NHibernate in Action 2.2 Understanding the architecture

NH API in a layered architecture

包含那么几个部分：

• 被Application调用执行CRUD的接口。包含 ISession, ITransaction, IQuery, ICriteria.
• 配置NH的结构。 包含Configuration
• 允许Application回调响应NHibernate内部事件的部分，比如IInterceptor, ILifecycle, iValidateble.  这一部分是对Entity中的Field或者Property的一些变化进行的响应，猜应该有 NewObject， DeleteObject, UpdateObject , Update Field等事件的响应，是实现业务规则的重要地方。
• 允许扩展NH的Mapping功能的部分。比如IUserType,  ICompositeUserType， IIdentifierGenerator。

另外NH的基础还是ADO.net, 作者也提到：

    NHibernate makes use of existing .net apis, including ADO.net and its ITransaction API. ADO.net provides a rudimentary level of abstraction of functionality common to relational databases, letting NHibernate support almost any database with ADO.net driver.

The core interfaces

ISession interface

• 负责CRUD操作， exposes NH’methods for finding, saving , updating,  and deleting objects.
• lightweight and inexpensive. 可以任意的Create 和 destroy的。
• not thread safe.
• the nh notion of a session is something between connection and transaction.  it may be easier to think of a session as a cache or collection of loaded objects relating to a single unit of work. we sometimes call the ISession a  persistence manager. ISession的作用应该就是一个Persistence manager,  应该说有点类似于DataSet，可以连接到数据库进行操作，也可以进行事务管理。

ISessionfactory interface

• isn’t lightweight!
• one sessionfactory for one database.
• caches generated SQL statements and other mapping metadata that NHibernate uses at runtime.
• secod-level cache.  it can also hold cached data that has been read in one unit of work and which may be reused in a futrue unit of work or session . this is possible if you configure class and collection mappings to use the scond-level cache.

Configuration interface

• specify the location of mapping documents
• set NHibernate-specifc properties before creating the ISesionfactory

ITransaction interface

• optional API.
• 其他的都没有说。

IQuery and ICriteria interface

• IQuery uses queries written in HQL.
• ICriteria lets you create and execute object-oriented criteria queries.

Callback interface

• callback interface allow the application to receive a notification when somthing interesting happens to an object- for example, when an object is loaded, saved, or deleted.
• the Ilifecycle and ivalidateble interface let a persistent object react to events relating to its own persistence lifecyle. the persistence lifecycle is encompassed by an object’s curd operation.
• the iinterceptor interface was introduced to let the application process callbacks without forcing the persistent classes to implement nhibernate-specific APIs.

Types

• 一句话，进行NH和Database 之间的映射。

Extension inteface

• 主要是Cache，Tranaction等功能

转载于:https://www.cnblogs.com/sunshinefly128/archive/2011/07/30/2122033.html