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function initPage() {}
</script><link href="../PRODUCT_PLUGIN/book.css" rel="stylesheet" type="text/css"/><link href="css/s60/style.css" rel="stylesheet" type="text/css" media="all"/></head><body onload="initPage();"><div class="body"><div class="contentLeft prTxt"><h1 class="pageHeading" id="GUID-894E87F7-7146-44DD-8CAF-60F7C446B0D8"><span>IDataSource.</span>RequestNotification()</h1><div>
<p><strong>Description:</strong></p>
<p>The <code>RequestNotification</code> method registers the <span>widget</span> to receive notifications of changes to the event
log.</p>
<p>This is an asynchronous method.</p>
<p><strong>Syntax:</strong></p>
<pre class="codeblock" id="GUID-AC8635A2-D9EC-4A09-A3A3-B7B767C99DEF">result = so.IDataSource.RequestNotification(criteria, callback);</pre>
<p><strong>Arguments:</strong></p>
<ul>
<li><p><code>criteria</code>:</p>
<p>This is an object that specifies the request for notification of changes
to the event log. For more information about the object properties and how
to define them, see section <a href="GUID-4F84676A-16EE-4A66-A6DC-67A57001A565.html#GUID-4F84676A-16EE-4A66-A6DC-67A57001A565">Criteria for requesting notification</a>.</p>
</li>
<li><p><code>callback</code>:</p>
<p>The <code>callback</code> argument is the name of the method
that is executed when an asynchronous <code>RequestNotification</code> call
has results or status information to return. You must define this method separately.
Follow the instructions in section <a href="GUID-C7C3B541-8D28-4DC6-9003-ECF57F26C608.html#GUID-C7C3B541-8D28-4DC6-9003-ECF57F26C608">Defining the callback handler for an asynchronous method</a> to
define the <code>callback</code> method.</p>
</li>
</ul>
<p><strong>Return value:</strong></p>
<p>The <code>RequestNotification</code> method returns an object
that contains a transaction ID for the <a href="GUID-C7C3B541-8D28-4DC6-9003-ECF57F26C608.html#GUID-C7C3B541-8D28-4DC6-9003-ECF57F26C608"><code>callback</code></a> instance,
an error code, and an error message (see the following table). When the asynchronous
call has completed, <code>callback</code> returns an object that contains
an error code and an error message (see <a href="GUID-C7C3B541-8D28-4DC6-9003-ECF57F26C608.html#GUID-E43BC9EA-3EBE-4C7F-A57E-A1C33BB01CF4">Table:
Callback return value</a>).</p>
<div class="tablenoborder"><a name="GUID-1903FF1D-3AEE-466C-863A-9556D5B17225"><!----></a><table cellpadding="4" cellspacing="0" summary="" id="GUID-1903FF1D-3AEE-466C-863A-9556D5B17225" frame="border" border="1" rules="all"><caption><strong>Table: </strong>Return value
properties for an asynchronous RequestNotification</caption>
<thead align="left">
<tr class="title "><th class="cellrowborder" valign="top" width="33.33333333333333%" id="d0e53881">
<p>Property</p>
</th><th class="cellrowborder" valign="top" width="33.33333333333333%" id="d0e53886">
<p>Description</p>
</th><th class="cellrowborder" valign="top" width="33.33333333333333%" id="d0e53891">
<p>Value</p>
</th></tr>
</thead>
<tbody>
<tr class="">
<td class="cellrowborder" valign="top" width="33.33333333333333%" headers="d0e53881 ">
<p><code>result.TransactionID</code></p>
</td>
<td class="cellrowborder" valign="top" width="33.33333333333333%" headers="d0e53886 ">
<p>This is a number used as an identification to match transactions started
with the asynchronous <code>GetList</code> call to one or more calls
it generates to <code>callback</code>.</p>
<p>This property is only valid for asynchronous calls.</p>
</td>
<td class="cellrowborder" valign="top" width="33.33333333333333%" headers="d0e53891 "> </td>
</tr>
<tr class="bg ">
<td class="cellrowborder" valign="top" width="33.33333333333333%" headers="d0e53881 ">
<p><code>result.ErrorCode</code></p>
</td>
<td class="cellrowborder" valign="top" width="33.33333333333333%" headers="d0e53886 ">
<p>This is a number that specifies a predefined error code.</p>
</td>
<td class="cellrowborder" valign="top" width="33.33333333333333%" headers="d0e53891 ">
<p>See <a href="GUID-0A215AF3-59F0-4158-842C-0D7B030E5EA4.html#GUID-0A215AF3-59F0-4158-842C-0D7B030E5EA4">Service API error codes</a>.</p>
</td>
</tr>
<tr class="">
<td class="cellrowborder" valign="top" width="33.33333333333333%" headers="d0e53881 ">
<p><code>result.ErrorMessage</code></p>
</td>
<td class="cellrowborder" valign="top" width="33.33333333333333%" headers="d0e53886 ">
<p>This is a text string that describes the error.</p>
</td>
<td class="cellrowborder" valign="top" width="33.33333333333333%" headers="d0e53891 ">
<p>See <a href="GUID-6C3D58CA-CA4F-432B-898B-4020064E3CE6.html#GUID-6C3D58CA-CA4F-432B-898B-4020064E3CE6">Logging Service API error messages</a>.</p>
</td>
</tr>
</tbody>
</table></div>
<p><strong>Example code:</strong></p>
<p/>
<p>For the complete source of a sample widget
that demonstrates how to use this Service API, see <a href="GUID-9C85B403-6CFC-4E17-A2B2-AD1AD2F7794D.html#GUID-9C85B403-6CFC-4E17-A2B2-AD1AD2F7794D">the
full example</a>.</p>
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