XML Schema - nillabls vs. minOccurs=0. Hi Mike, If your question is something like: Should I use nillable or minOccurs? The answer is simple: They do not have the same functions! But first, a little bit of vocabulary: in <iAmATag>this is content</iAmATag> <iAmATag> is a tagthis is content is a content<iAmATag>this is content</iAmATag> is an element 1) nillable means the element can be without content: example: in your xsd file: <xsd:element name="iCanGetNoContent" type="xsd:string"nillable="true"/> in your xml file: <iCanGetNoContent xsi:nil="true"></iCanGetNoContent> you simply indicate that if the element has no content, it is not anaccident, you wanted it that way.
All of these xml snippet would be validated with the preceding xsd snippet: <iCanGetNoContent>But now I have one</iCanGetNoContent> This one would not be validated: <iCanGetNoContent xsi:nil="true">Doh, you have to remove thexsi:nill</iCanGetNoContent> 2) minOccurs=0 is related to the complete element, not the content of theelement in your xsd file: in your xml file: Practical XML Schema.
XML has two main advantages: first, it offers a standard way of structuring data, and, second, we can specify the vocabulary the data uses. We can define the vocabulary (what elements and attributes an XML document can use) using either a document type definition (DTD) or the XML Schema language. DTDs were inherited from XML's origins as SGML (Standard Generalized Markup Language) and, as such, are limited in their expressiveness. DTDs are for expressing a text document's structure, so all entities are assumed to be text. The XML Schema language more closely resembles the way a database describes data. Schemas provide the ability to define an element's type (string, integer, etc.) and much finer constraints (a positive integer, a string starting with an uppercase letter, etc.).
As you'll see in this article, schemas themselves are quite straightforward—I find them easier than DTDs as there is no extra syntax to remember. A detour via the W3C XML 1.0XML NamespacesXML Schema XML 1.0 or 1.1 <? The basics of using XML Schema to define elements. XML Schema best practices - HP Dev Resource Central. Create flexible and extensible XML schemas. W3C XML Schema: DOs and DON'Ts. It's easy to learn and use W3C XML Schemas once you know how to avoid the pitfalls. Here are some DOs. You should at least learn the following things. DO use element declarations, attribute groups, model groups and simple types. DO use XML namespaces as much as possible.
Here are some DON'Ts. DO NOT try to be a master of XML Schema. The fact is, you don't lose anything by following these DON'Ts, as the rest of this paper demonstrates. Too long to remember? Consider W3C XML Schema as DTD + datatype + namespace Motivation for this document Several similar documents are already available on the web.
XML Schema is their new favorite toy. There has to be a different document. So the goal of this document is to provide a set of solid guidelines about what you should do and what you shouldn't do. I always welcome comments. Why you should avoid complex types If you don't know what a complex type is, then don't let it trouble you. So why spend your precious time learning something you don't need? Using XML schemas effectively in WSDL design - HP Dev Resource C. XML Schemas: Best Practices.