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  Subject: Enhancing Schema Diagrams.
Author: David Jaramillo
Date: 01 Feb 2006 09:15 AM
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Hello all,
we have switched from XMLSpy to Stylus Studio due to its superior validation capabilities among other aspects (XSLT, XQuery, etc.). Howevever we miss some of the graphical features we have been used to for representing the structure of schemas in diagrams. One of this features is showing the cardinality of elements (1..1, 0..*, etc). In the stylus represenattion it is difficult to (graphically) identify an element as optional, because border of the corresponding box is not dashed. It would also be useful to see the cardinality directly somewhere nearby the box.
Despite that one of the big enhancements of stylus XSD diagrams with respect to the competitors is the visualisation of the attributes directly in the diagram, In my opinion many of the adornements shown in the stylus diagrams are not necessary and makes it difficult to understand specially for newbies.
For intance, showing an element which is of type of a (global) derived complex type:
Stylus shows a box for the element, then in the next level a box of the (global) type and then in the next level another box for the derivation (extension, restriction) then antother level and box for the actual content of the element.
This makes diagrams bigger and difficut to understand.
It should be easier to understand to show the actual content directly in the level next to the element and show the type and derivation on demand only (if the user wants to). This way, the diagrams are more in line with the actual structure of the model.
Unfortunaletly there is no standard for diagraming XML Schemas. But we feel that the Stylus Diagrams are some cumbersome, even if "simplified"
Maybe some kind of "UML Class"-like diagrams could be the solution?
Any opinions?
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Subject: RE: Enhancing Schema Diagrams.
Author: David Jaramillo
Date: 03 Feb 2006 06:25 AM
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Hi David,
I can not tell you how it is with the latest version of XMLSpy, because I don't have it. I can tell how the situation was as we decided to switch. At that time we used XMLSpy 2004 rel.3.
There are many W3C XML Schema rules, which the XMLSpy validator does not check. For instance, load the following mini-schema (copy&paste and store it as "SampleSchema.xsd") in both XMLSpy and StylusStudio:
-----8<--------
<?xml version="1.0" encoding="ISO-8859-1"?>
<xs:schema targetNamespace="www.myorg.com/xml/mymodel" xmlns="www.myorg.com/xml/mymodel" xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="unqualified" attributeFormDefault="unqualified">
<xs:element name="Root">
<xs:complexType>
<xs:sequence>
<xs:element name="Item1" type="ExtendedType1"/>
<xs:element name="Item2"/>
<xs:element name="Item3"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:complexType name="Type1">
<xs:all>
<xs:element name="Text" type="xs:string"/>
<xs:element name="Number" type="xs:double"/>
<xs:element name="Boolean" type="xs:boolean"/>
</xs:all>
</xs:complexType>
<xs:complexType name="ExtendedType1">
<xs:complexContent>
<xs:extension base="Type1">
<xs:sequence>
<xs:element name="Extension"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
</xs:schema>
-----8<--------
Validate in XMLSpy, you get no errors, the schema is "valid".
Validate in Stylus Studio with the standard validator: you get the following error:
Validating SampleSchema.xsd...
file:///c://SampleSchema.xsd:21,37: An 'all' model group that's part of a complex type definition must constitute the entire content type of the definition
The XML document SampleSchema.xsd is NOT valid (1 errors)
The error message is in line with the W3C XML Schema Spefication!
Despite this, if you like you may choose another validation engine or define your own one in Stylus Studio. In XMLSpy you can not do this... what happen if you "trust" the altova validator?!. That's the reason why there are so many XML Schema around, which are supposed to be valid, but in reality they are not!. The developers probably trusted XML Spy.
I have tried the above example in XML Spy 2005 Home Edition, same result. I'm not going to install the latest version of XML Spy, if you get another result with it, then the problem is solved, but I don't think so. The example I showed it's just one situation in which XMLSpy fails at validating properly. there are many other...
However the graphical modeling capabilities in XMLSpy are IMHO better than in Stylus Studio. So we use both at the moment ;-).
I think visual modelling & diagram displaying in Stylus Studio can be improved.. then we can use only one tool for XML Schema development.
Regards,
David
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