1. Introduction of J2ME
Mobile solutions

2. Overview
What is J2ME.
How does J2ME work?
Java J2ME Carriers and Products.
The Two Configuration of J2ME.
Profiles in J2ME
MIDP & MIDlets
Wireless Java
J2ME Vendors and Products
References

3. What is J2ME ---J2ME in a Nutshell -A Desktop Quick Reference
J2ME is a family of specifications that defines various downsized versions of the standard Java 2 platform; these downsized versions can be used to program consumer electronic devices ranging from cell phones to highly capable Personal Data Assistants (PDAs), smart phones, and set-top boxes.
---J2ME in a Nutshell -A Desktop Quick Reference
By Kim Topley

4. Java Family
-- java.sun.com (2003)

5. J2ME Category ----Picture form Java.sun.com
Principle: Different hardware corresponds different JVMs, hardware which base on CDC have powerful JVMs, and hardware which base on CIDC have KVM to support.
----Picture form Java.sun.com

6. two configurations J2ME currently defines 1
Connected Limited Device Configuration (CLDC)
CLDC is aimed at the low end of the consumer electronics range. A typical CLDC platform is a cell phone or PDA with around 512 KB of available memory. For this reason, CLDC is closely associated with wireless Java, which is concerned with allowing cell phone users to purchase and download small Java applications known as MIDlets to their handsets. A large and growing number of cell phone vendors have signed agreements with Sun Microsystems that will allow them to begin using this technology, so the number of handsets with the capability to be programmed in Java will probably grow rapidly in the next few years.
----- J2ME in a Nutshell -A Desktop Quick Reference
By Kim Topley
A configuration is a specification that defines the software environment for a range of devices
defined by a set of characteristics that the specification relies on, usually such things as:
• The types and amount of memory available
• The processor type and speed
• The type of network connection available to the device
A configuration is supposed to represent the minimum platform for its target device and is not
permitted to define optional features. Vendors are required to implement the specification
fully so that developers can rely on a consistent programming environment and, therefore,
create applications that are as device-independent as possible.
No display, no user input interface…

7. two configurations J2ME currently defines 2
Connected Device Configuration (CDC)
CDC addresses the needs of devices that lie between those addressed by CLDC and the full desktop systems running J2SE. These devices have more memory (typically 2 MB or more) and more capable processors, and they can, therefore, support a much more complete Java software environment. CDC might be found on high-end PDAs
and in smart phones, web telephones, residential gateways, and set-top boxes.
----- J2ME in a Nutshell -A Desktop Quick Reference
By Kim Topley
A configuration is a specification that defines the software environment for a range of devices
defined by a set of characteristics that the specification relies on, usually such things as:
• The types and amount of memory available
• The processor type and speed
• The type of network connection available to the device
A configuration is supposed to represent the minimum platform for its target device and is not
permitted to define optional features. Vendors are required to implement the specification
fully so that developers can rely on a consistent programming environment and, therefore,
create applications that are as device-independent as possible.

8. Profiles J2ME currently defines
Mobile Information Device Profile (MIDP)
PDA Profile (PDAP)
Foundation Profile
Personal Basis and Personal Profiles
RMI Profile
Game Profile
A profile complements a configuration by adding additional classes that provide features
appropriate to a particular type of device or to a specific vertical market segment. Both J2ME
configurations have one or more associated profiles, some of which may themselves rely on
other profiles. These processes are described
in the following list:
Mobile Information Device Profile (MIDP)
This profile adds networking, user interface components, and local storage to CLDC.
This profile is primarily aimed at the limited display and storage facilities of mobile
phones, and it therefore provides a relatively simple user interface and basic
networking based on HTTP 1.1. MIDP is the best known of the J2ME profiles because
it is the basis for Wireless Java and is currently the only profile available for PalmOSbased
handhelds.
PDA Profile (PDAP)
The PDA Profile is similar to MIDP, but it is aimed at PDAs that have better screens
and more memory than cell phones. The PDA profile, which is not complete at the
time of writing, will offer a more sophisticated user interface library and a Java-based
API for accessing useful features of the host operating system. When this profile
becomes available, it is likely to take over from MIDP as the J2ME platform for small
handheld computers such as those from Palm and Handspring.
Foundation Profile
The Foundation Profile extends the CDC to include almost all of the core Java 2
Version 1.3 core libraries. As its name suggests, it is intended to be used as the basis
for most of the other CDC profiles.
Personal Basis and Personal Profiles
The Personal Basis Profile adds basic user interface functionality to the Foundation
Profile. It is intended to be used on devices that have an unsophisticated user interface
capability, and it therefore does not allow more than one window to be active at any
time. Platforms that can support a more complex user interface will use the Personal
Profile instead. At the time of writing, both these profiles are in the process of being
specified.
RMI Profile
The RMI Profile adds the J2SE Remote Method Invocation libraries to the Foundation
Profile. Only the client side of this API is supported.
Game Profile
The Game Profile, which is still in the process of being defined, will provide a
platform for writing games software on CDC devices. At the time of writing, it is not
certain whether this profile will be derived from the Foundation Profile or based
directly on CDC.

9. The Mobile Information Device Profile and MIDlets
The Mobile Information Device Profile, or MIDP for short, is one such profile, intended for use on small footprint devices with a limited user interface in the form of a small screen with some kind of input capability.
Java applications that run on MIDP devices are known as MIDlets. A MIDlet consists of atleast one Java class
The Mobile Information Device Profile, or MIDP for short,
is one such profile, intended for use on small footprint devices with a limited user interface in
the form of a small screen with some kind of input capability.
In the longer term, it is intended that these devices use the PDA profile, which is also hosted by CLDC

10. MIDP Hardware Requirements
Minimum Requirement
Display
96 X 54 Pixels 65,536 colors
Memory
32 KB workspace
128KB MIDP Implementation
8KB for MIDlets run
Input Device
the device has the equivalent of a keypad that allows the user to type the numbers 0 through 9,together with the equivalent of arrow keys and a select button
Connectivity
HTTP 1.1; TCP/IP

11. MIDlet Security
No “sand Box” as J2EE or J2SE. Because it is expensive in terms of memory resources.
No MIDlet APIs that allow access to information already on the device, such as address and telephone number lists or calendars, and it is not possible for a MIDlet to directly control the device.
A MIDlet can store information on a device, but that storage is private to that MIDlet and its suite, so the MIDlet can harm only its own data.

12. Wireless Java: Networking and Persistent Storage
Two Essentials
The devices that the J2ME platform is intended for are, by their nature, reliant for their usefulness on the ability to communicate with the outside world.
The ability to store information and access it from applications running on that device. The type of storage available, and the amount of space available, varies greatly from device to device.
The devices that the J2ME platform is intended for are, by their nature, reliant for their
usefulness on the ability to communicate with the outside world. Cell phones, of course, serve
no real purpose other than to exist on a network, while PDAs would be much less useful if
you could not connect them occasionally to a desktop computer to save your new customer
orders or upload more appointments from your departmental calendar. As important as
networking is, however, there is a certain cost to be paid for it in terms of the resources
needed for the software that implements the various networking protocols in use today. Given
the relatively small amount of memory and processing power available in cell phones and the
smaller PDAs, compromises have to be made in order to provide networking support for the
type of hardware on which profiles designed for the CLDC are run. The same constraints do
not exist for the larger devices that host CDC profiles. Not surprisingly, then, these two
different profile families incorporate completely different communication software
architectures. This chapter looks at networking and communications in the context of the
CLDC configuration and MIDP, which differs greatly from its CDC equivalent,

13. MIDlet Management and Storage
A MIDlet consists of one or more class files and associated resources stored in a JAR file. Several MIDlets may be combined into a MIDlet suite. All the MIDlets that make up a given suite are packaged in the same JAR file and are managed as a single unit: they are installed together in the simulated nonvolatile device storage Furthermore, they all execute in the same instance of the Java VM. MIDlets almost always be installed over a network or via a local connection to an associated host system. Because the JAR file that contains a MIDlet suite may be large, each suite has an associated Java Archive Descriptor file (JAD) that is small enough to download quickly, but which contains enough information about the suite to allow the user to decide whether to install it. The Application Management Software of a MIDP device (such as a cell phone) typically first downloads the JAD file, whose location is specified by its URL. If the user decides to install the MIDlet suite, the AMS downloads the JAR file, which can be located by using one of the attributes in the JAD. The MIDlet suite is then stored on the device, and subsequently, the MIDlets it contains can be loaded from the locally installed copy..

14. How does J2ME work? Example of mobile phones
The latest Java-enabled mobile devices, you can view a list of applications, games, and services and choose which one interests you. The application is then sent over the air to your handset, where it is installed and instantly available to use. You are no longer limited to the small selection of games and applications that came with your phone. And with new content being released daily from top entertainment and software companies, you can always find new, fun applications to download.
Example of mobile phones

15. Networking Architecture for Small Devices
Memory requirements
Was judged to be too great for the small footprint devices that CLDC is designed for.
Consistency
The differences are significant when it comes to using a serial device, because you need to install an extra package and use yet another programming model. Given the diversity of devices and communication mechanisms that the CLDC might be required to support, a more uniform API was clearly required.
Implementation flexibility
An architecture based entirely around interfaces, so that application code would not be tied to particular classes. Thus, vendors are free to provide socket and HTTP implementations that are appropriate for their specific devices.

16. HTTP Connections
The only communications protocol that every MIDP device is required to provide
HTTP makes use of stream sockets to carry messages between an HTTP client (usually a web browser) and a web server that often (but not always) returns an HTML page to the client.

17. Two Potential Problems
Many of handset devices, particularly cell phones, do not have a direct connection to the internet and therefore almost certainly do not support sockets.
The MIDP user interface components do not provide any support for displaying HTML, so there is no built-in browser capability in a MIDP device.
Answer
It is the responsibility of the device vendor to arrange for the device to be able to support HTTP even if it does not have a direct connection to the Internet. In most cases, this means that the device needs to connect to a gateway that can switch HTTP messages to whatever protocol is used to connect to the Internet gateway. In the wireless environment, for example, the device might use WSP (the Wireless Session Protocol) to connect to a WAP gateway that can bridge between a wireless network and the Internet. However this mapping is achieved, it must be done in such a way that the MIDP application cannot tell whether it is directly connected to the Internet.
Although HTTP is predominantly used to carry HTML from web servers to web browsers, it
is also possible to use it to carry other types of information such as XML, images, or even
binary data. This is because one of the message headers specifies the type of the data in the
message body. Furthermore, the communicating parties do not have to be a browser and a
web server. The examples in this section all involve MIDlets talking to a web server, but
HTTP is routinely used for other purposes, such as tunneling protocols. These allow the
transmission of data that would otherwise be barred from passing through corporate firewalls,
since most companies allow HTTP to transmitted through their firewalls or via a proxy server.
The HTTP support in J2ME gives you access to all these possibilities.

18. Java Technology Carriers
More than half of the tele-companies support J2ME lies in Asia, because of culture???
The people in North American don’t like add too many extra functions on their mobiles???
Comparing “Short-message service” in these two areas is a good example.

19. Java Technology Handsets
Mobiles, PDAs or COMBOs (Palm-based phone, Microsoft smart-phone, Blackberry…etc) , We will see the J2ME in many electronics soon, even in microwave ovens??
So we can upgrade our home electronics for new functions for a very low price, even for free in the near future.
To date, over 250 different handset models from more than 40 manufacturers have been developed with Java technology, with more than 100 million of these handsets shipped worldwide. ---

20. J2ME Programming Environments
JBUILDER 7 OR 8 + BORLAND MOBILESET 3.1 (Most Power Developing tools)
SUN JDK J2ME Wireless Toolkit
Jdk1.4+J2ME CLDC 1.04，MIDP 2.0
SDKs from the mobile providers, e.g. Nokia etc.
J2ME移动开发，菜鸟指南。 要进行J2ME的开发，首先必须要建立开发的平台，而在开发的平台选择上，我来介绍3条路。 1：功能比较全的平台JBUILDER； 搭建这个平台，我们必需要的材料有：JBUILDER 7 或 JBUILDER 8 ，BORLAND 的 MOBILESET 3。1。 可选材料有：（注意这些不是必须的，没有这些你也可以进行开发）你所想开发的手机SDK，例如要在NOKIA上开发必须准备NOKIA DEVELOPER‘S SUITE，还可以根据自己需要加一些模拟器如7210等(NOKIA SDK安装方法见附录1)。 有了以上的材料就足够我们搭建一个很不错的开发平台了。 搭建步骤： （1）：安装JBUILDER，并注册。（注意：D版JBUILDER 8用户，市面上有些D版JBUILDER 8破解有问题，会导致接下来安装的MOBILESET无法被激活的情况，也就是无论你怎么配置，在MIDP页面里的选项永远是灰的，请勿使用它 盘中的破解文件，用注册机注册，注册机使用方法见附录2。） （2）：正确安装JBUILDER，并、成功注册后，安装 MOBILESET 3。1，安装完成后，需要注册，MOBILESET是免费的，你可以向BORLAND索要注册码，也可以用 附录3 中的注册码注册。 （3）：完成以上2步必须步骤后，就可以安装你选装的DEVELOPER‘S SUITE和模拟器了(NOKIA SDK安装方法见附录1)。 （4）：正确完成了以上步骤，可以说这个平台已经搭建完成，就这么简单，下面你要做的就是在JBUILDER中NEW 一个PROJECT，在出现 的窗体中JDK选J2ME的，其他都使用默认的就可以了，完成配置后，再选NEW，这时候在最后的MIDP页面里两个选项应该是可选的，接下 来你就可以开发了。 2：个头比较小，使用满方便的平台 j2me_wireless_toolkit； 搭建这个平台，我们必需要的材料有：jdk1.4，j2me_wireless_toolkit1。04或j2me_wireless_toolkit2。0 beta1 可选材料有：（注意这些不是必须的，没有这些你也可以进行开发）你所想开发的手机SDK，例如要在NOKIA上开发必须准备NOKIA DEVELOPER‘S SUITE，还可以根据自己需要加一些模拟器如7210等(NOKIA SDK安装方法见附录1)。 有了以上的材料就足够我们搭建现在的平台。 （1）：首先安装jdk1.4，（在方法一中因为JBUILDER自带JDK所以不需要单独安装。） （2）：正确安装JDK后，才可以安装j2me_wireless_toolkit，不管1。04还是2。0 BETA1都可以，2个都装也可以。 （3）：完成以上2步必须步骤后，就可以安装你选装的DEVELOPER‘S SUITE和模拟器了(NOKIA SDK安装方法见附录1)。 （4）正确完成了以上步骤，可以说这个平台已经搭建完毕了，有些菜鸟可能会问这个j2me_wireless_toolkit是干什么的，其实它的作用就和JB UILDER差不多，用来编译你写的JAVA程序，但它本身不提供编辑等功能，所以你得用记事本或其他文本编辑软件写程序，使用方法见附录4 3：个头最小，但用起来最复杂的平台cldc+MIDP 搭建这个平台，我们必需要的材料有：jdk1.4，J2ME_CLDC_ 1。04，MIDP 2.0 对这个平台的使用方法我自己到现在还不是特别清楚，只粗略的介绍一下 （1）同样首先要安装jdk1.4 （2）将J2ME_CLDC_ 1。04，MIDP 2.0和解压到同一目录下如c:\j2me下，其实这两个就是在命令行下的编译器和JBUILDER，toolkit的作用 一样，但用起来更麻烦。 （3）详细使用方法见附录5 介绍完毕，希望能对刚起步的菜鸟有帮助，有什么错误的地方还请大家指正，文章中引用了其他作者的文字，向他们表示感谢

21. References http://jcp.org/jsr/detail/30.jsp
Topley,K. J2ME in a Nutshell -A Desktop Quick Reference

22. Thank you
Any Questions?