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RE: [EXI] Clarification required regarding use of types

From: santhanakrishnan <santhana@huawei.com>
Date: Wed, 14 May 2008 20:00:19 +0530
To: john.schneider@agiledelta.com, public-exi@w3.org
Message-id: <004801c8b5cf$09c65630$4a18120a@china.huawei.com>
Hi John

    Thank you very much for your clarification. Some parts are still not
clear to me. Consider the following case.

    Suppose I have the following schema definition. (shown below is a
segment of schema)

    .....

    <xs:simpleType name="TypeUri" final="list restriction">

           <xs:restriction base="xs:anyURI"/>

    </xs:simpleType>

<xs:element name="MyUri" type="TypeUri" minOccurs="0"/>

<xs:element name="MyString" type="xs:string" minOccurs="0"/>

.....

 

For this I would have a grammar like this.

For Simple Type Definition TypeUri

TypeUri_0:

           CH [schema-valid-value] TypeUri_1

TypeUri_1:

           EE

TypeUri_Empty_0:

           EE

 

For element MyUri 

MyUri_0:

           TypeUri_0

 

For element MyString

MyString_0:

           xs:string_0

As there is no grammar available for xs:string we will define one like this

xs:string_0:

           CH [schema-valid-value] xs:string_1

xs:string_0:

           EE

xs:string_Empty_0:

           EE

 

After all this grammar definitions still there is some ambiguity in the
definition of TypeUri. It is lacking the schema basic type information
unlike the xs:string type. Only when I know the schema basic type I can
perform the low level encoding/decoding of the value as per that. 

Also the specification talks about adding production AT(xsi:type) to the
element grammar when it is of some named sub type. What is the significance
of this AT(xsi:type) event ?  How and when it has to be generated ? 

Please clarify me in this regard and help me in resolving the confusion.

 

Thanks in advance,

Santhanakrishnan

 

 

 

 

 

  _____  

From: public-exi-request@w3.org [mailto:public-exi-request@w3.org] On Behalf
Of John Schneider
Sent: Thursday, May 01, 2008 11:54 PM
To: santhana@huawei.com; public-exi@w3.org
Subject: RE: [EXI] Clarification required regarding use of types

 

Hi Santhanakrishnan,

 

You're quite welcome. The grammar for user defined simple types and the
simple types built-in to XML Schema is identical. You can find it described
in section 8.5.3.1.3.1.

 

    Thanks,

 

    John

 


  _____  


From: public-exi-request@w3.org [mailto:public-exi-request@w3.org] On Behalf
Of santhanakrishnan
Sent: Wednesday, April 30, 2008 11:10 PM
To: john.schneider@agiledelta.com; public-exi@w3.org
Subject: RE: [EXI] Clarification required regarding use of types

Hi John

       Thank you very much for your clarification. Can you please let me
know the grammar for the Simple types or otherwise the alterations required
in section 8.5.3.1.3.1 to accommodate the simple types into EXI grammars.

 

Thanks in advance

Santhanakrishnan


  _____  


From: public-exi-request@w3.org [mailto:public-exi-request@w3.org] On Behalf
Of John Schneider
Sent: Thursday, April 10, 2008 9:40 PM
To: santhana@huawei.com; public-exi@w3.org
Subject: RE: [EXI] Clarification required regarding use of types

 

Santhanakrishnan,

 

Good catch! EXI includes support for all the data types defined in the XML
Schema language. It creates grammars for each of these, including the
xs:anyURI type used below. The grammars for the simple types defined by the
XML Schema Language are created in accordance to section 8.5.3.1.3.1 [1]. 

 

We will add text to the next version of the specification to clarify this.
Thank you for your very thorough review of the draft specification!

 

    Cheers!,

 

    John

 

[1] http://www.w3.org/TR/exi/#simpleTypeGrammars

 


  _____  


From: public-exi-request@w3.org [mailto:public-exi-request@w3.org] On Behalf
Of santhanakrishnan
Sent: Thursday, April 10, 2008 2:33 AM
To: public-exi@w3.org
Subject: [EXI] Clarification required regarding use of types

Hi John

       Consider the following two forms of declaring an element in the
schema

Form1

<xs:simpleType name="tSIP_URL" final="list restriction">

       <xs:restriction base="xs:anyURI"/>

</xs:simpleType>

<xs:element name="MyElement" type="tSIP_URL"/>

 

Form2

<xs:element name="MyElement" type="xs:anyURI"/>

 

As per the EXI specification for the Form1 I would create a Type and
TypeEmpty grammar for the tSIP_URL type and MyElement grammar have Type
grammar start symbol as RHS. Given below will be the grammar

 

tSIP_URL 0  :

              CH [schema-valid value ] Type i, 1 

       tSIP_URL 1  :

              EE

 

       tSIP_URLEmpty 0  : 

              EE

 

       MyElement 0:

              tSIP_URL 0

 

For Form2 no grammar would be created for MyElement. Just a particle term
grammar would be created

ParticleMyElement 0 :

              SE(MyElement) ParticleMyElement 1 

 

       ParticleMyElement 1 : 

              EE

 

Is my understanding correct till here? 

 

As per the specification we have to Evaluate the element contents using the
SE(MyElement) grammar. But we have not created any grammar for MyElement in
the Form2. So, how the contents of the MyElement can be encoded in this
case?

 

Even in the Schema informed grammar example given in the specification the
final grammar has productions of the form

SE("description") Term_description1,1

    But no grammars defined for "description" element content as such.

 

Please clarify my doubts regarding this

 

Regards

Santhanakrishnan

 
Received on Wednesday, 14 May 2008 14:31:53 UTC

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