protected function loadSchema($file)
{
if (isset($this->schemas[$file])) {
return $this->schemas[$file];
}
$retriever = $this->schema_retriever;
$refResolver = $this->schema_resolver;
$resolve_path = 'file://' . __DIR__ . '/schemas/';
$schema = $retriever->retrieve('file://' . __DIR__ . '/schemas/' . $file);
$refResolver->resolve($schema, $resolve_path);
$this->schemas[$file] = $schema;
return $schema;
}