org.eiichiro.acidhouse

Interface Session

public interface Session

Session is the central client-interfaced object to control NoSQL datastore on Acid House and represents interactive session between client and NoSQL datastore. Basic CRUD operations are like this, in App Engine example:

 import org.eiichiro.acidhouse.Session;
 import org.eiichiro.acidhouse.appengine.AppEngineDatastoreSession;
 ...
 
 // Creating entity.
 Entity1 entity11 = new Entity1();
 entity11.id = "Key11";
 entity11.i = 11;
 Entity1 entity12 = new Entity1();
 entity12.id = "Key12";
 entity12.i = 12;
 Session session = new AppEngineDatastoreSession();
 Transaction transaction = session.beginTransaction();
 
 try {
        session.put(entity11);
        session.put(entity12);
        transaction.commit();
 } catch (Exception e) {
        transaction.rollback();
        throw e;
 } finally {
        session.close();
 }
 
 
 // Reading entity.
 Session session = new AppEngineDatastoreSession();
 Entity1 entity11 = session.get(Entity1.class, "Key11");
 Entity1 entity12 = session.get(Entity1.class, "Key12");
 session.close();
 
 
 // Updating entity.
 Session session = new AppEngineDatastoreSession();
 Transaction transaction = session.beginTransaction();
 
 try {
        Entity1 entity11 = session.get(Entity1.class, "Key11");
        Entity1 entity12 = session.get(Entity1.class, "Key12");
        entity11.i = 1111;
        entity12.i = 1222;
        session.update(entity11);
        session.update(entity12);
        transaction.commit();
 } catch (Exception e) {
        transaction.rollback();
        throw e;
 } finally {
        session.close();
 }
 
 
 // Deleting entity.
 Session session = new AppEngineDatastoreSession();
 Transaction transaction = session.beginTransaction();
 
 try {
        Entity1 entity11 = session.get(Entity1.class, "Key11");
        Entity1 entity12 = session.get(Entity1.class, "Key12");
        session.delete(entity11);
        session.delete(entity12);
        transaction.commit();
 } catch (Exception e) {
        transaction.rollback();
        throw e;
 } finally {
        session.close();
 }
 

Author:

Eiichiro Uchiumi

Method Summary

Methods

Modifier and Type	Method and Description
Transaction	beginTransaction() Begins transaction.
void	close() Closes this session.
<E> Delete<E>	delete(Metamodel<E> metamodel) Returns Delete for the specified entity metamodel.
void	delete(Object entity) Deletes the specified entity from datastore.
<E,R> GetScalar<E,R>	get(Aggregation<R> aggregation) Returns GetScalar for the specified Aggregation.
<E> E	get(Class<E> clazz, Object key) Returns the entity instance corresponding to the specified key.
<E> GetList<E>	get(Metamodel<E> metamodel) Returns GetList for the specified entity metamodel.
void	put(Object entity) Puts the specified entity instance into datastore newly.
<E> Update<E>	update(Metamodel<E> metamodel) Returns Update for the specified entity metamodel.
void	update(Object entity) Updates entity with the specified entity instance.

Method Detail

beginTransaction

Transaction beginTransaction()

Begins transaction. You have to do transactional operation after calling this method.

Returns:

The transaction begun newly.

close

void close()

Closes this session.

get

<E> E get(Class<E> clazz,
        Object key)
      throws ConcurrentModificationException

Returns the entity instance corresponding to the specified key. It depends on the implementation of this interface whether an exception is thrown or null is returned if the entity is not found.

Type Parameters:

E - The entity type.

Parameters:

clazz - The entity type that you want to get.

key - The key corresponding to the entity that you want to get.

Returns:

The entity instance corresponding to the specified key.

Throws:

ConcurrentModificationException - If the entity corresponding to the specified key is being modified by the other transaction.

put

void put(Object entity)
         throws EntityExistsException

Puts the specified entity instance into datastore newly. This method must be invoked under a transaction. Depending on the implementation of this interface, if the entity that has the same key as the specified entity has been already stored, this method might throw EntityExistsException.

Parameters:

entity - The entity instance to be put into Session.

Throws:

EntityExistsException - If the entity that has the same key as the specified entity has already existed.

update

void update(Object entity)

Updates entity with the specified entity instance. This method must be invoked under a transaction.

Parameters:

entity - The entity instance to be updated.

delete

void delete(Object entity)

Deletes the specified entity from datastore. This method must be invoked under a transaction.

Parameters:

entity - The entity to be deleted.

get

<E> GetList<E> get(Metamodel<E> metamodel)

Returns GetList for the specified entity metamodel. This method is the entry point for getting-list Command Builder API.

Type Parameters:

E - The entity type to get with this GetList.

Parameters:

metamodel - The metamodel of the entity to get with this GetList.

Returns:

GetList for the specified entity class.

get

<E,R> GetScalar<E,R> get(Aggregation<R> aggregation)

Returns GetScalar for the specified Aggregation. This method is the entry point for aggregation Command Builder API.

Type Parameters:

R - The property value type to aggregate with this GetScalar.

Parameters:

aggregation - The Aggregation this method executes.

Returns:

GetScalar for the specified Aggregation instance.

update

<E> Update<E> update(Metamodel<E> metamodel)

Returns Update for the specified entity metamodel. This method is the entry point for updating Command Builder API.

Type Parameters:

E - The type of entity updated by this Update.

Parameters:

metamodel - The metamodel of the entity updated by this Update.

Returns:

The Update for the specified entity class.

delete

<E> Delete<E> delete(Metamodel<E> metamodel)

Returns Delete for the specified entity metamodel. This method is the entry point for deleting Command Builder API.

Type Parameters:

E - The type of entity deleted by this Delete.

Parameters:

metamodel - The metamodel of the entity deleted by this Delete.

Returns:

The Delete for the specified entity class.