"Chris Lieb" wrote:

> I am new to XML Schema and am running into a bit of a snag.  I have
> defined an XML-based scripting language for an updater program that I
> am working on.  I would like to make a schema for this language since
> malformed XML documents break the updater.  (I did not have time to add
> good error-handling code, so run-time errors can abound if the document
> is malformed.)
> 
> A sample doc might look something like this:
> 
> <manifest>
>   <version major="1" minor="0" revision="1" base="1.0.1\files\"
> doprevious="true">
>     <file action="copy" name="text.doc"/>
>     <folder action="create" name="temp"/>
>     <updater>
>       <file name="update.exe"/>
>       <file name="updaterlib.dll"/>
>     </updater>
>   </version>
>   <version major="1" minor="0" revision="0" base="1.0.0\files\"
> doprevious="false">
>     <dll action="register" name="updaterlib.dll"/>
>     <cmd location="server" command="patch.bat">
>       <file name="patch.dat"/>
>       <file name="patch.bat"/>
>     </cmd>
>   </version>
> </manifest>
> 
> Problem is that the second version element in the document, the updater
> element, the dll element, and the cmd element all get flagged as
> invalid.  I guess that this stems from using a sequence in the complex
> type.  What should I use to allow all children elements of version
> (file, folder, dll, msi, cmd, updater) to appear in any order and in
> whatever quantity (except updater, which can only appear once)?
> 
> 'all' looks like it comes close since it allows you to use elements in
> any order, except my reading tells me that it only allows each element
> to be used once and forces you to use all elements.  'choice' also
> appears to come close since it allows you to choose which element you
> want, but it only lets you choose one element from the set.
> 

Are you certain you need to allow for all possible combinations of all 
elements in any order...if you can whittle down the possible combinations to 
only those combinations that should be allowed to occur you can use 
xs:sequence embedded inside of xs:choice, like:

      <xs:choice>
        <xs:sequence>
          <xs:element ref="dll"/>
          <xs:element ref="cmd"/>
        </xs:sequence>
        <xs:sequence>
          <xs:element ref="file"/>
          <xs:element ref="folder"/>
          <xs:element ref="updater"/>
        </xs:sequence>
      </xs:choice>
 
If indeed all possible combinations are possible, then the above is not a 
very attractive solution.

> Also, one last thing: How do you set the max occurrence of an element
> to be infinite?
> 

maxOccurs="unbounded"


> PS
> I'm not posting the XSD right now.  If you want it, I would be more
> than happy to provide it.  I am a little embarassed that I am designing
> the XSD in Visual Studio 2005 instead of hand-coding it.  I have no
> idea if the XSD generated by VS2005 is considered to be of good
> quality.
> 

I've used a few different xsd generators...I'd suggest getting familiar 
enough with XML Schema to know whether or not you like what it is generating. 
 Each generator makes its own assumptions about certain things, and you won't 
always like what it assumes.  I have only tried the XSD in VS 2003, and I 
don't know if it applies to the one in 2005, but the 2003 version cannot 
generate schemas for a broad class of XML files (whereas other generators 
don't have a problem).  I found that to be an annoying limitation and have 
stayed away since.