IWMSCacheProxy.AddCacheItem (Visual Basic .NET)

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IWMSCacheProxy.AddCacheItem (Visual Basic .NET)

The AddCacheItem method is called by the server to prestuff a cache.

Syntax

Parameters

bstrOriginUrl

[in] String containing the URL on the origin server of the content to be cached.

bstrPrestuffUrl

[in] String containing the URL identifying the location for the cache. If NULL, the method uses bstrOriginUrl.

lExpiration

[in] Integer containing the amount of time, in seconds, that the cache item is available to be streamed after it has been cached. For example, a value of 86,400 indicates that cached content can be streamed for 24 hours after it is downloaded from the origin server.

lBandwidth

[in] Integer containing the maximum bandwidth that the server can use when streaming content into cache storage.

lRemoteEventFlags

[in] Integer containing the remote events that must be passed back to the origin server. This must be one of the following values from the WMS_EVENT_TYPE enumeration.

Event	Description
WMS_EVENT_REMOTE_CACHE_OPEN	A remote cache proxy server has opened cached content or established a connection to an upstream server.
WMS_EVENT_REMOTE_CACHE_CLOSE	A remote cache proxy server has closed a content file or disconnected a client from an upstream server.
WMS_EVENT_REMOTE_CACHE_LOG	A client submitted a rendering log to indicate that it streamed content from a local cache, or a cache proxy server submitted a remote log to indicate that it either streamed content from cache or proxied it from an upstream server.

pCallback

[in] IWMSCacheProxyCallback object containing the callback function. This can be Nothing if no callback is requested.

varContext

[in] Object containing a value defined by the server to identify which call to AddCacheItem the plug-in is responding to when it calls IWMSCacheProxyCallback.OnAddCacheItem. The plug-in must pass this value back unaltered.

Return Values

This method does not return a value.

Remarks

This method can be called whenever an item must be added to a cache. It is always called by the server when the IWMSCacheProxyPlugin.PreStuff method is called. The plug-in calls IWMSCacheProxyCallback.OnAddCacheItem to respond to the AddCacheItem method.

Example Code

Imports Microsoft.WindowsMediaServices.Interop
Imports System.Runtime.InteropServices

Imports Microsoft.WindowsMediaServices.Interop
Imports System.Runtime.InteropServices

Public Sub AddCacheItem(ByVal OriginUrl As String, _
                        ByVal PrestuffUrl As String, _
                        ByVal lExpiration As Integer, _
                        ByVal lBandwidth As Integer, _
                        ByVal lRemoteEventFlags As Integer, _
                        ByVal Callback As IWMSCacheProxyCallback, _
                        ByVal varContext As Object) _
  Implements IWMSCacheProxy.AddCacheItem

    Dim ci As ContentInfo
    Dim PresentationContext As IWMSContext
    Dim pUnknown As IntPtr

    Try
      ' The ContentInfo class is user-defined and contains
      ' information about cached content.
      ci = New ContentInfo(OriginUrl, PrestuffUrl)
      ci.lExpiration = lExpiration

      ' Create a presentation context. The CacheProxyServer
      ' object is your plug-in's implementation of the 
      ' IWMSCacheProxyServer object.
      ClassObject.AllocIWMSContext( _
                        GetType(IWMSContext).GUID, _
                        WMS_CONTEXT_TYPE.WMS_USER_CONTEXT_TYPE, _
                        Nothing, _
                        pUnknown)
      PresentationContext = Marshal.GetTypedObjectForIUnknown( _
                        pUnknown, _
                        GetType(IWMSContext))

      ' Retrieve content information.
      CacheProxyServer.GetContentInformation(OriginUrl, _
                                             PresentationContext, _
                                             Nothing, _
                                             Nothing, _
                                             Me, _
                                             ci)

      ' The server calls OnGetContentInformation() in response
      ' to the preceding call and sends the plug-in a cache
      ' information context. The context contains a reference to
      ' an IWMSDataContainerVersion object that the plug-in can use
      ' to retrieve content information and place it in the
      ' user-defined ContentInfo class. If the 
      ' WMS_DATA_CONTAINER_VERSION_CACHE_FLAGS enumeration member
      ' indicates that the content can be downloaded, the plug-in calls 
      ' DownloadContent(). When the download is complete, the 
      ' OnGetContentInformation() function can call OnAddCacheItem() to
      ' signal that the appropriate event notices should be raised.

  Catch
      Throw New COMException()
  End Try

End Sub

Requirements

Reference: Add a reference to Microsoft.WindowsMediaServices.

Namespace: Microsoft.WindowsMediaServices.Interop.

Assembly: Microsoft.WindowsMediaServices.dll.

Library: WMSServerTypeLib.dll.

Platform: Windows Server 2003, Enterprise Edition; Windows Server 2003, Datacenter Edition; Windows Server 2008.

See Also

• IWMSCacheProxy Object (Visual Basic .NET)

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