Java Reference
In-Depth Information
•
JPEG support
: The
Image
class must be able to support JPEG images as well as PNG
images required by MIDP 2.0.
•
GSM SMS
: The WMA implementation must support GSM SMS, including the
ability to deliver SMS messages to MIDlets via the push registry.
•
HTTP 1.1
: Each device must provide HTTP 1.1 for all supported media types, as
required by MIDP 2.0.
In addition, the JTWI requires CLDC 1.0 or 1.1, MIDP 2.0, and WMA 1.1. Vendors may
include MMAPI 1.1 as well.
Examining the JTWI Required Elements
To reach the lowest tier of devices (and thereby encompass a large number of target
devices), the JTWI requires relatively few packages. However, to ensure compatibility
between those devices, the JTWI requires the following elements:
•
CLDC
: The JTWI requires CLDC 1.0, as defined in JSR 30. Vendors may substitute
CLDC 1.1, as defined in JSR 139, because CLDC 1.1 is a strict superset of CLDC 1.0.
The CLDC—either 1.0 or 1.1— provides a robust core foundation upon which all
applications depend (see Chapter 2).
•
MIDP
: The JTWI requires MIDP 2.0, as defined in JSR 30. This provides the UI,
persistent store, and communications layer that many applications require (see
Chapters 2, 3, 4, and 5).
•
WMA
: The JTWI requires WMA 1.1, as defined in JSR 120—including SMS—to
enable applications to take advantage of the wireless network on which JTWI-
compliant devices operate (see Chapter 14).
The JTWI provides some clarification for each of these JSRs, as I note in the previous
section. The curious (or excessively pedantic) should refer to JSR 185 for details.
Examining the JTWI Optional Elements
At the time JSR 185 was written, multimedia interfaces were just becoming available
on some mid- and high-tier mobile handsets. To encourage adoption of the MMAPI
(which I described in Chapter 16) where it can be made available, the JTWI requires
that if a device supports multimedia access through Java ME, it be made available
through MMAPI 1.1. If an MMAPI implementation exists on a JTWI device, the device
must support the following features:
