I have a singelton ServerSession from which I get ClientSession instances and I have an Employee entity. Have a look at following code sequence and the comments:
//Query for employee Bob
ExpressionBuilder eb = new ExpressionBuilder();
_expression_ exp = eb.get("name").equal("Bob");
ReadAllQuery raq = new ReadAllQuery(Employee.class);
raq.setSelectionCriteria(exp);
//ClientSession A
Session csA = DBSessionProvider.getInstance().getNewClientSession();
Vector<Employee> resultSetEmployeeCsA = (Vector<Employee>) csA.executeQuery(raq); //ask for Bob
csA.release();
System.out.println(resultSetEmployeeCsA.size()); //out: 1
Employee empBobA = resultSetEmployeeCsA.firstElement();
System.out.println(empBobA.name); //out: Bob
empBobA.name = "Jake";
System.out.println(empBobA.name); //out: Jake
//ClientSession B
Session csB = DBSessionProvider.getInstance().getNewClientSession();
Vector<Employee> resultSetEmployeeCsB = (Vector<Employee>) csB.executeQuery(raq); //ask for Bob!
csB.release();
System.out.println(resultSetEmployeeCsB.size()); //out: 1, expected 0
if (!resultSetEmployeeCsB.isEmpty())
{
Employee empBobB = resultSetEmployeeCsB.firstElement();
System.out.println(empBobB.name); //out: Jake but asked for Bob (?!?)
}
//Query for Employee Jake
ExpressionBuilder ebJ = new ExpressionBuilder();
_expression_ expJ = ebJ.get("name").equal("Jake");
ReadAllQuery raqJ = new ReadAllQuery(Employee.class);
raqJ.setSelectionCriteria(expJ);
//ClientSession C
Session csC = DBSessionProvider.getInstance().getNewClientSession();
Vector<Employee> resultSetEmployeeCsC = (Vector<Employee>) csC.executeQuery(raqJ); //ask for Jake
csC.release();
System.out.println(resultSetEmployeeCsC.size()); //out: 0, expected 1
//UnitOfWork
UnitOfWork uow = DBSessionProvider.getInstance().getNewClientSession().acquireUnitOfWork();
Vector<Employee> resultSetUOW = (Vector<Employee>) uow.executeQuery(raq); //ask for Bob!
System.out.println(resultSetUOW.size()); //out: 1, expected 0
if (!resultSetUOW.isEmpty()) //expected empty resultSet!
{
Employee empBobUOW = resultSetUOW.firstElement();
System.out.println(empBobUOW.name); //out: Jake but asked for Bob (?!?)
}
uow.commit();
//nothing commited, calculateChanges():
employee.name = Jake == empBobUOW.name
//Logically, but looks strange:
employee.name differs from DB and is not commited
}
To my mind you are able to manipulate ServerSession entities (read by ClientSession) and the manipulated entities are the base for following Sessions. I expect, a new created Session has to contain the indeed state of the Entities (from DB?) and not an uncommitet state from another Session.
Do I get the concept of Sessions wrong? Is the way I discribed in my code possible but bad practice, so I have to keep attention not to do so?
