title: cache_wsdl constant meanings
body: <p>I'm working on some code that makes SOAP calls to a web service. While making changes on the server side of things, I needed to refresh the WSDL very frequently, so I was using <code>'cache_wsdl' =&gt; WSDL_CACHE_NONE</code> in my options for the constructor. Changes on the server side have settled down and I now want to cache the WSDL. I did some quick timing on single requests to see if there was any performance increase and didn't really see any. I understand <code>WSDL_CACHE_DISK</code> will save a copy of the wsdl in my /tmp directory, which saves on a request, and makes sense to me. <strong>But I'm not sure how <code>WSDL_CACHE_MEMORY</code> or <code>WSDL_CACHE_BOTH</code> changes behavior?</strong> Does <code>wsdl_cache_memory</code> store the xml or parsed wsdl in memory... between requests... for a day? How does this differ between CLI and Web? I can not find any documentation on how these flags actually affect behavior.</p>