This documentation is archived and is not being maintained.

XmlReaderSettings.XmlResolver Property

Sets the XmlResolver used to access external documents.

Namespace:  System.Xml
Assembly:  System.Xml (in System.Xml.dll)

Public WriteOnly Property XmlResolver As XmlResolver

Property Value

Type: System.Xml.XmlResolver
An XmlResolver used to access external documents. If set to Nothing, an XmlException is thrown when the XmlReader tries to access an external resource. The default is a new XmlUrlResolver with no credentials.

The XmlResolver is used to locate and open an XML instance document, or to locate and open any external resources referenced by the XML instance document. This can include entities, DTD, or schemas. The XmlResolver.Credentials property can be used to specify any credentials required for network authentication.

Security noteSecurity Note

Because the XmlResolver can contain sensitive information such as user credentials, you should be careful when caching XmlReaderSettings objects, or when passing the XmlReaderSettings object from one component to another.

An XmlSecureResolver can be used to access external documents. The XmlSecureResolver class helps to secure another implementation of XmlResolver by wrapping the XmlResolver object and restricting the resources that the underlying XmlResolver has access to. For more information, see How to: Use the XmlSecureResolver Class.

The ProcessInlineSchema and ProcessSchemaLocation validation flags of an XmlReaderSettings object are not set by default. When these flags are set, the XmlResolver of the XmlReaderSettings object is used to resolve schema locations encountered in the instance document in the XmlReader. If the XmlResolver object is Nothing, schema locations are not resolved even if the ProcessInlineSchema and ProcessSchemaLocation validation flags are set.

Schemas added during validation add new types and can change the validation outcome of the document being validated. As a result, external schemas should only be resolved from trusted sources.

The following example creates an XmlReader that uses an XmlSecureResolver with default credentials.

' Create an XmlSecureResolver with default credentials.
Dim myResolver As New XmlSecureResolver(New XmlUrlResolver(), "http://serverName/data/")
myResolver.Credentials = CredentialCache.DefaultCredentials

Dim settings As New XmlReaderSettings()
settings.XmlResolver = myResolver

' Create the reader.
Dim reader As XmlReader = XmlReader.Create("http://serverName/data/books.xml", settings)

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.