The learning process of Java EE (excerpt)

j2ee| process
The above learning process if it is relatively smooth, to this step, difficulty and suddenly improve. Because the above knowledge content is only involved in one aspect, and such as EJB,JMS,JTA, such as the core of the Java EE specification is often a combination of the use of a number of techniques of the crystallization, so it is difficult to master the larger.

First of all, we must learn good Jndi,jndi is the app Server Locator Server resource (EJB component, DATASOUCE,JMS) lookup method, if not familiar with Jndi, ejb,jms these things can hardly learn. Jndi is actually javax.naming.* this bag, it is very simple to use. The difficulty is in configuring the server resource files. For the server resource file configuration, you need to look at the specific documentation specifications, such as Web.xml, Ejb-jar.xml, and so on. For each of the different app servers, there are also their own service resource profiles that need to be familiar.

You can then learn JTA, mainly to understand JTA's approach to the control of the transaction, and where to use JTA. As a simple example, we know that the general situation can be transaction control for a database connection (Conn.setautocommit (false),...., Conn.commit ()) as an atomic operation, But suppose my business requirement is to make the operation of two different databases an atomic operation, can you do it? At this time can only use JTA. Suppose the procedure is to insert a record into a database, then delete the B database another record, we write the code can not control the whole operation as an atomic operation. With JTA, the app server is the way to complete the control.

Learning about object serialization and Rmi,rmi is the basis of EJB before learning EJB. Then, to learn about JMS and EJB, the key to EJB is to understand how EJBS implement calls to remote objects through RMI, and under what circumstances EJB is used.

After learning ejb,jms These things, you may be aware of the impatience to learn two areas of knowledge, one is UML, the other is design pattern. Java enterprise Software Design attaches great importance to the framework of the design, a good software framework is the prerequisite for the success of software development. At this time, should begin to focus on the study of design patterns and framework of learning, through learning and practical programming experience to master the EJB design pattern and Java EE core model.

Java-ee norms inside, in addition to EJB,JMS,JTA,SERVLET/JSP,JDBC, there are a lot of enterprise technology, here is not one of the introduction.

There is also a new domain Web Services. Web Services doesn't have anything new at all, it's like a binder that can unify different services to provide a unified calling interface, and as a user, I just get the WSDL (the description of the service) given to me by the service provider, and that's enough, I have no idea whether the service provided by the server provider is an EJB component, or. NET component, or what CORBA component is, or what other implementations, I don't need to know. The greatest part of WEB services is the sharing of Internet services across the world through a unified approach to service delivery and invocation, which is a very exciting technical area. WEB services do not seem to have any good books at the moment, but they can be learned by looking up information on the web.