Java™ technology includes two elements: a programming
language, and an application environment in which programs
written in the Java™ language can be executed. The Java™
programming language syntax is similar to C++, both being
object oriented. The main difference between the C++ and
Java™ languages is that the application developer needs
to compile the C++ source code into a native machine code
that works only on the specific target device, whereas
the Java™ language code is interpreted in the target device
by a so-called Java™ virtual machine. This is the mechanism
that makes Java™ applications portable, i.e. a Java™ application
works in all devices with a similar Java™ platform.
The Nokia 7250 supports the Java™ 2 Micro Edition (J2ME)
platform, a part of Java™ technology specially designed
for consumer electronics products. More specifically,
the platform is based on the industry standard Mobile
Information Device Profile 1.0 (MIDP 1.0), which provides
essential functionality to create applications for mobile
phones. Java™ applications created for this platform are
commonly called "MIDlets."
3. What are the benefits of Java™
technology for phone users?
Traditionally, handsets have come with a limited set of
pre-installed applications, such as a calendar, a clock
and a few games. Java™ technology is radically changing
this. It enables phone users to download new applications
into their phones. Thus, phone users benefit from the
creative potential of thousands of application developers.
Examples of downloadable Java™ applications include games,
sports training calendars, bilingual phrase books and
map applications. Java™ technology makes the phone more
exciting to use, and lets phone users personalize their
handset by selecting the applications they want. The Nokia
7250 supports the downloading of Java™ applications both
over the WAP connection and by using PC Suite.
4. What's the benefit of downloadable
applications in my Nokia 7250?
You can enrich your phone’s functionality with the applications you need for managing your work and free time, such as travel, shopping and entertainment-related applications, and interactive and graphical games. You can also personalize your phone with other kinds of downloadable applications.
Java™ applications are executed locally in the device and provide convenient usage, thanks to a fast response without network delay.
5. How many applications can be
downloaded into the Nokia 7250?
The memory reserved for the Java™ applications in the
Nokia 7250 is dynamic. The maximum size of a MIDlet downloaded
OTA (over-the-air via WAP) is 64 kB. You can download
four maximum-sized MIDlets to the Nokia 7250. If the downloaded
MIDlets are smaller, there is space for more MIDlets.
Using Nokia PC Suite, you can transfer 64 kB of MIDlets
from a PC to your Nokia 7250 .
(Note: The capacity described here refers to the overall
application memory. The Nokia 7250 is pre-loaded with
some Java™ MIDlets that occupy a certain amount of memory.
The MIDlets in the phone can be erased and new MIDlets
can be downloaded to replace them.)
Many parties offer Java™ applications. Operators play
a key role in ensuring that their subscribers have easy
access to downloadable applications. Because the Nokia
7250 supports application downloading via PC Suite, you
can also get MIDlets from the Internet and download them
to your handset.
8. Are all Java™ applications
suitable for my Nokia 7250 phone?
The Nokia 7250 supports the download of standard MIDlets,
i.e. applications that use the Application Programming
Interfaces defined in the MIDP 1.0 specification. The
maximum size of the downloadable MIDlet is 64 kB.
9. What is the security of Java™
applications in the Nokia 7250?
The Java™ platform in the Nokia 7250 has extensive
security mechanisms. Your confirmation is needed for
the Java™ application to make a network connection.
To make sure that you know whether the application is
connected or not, a network connection indicator is shown
in the upper left-hand corner of the display whenever
the application is connected. To ensure that you are
aware of the tariff for the network connection, the applications
can be connected only through the WAP gateway defined
in the WAP settings.
To make sure that the Java™ applications do not
expose your sensitive data, the applications cannot read
your private data on the device. For example, the Java™ applications
cannot access the phone book, calendar, text messages
and call register. The only data that the applications
can access is the application’s own data, i.e.
the data the application itself has stored in the device.
Experts in the telecommunications industry within the
Java™ Community Process (JCP) have defined this
functionality.
It is important to note that if you input (using the
keypad) information to the application, the application
can potentially send that over the network connection.
Thus, you should not provide sensitive information to
a Java™ application unless you trust the application.
In the Nokia 7250, the Java™ applications establish the
HTTP connection over the WAP stack. Thus, the transport
layer security is based on the security provided by the
WAP stack, namely the Wireless Transport Layer Security
(WTLS) protocol. Because of some weaknesses in the WAP
security model, mainly because there is no real end-to-end
security between the client and the http server, it is
not recommended to transfer extremely valuable information
over WAP. The gap in the end-to-end security is caused
by the fact that the WAP gateway decrypts WTLS and re-encrypts
the content using SSL to connect to the content server.
If you are not using a trusted gateway (i.e. one
freely available on the Internet), there is the potential
that confidential information can be compromised during
the transfer from WTLS to SSL and vice-versa.
The Java™ application execution is insulated from the
native functionality of the phone. If there is a problem
with the Java™ application, the native functionality of
the phone is not affected. In case of a problem, the Java™
application execution is stopped. Thus, Java™ applications
cannot crash the phone. Phone users can also always stop
the execution of a Java™ application by pushing the red
("stop the call") key.
This varies depending on the market, the operator and
the type of the application. Commercial entertainment
applications such as games typically cost 2-3 USD.
11. What is the bearer for Java™ applications?
How network-dependent are the applications? Can they
be used without network coverage?
Java™ applications can be downloaded using the WAP browser
over Circuit Switched Data and GPRS connections. Once
the MIDlet is downloaded, the application can run independent
of network coverage as long as the MIDlet is stand-alone
and does not depend on a network component for processing.
A MIDlet can also be connected to server resources.
This
connection is established also over WAP.
12. Can the Java™ applications
play polyphonic tones?
No. The implementation supports the generation of single
tones. The Java™ Community Process has not yet defined
specification for polyphonic audio API for Java™ 2 Micro
Edition.
13. Can Java™ applications
be downloaded regardless of time and place, e.g. can they
be downloaded when travelling in the US?
This is dependent on the data coverage of a given network
and the roaming agreements that are in place. Some operators
in the US operate with the "Walled Garden" approach where
they discourage end-users from going beyond the given
carrier's portal.
