Schema Resolver

The schema resolver is an essential piece of the XML language since it is what loads the XML schema data that is used to drive features such as automated IntelliPrompt and validation.

The IXmlSchemaResolver interface provides the base requirements for this functionality. It is installed into a language as a "feature" language service.

The XmlSchemaResolver class is the default implementation of the IXmlSchemaResolver interface.

Managing the .XSD Schemas Used

The schema resolver can manage one to many .XSD schemas at a time. These .XSD's are used to provide automated IntelliPrompt completion lists and quick info, and are also used to validate XML documents.

The XmlSchemaResolver class has numerous methods for loading XML schema data directly, or from files, streams, strings, etc.

Using Default Namespace Prefix Mappings

The IXmlSchemaResolver.DefaultNamespace property gets or sets the default namespace to use for any XML documents where the root element doesn't have an xmlns specified. The result of specifying a default namespace is the same as if a xmlns attribute was set on the document's root element. Automated IntelliPrompt, validation, etc. will treat it as such.

The DefaultNamespace property actually just gets/sets the entry in the DefaultNamespacePrefixMappings dictionary property for an empty string, meaning default namespace prefix.

Other namespace prefixes can be mapped by default in the DefaultNamespacePrefixMappings property too, and similar to the processing of the DefaultNamespace property, automated IntelliPrompt, validation, etc. will use these mappings.

This code creates a schema resolver, sets the default namespace to XHTML and also maps a foo namespace prefix, similar to if the root element had xmlns="http://www.w3.org/1999/xhtml" xmlns:foo="http://tempuri.org/bar.xsd" :

XmlSchemaResolver resolver = new XmlSchemaResolver();
resolver.DefaultNamespace = "http://www.w3.org/1999/xhtml";
resolver.DefaultNamespacePrefixMappings.Add("foo", "http://tempuri.org/bar.xsd");

Use of these properties is entirely optional and should only be used in cases where xmlns attributes are not required to be specified in the document's root element. xmlns attribute settings in the XML that have the same namespace prefixes as keys in the DefaultNamespacePrefixMappings property will take precedence over the default mappings.

Schema Data Helper Methods

Schema resolvers have a number of helper methods that provide data based on the XML schemas that are loaded. This data is consumed by other language services such as the built-in functionality and services that provide context and automated IntelliPrompt, and do not typically need to be consumed in your code.

Registering with a Syntax Language

Any object that implements IXmlSchemaResolver can be associated with a syntax language by registering it as an IXmlSchemaResolver service on the language.

This code creates a schema resolver, initializes it with a schema from the file specified in the path variable and registers it with the syntax language that is already declared in the language variable:

XmlSchemaResolver resolver = new XmlSchemaResolver();
resolver.LoadSchemaFromFile(path);
language.RegisterXmlSchemaResolver(resolver);

Disabling the Functionality

Since this feature is installed as a "feature" service on the language and is installed on XmlSyntaxLanguage by default, it can be disabled by uninstalling the service from the language.