<esi:try> 
    <esi:attempt>
        <esi:comment text="Include an ad"/> 
        <esi:include src="http://www.example.com/ad1.html"/> 
    </esi:attempt>
    <esi:except> 
        <esi:comment text="Just write some HTML instead"/> 
        <a href="www.akamai.com">www.example.com</a>
    </esi:except> 
</esi:try>