Edit comment LC-2177 for Efficient Extensible Interchange Working Group

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Comment LC-2177

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

Response status:

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

Comment:

6) Is it conformant to not follow the attribute order in the case of a schema-informed grammar encoded element in deviation mode?
As stated in section 6, it seems not conformant.
In some cases, grammars can support attributes in no particular order, such as the example below (correct me if I got something wrong).
<xs:complexType name="test">
<xs:attribute name="name" type="xs:string"/>
<xs:anyAttribute namespace="#any"/>
</xs:complexType>
<xs:element name="test" type="test"/>

While the benefit of ordering the attributes at the grammar level and the general compression benefit for encoders to follow the given order are obvious, I do not see compelling reasons of including this constraint in the format itself.
At the encoder side, the encoder may decide to order attributes or not.
If encoding fails due to bad ordering (in strict mode) or if the compression ratio is bad, the encoder can always decide to order the attributes.
At the decoder side, the decoder is only following the grammars so it does not really care about the ordering.
There is even a drawback as this is one (major ?) difference between schema-informed and schema-less processing.
Am I missing something obvious?

Related issues: (space separated ids)

WG Notes: yes, we are going to change this to a should. JK needs to revise draft response and send it to group for review.

Resolution: You are not missing anything. There is indeed no reason, when seen purely from the interoperability point of view, to require a specific ordering of the attributes when strict is false. When the encoder does not order the attributes, the out-of-place attributes will just get encoded as deviations, which is understandable by the decoder, as you say. We will change the specification so that it no longer requires the attributes to be sorted in either kind of stream, excepting naturally the case when strict is true. Also, the xsi:type and xsi:nil attributes still have to come first, since their presence affects the grammar used for the rest of the element content. The specification will still strongly recommend the attributes to be ordered for any element that is encoded with a schema-informed grammar, as not ordering them will hurt compactness. In particular, when there are multiple mandatory attributes, not ordering them may cause also the content of that element, not just the attribute list, to be encoded as deviations.

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