Java Reference
In-Depth Information
secure connections through HTTPS are usually available on MIDP 2.0 implementations,
but some devices may lack HTTPS support. Raw (stream or datagram) socket support is
less common, and serial support is significantly less common than even stream or data-
gram support. Other schemes, like those supporting SMS (which I describe in Chapter 14),
Bluetooth, and the FCOP (see Chapter 7), vary in their availability depending on the
carrier and handset class you target. It's worth your effort to do some market research as
you define the features for your application to ascertain how many devices implement
the optional packages you need. Table 12-2 summarizes the availability of specific
Connection
implementations by profile.
Table 12-2.
Connection Implementations
Connection
Required?
CLDC 1.0,
MIDP 1.0
MIDP 2.0
Foundation and
1.1
Related Profiles
CommConnection
N
✓
Connection
Y
✓
✓
✓
✓
ContentConnection
Y
✓
✓
✓
✓
DatagramConnection
N
✓
✓
✓
✓
HttpConnection
Y
✓
✓
✓
HttpsConnection
Y
✓
InputConnection
Y
✓
✓
✓
✓
OutputConnection
Y
✓
✓
✓
✓
SecureConnection
N
✓
ServerSocketConnection
N
✓
SocketConnection
N
✓
StreamConnection
Y
✓
✓
✓
✓
StreamConnectionNotifier
Y
✓
✓
✓
✓
UDPDatagramConnection
N
✓
The GCF isn't perfect: critics may fairly claim that the
Connection
class doesn't go far
enough in abstracting common communications operations into abstract methods, so
that many conceptually similar operations (such as sending a datagram to a remote host
or sending a protocol data unit to a smart card) have widely varying interface semantics
in different subclasses of the
Connection
class. This is unfortunate, because it makes
learning about the various communications options available through optional packages
more difficult, and it makes taking a component-oriented approach to developing com-
municating applications impossible without the use of adapter classes.
