这个就不用说太多了，是标准的！

		if(empty($_REQUEST['openid_mode'])){
			if(empty($_REQUEST['OpenID']))
				LocationHtml($LoginUrl, 'OpenID is null!');
			$openid_url = formUrl($_REQUEST['OpenID']);
			$openid_server_list = getOpenIDServer($openid_url);
			if(empty($openid_server_list))
				LocationHtml($LoginUrl, 'OpenID server is null!');

			if(!empty($openid_server_list[1]))
				$openid_server = $openid_server_list[1];
			if(!empty($openid_server_list[2]))
				$openid_server = $openid_server_list[2];
			$data['openid.ns'] = 'http://specs.openid.net/auth/2.0';
			$data['openid.mode'] = 'associate';
			$data['openid.assoc_type'] = 'HMAC-SHA1';
			$data['openid.session_type'] = 'no-encryption';
			$AssocHandle = getAssociationHandle($openid_server.'?'.http_build_query($data));
			setcookie('cookieAssocHandle', $AssocHandle);
			unset($data);

			$data['openid.assoc_handle'] = $AssocHandle;
			$data['openid.ax.mode'] = 'fetch_request';
			$data['openid.ax.required'] = 'attr1,attr2,attr3,attr4,attr5';
			$data['openid.ax.type.attr1'] = 'http://axschema.org/contact/email';
			$data['openid.ax.type.attr2'] = 'http://axschema.org/namePerson/first';
			$data['openid.ax.type.attr3'] = 'http://axschema.org/namePerson/last';
			$data['openid.ax.type.attr4'] = 'http://axschema.org/contact/country/home';
			$data['openid.ax.type.attr5'] = 'http://axschema.org/pref/language';
			$data['openid.claimed_id'] = $openid_url;
			$data['openid.identity'] = $openid_url;
			$data['openid.mode'] = 'checkid_setup';
			$data['openid.ns'] = 'http://specs.openid.net/auth/2.0';
			$data['openid.ns.ax'] = 'http://openid.net/srv/ax/1.0';
			$data['openid.ns.sreg'] = 'http://openid.net/extensions/sreg/1.1';
			$data['openid.realm'] = $RealmUrl;
			$data['openid.return_to'] = $AuthUrl;
			$data['openid.sreg.optional'] = 'nickname,email,fullname,dob,gender,postcode,country,language,timezone';
			$data['openid.sreg.policy_url'] = $PolicyUrl;
			$data['openid.sreg.required'] = 'email';
			$data['openid.trust_root'] = $RealmUrl;

			$LocationUrl  = $openid_server.'?'.http_build_query($data);
		}else{
			if('id_res' == $_REQUEST['openid_mode']
				&& $AssocHandle == $_REQUEST['openid_assoc_handle']){
				$openid = !empty($_REQUEST['openid_claimed_id']) ? formUrl($_REQUEST['openid_claimed_id']) : formUrl($_REQUEST['openid_identity']);
				$email = $_REQUEST['openid_sreg_email'];
				$fullname = $_REQUEST['openid_sreg_fullname'];
				$nickname = $_REQUEST['openid_sreg_nickname'];
				$timezone = $_REQUEST['openid_sreg_timezone'];
				echo('<pre>');
				echo("<a href=$LoginUrl>BACK</a>\n\n");
				print_r($_REQUEST);
				echo('</pre>');
			}
		}
		break;

部分函数请参考：
Yahoo的OpenID登陆
Windows Live ID当作OpenID使用的方法
Google的OpenID的登陆