B) reading in parallel a schema which, for generically describing said format;

a) defines one or more types of data which may have one or more facets, notably;

a type of data corresponding to binary segments of indefinite length which have at least a facet that relates to said import mode

and, when said format uses binary words of predefined length or lengths, one or more types of data corresponding to said binary words of predefined length or lengths which have at least a facet that relates to said length, and when said binary words contain one or more padding bits, a facet that relates to said padding bits,

b) comprises a plurality of elements for which it describes a name, a type of data, an interleaving, an order and a number of predefined or random occurrences, the occurrence of an element being mandatory or optional,

C) coding said data as a function of the type defined,

D) constituting a bit stream from the coded data.

4. A computer program comprising instructions for implementing a method of generating a bit stream as claimed in claim 3.

5. A schema defining one or more types of data which may have one or more facets, and comprising a plurality of elements for which it describes a name, a type of data, an interleaving, an order and a number of predefined and random occurrences, the occurrence of an element being mandatory or optional, characterized in that said schema has at least one of the following characteristic features:

said schema defines a type of data which corresponds to binary segments of indefinite length and which has at least a facet relating to a data import mode and optionally a facet relating to a stop flag of a binary segment,

said schema defines one or more types of data which correspond to binary words of predefined length or lengths and which have at least a facet relating to said length and, optionally, a facet relating to padding bits contained in said binary words,

said schema defines one or more variables constituted by a data access path and it comprises one or more conditional branches for describing various structures or possible contents as a function of the value of the or said variables.

6. A processing unit which comprises memory means for storing a schema as claimed in claim 5, and memory means for storing a program which contains instructions for implementing a syntactic analysis method of a bit stream based on said schema for generating a document which represents said bit stream which is an instance of said schema, and/or a program which contains instructions for implementing a bit stream generation method based on said schema and on a document representing said bit stream which is an instance of said schema.

7. A transmission system comprising at least a source entity and at least a destination entity, said source entity comprising memory means for storing a schema as claimed in claim 5, and memory means for storing a program which contains instructions for implementing a syntactic analysis method of a bit stream based on said schema for generating a document which represents said bit stream which is an instance of said schema, and/or a program which contains instructions for implementing a method of generating a bit stream based on said schema and on a document representing said bit stream which is an instance of said schema.