CacheDuration Property

WebMethodAttribute.CacheDuration Property

Gets or sets the number of seconds the response should be held in the cache.

Namespace:  System.Web.Services
Assembly:  System.Web.Services (in System.Web.Services.dll)

Public Property CacheDuration As Integer

Property Value

Type: System.Int32
The number of seconds the response should be held in the cache. The default is 0, which means the response is not cached.

When caching is enabled requests and responses are held in memory on the server for at least the cache duration so caution must be used if you expect requests or responses to be very large or you expect requests to vary widely.

There are two issues that can affect output caching in an ASP.NET 2.0 Web service application.

In ASP.NET 2.0 the HTTP method of the test page has changed from GET to POST. However, POSTs are not normally cached. If you change the test page in an ASP.NET 2.0 Web service application to use GET, caching works properly.

In addition, HTTP indicates that a user agent (the browser or calling application) should be able to override server caching by setting the "Cache-Control" to "no-cache". ASP.NET applications, therefore, ignore cached results when they find a "no-cache" header.

The following example places the result of the call to the ServiceUsage XML Web service method in the cache for 60 seconds. Any time an XML Web service client executes the ServiceUsage XML Web service method during that time, the same result is returned.

<%@ WebService Language="VB" Class="Counter" %>

Imports System.Web.Services
Imports System
Imports System.Web

Public Class Counter
    Inherits WebService  

    <WebMethod(Description := "Number of times this service has been accessed", _
        CacheDuration := 60, _
        MessageName := "ServiceUsage")> _
    Public Function ServiceUsage() As Integer

        ' If the XML Web service has not been accessed, initialize it to 1.
        If Application("MyServiceUsage") Is Nothing Then
            Application("MyServiceUsage") = 1
            ' Increment the usage count.
            Application("MyServiceUsage") = CInt(Application("MyServiceUsage")) + 1
        End If

        ' Return the usage count.
        Return CInt(Application("MyServiceUsage"))
    End Function
End Class

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1
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