XmlReaderSettings Class

Definition

Namespace:

System.Xml

Assembly:

System.Xml.ReaderWriter.dll

Specifies a set of features to support on the XmlReader object created by the Create method.

public ref class XmlReaderSettings sealed

public sealed class XmlReaderSettings

type XmlReaderSettings = class

Public NotInheritable Class XmlReaderSettings

Inheritance

Object

XmlReaderSettings

Examples

The following example creates an XmlReader that uses an XmlUrlResolver with the necessary credentials.

// Create an XmlUrlResolver with the credentials necessary to access the Web server.
var resolver = new XmlUrlResolver();
var myCred = new NetworkCredential(UserName, SecurelyStoredPassword, Domain);
resolver.Credentials = myCred;

var settings = new XmlReaderSettings();
settings.XmlResolver = resolver;

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

' 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)

Remarks

You use the Create method to obtain XmlReader instances. This method uses the XmlReaderSettings class to specify which features to implement in the XmlReader object it creates.

See the Remarks sections of the XmlReader and Create reference pages for information about which settings to use for conformance checks, validation, and other common scenarios. See the XmlReaderSettings() constructor for a list of default settings.

Security considerations

Consider the following when using the XmlReaderSettings 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 null, 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 XmlReaderSettings 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.

• The SourceUri property of an XmlSchemaValidationException returns the URI path to the schema file that caused the exception. The SourceUri property should not be exposed in untrusted scenarios.

• 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.

• XmlReaderSettings objects 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.

• 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.

• Do not accept supporting components, such as NameTable, XmlNamespaceManager, and XmlResolver objects, from an untrusted source.

• 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.

Constructors

XmlReaderSettings()

Initializes a new instance of the XmlReaderSettings class.

Properties

Async	Gets or sets whether asynchronous XmlReader methods can be used on a particular XmlReader instance.
CheckCharacters	Gets or sets a value indicating whether to do character checking.
CloseInput	Gets or sets a value indicating whether the underlying stream or TextReader should be closed when the reader is closed.
ConformanceLevel	Gets or sets the level of conformance which the XmlReader will comply.
DtdProcessing	Gets or sets a value that determines the processing of DTDs.
IgnoreComments	Gets or sets a value indicating whether to ignore comments.
IgnoreProcessingInstructions	Gets or sets a value indicating whether to ignore processing instructions.
IgnoreWhitespace	Gets or sets a value indicating whether to ignore insignificant white space.
LineNumberOffset	Gets or sets line number offset of the XmlReader object.
LinePositionOffset	Gets or sets line position offset of the XmlReader object.
MaxCharactersFromEntities	Gets or sets a value indicating the maximum allowable number of characters in a document that result from expanding entities.
MaxCharactersInDocument	Gets or sets a value indicating the maximum allowable number of characters in an XML document. A zero (0) value means no limits on the size of the XML document. A non-zero value specifies the maximum size, in characters.
NameTable	Gets or sets the XmlNameTable used for atomized string comparisons.
ProhibitDtd	Obsolete. Gets or sets a value indicating whether to prohibit document type definition (DTD) processing. This property is obsolete. Use DtdProcessing instead.
Schemas	Gets or sets the XmlSchemaSet to use when performing schema validation.
ValidationFlags	Gets or sets a value indicating the schema validation settings. This setting applies to XmlReader objects that validate schemas (ValidationType property set to ValidationType.Schema).
ValidationType	Gets or sets a value indicating whether the XmlReader will perform validation or type assignment when reading.
XmlResolver	Sets the XmlResolver used to access external documents.

Methods

Clone()	Creates a copy of the XmlReaderSettings instance.
Equals(Object)	Determines whether the specified object is equal to the current object. (Inherited from Object)
GetHashCode()	Serves as the default hash function. (Inherited from Object)
GetType()	Gets the Type of the current instance. (Inherited from Object)
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
Reset()	Resets the members of the settings class to their default values.
ToString()	Returns a string that represents the current object. (Inherited from Object)

Events

ValidationEventHandler

Occurs when the reader encounters validation errors.

See also

• XML Documents and Data