Tài liệu Lập trình mạng P7 ppt

Java Training Introduction to Java Mail What is JavaMail? -1  JavaMail is an API for sending and receiving email using Java. The current version is 1.3.1 and can be downloaded from Sun's website at: http://java.sun.com/products/javamail/  Possible uses:  Send email from web pages using servlets  Create a GUI email client  Send email from Java stored procedures  Send email from any type of Java application  Spam your friends and enemies! (read email addresses from a database, write a for () loop, and away the emails go!) What is JavaMail? -2  To send JavaMail, you'll need to add at least two JAR files from Sun to your classpath (placing them in a lib directory may be a good idea)  activation.jar  mail.jar (Note: You can download these files from the Java Zone)  For more complex emailing tasks (like receiving or managing pop3 or imap mail servers), you'll need to download additional files like pop3.jar and imap.jar.  You will also need access to a mail server and possibly a username/password for that mail server How Does Email Work?  In general, each internet domain has an email server.  When you send out an email  Your email client program sends the message to your email server  Your email server contacts the addressee's email server using the SMTP (simple mail transfer protocol)  Your email server verifies that the addressee's user name is valid  Your email server then transfers the email to the addressee's email server  When the addressee logs into his email server (using his email client program), he gets his email Mail Servers (sendmail)-1  sendmail is the most commonly used mail server in the world, as it generally comes free with Unix and Linux installations  very powerful and flexible. Supports POP3 and IMAP  well documented (lots of books on setting up sendmail)  long track record (first version appeared in early '80s)  tedious to set up (lots of cryptic configuration files)  free  www.sendmail.org Mail Servers (qmail)-2  qmail is probably the most popular alternative to sendmail in the UNIX world  perhaps more secure than sendmail (at least older versions of sendmail)  Easier to set up and administer than sendmail  pretty good documentation (several books written on qmail in the past few years)  free  http://www.qmail.org/top.html Mail Servers (MS Exchange)-2  MS Exchange is widely used in the Windows world, especially in corporate environments that use MS Office (and hence MS Outlook)  Expensive  Integrated into MS Active Directory  GUI administration tools are easier to learn for Windows people  MS Outlook is a powerful and slick email program that will work with Exchange, sendmail, or qmail. It does, however, have a history of security vulnerabilities and some organizations refuse to use it because of that. POP3, IMAP, MAPI -1  Currently, the most popular protocols are  POP3 (Post Office Protocol, version 3)  IMAP (Internet Message Access Protocol)  MAPI (Messaging Application Programming Interface-- Microsoft Windows email interface) POP3  POP3 is the oldest and most widely used. It was designed to support offline mail processing.  Mail is delivered to a server and a user's computer runs a mail client program to download any new mail  Once messages are delivered, they are generally deleted from the mail server  This minimizes disk space requirements for mail server, but ties the mail to a particular machine. If user goes to another computer, he can't access his mail  POP3 has limited support for reading mail online (and leaving the mail on the mail server)  Simpler protocol than IMAP makes it easier to implement. More POP3 mail clients available IMAP  IMAP  Developed at University of Washington  Primarily used to access mail and leave it on the mail server. This allows users to access their mail from any computer  Requires more disk space to store email messages  Can work in "offline" mode like POP3  Easy to manage multiple mailboxes  Supports tagging emails with flags like "read", "deleted", "answered", etc.