Java Reference
In-Depth Information
MMS uses many metaphors taken from e-mail protocols, including the notions of a
message subject, message body, and multiple message parts. MMS messages can be sent
to multiple recipients as well. As with SMS, a special server (the MMS Center) routes
MMS messages to and from wireless terminals. Although people exchange fewer MMS
messages than SMS messages, from your perspective as an application developer, the
business landscape is much the same. Companies can acquire short codes on specific
networks and register those short codes with aggregators—that is, companies that oper-
ate servers that route MMS messages between the Web and the cellular network.
Because MMS is a newer service, it does have some downsides as well. Fewer
people have MMS-enabled phones or pay for the service to receive MMS messages.
Moreover, while SMS is largely interoperable among all the world's carriers, MMS is
not. In the United States, for example, only a few major carriers have agreed on MMS
interoperability. If you and I use different carriers, we may or may not be able to
exchange MMS messages.
Introducing the Cell Broadcast Service
While SMS is a point-to-point messaging service—an originator must specify a specific
recipient when sending a message—SMS-CB is a point-to-area (also called a
one-to-
many
) protocol that enables application developers and operators to target many
wireless terminals for a single message. A relatively recent addition to the messaging
standards available on wireless wide area networks (WANs), SMS-CB has only seen
recent adoption on a few networks for applications including advertising, weather alerts,
location-based news, and so forth.
When using SMS-CB, messages are shorter (82 bytes of compressed text or binary
data) but may be concatenated to provide a mechanism to deliver longer messages.
Instead of addressing messages to a specific recipient, you address them to a range
of cells, typically within a specific geographic area. Some advanced networks provide
interfaces that incorporate geographic information to eliminate the need for SMS-CB
applications to refer to specific cells; instead, with these interfaces, you can refer to areas
by their latitude and longitude.
Introducing Wireless Messaging API
WMA extends the GCF (which you first encountered in detail in Chapter 12) to include
the notion of various kinds of messages, similar in concept to UDP datagrams. Defining
the
javax.wireless.messaging
package, JSR 120 details WMA version 1.0, while JSR 205
details WMA version 2.0.
