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     5       function initPage() {}
       
     6     </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-B4897257-F7BC-4C32-9C6C-A577FDAC5D09"><span>ISensor.</span>RegisterForNotification()</h1><div>
       
     7 <p><strong>Description:</strong></p>
       
     8 <p>The <code>RegisterForNotification</code> method registers the
       
     9 client to receive data from one sensor channel.</p>
       
    10 <p>This is an asynchronous method.</p>
       
    11 <p><strong>Syntax:</strong></p>
       
    12 
       
    13 <pre class="codeblock" id="GUID-76779290-2870-4637-925E-009722ED727B">result = so.ISensor.RegisterForNotification(criteria, callback);</pre>
       
    14 <p><strong>Arguments:</strong></p>
       
    15 <ul>
       
    16 <li><p><code>criteria</code>:</p>
       
    17 
       
    18 <p>This is an object that specifies the sensor channel to listen for data.
       
    19 For more information about the object properties and how to define them, see
       
    20 section <a href="GUID-B024688A-3701-4282-9C98-D984477E00C2.html#GUID-B024688A-3701-4282-9C98-D984477E00C2">Criteria for receiving sensor data</a>.</p>
       
    21 
       
    22 </li>
       
    23 <li><p><code>callback</code>:</p>
       
    24 
       
    25 <p>The <code>callback</code> argument is the name of the method
       
    26 that is executed when a <code>RegisterForNotification</code> call
       
    27 has results or status information to return. You must define this method separately.
       
    28 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
       
    29 define the <code>callback</code> method.</p>
       
    30 
       
    31 </li>
       
    32 </ul>
       
    33 <p><strong>Return value:</strong></p>
       
    34 <p>The <code>RegisterForNotification</code> method returns an object
       
    35 that contains the initial return value for the asynchronous call it started
       
    36 (see the following table). The actual sensor data is returned by the <a href="GUID-C7C3B541-8D28-4DC6-9003-ECF57F26C608.html#GUID-C7C3B541-8D28-4DC6-9003-ECF57F26C608"><code>callback</code></a> method
       
    37 in the <code>ReturnValue</code> property of its result object. The
       
    38 returned data is described in section <a href="GUID-7FD32D4D-871F-4251-844C-6CB59B593730.html#GUID-7FD32D4D-871F-4251-844C-6CB59B593730">Returned sensor data</a>.</p>
       
    39 <div class="tablenoborder"><a name="GUID-F78FBD65-AAE7-4C1C-B5E5-5002FFC613B4"><!----></a><table cellpadding="4" cellspacing="0" summary="" id="GUID-F78FBD65-AAE7-4C1C-B5E5-5002FFC613B4" frame="border" border="1" rules="all"><caption><strong>Table: </strong>Return value
       
    40 properties for RegisterForNotification</caption>
       
    41 <thead align="left">
       
    42 <tr class="title "><th class="cellrowborder" valign="top" width="33.33333333333333%" id="d0e64207">
       
    43 <p>Property</p>
       
    44 </th><th class="cellrowborder" valign="top" width="33.33333333333333%" id="d0e64212">
       
    45 <p>Description</p>
       
    46 </th><th class="cellrowborder" valign="top" width="33.33333333333333%" id="d0e64217">
       
    47 <p>Value</p>
       
    48 </th></tr>
       
    49 </thead>
       
    50 <tbody>
       
    51 <tr class="">
       
    52 <td class="cellrowborder" valign="top" width="33.33333333333333%" headers="d0e64207 ">
       
    53 <p><code>result.TransactionID</code></p>
       
    54 </td>
       
    55 <td class="cellrowborder" valign="top" width="33.33333333333333%" headers="d0e64212 ">
       
    56 <p>This is a number used as an identification to match transactions started
       
    57 with the <code>RegisterForNotification</code> call to one or more
       
    58 calls it generates to <code>callback</code>.</p>
       
    59 </td>
       
    60 <td class="cellrowborder" valign="top" width="33.33333333333333%" headers="d0e64217 ">&nbsp;</td>
       
    61 </tr>
       
    62 <tr class="bg ">
       
    63 <td class="cellrowborder" valign="top" width="33.33333333333333%" headers="d0e64207 ">
       
    64 <p><code>result.ErrorCode</code></p>
       
    65 </td>
       
    66 <td class="cellrowborder" valign="top" width="33.33333333333333%" headers="d0e64212 ">
       
    67 <p>This is a number that specifies a predefined error code.</p>
       
    68 </td>
       
    69 <td class="cellrowborder" valign="top" width="33.33333333333333%" headers="d0e64217 ">
       
    70 <p>See <a href="GUID-0A215AF3-59F0-4158-842C-0D7B030E5EA4.html#GUID-0A215AF3-59F0-4158-842C-0D7B030E5EA4">Service API error codes</a>.</p>
       
    71 </td>
       
    72 </tr>
       
    73 <tr class="">
       
    74 <td class="cellrowborder" valign="top" width="33.33333333333333%" headers="d0e64207 ">
       
    75 <p><code>result.ErrorMessage</code></p>
       
    76 </td>
       
    77 <td class="cellrowborder" valign="top" width="33.33333333333333%" headers="d0e64212 ">
       
    78 <p>This is a text string that describes the error.</p>
       
    79 </td>
       
    80 <td class="cellrowborder" valign="top" width="33.33333333333333%" headers="d0e64217 ">
       
    81 <p>See <a href="GUID-46FAFCDA-BCF3-41CB-B154-C17BBF7CD755.html#GUID-46FAFCDA-BCF3-41CB-B154-C17BBF7CD755">Sensor Service API error messages</a>.</p>
       
    82 </td>
       
    83 </tr>
       
    84 </tbody>
       
    85 </table></div>
       
    86 <p><strong>Remarks:</strong></p>
       
    87 <ul>
       
    88 <li><p><code>RegisterForNotification</code> retrieves sensor
       
    89 data until cancelled with <a href="GUID-3A306F4B-638D-4133-8575-2E269E565B7F.html#GUID-3A306F4B-638D-4133-8575-2E269E565B7F"><code>Cancel</code></a>.</p></li>
       
    90 <li><p>Invoking the same call on the same sensor channel from the
       
    91 same user without cancelling the previous <code>RegisterForNotification</code> request
       
    92 results in an error, since the channel is already listening on the pre-registered
       
    93 notifications.</p></li>
       
    94 </ul>
       
    95 <p><strong>Example code:</strong></p>
       
    96 <p/>
       
    97 <p>For the complete source of a sample widget
       
    98 that demonstrates how to use this Service API, see <a href="GUID-350F3C29-923E-4C30-8B14-C3D594BB8E39.html#GUID-350F3C29-923E-4C30-8B14-C3D594BB8E39">the
       
    99 full example</a>.</p>
       
   100 
       
   101 
       
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