When i receive a message, how do I know which schema to use to validate against??

my current code is this, and it works smoothly.


SAXBuilder builder = new SAXBuilder(" org.apache.xerces.parsers.SAXParser ", true);
builder.setFeature("http://apache.org/xml/features/validation/schema ", true);
       
builder.setProperty(
    " http://apache.org/xml/properties/schema/external-noNamespaceSchemaLocation", 
    "schema1.xsd");
       
//Load the xml
Document document;
document = builder.build("incoming.xml ");