Retrieving Playlist Entries

  • Article

The following code examples illustrate how to retrieve all of the elements in a playlist and the names and values of any attributes assigned to them.

Visual Basic .NET Example

Imports Microsoft.WindowsMediaServices.Interop
Imports interop_msxml

Private Sub RetrieveEntries()

  ' Declare variables.
  Dim Server As WMSServer
  Dim Playlist As IXMLDOMDocument
  Dim Node As IXMLDOMNode
  Dim NodeList As IXMLDOMNodeList
  Dim AttrNode As IXMLDOMNode
  Dim NodeAttributes As IXMLDOMNamedNodeMap
  Dim NodeName As String
  Dim NodeType As String
  Dim AttrName As String
  Dim AttrValue As String
  Dim I As Long
  Dim J As Long

  Try
    ' Create new server and playlist objects.
    Server = New WMSServer()
    Playlist = Server.CreatePlaylist

    ' Load an existing playlist from a file.
    Playlist.load("c:\wmpub\wmroot\playlist.wsx")

    ' Retrieve a list of all nodes in the playlist file.
    NodeList = Playlist.getElementsByTagName("*")

    ' Retrieve all elements and the attributes assigned to them.
    For I = 0 To NodeList.length - 1

      ' Retrieve the next node in the playlist.
      Node = NodeList.item(I)

      ' Retrieve the name and type of the node.
      NodeName = Node.nodeName
      NodeType = Node.nodeType

      ' If the node is an element, retrieve the attributes.
      If NodeType = interop_msxml.DOMNodeType.NODE_ELEMENT Then
        NodeAttributes = Node.attributes

        ' Loop through all elements and retrieve the
        ' name and value of each.
        For J = 0 To NodeAttributes.length - 1
          AttrNode = NodeAttributes.item(J)
          AttrName = AttrNode.nodeName
          AttrValue = AttrNode.nodeValue
          Next
      End If
   Next

  Catch Err As Exception
    ' TODO: Exception handler goes here.

  Finally
    ' TODO: Clean-up code goes here.

  End Try

End Sub

C# Example

using Microsoft.WindowsMediaServices.Interop;
using interop_msxml;

// Declare variables.
IXMLDOMDocument playlist;
IXMLDOMNode attr_node, node;
IXMLDOMNodeList node_list;
IXMLDOMNamedNodeMap node_attributes;
DOMNodeType node_type;
string attr_name, attr_value, node_name;
int i,j;

try
{
  // Create new server and playlist objects.
  WMSServer server = new WMSServerClass();
  playlist = (IXMLDOMDocument)server.CreatePlaylist();

  // Load an existing playlist from a file.
  playlist.load("c:\\wmpub\\wmroot\\playlist.wsx");

  // Retrieve a list of all nodes in the playlist file.
  node_list = playlist.getElementsByTagName("*");

  // Retrieve all elements and attributes.
  for (i=0; i<node_list.length; i++)
  {
    // Retrieve the next node in the playlist.
    node = node_list[i];

    // Retrieve the name and type of the node.
    node_name = node.nodeName;
    node_type = node.nodeType;

    // If the node is an element, retrieve its attributes.
    if (node_type == DOMNodeType.NODE_ELEMENT)
    {
      node_attributes = node.attributes;

      // Retrieve the attributes for each element
      for (j=0; j < node_attributes.length; j++)
      {
        attr_node = node_attributes[j];
        attr_name = attr_node.nodeName;
        attr_value = (string)attr_node.nodeValue;
      }
    }
  }
}

catch(Exception)
{
  // TODO: Exception handler goes here.
}

finally
{
  // TODO: Clean-up code goes here.
}

C++ Example

// Include header files.
#include <windows.h>
#include <atlbase.h>    // Includes CComBSTR and CComVariant.
#include "wmsserver.h"

// Declare variables and interfaces.
IWMSServer            *pServer;
IXMLDOMDocument       *pPlaylist;
IXMLDOMNode           *pAttrNode, *pNode;
IXMLDOMNodeList       *pNodeList;
IXMLDOMNamedNodeMap   *pNodeAttr;
DOMNodeType           *pNodeType;
CComBSTR               bstrAttrName, bstrAttrValue;
CComBSTR               bstrTemp, bstrName;
CComVariant            varValue;
int                    i, j;
long                   lLength;
HRESULT                hr;

// Initialize the COM library and retrieve a pointer
// to an IWMSServer interface.
hr = CoInitialize(NULL);
if (FAILED(hr))goto EXIT;

hr = CoCreateInstance(CLSID_WMSServer,
                      NULL,
                      CLSCTX_ALL,
                      IID_IWMSServer,
                      (void **)&pServer);
if (FAILED(hr))goto EXIT;

// Create the playlist object.
hr = pServer->CreatePlaylist(&pPlaylist); 
if (FAILED(hr))goto EXIT;

// Retrieve the list of all nodes in the XML playlist file.
bstrTemp = "*";
hr = pPlaylist->getElementsByTagName(bstrTemp, &pNodeList);
if (FAILED(hr))goto EXIT;

// Retrieve all elements and their attributes.
hr = pNodeList->get_length(&lLength);
if (FAILED(hr))goto EXIT;

for (i=0; i < lLength; i++)
{
  // Retrieve the next node in the playlist.
  hr = pNodeList->get_item((long)i, &pNode);
  if (FAILED(hr))goto EXIT;

  // Retrieve the name and type of the node.
  hr = pNode->get_nodeName(&bstrName);
  if (FAILED(hr))goto EXIT;

  hr = pNode->get_nodeType(pNodeType);
  if (FAILED(hr))goto EXIT;

  // If the node is an element, retrieve the attributes.
  if (*pNodeType == NODE_ELEMENT)
  {
    hr = pNode->get_attributes(&pNodeAttr);
    if (FAILED(hr))goto EXIT;

    // Loop through all elements and retrieve the
    // name and value of each.
    hr = pNodeAttr->get_length(&lLength);
    if (FAILED(hr))goto EXIT;

    for (j=0; j < lLength; j++)
    {
      hr = pNodeAttr->get_item((long)j, &pAttrNode);
      if (FAILED(hr))goto EXIT;

      hr = pAttrNode->get_nodeName(&bstrAttrName);
      if (FAILED(hr))goto EXIT;

      hr = pAttrNode->get_nodeValue(&varValue);
      if (FAILED(hr))goto EXIT;
    }
  }
}

EXIT:
// TODO: Release temporary objects and uninitialize COM.

See Also (General)

See Also (Visual Basic .NET)

See Also (C#)

See Also (C++)