Chapter 1: Apache Tomcat Java EE API Description
Chapter 1: Apache Tomcat Java EE API Description Java Transaction API ( JTA) JavaMail JTA enables applications to gracefully handle failures in one or more of their components by establishing transactions. During a transaction, multiple events can occur, and if any one of them fails, the state of the application can be rolled back to the way it was before the transaction began. JTA provides the functionality of database- transactions technology across an entire distributed application. Provides the capability to send and receive e-mail via the industry-standard POP/SMTP/IMAP protocols. In addition to the Java EE specific APIs, Java EE applications also rely heavily on Java SE APIs. In fact, over the years, several of the Java EE APIs have been migrated to the Java SE platform. Two such APIs are the Java Naming and Directory Interface ( JNDI), used for interfacing with LDAP-compliant directories (and much more), and the Java API for XML Processing ( JAXP), which is used for parsing and transforming XML (using XSLT). The vast collection of Java EE and Java SE APIs form a platform for enterprise software development unparalleled in the industry. Java EE Application Servers As mentioned, an API simply defines services that a service provider (i.e., the implementation) makes available to applications. Thus, an API without an implementation is useless. While the JCP does provide RIs of all the APIs, using them piecemeal is not the most efficient way to build applications. Enter the Java EE application server. Various third parties provide commercial-grade implementations of the Java EE APIs. These implementations are typically packaged as a Java EE application server. Whereas Tomcat provides an implementation of the Servlet and JSP APIs (and is thus called a Servlet container), application servers provide a superset of Tomcat s functionality: the Servlet and JSP APIs plus all the other Java EE APIs, and some Java SE APIs (such as JNDI). Dozens of vendors have created Java EE compatible application servers. Being called Java EE compliant means that a vendor of an application server has paid Sun a considerable sum, and has passed various compatibility tests. Such vendors are said to be Java EE licensees. The two most widely used commercial Java EE application servers are Websphere from IBM and Weblogic from BEA. Other than these, there are a number of open source implementations too, such as the following: . JBoss (www.jboss.org) . JOnAS ( jonas.objectweb.org) . Geronimo ( geronimo.apache.org) . Glassfish ( glassfish.dev.java.net) Agree on Standards, Compete on Implementation Developers who use the Java EE APIs can use a Java EE compatible application server from any vendor, and it is guaranteed to work with their applications. This flexibility is intended to help customers avoid
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