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:
/>
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

/>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.