MessageQuery.Evaluate Method
Definition
Important
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When overridden in a derived class, runs a query against the message and returns a value that satisfies the query.
Overloads
| Evaluate<TResult>(Message) |
When overridden in a derived class, runs a query against the message and returns a result. The body cannot be queried. |
| Evaluate<TResult>(MessageBuffer) |
When overridden in a derived class, runs a query against the message and returns a result. |
Remarks
The difference between the two overloads is that one takes a Message parameter and is not permitted to examine the body; the other takes a MessageBuffer parameter and can examine any part of the message. Message headers are automatically buffered and can be queried without being consumed. However, if the body is to be queried, then the entire message must be buffered because an unbuffered message body can be consumed by the query.
Evaluate<TResult>(Message)
When overridden in a derived class, runs a query against the message and returns a result. The body cannot be queried.
public:
generic <typename TResult>
abstract TResult Evaluate(System::ServiceModel::Channels::Message ^ message);public abstract TResult Evaluate<TResult> (System.ServiceModel.Channels.Message message);abstract member Evaluate : System.ServiceModel.Channels.Message -> 'ResultPublic MustOverride Function Evaluate(Of TResult) (message As Message) As TResultType Parameters
- TResult
The type of the value to return.
Parameters
- message
- Message
The message to query.
Returns
TResult
An enumerable collection of results that satisfy the query.
Applies to
Evaluate<TResult>(MessageBuffer)
When overridden in a derived class, runs a query against the message and returns a result.
public:
generic <typename TResult>
abstract TResult Evaluate(System::ServiceModel::Channels::MessageBuffer ^ buffer);public abstract TResult Evaluate<TResult> (System.ServiceModel.Channels.MessageBuffer buffer);abstract member Evaluate : System.ServiceModel.Channels.MessageBuffer -> 'ResultPublic MustOverride Function Evaluate(Of TResult) (buffer As MessageBuffer) As TResultType Parameters
- TResult
The type of the object to return.
Parameters
- buffer
- MessageBuffer
The message to query.
Returns
TResult
An enumerable collection of results that satisfy the query.
Examples
The following example creates a message and XPath message queries. The queries are evaluated by the XPathMessageQuery objects contained in an XPathMessageQueryCollection object. The results of each query are tested using the ResultType property of the XPathResult class.
using System;
using System.IO;
using System.Xml;
using System.ServiceModel.Dispatcher;
using System.ServiceModel;
using System.ServiceModel.Channels;
using System.Xml.XPath;
namespace MessageQueryExamples
{
class Program
{
static void Main(string[] args)
{
// The XPathMessageQueryCollection inherits from MessageQueryCollection.
XPathMessageQueryCollection queryCollection = MessageHelper.SetupQueryCollection();
// Create a message and a copy of the message. You must create a buffered copy to access the message body.
Message mess = MessageHelper.CreateMessage();
MessageBuffer mb = mess.CreateBufferedCopy(int.MaxValue);
// Evaluate every query in the collection.
foreach (XPathMessageQuery q in queryCollection)
{
// Evaluate the query. Note the result type is an XPathResult.
XPathResult qPathResult = q.Evaluate<XPathResult>(mb);
// Use the XPathResult to determine the result type.
Console.WriteLine("Result type: {0}", qPathResult.ResultType);
// The following code prints the result according to the result type.
if (qPathResult.ResultType == XPathResultType.String)
Console.WriteLine("{0} = {1}", q.Expression, qPathResult.GetResultAsString());
if (qPathResult.ResultType == XPathResultType.NodeSet)
{
// Iterate through the node set.
XPathNodeIterator ns = qPathResult.GetResultAsNodeset();
foreach (XPathNavigator n in ns)
Console.WriteLine("\t{0} = {1}", q.Expression, n.Value);
}
if (qPathResult.ResultType == XPathResultType.Number)
Console.WriteLine("\t{0} = {1}", q.Expression, qPathResult.GetResultAsNumber());
if (qPathResult.ResultType == XPathResultType.Boolean)
Console.WriteLine("\t{0} ={1}", q.Expression, qPathResult.GetResultAsBoolean());
if (qPathResult.ResultType == XPathResultType.Error)
Console.WriteLine("\tError!");
}
Console.WriteLine();
// The alternate code below demonstrates similar funcionality using a MessageQueryTable.
// The difference is the KeyValuePair that requires a key to index each value.
// The code uses the expression as the key, and an arbitrary value for the value.
//MessageQueryTable<string> mq = MessageHelper.SetupTable();
//foreach (KeyValuePair<MessageQuery, string> kv in mq)
//{
// XPathMessageQuery xp = (XPathMessageQuery)kv.Key;
// Console.WriteLine("Value = {0}", kv.Value);
// Console.WriteLine("{0} = {1}", xp.Expression, xp.Evaluate<string>(mb));
//}
Console.ReadLine();
}
}
public class MessageHelper
{
static string messageBody =
"<PurchaseOrder date='today'>" +
"<Number>ABC-2009-XYZ</Number>" +
"<Department>OnlineSales</Department>" +
"<Items>" +
"<Item product='nail' quantity='1'>item1</Item>" +
"<Item product='screw' quantity='2'>item2</Item>" +
"<Item product='brad' quantity='3'>" +
"<SpecialOffer/>" +
"Special item4" +
"</Item>" +
"<Item product='SpecialNails' quantity='9'>item5</Item>" +
"<Item product='SpecialBrads' quantity='11'>" +
"<SpecialOffer/>" +
"Special item6" +
"</Item>" +
"<Item product='hammer' quantity='1'>item7</Item>" +
"<Item product='wrench' quantity='2'>item8</Item>" +
"</Items>" +
"<Comments>" +
"Rush order" +
"</Comments>" +
"</PurchaseOrder>";
public static string xpath = "/s12:Envelope/s12:Body/PurchaseOrder/Items/Item[@quantity = 1]";
public static string xpath2 = "/s12:Envelope/s12:Body/PurchaseOrder/Items/Item[@product = 'nail']";
public static string xpath3 = "/s12:Envelope/s12:Body/PurchaseOrder/Comments";
public static string xpath4 = "count(/s12:Envelope/s12:Body/PurchaseOrder/Items/Item)";
public static string xpath5 = "substring(string(/s12:Envelope/s12:Body/PurchaseOrder/Number),5,4)";
public static string xpath6 = "/s12:Envelope/s12:Body/PurchaseOrder/Department='OnlineSales'";
public static string xpath7 = "//PurchaseOrder/@date";
public static string xpath8 = "//SpecialOffer/ancestor::Item[@product = 'brad']";
// Invoke the correlation data function.
public static string xpath9 = "sm:correlation-data('CorrelationData1')";
public static string xpath10 = "sm:correlation-data('CorrelationData2')";
public static string xpath11 = "/s12:Envelope/s12:Body/PurchaseOrder/Items/Item[@quantity = 2]";
public static Message CreateMessage()
{
StringReader stringReader = new StringReader(messageBody);
XmlTextReader xmlReader = new XmlTextReader(stringReader);
Message message = Message.CreateMessage(MessageVersion.Soap12WSAddressing10, "http://purchaseorder", xmlReader);
// Add two correlation properties using lambda expressions. The property names are
// CorrelationData1 and CorrelationData2. The first goes to "value1" and the
// second to "value2". You can use your own property names and values.
CorrelationDataMessageProperty data = new CorrelationDataMessageProperty();
data.Add("CorrelationData1", () => "value1");
data.Add("CorrelationData2", () => "value2");
message.Properties[CorrelationDataMessageProperty.Name] = data;
return message;
}
public static XPathMessageQueryCollection SetupQueryCollection()
{
// Create the query collection and add the XPath queries to it. To create
// the query, you must also use a new XPathMessageContext.
XPathMessageQueryCollection queryCollection = new XPathMessageQueryCollection();
XPathMessageContext context = new XPathMessageContext();
queryCollection.Add(new XPathMessageQuery(xpath, context));
queryCollection.Add(new XPathMessageQuery(xpath2, context));
queryCollection.Add(new XPathMessageQuery(xpath3, context));
queryCollection.Add(new XPathMessageQuery(xpath4, context));
queryCollection.Add(new XPathMessageQuery(xpath5, context));
queryCollection.Add(new XPathMessageQuery(xpath6, context));
queryCollection.Add(new XPathMessageQuery(xpath7, context));
queryCollection.Add(new XPathMessageQuery(xpath8, context));
queryCollection.Add(new XPathMessageQuery(xpath9, context));
queryCollection.Add(new XPathMessageQuery(xpath10, context));
queryCollection.Add(new XPathMessageQuery(xpath11, context));
return queryCollection;
}
public static MessageQueryTable<string> SetupTable()
{
// This is optional code to demonstrate using a MessageQueryTable.
// Compare this to the MessageQueryCollection.
MessageQueryTable<string> table = new MessageQueryTable<string>();
XPathMessageContext context = new XPathMessageContext();
// The code adds a KeyValuePair to the table. Each pair requires
// a query used as the Key, and a value that is paired to the key.
table.Add(new XPathMessageQuery(xpath, context), "value10");
table.Add(new XPathMessageQuery(xpath2, context), "value20");
table.Add(new XPathMessageQuery(xpath3, context), "value30");
table.Add(new XPathMessageQuery(xpath4, context), "value40");
table.Add(new XPathMessageQuery(xpath5, context), "value50");
table.Add(new XPathMessageQuery(xpath6, context), "value60");
table.Add(new XPathMessageQuery(xpath7, context), "value70");
table.Add(new XPathMessageQuery(xpath8, context), "value80");
table.Add(new XPathMessageQuery(xpath9, context), "value90");
table.Add(new XPathMessageQuery(xpath10, context), "value100");
table.Add(new XPathMessageQuery(xpath11, context), "value110");
return table;
}
}
}
Imports System.IO
Imports System.Xml
Imports System.ServiceModel.Dispatcher
Imports System.ServiceModel
Imports System.ServiceModel.Channels
Imports System.Xml.XPath
Namespace MessageQueryExamples
Public Class Program
Public Shared Sub Main(ByVal args As String())
' The XPathMessageQueryCollection inherits from MessageQueryCollection.
Dim queryCollection As XPathMessageQueryCollection = MessageHelper.SetupQueryCollection()
' Create a message and a copy of the message. You must create a buffered copy to access the message body.
Dim mess As Message = MessageHelper.CreateMessage()
Dim mb As MessageBuffer = mess.CreateBufferedCopy(Integer.MaxValue)
' Evaluate every query in the collection.
Dim q As XPathMessageQuery
For Each q In queryCollection
' Evaluate the query. Note the result type is an XPathResult.
Dim qPathResult As XPathResult = q.Evaluate(Of XPathResult)(mb)
' Use the XPathResult to determine the result type.
Console.WriteLine("Result type: {0}", qPathResult.ResultType)
' The following code prints the result according to the result type.
If qPathResult.ResultType = XPathResultType.String Then
Console.WriteLine("{0} = {1}", q.Expression, qPathResult.GetResultAsString())
End If
If (qPathResult.ResultType = XPathResultType.NodeSet) Then
' Iterate through the node set.
Dim ns As XPathNodeIterator = qPathResult.GetResultAsNodeset()
Dim n As XPathNavigator
For Each n In ns
Console.WriteLine(" {0} = {1}", q.Expression, n.Value)
Next
End If
If qPathResult.ResultType = XPathResultType.Number Then
Console.WriteLine(" {0} = {1}", q.Expression, qPathResult.GetResultAsNumber())
End If
If qPathResult.ResultType = XPathResultType.Boolean Then
Console.WriteLine(" {0} ={1}", q.Expression, qPathResult.GetResultAsBoolean())
End If
If qPathResult.ResultType = XPathResultType.Error Then
Console.WriteLine(" Error!")
End If
Next
Console.WriteLine()
' The alternate code below demonstrates similar funcionality using a MessageQueryTable.
' The difference is the KeyValuePair that requires a key to index each value.
' The code uses the expression as the key, and an arbitrary value for the value.
'Dim mq As MessageQueryTable(Of String) = MessageHelper.SetupTable()
'Dim kv As KeyValuePair(Of MessageQuery, String)
'For Each kv In mq
' '
' Dim xp As XPathMessageQuery = CType(kv.Key, XPathMessageQuery)
' Console.WriteLine("Value = {0}", kv.Value)
' Console.WriteLine("{0} = {1}", xp.Expression, xp.Evaluate(Of String)(mb))
'Next
Console.ReadLine()
End Sub
Private Shared Sub Evaluate(ByVal p1 As Object)
Throw New NotImplementedException
End Sub
End Class
Public Class MessageHelper
Shared messageBody As String = _
"<PurchaseOrder date='today'>" + _
"<Number>ABC-2009-XYZ</Number>" + _
"<Department>OnlineSales</Department>" + _
"<Items>" + _
"<Item product='nail' quantity='1'>item1</Item>" + _
"<Item product='screw' quantity='2'>item2</Item>" + _
"<Item product='brad' quantity='3'>" + _
"<SpecialOffer/>" + _
"Special item4" + _
"</Item>" + _
"<Item product='SpecialNails' quantity='9'>item5</Item>" + _
"<Item product='SpecialBrads' quantity='11'>" + _
"<SpecialOffer/>" + _
"Special item6" + _
"</Item>" + _
"<Item product='hammer' quantity='1'>item7</Item>" + _
"<Item product='wrench' quantity='2'>item8</Item>" + _
"</Items>" + _
"<Comments>" + _
"Rush order" + _
"</Comments>" + _
"</PurchaseOrder>"
Public Shared xpath As String = "/s12:Envelope/s12:Body/PurchaseOrder/Items/Item[@quantity = 1]"
Public Shared xpath2 As String = "/s12:Envelope/s12:Body/PurchaseOrder/Items/Item[@product = 'nail']"
Public Shared xpath3 As String = "/s12:Envelope/s12:Body/PurchaseOrder/Comments"
Public Shared xpath4 As String = "count(/s12:Envelope/s12:Body/PurchaseOrder/Items/Item)"
Public Shared xpath5 As String = "substring(string(/s12:Envelope/s12:Body/PurchaseOrder/Number),5,4)"
Public Shared xpath6 As String = "/s12:Envelope/s12:Body/PurchaseOrder/Department='OnlineSales'"
Public Shared xpath7 As String = "//PurchaseOrder/@date"
Public Shared xpath8 As String = "//SpecialOffer/ancestor::Item[@product = 'brad']"
' Invoke the correlation data function.
Public Shared xpath9 As String = "sm:correlation-data('CorrelationData1')"
Public Shared xpath10 As String = "sm:correlation-data('CorrelationData2')"
Public Shared xpath11 As String = "/s12:Envelope/s12:Body/PurchaseOrder/Items/Item[@quantity = 2]"
Public Shared Function CreateMessage() As Message
Dim stringReader As New StringReader(messageBody)
Dim xmlReader As New XmlTextReader(stringReader)
Dim message As Message = message.CreateMessage( _
MessageVersion.Soap12WSAddressing10, "http://purchaseorder", xmlReader)
' Add two correlation properties using lambda expressions. The property names are
' CorrelationData1 and CorrelationData2. The first goes to "value1" and the
' second to "value2". You can use your own property names and values.
Dim data As New CorrelationDataMessageProperty()
data.Add("CorrelationData1", Function() "value1")
data.Add("CorrelationData2", Function() "value2")
message.Properties(CorrelationDataMessageProperty.Name) = data
Return message
End Function
Public Shared Function SetupQueryCollection() As XPathMessageQueryCollection
' Create the query collection and add the XPath queries to it. To create
' the query, you must also use a new XPathMessageContext.
Dim queryCollection As New XPathMessageQueryCollection()
Dim context As XPathMessageContext = New XPathMessageContext()
queryCollection.Add(New XPathMessageQuery(xpath, context))
queryCollection.Add(New XPathMessageQuery(xpath2, context))
queryCollection.Add(New XPathMessageQuery(xpath3, context))
queryCollection.Add(New XPathMessageQuery(xpath4, context))
queryCollection.Add(New XPathMessageQuery(xpath5, context))
queryCollection.Add(New XPathMessageQuery(xpath6, context))
queryCollection.Add(New XPathMessageQuery(xpath7, context))
queryCollection.Add(New XPathMessageQuery(xpath8, context))
queryCollection.Add(New XPathMessageQuery(xpath9, context))
queryCollection.Add(New XPathMessageQuery(xpath10, context))
queryCollection.Add(New XPathMessageQuery(xpath11, context))
Return queryCollection
End Function
Public Shared Function SetupTable() As MessageQueryTable(Of String)
' This is optional code to demonstrate using a MessageQueryTable.
' Compare this to the MessageQueryCollection.
Dim table As MessageQueryTable(Of String) = New MessageQueryTable(Of String)()
Dim context As XPathMessageContext = New XPathMessageContext()
' The code adds a KeyValuePair to the table. Each pair requires
' a query used as the Key, and a value that is paired to the key.
table.Add(New XPathMessageQuery(xpath, context), "value10")
table.Add(New XPathMessageQuery(xpath2, context), "value20")
table.Add(New XPathMessageQuery(xpath3, context), "value30")
table.Add(New XPathMessageQuery(xpath4, context), "value40")
table.Add(New XPathMessageQuery(xpath5, context), "value50")
table.Add(New XPathMessageQuery(xpath6, context), "value60")
table.Add(New XPathMessageQuery(xpath7, context), "value70")
table.Add(New XPathMessageQuery(xpath8, context), "value80")
table.Add(New XPathMessageQuery(xpath9, context), "value90")
table.Add(New XPathMessageQuery(xpath10, context), "value100")
table.Add(New XPathMessageQuery(xpath11, context), "value110")
Return table
End Function
End Class
End Namespace
