One of the most powerful aspects of J2EE is the broad range of middleware services it provides to developers. The set of service APIs that are currently a part of the J2EE specification is summarized in table 1.2. As you see, J2EE provides built-in support for publishing and locating resources, asynchronous messaging, transactions, and a host of other services. If you have worked with J2EE in the past, you are probably familiar with many of these. One API that is of particular interest to us in this book is JAXP, which we discuss in detail in the next chapter. You will also see XML as middleware for your data throughout the remaining chapters.
Table 1.2 J2EE middleware services
Enterprise Java API
Application in J2EE
Java Naming and Directory Services (JNDI)
Provides a standard mechanism for locating resources, including remote objects, environment properties, and directory services.
Java Database Connectivity (JDBC)
Provides vendor-neutral access to enterprise relational database management systems.
Java Message Service (JMS)
Provides reliable point-to-point and publish/subscribe messaging for J2EE components.
Java Transaction API (JTA)
Provides mechanisms for declaring, accessing, and coordinating transactional processing.
Provides support for sending Internet email from J2EE applications.
Java Activation Framework (JAF)
A mechanism of inspecting arbitrary data and instantiating objects to process it, required by the JavaMail API.
Java API for XML Parsing (JAXP)
Provides basic support for XML access from Java and a service provider interface for parsers and transformers.