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  <refentry id="function.com-get-active-object">
   <refnamediv>
    <refname>com_get_active_object</refname>
    <refpurpose>
     Returns a handle to an already running instance of a COM object
    </refpurpose>
   </refnamediv>
   <refsect1>
    <title>Description</title>
    <methodsynopsis>
     <type>variant</type><methodname>com_get_active_object</methodname>
     <methodparam><type>string</type><parameter>progid</parameter></methodparam>
     <methodparam choice="opt"><type>int</type><parameter>code_page</parameter></methodparam>
    </methodsynopsis>

    <para>
     <function>com_get_active_object</function> is similar to creating a new
     instance of a <xref linkend="class.com"/> object, except that it will
     only return an object to your script if the object is already running.
     OLE applications use something known as the Running Object Table to
     allow well-known applications to be launched only once; this function
     exposes the COM library function GetActiveObject() to get a handle on a
     running instance.
    </para>
    <para>
     <parameter>progid</parameter> must be either the ProgID or CLSID for the
     object that you want to access (for example
     <literal>Word.Application</literal>).  <parameter>code_page</parameter>
     acts in precisely the same way that it does for the <xref
     linkend="class.com"/> class.
    </para>
    <para>
     If the requested object is running, it will be returned to your script
     just like any other COM object.  Otherwise a <literal>com_exception</literal>
     will be raised.  There are a variety of reasons why
     this function might fail, the most common being that the object is not
     already running.  In that situation, the exception error code will be
     <constant>MK_E_UNAVAILABLE</constant>; you can use the
     <literal>getCode</literal> method of the exception object to check the
     exception code.
    </para>

    <warning>
     <para>
      Using <function>com_get_active_object</function> in a web server context
      is not always a smart idea.  Most COM/OLE applications are not designed
      to handle more than one client concurrently, even (or especially!)
      Microsoft Office.  You should read <ulink
      url="&url.msoffice.serverside;">Considerations for Server-Side
      Automation of Office</ulink> for more information on the general issues
      involved.
     </para>
    </warning>

   </refsect1>
  </refentry>

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