Advice on ways to extend a type using XSD

[Charles Fineman]

Say i've got a type that appears in a request... say it represents a
shipment. I want it to contain things like from and to address elements
as well as a sequence of the pieces being shipped.

Say the operation is supposed to calculate the cost to ship each piece.
I would like the response type to look just like the request type but
with a price element under each of the item types. For example:

Request:
<shipment>
<from/>
<to/>
<pieces>
<piece>
<weight>100</weight>
</piece>
<piece>
<weight>5</weight>
</piece>
</pieces>
</shipment>

Response:
<shipment>
<from/>
<to/>
<pieces>
<piece>
<weight>100</weight>
<cost>10.00</cost>
</piece>
<piece>
<weight>5</weight>
<cost>5.00</cost>
</piece>
</pieces>
</shipment>

It would be great if I could easily extend the request type to turn it
into the response type but I'm not sure there is an easy way to do that.

Any thoughts?

 

[Martin Honnen]

Say i've got a type that appears in a request... say it represents a
shipment. I want it to contain things like from and to address elements
as well as a sequence of the pieces being shipped.

Say the operation is supposed to calculate the cost to ship each piece.
I would like the response type to look just like the request type but
with a price element under each of the item types. For example:

Request:
<shipment>
<from/>
<to/>
<pieces>
<piece>
<weight>100</weight>
</piece>
<piece>
<weight>5</weight>
</piece>
</pieces>
</shipment>

Response:
<shipment>
<from/>
<to/>
<pieces>
<piece>
<weight>100</weight>
<cost>10.00</cost>
</piece>
<piece>
<weight>5</weight>
<cost>5.00</cost>
</piece>
</pieces>
</shipment>

It would be great if I could easily extend the request type to turn it
into the response type but I'm not sure there is an easy way to do that.

One possible way is to have an element with minOccurs="0":
<xs:element name="pieces">
<xs:complexType>
<xs:sequence>
<xs:element name="piece" maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:element name="weight" type="xs:double" />
<xs:element name="cost" minOccurs="0" maxOccurs="1"
type="xs:double" />
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>

That way you can have <weight> and <cost> children or only a <weight> child.

 

[Charles Fineman]

Agreed, but I'm hoping to keep the typing as "strong" as possible. It's
clear that I can extend the immediate children of the type (using
xs:extension) but it does not look like I can extend, say, the
grandchildren.

I would rather not define a ton of global types just for the purposes of
extension (is there a way to create global types that are local to the
file?). I could also use groups and just define a completely separate
complex type (but that's effectively the same as using extension in this
case I believe).