Schema representation of a "bitmask" type?

[Andrey Brozhko]

Hi

I need to represent custom type system (ints, bytes, chars, enums,
bitmasks, arrays and some other types) in xml. It is easy to see how to
represent enums in xml (using xs:enumeration) , the same is true for
numeric types. Even arrays have an obvious description in schema:

<complexType name="IntArray" >
<sequence>
<element name="item" type="int" minOccurs="0" maxOccurs="unbo unded"/>
</sequence>
</complexType>

But how about bitmasks? What's the most beautiful way to represent a
bitmask where values have names? It's just like enumeration but the
value at any time can be a disjunction of any number of valid names.
For example: if we have x = 0x01, y = 0x02 etc then the value may be
either x, or x|y, or y etc.. but it can not be specified with 0x01. I
don't think having "<myAttribute>x |y</myAttribute>" in the xml document
is a good idea. Any suggestions?

Cheers,
Kapitan

[Andrey Brozhko]

OK, here is what I come up with:

<xs:simpleTyp e name="MyBitmapT ype">
<xs:choice>
<xs:element name="item" minOccurs="1" maxOccurs="unbo unded">
<xs:simpleTyp e>
<xs:restricti on base="xs:string ">
<xs:enumerati on value="firstVal ue"/>
<xs:enumerati on value="secondVa lue"/>
<xs:enumerati on value="thirdVal ue"/>
</xs:restriction>
</xs:simpleType>
</xs:element>
</xs:choice>
</xs:simpleType>
In this case something like:

<?xml version="1.0" encoding="UTF-8"?>
<test>
<item>firstValu e</item>
<item>secondVal ue</item>
</test>

can be validated (which can be understood as "firstValue | secondValue").
Unfortunately, it validates the following thing as well:

<?xml version="1.0" encoding="UTF-8"?>
<test>
<item>firstValu e</item>
<item>firstValu e</item>
</test>

which is not exactly wrong (as you can do "firstValue | firstValue" and
the result will be OK), but it is not pretty... any suggestions?

Andrey Brozhko wrote:

Hi

I need to represent custom type system (ints, bytes, chars, enums,
bitmasks, arrays and some other types) in xml. It is easy to see how to
represent enums in xml (using xs:enumeration) , the same is true for
numeric types. Even arrays have an obvious description in schema:

<complexType name="IntArray" >
<sequence>
<element name="item" type="int" minOccurs="0" maxOccurs="unbo unded"/>
</sequence>
</complexType>

But how about bitmasks? What's the most beautiful way to represent a
bitmask where values have names? It's just like enumeration but the
value at any time can be a disjunction of any number of valid names.
For example: if we have x = 0x01, y = 0x02 etc then the value may be
either x, or x|y, or y etc.. but it can not be specified with 0x01. I
don't think having "<myAttribute>x |y</myAttribute>" in the xml document
is a good idea. Any suggestions?

Cheers,
Kapitan