Re: [Tockit-general] Storing type definitions

[Peter B. <pe...@pe...>]

PS: another option would be integrating the XML Schema definitions into 
other structures. The current Siena prototype uses this structure:

<type 
class="net.sourceforge.toscanaj.model.manyvaluedcontext.types.NumericalType" 
name="Day" typeId="Day">
     <range min="1.0" max="3.0" numberOfDecimals="0" />
</type>

Here the inner bit is particular to the implementing class, which is 
instantiated dynamically from the "class" attribute using a constructor 
taking an JDOM Element with the information in it. The name in this case 
is the actual name used in the program, i.e. what was referred to as 
<label> before. The string example could thus look like this:

<type class="org.tockit.xsd.SimpleDatatype" name="A textual type" 
typeID="textual1">
   <xs:simpleType>
       <xs:restriction base="xs:string">
           <xs:enumeration value="one"/>
           <xs:enumeration value="two"/>
           <xs:enumeration value="three"/>
       </xs:restriction>
   </xs:simpleType>
</type>

Advantages:
- the XSD bit doesn't contain any foreign XML anymore, all extra bits 
are outside
- other non-XSD types can be supported easily

The class attribute could actually default to some XSD simple type 
implementation, thus making the XML  more concise.

  Peter


Peter Becker wrote:

> Hello all,
>
> after a long time I finally managed to have a look at the problem of 
> storing types in structures such as many-valued contexts. As I've said 
> on ICFCA in Sydney, I think reusing XML Schema, Part 2 [1] would be a 
> good idea. Not only is that W3C endorsed (whatever that is good for 
> ;-) ), but it is also used by other projects. And it is an existing 
> specification for a whole range of basic types, how to extend them and 
> how to store that in XML.
>
> At the moment I am working on moving the two types Siena supports into 
> this schema. These types are a decimal type (with attributes such as 
> minimum value, maximum value (both inclusive or exclusive) and the 
> number of allowed fraction digits) and a textual type (string 
> enumeration). These types are easy to map into XML Schema, the only 
> little problem I had is that the names in XML Schema have to be 
> so-called NCNames, which means only digits, basic latin characters and 
> the underscore are allowed and digits only from the second character 
> onwards. This problem can be avoided by attaching extra information 
> into the annotation part of the type, using the <appinfo> element, 
> which is meant for this purpose.
>
> Enough waffle, I think the examples should give a good idea how these 
> types would look like, first the decimal one, the example type goes 
> from 2 inclusive to 4 exclusive and allows two fraction digits. The 
> internal name is "decimal1", the name used in the program is "A 
> decimal type". "xs" is the standard XML Schema namespace:
>
>    <xs:simpleType name="decimal1">
>        <xs:annotation>
>            <xs:appinfo>
>                <label>A decimal type</label>
>            </xs:appinfo>
>        </xs:annotation>
>        <xs:restriction base="xs:decimal">
>            <xs:minInclusive value="2"/>
>            <xs:maxExclusive value="4"/>
>            <xs:fractionDigits value="2"/>
>        </xs:restriction>
>    </xs:simpleType>
>
> Note that the label doesn't have a namespace, which means it takes the 
> default. We should probably put this stuff into some proper namespace, 
> of course I'd use something like "http://www.tockit.org". I don't 
> think we really need to create a subspace, but I am not sure about 
> that yet.
>
> A string type allowing the values "one", "two" and "three" looks like 
> this:
>
>    <xs:simpleType name="textual1">
>        <xs:annotation>
>            <xs:appinfo>
>                <label>A textual type</label>
>            </xs:appinfo>
>        </xs:annotation>
>        <xs:restriction base="xs:string">
>            <xs:enumeration value="one"/>
>            <xs:enumeration value="two"/>
>            <xs:enumeration value="three"/>
>        </xs:restriction>
>    </xs:simpleType>
>
> Apart from the slightly complicated way of getting the user-defined 
> label into the system, I quite like the structures. And I think the 
> specification of the basic types and how to extend them is nice and 
> covers a lot of ground with the standard types. I think aiming to 
> implement these alongside with UI elements for editing the type 
> definitions, the values and predicates on the values would be a good 
> way to progress in the many-valued context area.
>
>  Peter
>
>
> [1] http://www.w3.org/TR/xmlschema-2/
>
>
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