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Value (WSD)

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The WSD Value construct allows you to extend the bidi communications schema with queries that retrieve data from a particular schema element in the Web service interface.

Attribute Description
drvPrinterEvent (Optional) A Boolean value that indicates whether the port monitor sends notifications to the driver. A TRUE value indicates that the port monitor sends notifications to the driver; FALSE indicates that the port monitor does not send notifications to the driver.
filter The XPath query that the WSD monitor will apply to the XML document that is specified by the query. See the discussion later in this topic.
name The name of the schema value.
query The type of query that the WSD monitor will perform.
type The type of data in the Value construct, a value in the BIDI_TYPE enumeration.
xmllang (Optional) A boolean value that, when TRUE, means that the associated Value construct should be treated as a localizable string value. This means that the XPath query defined above is expected to return a list of nodes differentiated by their xml:lang attributes. The WSD monitor will then search the list of values for the best locale match. The default value is FALSE.

The XPath language is implemented in Windows and provides a convenient way to specify elements in an XML file. See the XPath Reference for more information.

The xmllang attribute is used only when the type attribute of the Value construct is either "BIDI_STRING" or "BIDI_TEXT".

The Value construct is defined in WsdBidi.xsd.

Example

In the following code example, the WSD monitor determines the size, as an integer value, of RAM memory.

<Schema xmlns:nprt='https://schemas.microsoft.com/windows/2005/05/wdp/print'>
  <Property name='Printer'>
    <Property name='DeviceInfo'>
      <Value name='PrinterString'
 query='nprt:PrinterDescription'
 filter='nprt:PrinterDescription/nprt:PrinterName'
 type='BIDI_STRING'
 xmllang='true'/>
    </Property>
    <Property name='Configuration'>
      <Property name='Memory'>
        <Value name='Size'
          query='wprt:PrinterConfiguration'
          filter='wprt:PrinterConfiguration/wprt:Storage/wprt:StorageEntry[wprt:Type="RAM"]/wprt:Size'
          type='BIDI_INT'/>
      </Property>
    </Property>
   </Property>
</Schema>

The preceding example results in the following queries:

\Printer.DeviceInfo:PrinterString
\Printer.Configuration.Memory:Size