Book Image

NHibernate 2 Beginner's Guide

By : Aaron Cure
Book Image

NHibernate 2 Beginner's Guide

By: Aaron Cure

Overview of this book

<p>NHibernate is an open source object-relational mapper, or simply put, a way to retrieve data from your database into standard .NET objects. Quite often we spend hours designing the database, only to go back and re-design a mechanism to access that data and then optimize that mechanism. This book will save you time on your project, providing all the information along with concrete examples about the use and optimization of NHibernate.<br /><br />This book is an approachable, detailed introduction to the NHibernate object-relational mapper and how to integrate it with your .NET projects. If you're tired of writing stored procedures or maintaining inline SQL, this is the book for you.<br /><br />Connecting to a database to retrieve data is a major part of nearly every project, from websites to desktop applications to distributed applications. Using the techniques presented in this book, you can access data in your own database with little or no code.<br /><br />This book covers the use of NHibernate from a first glance at retrieving data and developing access layers to more advanced topics such as optimization and Security and Membership providers. It will show you how to connect to multiple databases and speed up your web applications using strong caching tools. We also discuss the use of third-party tools for code generation and other tricks to make your development smoother, quicker, and more effective.</p>
Table of Contents (19 chapters)
NHibernate 2
Credits
About the Author
About the Reviewers
Preface
Index

What is a session factory?


The NHibernate framework uses the abstract factory pattern (see http://en.wikipedia.org/wiki/Abstract_factory_pattern) for creating sessions, and this factory is created from a Configuration object.

The following line of code builds a Session Factory object from our configuration (cfg) object that we'll use to create sessions:

ISessionFactory sessionFactory = cfg.BuildSessionFactory();

From now on, when we want to create a session, we just ask the session factory to open a session for us as follows:

ISession session = sessionFactory.OpenSession();

In addition to opening the session, we want to wrap our statements in a "transaction" to decrease database overhead. I know what you are thinking, wouldn't creating a transaction for every statement actually INCREASE database overhead? In reality, the database already uses implicit transactions for every call we make, so by explicitly telling it to create a single transaction for all of our operations, we are actually reducing...