KCSessionManager (IDBS2)

java.lang.Object
- it.unimi.dico.islab.idbs2.kc.session.KCSessionManager

```
public class KCSessionManager
extends Object
```
Class for Hibernate Session automatic management. This class offers only static methods, usually protected, for Hibernate session management which are used from other classes of this package.

N.B.: All the operations executed through manager classes will be exectued referring to this class's internal session

Author:

Vegeziel

Field Summary

Fields
Modifier and Type	Field and Description
`protected static boolean`	`AUTO_DATABASE_COHERENCE`
`static DocumentManager`	`dm` `DocumentManager` reference, used to manage `Document` objects.
`static KCManager`	`kcm` `KCManager` reference, used to manage `KnowledgeChunk` objects.
`static PredicateManager`	`pm` `PredicateManager` reference, used to manage `Predicate` objects.
`static TermManager`	`tm` `TermManager` reference, used to manage `Term` objects.
`static TypeManager`	`tym` `TypeManager` reference, used to manage `Type` objects.

Method Summary

Methods
Modifier and Type	Method and Description
`static void`	`beginTransaction()` Start a new transaction for the internal Session.
`protected static void`	`checkActiveTransaction()` Check if the internal session has an active transaction, otherwise creates automatically a new transaction warning the user.
`static void`	`commitTransaction()` Commit the internal session active transaction.
`static Boolean`	`getAutoDatabaseCoherence()`
`protected static Session`	`getInternalSession()`
`static SessionFactory`	`getSessionFactory()` Returns an Hibernate Session Factory created for this kc model.
`static SessionFactory`	`getSessionFactory(File conf)` Same as `getSessionFactory()`.
`protected static void`	`saveOrUpdateObject(Object obj)` Give persistence (on relational database) to an object mapped with Hibernate using the internal `Session Factory` of this class.
`void`	`setAutoDatabaseCoherence(boolean active)` Activate/deactivate the database coherence system; this system could be useful when adding new KCs to and existing and already filled database.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - kcm
```
public static KCManager kcm
```
    KCManager reference, used to manage KnowledgeChunk objects.
  - dm
```
public static DocumentManager dm
```
    DocumentManager reference, used to manage Document objects.
  - tym
```
public static TypeManager tym
```
    TypeManager reference, used to manage Type objects.
  - tm
```
public static TermManager tm
```
    TermManager reference, used to manage Term objects.
  - pm
```
public static PredicateManager pm
```
    PredicateManager reference, used to manage Predicate objects.
  - AUTO_DATABASE_COHERENCE
```
protected static boolean AUTO_DATABASE_COHERENCE
```
- Method Detail
  - saveOrUpdateObject
```
protected static void saveOrUpdateObject(Object obj)
```
    Give persistence (on relational database) to an object mapped with Hibernate using the internal Session Factory of this class. This method is defined only in this class (as it is the main class of this package) and is called by every saveOrUpdate method of other classes of this package.
    
    Parameters:
    obj - The Hibernate mapped object to be persisted.
  - checkActiveTransaction
```
protected static void checkActiveTransaction()
```
    Check if the internal session has an active transaction, otherwise creates automatically a new transaction warning the user.
  - beginTransaction
```
public static void beginTransaction()
```
    Start a new transaction for the internal Session.
  - commitTransaction
```
public static void commitTransaction()
```
    Commit the internal session active transaction. This method MUST be called if some KnowledgeChuks hava been saved or modified using internal session. Otherwise the saved data won't be materialized.
  - getSessionFactory
```
public static SessionFactory getSessionFactory()
```
    Returns an Hibernate Session Factory created for this kc model. This Session Factory will be different at any call of this method and is different from the internal Session Factory used by other methods (e.g. saveOrUpdate and getKnowledgeChunkById).
    
    This session factory is created using the config/kcDatabaseConfiguration.xml file.
    
    Returns:
    Hibernate SessionFactory
  - getSessionFactory
```
public static SessionFactory getSessionFactory(File conf)
```
    Same as getSessionFactory(). Only difference is that the configuration file the SessionFactory will be built upon is passed as argument. This method can be used to obtain new SessionFactories for databases different from the standard one.
    
    Parameters:
    conf - the configuration file in a standard xml Hibernate version.
    
    Returns:
    the created SessionFactory.
  - setAutoDatabaseCoherence
```
public void setAutoDatabaseCoherence(boolean active)
```
    Activate/deactivate the database coherence system; this system could be useful when adding new KCs to and existing and already filled database. When activated the behavior of the addType, addTerm, and addDocument methods are changed. For better understanding we present the following example based on the addType method:
    1. The method addType is called
    2. The Primary Key of the new Type is computed
    3. The database is queried looking for an already present identical value of the key
    When the database coherence system is disabled, steps 3 and 3.1 are not executed and step 3.2 is executed as default; in this situation when an inserted type is already present for this KC on the database, a Primary Kew Violation Exception is raised.
  - getAutoDatabaseCoherence
```
public static Boolean getAutoDatabaseCoherence()
```
    Returns:
    true if the autoDatabaseCoherence system is active, false otherwise.
    See Also:
    for better explanation.
  - getInternalSession
```
protected static Session getInternalSession()
```
    Returns:
    the internal hibernate session. This method should only be called by classes of this library.

Class KCSessionManager

Field Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

kcm

dm

tym

tm

pm

AUTO_DATABASE_COHERENCE

Method Detail

saveOrUpdateObject

checkActiveTransaction

beginTransaction

commitTransaction

getSessionFactory

getSessionFactory

setAutoDatabaseCoherence

getAutoDatabaseCoherence

getInternalSession