1 Overview

This chapter describes essential Oracle Java Micro Edition Embedded Client terms and concepts, including the kinds of devices that are the domain of the product, the roles that product users play, host and target platforms, and options for application development.

This chapter includes the following topics:

Domains and Devices
Users and Documentation
Components
Platforms
Developing Applications

Domains and Devices

The benefits of writing applications in the Java programming language can be realized across a range of computing domains from corporate applications running on large servers to personal applications hosted by small mobile phones. In all of these environments, a Java virtual machine executes Java bytecodes, which are the basis of Java application portability. However, to exploit the resources of large computers and accommodate the constraints of very small ones, there must be more than one Java platform — a virtual machine and set of libraries that provide services to Java applications.

Oracle Java Micro Edition Embedded Client is one of a family of Java platforms available from Oracle. Other family members include Java Standard Edition (Java SE, for desk- and laptop computers and servers), and Oracle Java Wireless Client, typically used for feature phones. Oracle Java Micro Edition Embedded Client falls between the Standard Edition and the Wireless Client. It is designed for devices whose computational resources are between those of phones and laptop computers. Typical application domains are televisions, Blu-ray Disc players, and set-top boxes; printers, IP phones, ebook readers, and smart utility meters.

Oracle Java Micro Edition Embedded Client and the applications that use it run on a device. A device is usually a specialized computer and peripheral components embedded in a machine or appliance whose users do not think of as a computer. A device is called a target device when it is necessary to distinguish it from a host device (or host computer), which is a personal computer that is used for developing Oracle Java Micro Edition Embedded Client or Oracle Java Micro Edition Embedded Client applications. A device consists of a CPU, memory, peripheral hardware, and an operating system. The peripheral hardware might include device-specific components in addition to those found on a typical small embedded computer.

Users and Documentation

The Oracle Java Micro Edition Embedded Client documentation set distinguishes the following users:

Device users: These are the end users of the device that incorporates Oracle Java Micro Edition Embedded Client. They are not aware of Oracle Java Micro Edition Embedded Client's presence. They use the device as a smart meter, a printer, an eBook reader, and so on. Device user documentation is written by the organization that uses Oracle Java Micro Edition Embedded Client to create a device.
Application developers: Java programmers who build the software that uses Oracle Java Micro Edition Embedded Client and interacts with device users. These developers know about Oracle Java Micro Edition Embedded Client's Java programming interfaces but not its implementation. The primary document for application developers is the Oracle Java Micro Edition Embedded Client Developer's Guide.
Customizer: Customizers adjust the Oracle Java Micro Edition Embedded Client to fit requirements for memory footprint, performance, special hardware, and so on. The primary document for customizers is the Oracle Java Micro Edition Embedded Client Customization Guide.

One person might act as multiple users. For example, a customizer might also be an application developer.

Components

Oracle Java Micro Edition Embedded Client includes the components shown in Table 1-1. As noted in the table, some components can be removed to reduce device memory requirements.

Table 1-1 Headless Configuration Main Components

Component	Spec Version	Description
Connected Device Configuration (CDC)	JSR 218 1.1.2	Java virtual machine with interpreter and compiler, plus basic libraries.
Foundation Profile (FP)	JSR 219 1.1.2	Input/output, utility, security classes that supplement the CDC APIs to the functional level of the Java SE 1.4 platform.
Security Optional Package (SecOp)	JSR 219 1.0.1	Optional component of Foundation Profile that defines cryptographic APIs. Removable.
J2ME Remote Method Invocation (RMI)	JSR 66 1.0	Remote invocation of Java methods. Removable.
Java Data Base Connection for CDC/FP (JDBC)	JSR 169 1.0	Relational database query and update, subset of full JDBC. Removable.
XML API	JSR 280 1.0	Subsets of XML parsing APIs. Removable.

Platforms

Besides distinguishing among the Java editions (SE, and so on, see Domains and Devices), in the context of Oracle Java Micro Edition Embedded Client, there is a second meaning for "platform". An Oracle Java Micro Edition Embedded Client platform is a computer on which an Oracle Java Micro Edition Embedded Client binary runs. The Oracle Java Micro Edition Embedded Client Release Notes describe the platforms supported in this release. There are both host and target platforms. The target platforms for the headless configuration differ from those for the headful configuration, because the latter must include graphics support.

Developing Applications

Oracle Java Micro Edition Embedded Client application development is cross-platform. Target devices run Oracle Java Micro Edition Embedded Client applications, but their limited resources are too limited for application development. Developers code and compile on a host computer. They test by transferring their code to a device or emulator. Debugging and profiling is performed across a network, using the host computer as a console and instrumentation on the device.

Oracle Java Micro Edition Embedded Client applications can be developed with standard command-line tools, such as javac and make or ant. You can also use the NetBeans or Eclipse Integrated Development Environments (IDEs).