J Hendrich wrote:
> "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.

I would like to allow items in any order in any quantity.  I feel that
it might restrict thing in the future if I force you to always define
folders before files and so forth.  The only restriction that I want to
place on the order is to force the <updater> node (max of 1, min of 0)
to always be the last item for a version.

I guess that I might not actually need a schema for the manifest files
since I am making a GUI to allow others to easily edit the manifest
file without needing to know all of the rules that I have or even XML.
Even if they did know XML, I am not currently validating it in the
updater using XML Schema, but rather by manually checking values.

I could make a change to the updater to force validation against a
schema, but I don't know if MSXML4 supports this, or how to access it
through VB6.  Any ideas?

Do you think that a schema would actually be useful in this case?

Chris