一个简单的magento模型，实体配置

<?xml version="1.0" encoding="UTF-8"?>
<config>
<modules>
<App_Helloworld>
<version>0.2.0</version>
</App_Helloworld>
</modules>
<global> 
<models> 
<helloworld> 
        <class>App_Helloworld_Model</class> 
        <resourceModel>helloworld_mysql4</resourceModel> 
    </helloworld>    
     <helloworld_mysql4> 
	       <class>App_Helloworld_Model_Resource_Mysql4</class> 
	       <entities> 
	           <blogpost> 
	               <table>blog_posts</table> 
	           </blogpost> 
	       </entities> 
	    </helloworld_mysql4>    
    </models> 
<!--resource 可略，使用默认 -->
     <resources> 
	    <helloworld_write> 
	        <connection> 
	            <use>default_write</use> 
	        </connection> 
	    </helloworld_write> 
	    <helloworld_read> 
	        <connection> 
	            <use>default_read</use> 
	        </connection> 
	    </helloworld_read>       
	</resources>
</global>
</config>