Question

I’m using PHP xmlreader to validate and parse xml data. This xml is validated with some xsd schema from local file via XMLReader::setSchema function and remote xsd schema from http:// via xsd:import/include. Eveything work fine, but it fetch xsd schema from net and read from disk everytime when called.

So my questions is:

Is there a method for caching remote xsd schema in local RAM?
For local schema files, I think tmpfs in Linux will work fine, but is there another way to cache local xsd schema files ?

Solution

Thank VolkerK for pointing out the xmlcatalog system. It work fine with libxml/php xmlreader. In Linux, just edit file /etc/xml/catalog (It come from xml-common when you are in Fedora) add some entries like (for example):

<rewriteURI uriStartString="http://schemas.xmlsoap.org/soap/envelope/" rewritePrefix="/etc/xml/SOAP-Envolope.xsd"/>
<rewriteURI uriStartString="http://schemas.xmlsoap.org/soap/encoding/" rewritePrefix="/etc/xml/SOAP-Encoding.xsd"/>

and manual download schema (e.g http://schemas.xmlsoap.org/soap/encoding/ -> /etc/xml/SOAP-Encoding.xsd) then php xmlreader work like expected when parsing SOAP Messages.

Answer 1

php’s xmlreader uses libxml and libxml supports xml catalouges:

What is a catalog? Basically it’s a lookup mechanism […]

It is basically used for 3 things:
[…]

• providing a local cache mechanism allowing to load the entities associated to public identifiers or remote resources, this is a really important feature for any significant deployment of XML or SGML since it allows to avoid the aleas and delays associated to fetching remote resources.

Haven’t tried it but I guess it’s worth a test run.