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The J2EE platform service technologies allow applications to access a wide range of services in a uniform manner. This section describes technologies that provide access to databases, transactions, naming and directory services, and enterprise information systems.
The JDBCTM API provides database-independent connectivity between the J2EE platform and a wide range of tabular data sources. JDBC technology allows an Application Component Provider to:
The J2EE platform requires both the JDBC 2.0 Core API (included in the J2SE platform), and the JDBC 2.0 Extension API, which provides row sets, connection naming via JNDI, connection pooling, and distributed transaction support. The connection pooling and distributed transaction features are intended for use by JDBC drivers to coordinate with a J2EE server. Access to databases and enterprise information systems is covered in detail in Chapter 6.
The Java Transaction API (JTA) allows applications to access transactions in a manner that is independent of specific implementations. JTA specifies standard Java interfaces between a transaction manager and the parties involved in a distributed transaction system: the transactional application, the J2EE server, and the manager that controls access to the shared resources affected by the transactions.
The Java Transaction Service (JTS) specifies the implementation of a transaction manager that supports JTA and implements the Java mapping of the Object Management Group Object Transaction Service 1.1 specification. A JTS transaction manager provides the services and management functions required to support transaction demarcation, transactional resource management, synchronization, and propagation of information that is specific to a particular transaction instance.
The Java Naming and Directory InterfaceTM (JNDI) API provides naming and directory functionality. It provides applications with methods for performing standard directory operations, such as associating attributes with objects and searching for objects using their attributes. Using JNDI, an application can store and retrieve any type of named Java object.
Because JNDI is independent of any specific implementations, applications can use JNDI to access multiple naming and directory services, including existing naming and directory services such as LDAP, NDS, DNS, and NIS. This allows applications to coexist with legacy applications and systems.
A future version of the J2EE platform will support the Connector architecture, a standard API for connecting the J2EE platform to enterprise information systems, such as enterprise resource planning, mainframe transaction processing, and database systems. The architecture defines a set of scalable, secure, and transactional mechanisms that describe the integration of enterprise information systems with an EJB server and enterprise applications.
To use the Connector architecture, an enterprise information system vendor provides a standard connector for its enterprise information system. The connector has the capability to plug in to any EJB server that supports the Connector architecture. Similarly, an EJB server vendor extends its system once to support this Connector architecture and is then assured of a seamless connectivity to multiple enterprise information systems.