Java Reference
In-Depth Information
16.1.2
Domain models
The Post Office Protocol - Version 3 (POP3) defined in RFC-1939 (Network
Working Group 1996) is intended to permit a workstation to dynamically
access a maildrop on a server host in a useful fashion. Usually, this means
that the POP3 protocol is used to allow a workstation to retrieve mail that
the server is holding for it.
Initially, the server host starts the POP3 service by listening on TCP port
110. When a client host wishes to make use of the service, it establishes a
TCP connection with the server host. When the connection is established,
the POP3 server sends a greeting. The client and POP3 server then exchange
commands and responses (respectively) until the connection is closed or
aborted.
Commands in POP3 consist of a case-insensitive keyword, possibly
followed by one or more arguments. Keywords and arguments consist of
printable ASCII characters. Keywords and arguments are each separated by
a space. Keywords are three or four characters long. Each argument may be
up to 40 characters long. Responses in POP3 consist of a status indicator and
a keyword possibly followed by additional information. The server states and
the commands' specification can be found in the RFC.
The Wireless Access Protocol (WAP) is a suite of standards to provide
access to the internet over wireless communication networks (see WAP
Forum Specification).
The Wireless Application Environment (WAE) is part of the WAP Forum
specification of an application framework for wireless terminals such as
mobile phones, pagers and PDAs. The contents are structured according to
the Wireless Markup Language (WML) that is homologous to HTML. WML is
identified by the MIME type “text
vnd.wap.wml”. The WAP content can be
provided either directly to the mobile network or on the internet; in the
latter case a suitable WAP gateway takes care of protocol conversion. For
further details see WAP Forum Specification.
GSM was born as a standard for digital mobile voice communications.
Currently, second-generation GSM networks deliver high quality and secure
mobile voice and data services (such as SMS
text messaging) with full
roaming capabilities in several parts of the world. The SMS are short text
messages that can be sent though the GSM network to any user; if the user
is not connected to the network the message is queued for a certain time and
delivered to the user as soon as he or she connects to the GSM network. GSM
phones can be connected to a PC and act as interfaces to the GSM network;
in particular they can be used to send SMS messages. The interface to
interact with a GSM phone is described in (ETSI 1996).
16.1.3
Main features
The UbiMail system exhibits the following main features:
Access to mail server
. It must be able to connect to existing mail servers
and fetch mail from them.
■
