Edit comment LC-2175 for Efficient Extensible Interchange Working Group

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Comment LC-2175

Comment Shortname:

Commenter: FABLET Youenn <Youenn.Fablet@crf.canon.fr>

Message-id:

Section of the document concerned:

[Free text description]Document as a wholeEfficient XML Interchange (EXI) Format 1.0 /**/ code... Efficient XML Interchange (EXI) Format 1.0 W3C Working Draft 28 July 2008 Abstract Status of this Document Table of Contents Appendices 1. Introduction [Definition:]   [Definition:]   [Definition:]   1.1 History and Design 1.2 Notational Conventions and Terminology [Definition:]   2. Design Principles 3. Basic Concepts 4. EXI Streams [Definition:]   [Definition:]   [Definition:]   [Definition:]   [Definition:]   [Definition:]   [Definition:]   4. EXI Streams [Definition:]  An EXI stream is an EXI heade... 4. EXI Streams [Definition:]  An EXI stream is an EXI heade... name prefix local-element-ns public qname system text uri value 5. EXI Header [Definition:]   5.1 EXI Cookie [Definition:]   5.2 Distinguishing Bits [Definition:]   5.3 EXI Format Version [Definition:]   Example 5-1. EXI Format Version Examples 5.4 EXI Options [Definition:]   [Definition:]   [Definition:]   [Definition:]   [Definition:]   [Definition:]   [Definition:]   [Definition:]   [Definition:]   [Definition:]   [Definition:]   [Definition:]   [Definition:]   [Definition:]   [Definition:]   [Definition:]   6. Encoding EXI Streams [Definition:]   6.1 Determining Event Codes Example 6-1. Example productions with event codes 6.2 Representing Event Codes Example 6-2. Example event code encoding 6.3 Fidelity Options Preserve.prefixes Preserve.lexicalValues 7. Representing Event Content [Definition:]   7. Representing Event Content The content of each event in... 7. Representing Event Content The content of each event in... 7.1 Built-in EXI Datatype Representations 7.1.1 Binary 7.1.2 Boolean 7.1.3 Decimal 7.1.4 Float 7.1.5 Integer 7.1.6 Unsigned Integer Example 7-1. Example algorithm for decoding an Unsigned Inte... 7.1.7 QName 7.1.8 Date-Time 7.1.9 n-bit Unsigned Integer 7.1.10 String 7.1.10.1 Restricted Character Sets 7.1.11 List 7.2 Enumerations 7.3 String Table 7.3.1 String Table Partitions [Definition:]   7.3.2 Partitions Optimized for Frequent use of Compact Identifiers 7.3.3 Partitions Optimized for Frequent use of String Literals 7.4 Datatype Representation Map [Definition:]   Example 7-2. datatypeRepresentationMap indicating all Decima... Example 7-3. datatypeRepresentationMap illustrating a user-d... 8. EXI Grammars 8.1 Grammar Notation 8.1.1 Fixed Event Codes Example 8-1. Example productions with fixed event codes 8.1.2 Variable Event Codes Example 8-2. Example productions that use macro non-terminal... Example 8-3. Example non-terminal macros and its productions... Example 8-4. Expanded productions equivalent to the producti... 8.2 Grammar Event Codes Example 8-5. Example productions with event codes 8.3 Pruning Unneeded Productions Example 8-6. Example productions with full fidelity Example 8-7. Example productions after pruning 8.4 Built-in XML Grammars 8.4.1 Built-in Document Grammar 8.4.2 Built-in Fragment Grammar 8.4.3 Built-in Element Grammar [Definition:]   8.5 Schema-informed Grammars 8.5.1 Schema-informed Document Grammar 8.5.2 Schema-informed Fragment Grammar 8.5.3 Schema-informed Element Fragment Grammar 8.5.4 Schema-informed Element and Type Grammars [Definition:]   [Definition:]   8.5.4.1 EXI Proto-Grammars 8.5.4.1.1 Grammar Concatenation Operator 8.5.4.1.2 Element Grammars 8.5.4.1.3 Type Grammars 8.5.4.1.3.1 SimpleType Grammars 8.5.4.1.3.2 Complex Type Grammars 8.5.4.1.3.3 Complex Ur-Type Grammar 8.5.4.1.4 Attribute Uses 8.5.4.1.5 Particles 8.5.4.1.6 Element Terms 8.5.4.1.7 Wildcard Terms 8.5.4.1.8 Model Group Terms 8.5.4.1.8.1 Sequence Model Groups 8.5.4.1.8.2 Choice Model Groups 8.5.4.1.8.3 All Model Groups 8.5.4.2 EXI Normalized Grammars 8.5.4.2.1 Eliminating Productions with no Terminal Symbol 8.5.4.2.2 Eliminating Duplicate Terminal Symbols 8.5.4.3 Event Code Assignment 8.5.4.4 Undeclared Productions 8.5.4.4.1 Adding Productions when Strict is False Like an element, an attribute may occur in a schema-invalid... 8.5.4.4.2 Adding Productions when Strict is True 9. EXI Compression 9.1 Blocks 9.2 Channels 9.2.1 Structure Channel 9.2.2 Value Channels 9.3 Compressed Streams 10. Conformance 10.1 EXI Stream Conformance [Definition:]   [Definition:]   [Definition:]   10.2 EXI Processor Conformance A References A.1 Normative References IETF RFC 1951 IETF RFC 2119 ISO/IEC 10646 Unicode Database XML 1.0 XML Information Set XML Schema Structures XML Schema Datatypes A.2 Other References Efficient XML EXI Measurements Note EXI Primer EXI Evaluation Greibach Normal Form Huffman Coding ISO/IEC 19757-2:2003 SOAP 1.2 XBC Measurement Methodologies XBC Use Cases XBC Properties B Infoset Mapping B.1 Document Information Item B.2 Element Information Items B.3 Attribute Information Item B.4 Processing Instruction Information Item B.5 Unexpanded Entity Reference Information item B.6 Character Information item B.7 Comment Information item B.8 Document Type Declaration Information item B.9 Unparsed Entity Information Item B.10 Notation Information Item B.11 Namespace Information Item C XML Schema for EXI Options Header D Initial Entries in String Table Partitions D.1 Initial Entries in Uri Partition D.2 Initial Entries in Prefix Partitions D.3 Initial Entries in Local-Name Partitions E Deriving Character Sets from XML Schema Regular Expressions E Deriving Character Sets from XML Schema Regular Expressio... F Example Encoding (Non-Normative) G Schema-informed Grammar Examples (Non-Normative) Example G-1. Example XML Schema fragment G.1 Proto-Grammar Examples   Term_description   Term_description 0 :...   Term_description   Term_description 0 :...   Term_description   Term_description 0 :...   Particle_description   Term_description ...   Particle_quantity   Term_quantity 0 :...   Particle_quantity   Term_quantity 0 :...   Term_sequence   Term_description0 :...   Particle_sequence   Term_description0,0...   Use_sku   Use_sku 0 : AT("sku") Use_...   Use_sku   Use_sku 0 : AT("sku") Use_...   ProtoG_ProductElement   Use_color 0 :...   ProtoG_OrderElement   Term_prod... G.2 Normalized Grammar Examples   NormG_ProductElement Event Code Use_col...   NormG_ProductElement Event Code Use_col... G.3 Complete Grammar Examples   CompleteG_ProductElement Event Code Use...   CompleteG_ProductElement Event Code Use... H Recent Specification Changes (Non-Normative) H.1 Changes from Third Public Working Draft H.2 Changes from Second Public Working Draft H.3 Changes from First Public Working Draft I Acknowledgements (Non-Normative)
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Refinement of the section concerned:

Status:

open proposal pending resolved_yes resolved_no resolved_partial other assigned to Nobody Bournez, Carine Brutzman, Don Cokus, Michael Fernández, Javier D. Heuer, Joerg Käbisch, Sebastian Kamiya, Takuki Kuntschke, Richard Matsukura, Ryuichi McGregor, Don Peintner, Daniel Quin, Liam Shah, Grishma ZERGAOUI, Mohamed

Type: substantive editorial typo question general comment undefined

Resolution status:

Response drafted Resolution implemented Reply sent to commenter

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No response from Commenter yet Commenter approved disposition Commenter objected to disposition
Commenter's response (URI):

Comment:

4) Typed encoding in schema-less mode
EXI enables limited typed encoding support in schema-less encoding.
Since only predefined types are supported, xsi:type seems mainly useful to encode base64 chunks with the binary encoding.
Even in that case, the usability is not so good : in some cases, elements whose content is base64 have also attributes. For instance ds:SignatureValue has an optional ID attribute.
Of course, one could still use xsi:type=base64Binary in deviation mode but interoperability may be pretty bad and putting a wrong xsi:type for the purpose of compression seems broken.
Also to be noted that:
- Attribute values cannot be typed encoded with schema-less grammars.
- Other useful types like "list of float","list of integers" cannot be used without external schema knowledge.
Improved out-of-the-box support of this use case would be very helpful.

Related issues: (space separated ids)

WG Notes:

Resolution: We feel that EXI should fit smoothly into the XML stack. To avoid any problems EXI supports type information in the same fashion as XML does. The groups intention is not to super-set XML. XML allows one to specify typed-values with the attribute xsi:type. EXI provides the same mechanism and both work on elements only. EXI makes use of XML Schema and its types form the basis for typed values in the entire W3C environment. Introducing new types or another type system is not the scope of our group and might affect XML processing in general. A newly invented typing system would be processed in the context of EXI only. Such type information would be lost when documents are converted from EXI to XML then back to EXI. This may cause an issue, since it may look like XML cannot preserve what EXI is describing. The solution for arbitrary types in EXI (as well as in XML) is using schema information. Please note that partial schema information are sufficient for EXI. In the use-case you provided a ds:SignatureValue element with the according type information for content and attributes achieves the desired result. An EXI processor picks the given type information for element content as well as the attributes.

(Please make sure the resolution is adapted for public consumption)