The Research And Implementation Of JavaMail Specification

In recent years, in the Internet/Intranet/Extranet development environment, the enterprise level application system mostly used three or the multilayered application pattern. As we all know, this is called the "three/multilayer Computing".Therefore, it is needed to construct an entire application framework for the development, deployment, run and managerment of these applications to provide them with an appropriated corresponding platform as the infrustracture, which is based on the computer net and distributed computing technologies. Actually, The key of such a platform is the application sever in the middle layer. During the past several years, the most significant progress in the application server market was the appearance of J2EE (Java 2 Platform Enterprise Edition). It is a standard platform specified by the Sun Corporation to develop, deploy, run and manage Java distributed applications. It has provided with the full support of EJB, Java Servlet, and JSP etc. As the most important component of J2EE, EJB is the core of the distributed computing model. J2EE specification defined EJB container as the environment to deploy business components. EJB container is responsible for managing EJB components, and provides important services at system level--transaction, security, remote call, database access etc. Jaap (Just another appServer provider) project engages in researching and developing application server at enterprise level according to J2EE specification. The Jaap is a J2EE open source project, including a group of software packages of services and tool kits. The JMX, the EJB container, JDO and JavaMail implementation, have been completed in early stage. JavaMail API is an optional standard extensive package,which can be used to read ,write and send electronic message. You can use the package to develop an enterprise application which includes mail User Agent (Mail User Agent, MUA) , it is similar to the following programs :Eudora, Pine and Microsoft Outlook . Its main goal is not to act as the Mail Transfer Agent (MTA) programs which are usally used to transmit, and retransmit the messages. In other words, the final user may use the MUA type programs to read and write electronic messages. MUA depends upon MTA to process the actual transmission duty. Usually developing the JavaMail programs also need the JavaBeans Activation Framework (JAF) from Sun Microsystems. The goal of JavaMail API is to provide independence of specific protocol. The method is to divide this API into two parts: 1. The first part defines a group of element which are needed for modeling a mailing system,which provides a platform-independent and protocol-independent framework to build mail and messaging applications.This part is named API(Application Program Interface) . 2. The second part is the protocol realization layer, whicih use specific protocol language to extend or implement the classes or interface of the first layer of JavaMail, these protocols include: SMTP, POP, IMAP and NNTP. In an application, if you want to useJavaMail API to communicate with the server, you must provide the corresponding protocol for it. This part is named SPI(Service Provider Interface) The author analysiszes the whole framework of JavaMail,and give a corresponding implementation , has focused on the research and the realization of protocol layer . The following issues illustrate the reasons: JavaMail only defines a framework of platform-independent and protocol-independent, or to say it defines a set of standard classes and interfaces to be used for the protocol, therefore the third party are allowed to follow this standard to develop their own sevice according to specific protocol to strengthen the function of JavaMail, then provid the individual service.The main contribution of this article is: in the frame level, JavaMail is analyzed and improved to support the Chinese name of an attachment ; In the protocol realization level,it is strengthened in POP3 protocol function, the NNTP protocol realization(Sun Microsystems, Inc has not give this NNTP provider), and the analysis has been carried on the JavaMail secure issues and efforts are made to take some significant exploration.