legacy/src/main/java/thredds/catalog/InvCatalogFactory.java
public void readXMLasynch(String uriString, CatalogSetCallback callback) {
    InvCatalogImpl cat = readXML(uriString);
    callback.setCatalog(cat);
  }
public void readXMLasynch(String uriString, CatalogSetCallback callback) {
    InvCatalogImpl cat = readXML(uriString);
    callback.setCatalog(cat);
  }
This allows the possibility of reading a catalog in another thread. The default
implementation does not do that, but a subclass may override and implement.
If the catalog is read successfully, it is passed on to the callback.

@param uriString : read this catalog.
@param callback  : call this if successfully read.
@see CatalogSetCallback