Assembly: System.Xml (in System.Xml.dll)
In the .NET Framework version 2.0 release, the Create method is the preferred mechanism for obtaining XmlReader instances. The Create method uses the class to specify which features to implement in the created XmlReader object.
For more information, see Creating XML Readers.
The following are things to consider when using the class.
The ProcessInlineSchema and ProcessSchemaLocation validation flags of an object are not set by default. When these flags are set, the XmlResolver of the 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.
Validation error messages may expose sensitive content model information. Validation error and warning messages are handled using the ValidationEventHandler delegate, or are exposed as an XmlSchemaValidationException if no event handler is provided to the object (validation warnings do not cause an XmlSchemaValidationException to be thrown). This content model information should not be exposed in untrusted scenarios. Validation warning messages are suppressed by default and can be reported by setting the ReportValidationWarnings flag.
Disabling the ProcessIdentityConstraints flag (enabled by default) is recommended when validating, untrusted, large XML documents in high availability scenarios against a schema with identity constraints over a large part of the document.
objects can contain sensitive information such as user credentials. You should be careful when caching objects, or when passing the object from one component to another.
DTD processing is disabled by default. If you enable DTD processing, you need to be aware of including DTDs from untrusted sources and possible denial of service attacks. Use the XmlSecureResolver to restrict the resources that the XmlReader can access.
Memory usage of an application that uses XmlReader may have a correlation to the size of the parsed XML document. One form of denial of service attack is when excessively large XML documents are submitted to be parsed. You can limit the size of the document that can be parsed by setting the MaxCharactersInDocument property and then limit the number of characters that result from expanding entities by setting the MaxCharactersFromEntities property.
' Create an XmlUrlResolver with the credentials necessary to access the Web server. Dim resolver As New XmlUrlResolver() Dim myCred As System.Net.NetworkCredential myCred = New System.Net.NetworkCredential(UserName, SecurelyStoredPassword, Domain) resolver.Credentials = myCred Dim settings As New XmlReaderSettings() settings.XmlResolver = resolver ' Create the reader. Dim reader As XmlReader = XmlReader.Create("http://serverName/data/books.xml", settings)
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.