Session Factory scope - Hibernate - Java

Session factory objects are to be implemented using the singleton design pattern. Instances of SessionFactory are thread-safe and typically shared throughout an application. As these objects are heavy weight because they contains the connection information, hibernate configuration information and mapping files,location path. So creating number of instances will make our application heavy weight. But the session objects are not thread safe. So in short it is - SessionFactory objects are one per application and Session objects are one per client.
Hence it would be one SessionFactory per DataSource. Your application may have more than one DataSource so you may have more than one SessionFactory in that instance. But you would not want to create a SessionFactory more than once in an application.
Advantages: Obviously its improving performance of your application :)
UPDATE - Extract from Hibernate Doc
The internal state of a SessionFactory is immutable. Once it is created this internal state is set. This internal state includes all of the metadata about Object/Relational Mapping.

Comments

Post a Comment

Popular posts from this blog

public vs protected vs default access modifiers - Java

| Class | Package | Subclass | Subclass | World | | |(same pkg)|(diff pkg)| ————————————+———————+—————————+——————————+——————————+———————— public | + | + | + | + | + ————————————+———————+—————————+——————————+——————————+———————— protected | + | + | + | + | ————————————+———————+—————————+——————————+——————————+———————— no modifier | + | + | + | | ————————————+———————+—————————+——————————+——————————+———————— private | + | | | | + : accessible blank : not accessible
Read more

Class, Reference and Object

If you like housing metaphors a  class  is like the blueprint for a house. Using this blueprint, you can build as many houses as you like. each house you build (or instantiate, in OO lingo) is an  object , also known as an  instance . each house also has an address, of course. If you want to tell someone where the house is, you give them a card with the address written on it. That card is the object's  reference . If you want to visit the house, you look at the address written on the card. This is called  dereferencing . You can copy that reference as much as you like, but there's just one house -- you're just copying the card that has the address on it, not the house itself. Java methods are always pass-by-value, but the value could be an object's reference. So, if I have: Foo myFoo = new Foo (); // 1 callBar ( myFoo ); // 2 myFoo . doSomething () // 4 void callBar ( Foo foo ) { foo = new Foo (); ...
Read more