Polymorphism in XSD

[Mike Jansen]

I'm trying to mirror some classes in an XML Schema:

abstract class EndPoint
class FileEndPoint: EndPoint
class FtpEndPoint: EndPoint

How can I mirror these in XML such that:

<EndPoint> could contain either ...
<EndPoint type="file" folder="..."/>
or
<EndPoint type="ftp" site="site.com" port="21" .../>

....depending on whether or not it was a FileEndPoint or FtpEndPoint. I have
seen mention of "equivalence", but have not been able to track anything
specific down. substitutionGroup doesn't give me what I want because the
app has to know different element names. "extension" doesn't seem to quite
do it either because you are still renaming an element. I'd like all the
attributes for the class -- whether from the base or derived class -- to be
in the same element.

Appreciate any help.

Thanks,
Mike Jansen
(mjansen)(at)(primepro-com)

[Maksim]

Just a quick sketch ( could be done better) but you will see a possible way.

<xs:complexType name="EndPoint_t" abstract="1" />

<xs:complexType name="FileEndPoint_t">
<xs:complexContent>
<xs:extension base="EndPoint_t">
<xs:attribute name="folder" use="required" type="xs:anyURI" />
</xs:extension>
</xs:complexContent>
</xs:complexType>

<xs:complexType name="FtpEndPoint_t">
<xs:complexContent>
<xs:extension base="EndPoint_t">
<xs:attribute name="site" use="required" type="xs:anyURI" />
<xs:attribute name="port" use="required" type="xs:int" />
</xs:extension>
</xs:complexContent>
</xs:complexType>

<!-- choise #1 -->
<!-- will require something like
<EndPoint folder="..." xsi:type="file_t"/>
-->
<xs:element name="EndPoint" type="EndPoint_t" />

<!-- choise #2 -->
<!-- will look like
<EndPoints>
<file folder="..." />
-->
<xs:element name="EndPoints">
<xs:complexType>
<xs:choice>
<xs:element name="file" type="FileEndPoint_t" />
<xs:element name="ftp" type="FtpEndPoint_t" />
</xs:choice>
</xs:complexType>
</xs:element>
"Mike Jansen" wrote:

I'm trying to mirror some classes in an XML Schema:

abstract class EndPoint
class FileEndPoint: EndPoint
class FtpEndPoint: EndPoint

How can I mirror these in XML such that:

<EndPoint> could contain either ...
<EndPoint type="file" folder="..."/>
or
<EndPoint type="ftp" site="site.com" port="21" .../>

....depending on whether or not it was a FileEndPoint or FtpEndPoint. I have
seen mention of "equivalence", but have not been able to track anything
specific down. substitutionGroup doesn't give me what I want because the
app has to know different element names. "extension" doesn't seem to quite
do it either because you are still renaming an element. I'd like all the
attributes for the class -- whether from the base or derived class -- to be
in the same element.

Appreciate any help.

Thanks,
Mike Jansen
(mjansen)(at)(primepro-com)

[Mike Jansen]

Maksim,

Thanks. I had tried the <xs:choice> and its currently the one I'm going
with.

I liked better your other option where you use <xs:extension>, create the
element with the type of the base class, and then in the instance use
xsi:type, but I couldn't get that to validate properly in Visual Studio.NET.
(It seems VS.NET doesn't handle the xs:extension that great in the XML
editor, as far as validation and intellisense).

Thanks for your input and any further thoughts.

Mike

"Maksim" <Ma****@discussions.microsoft.com> wrote in message
news:8B**********************************@microsof t.com...

Just a quick sketch ( could be done better) but you will see a possible way.
<xs:complexType name="EndPoint_t" abstract="1" />

<xs:complexType name="FileEndPoint_t">
<xs:complexContent>
<xs:extension base="EndPoint_t">
<xs:attribute name="folder" use="required" type="xs:anyURI" />
</xs:extension>
</xs:complexContent>
</xs:complexType>

<xs:complexType name="FtpEndPoint_t">
<xs:complexContent>
<xs:extension base="EndPoint_t">
<xs:attribute name="site" use="required" type="xs:anyURI" />
<xs:attribute name="port" use="required" type="xs:int" />
</xs:extension>
</xs:complexContent>
</xs:complexType>

<!-- choise #1 -->
<!-- will require something like
<EndPoint folder="..." xsi:type="file_t"/>
-->
<xs:element name="EndPoint" type="EndPoint_t" />

<!-- choise #2 -->
<!-- will look like
<EndPoints>
<file folder="..." />
-->
<xs:element name="EndPoints">
<xs:complexType>
<xs:choice>
<xs:element name="file" type="FileEndPoint_t" />
<xs:element name="ftp" type="FtpEndPoint_t" />
</xs:choice>
</xs:complexType>
</xs:element>
"Mike Jansen" wrote:

I'm trying to mirror some classes in an XML Schema:

abstract class EndPoint
class FileEndPoint: EndPoint
class FtpEndPoint: EndPoint

How can I mirror these in XML such that:

<EndPoint> could contain either ...
<EndPoint type="file" folder="..."/>
or
<EndPoint type="ftp" site="site.com" port="21" .../>

....depending on whether or not it was a FileEndPoint or FtpEndPoint. I have seen mention of "equivalence", but have not been able to track anything
specific down. substitutionGroup doesn't give me what I want because the app has to know different element names. "extension" doesn't seem to quite do it either because you are still renaming an element. I'd like all the attributes for the class -- whether from the base or derived class -- to be in the same element.

Appreciate any help.

Thanks,
Mike Jansen
(mjansen)(at)(primepro-com)

[Maksim]

In case if you do not know that:

here is a little trick you could use. Put your schema into the
"<VISUAL STUDIO ROOT>\Common7\Packages\schemas\xml" folder.

Then you can create corresponding xml and that "popup helper" (IntelliSense)
will offer you to choose a namespace
as soon as you type "xmlns=", then you can validate you your xml.

Here is a link to W3C document that talks about abstract types

http://www.w3.org/TR/xmlschema-0/#abstract

Regards

"Mike Jansen" wrote:

Maksim,

Thanks. I had tried the <xs:choice> and its currently the one I'm going
with.

I liked better your other option where you use <xs:extension>, create the
element with the type of the base class, and then in the instance use
xsi:type, but I couldn't get that to validate properly in Visual Studio.NET.
(It seems VS.NET doesn't handle the xs:extension that great in the XML
editor, as far as validation and intellisense).

Thanks for your input and any further thoughts.

Mike

"Maksim" <Ma****@discussions.microsoft.com> wrote in message
news:8B**********************************@microsof t.com...

Just a quick sketch ( could be done better) but you will see a possible

way.

<xs:complexType name="EndPoint_t" abstract="1" />

<xs:complexType name="FileEndPoint_t">
<xs:complexContent>
<xs:extension base="EndPoint_t">
<xs:attribute name="folder" use="required" type="xs:anyURI" />
</xs:extension>
</xs:complexContent>
</xs:complexType>

<xs:complexType name="FtpEndPoint_t">
<xs:complexContent>
<xs:extension base="EndPoint_t">
<xs:attribute name="site" use="required" type="xs:anyURI" />
<xs:attribute name="port" use="required" type="xs:int" />
</xs:extension>
</xs:complexContent>
</xs:complexType>

<!-- choise #1 -->
<!-- will require something like
<EndPoint folder="..." xsi:type="file_t"/>
-->
<xs:element name="EndPoint" type="EndPoint_t" />

<!-- choise #2 -->
<!-- will look like
<EndPoints>
<file folder="..." />
-->
<xs:element name="EndPoints">
<xs:complexType>
<xs:choice>
<xs:element name="file" type="FileEndPoint_t" />
<xs:element name="ftp" type="FtpEndPoint_t" />
</xs:choice>
</xs:complexType>
</xs:element>
"Mike Jansen" wrote:

I'm trying to mirror some classes in an XML Schema:

abstract class EndPoint
class FileEndPoint: EndPoint
class FtpEndPoint: EndPoint

How can I mirror these in XML such that:

<EndPoint> could contain either ...
<EndPoint type="file" folder="..."/>
or
<EndPoint type="ftp" site="site.com" port="21" .../>

....depending on whether or not it was a FileEndPoint or FtpEndPoint. I have seen mention of "equivalence", but have not been able to track anything
specific down. substitutionGroup doesn't give me what I want because the app has to know different element names. "extension" doesn't seem to quite do it either because you are still renaming an element. I'd like all the attributes for the class -- whether from the base or derived class -- to be in the same element.

Appreciate any help.

Thanks,
Mike Jansen
(mjansen)(at)(primepro-com)