Issue while registering webclient plug-in with vCenter server

Issue while  registering webclient plug-in with vCenter server

I willing to register my sample web client plug-in with vCenter server, for that I tried with these steps

1. Created the vim.Extension data object in an XML file.
   
2. Placed this file on vCenter Server at the location (…\VMware\Infrastructure\VirtualCenter Server\extensions\xyz). Here “xyz” is sample plug in name.
   

It does not work. I check vSphere web client  sample plug-in does not download and deployed. virgor server log  also doesn’t have any error or entry for this sample plug-in. Please help me to  register my plug-in in vcenter server.

My vim.Extension data object XML file is as below

<?xml version="1.0" encoding="ISO-8859-1"?>

<config>

                <extension>

                                <description>

                                                <label>XYZ plugin</label>

                                                <summary>XYZ plugin</summary>

                                </description>

                                <key>com.acme.XYZPlugin.XYZPlugin</key>

                                <company>XYZ</company>

                                <version>1.0.0</version>

                                <client>

                                                <version>1.0.0</version>

                                                <description>

                                                                <label>XYZ plugin</label>

                                                                <summary>XYZ plugin</summary>

                                                </description>

                                                <company>XYZ</company>

                                                <type>vsphere-client-serenity</type>

                                                <url>http://xx.xx.xxx.128:8080/examples/XYZPlugin.zip</url>

                                </client>

                                <lastHeartbeatTime>2013-02-22T11:25:52.814418Z</lastHeartbeatTime>

                </extension>

</config>

I think I am not following the proper process required to register web client plug-in, please let me know the exact steps to register web client with vCenter server.