I have a situation that I would like to understand better :) (this mail is
to every sedna user, not just to Charles Foster because he wrote XML:DB API)
:)
I execute the following commands in a newly created database (database is
named "basic") :
CREATE COLLECTION "locked"
LOAD "books.xml" "books.xml" "locked"
(Collection can be named anything and "books.xml" can be any type of file)
Using the XML:DB API I have the following class (skip the class code, and
check my explanation, comeback later to see what it does)
import org.xmldb.api.DatabaseManager;
import org.xmldb.api.base.Collection;
import org.xmldb.api.modules.TransactionService;
import org.xmldb.api.modules.XMLResource;
public class ManySessions
{
public static void main(String[] args) throws Exception
{
org.xmldb.api.base.Database dbDriver =
(org.xmldb.api.base.Database)Class.forName("net.cfoster.sedna.DatabaseImpl").newInstance();
DatabaseManager.registerDatabase(dbDriver);
org.xmldb.api.base.Database sednaDatabase;
Class clazz = Class.forName("net.cfoster.sedna.DatabaseImpl");
sednaDatabase = (org.xmldb.api.base.Database)(clazz.newInstance());
Collection col =
DatabaseManager.getCollection("xmldb:sedna://localhost:5050/basic","SYSTEM","MANAGER").getChildCollection("locked");
TransactionService service = (TransactionService)
col.getService("TransactionService", "1.0");
service.begin();
XMLResource
resource=(XMLResource)col.createResource("locker.xml",XMLResource.RESOURCE_TYPE);
resource.setContent("<test>Text</test>");
col.storeResource(resource);
System.out.println("Go to Sleep");
Thread.sleep(30000);
System.out.println("Awake from Sleep");
//Commit
service.commit();
col.close();
}}
This class basically begins a transaction, inserts the "locker.xml" document
in the "locked" collection and then sleeps for 30 seconds, before committing
the transaction.
I execute the ManySessions class and when the "Go to Sleep" message appears,
I go to the command line and execute
se_term -file new.xquery basic
Where the contents of "new.xquery" are:
let $m := document("books.xml","locked") return $m
The result is that se_term "hangs" waiting for the Java Class to commit the
transaction.
My question is.... is it supposed to "lock" the entire collection when
storing a resource (inside a transaction)? Am I doing something wrong?
I had a problem of dead-lock when trying to write and read the same
document, but in this situation I'm storing document A and reading from
document B in the same
collection.
I have tried, without the Thread.sleep (making multiple inserts to take
time) and connecting with different users, but same result.
How can I resolve this situation?
Another thing I'm interested.... I've tried using the metacommands in
se_term but the execution always fails giving me a syntax error, even when
running
the example in the documentation (executing from a xquery file) :
\nac
CREATE DOCUMENT "test"&
UPDATE INSERT <test>{"test"}</test> INTO fn:doc("test")&
fn:doc("test")&
\commit
SEDNA Message: ERROR XPST0003
It is a static error if an expression is not a valid instance of the grammar
def
ined in A.1 EBNF.
Details: at (7:1), unexpected symbol: '\'
at (7:1), syntax error, unexpected lexical error
at (8:23), unexpected symbol: '&'
at (9:29), syntax error, unexpected </, expecting end of file or statem
ent separator
What am I doing wrong?
Many thanks in advance for any help you can give =)
--
Pedro Pereira
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