Question

I have to use an xml database (Sedna) to store and retrieve Java objects. Every custom class in the project is stored into a collection. I have the following problem : I’m not sure how the objects are written into the collection. That is to say, I don’t know their exact xml structure, so I can’t do a proper query on them.

Is there a query that, for a given collection, will show me the content of a collection?

Host h = new Host();
h.name = "test1";
h.freeSpace = 32;
String id1 = this.addHost(h);

//addHost method
try
{
  Collection c = this.findCollection("Hosts"); //gives me the Hosts collection
  if (c == null)
    return null;

  h.id = c.createId();
  BinaryResource br = (BinaryResource) c.createResource(h.id, BinaryResource.RESOURCE_TYPE);
  br.setContent(h);
  c.storeResource(br);
  return h.id;

} catch (XMLDBException e) {
  System.err.println("Error adding Host entry into the database: " + e.getMessage());
  return null;
}

Answer 1

To view structure (schema) of your database or collection or document query one of the following system documents (Retrieving Metadata):

• $schema – descriptive schema
  of all documents and collections with
  some schema-related information;

• $schema_<name> – the
  descriptive schema of the document or
  collection named ;

For example, run se_term, and execute doc('$schema_test') to get structure of the ‘test’ document/collection.

How do you store your resources? Please give us snippet of code. It’s very hard to understand even which one API do you use (XML:DB, XQJ, native Sedna Java API).