Mobile devices Toolkit

J2ME or BREW for wireless development?

Tags:
Internet,
Sun Microsystems,
Java,
J2ME

Puneet Gupta Builder.com

Published: 18 Jul 2002 11:59 BST

Wireless Internet is more than just "wireless access to the Internet." It's about different types of small mobile devices and the ability to provide anytime, anywhere access to information in an easy and effective way. So far, WAP has been more or less the only standard providing basic access to Web-based services using a microbrowser on the mobile device. However, next-generation wireless devices, such as smart phones, raise application functionality expectations. Two vendors, Sun and Qualcomm, are attempting to meet this challenge by offering a new model for online access to wireless applications.

Sun Microsystems's Java 2 Micro Edition (J2ME) and Qualcomm's Binary Runtime Environment for Wireless (BREW) are two emerging technologies that provide a new model for online access by allowing applications to be downloaded from the Web. The apps can then take care of fetching more data from the Web or be executed offline. These technologies provide the developer community with enormous opportunity for building and distributing feature-rich mobile and wireless applications. The key benefits of J2ME and BREW include an enhanced user interface, improved application usability on small screens, and the ability to download and store new applications that can be run offline, thereby eliminating the need for constant network connection. Let's look at the similarities and differences of these competing technologies.

J2ME: "Special Edition Java"
J2ME is Java technology specially customized for small consumer and embedded devices with limited processor, memory, display, and input capabilities. J2ME architecture is based on families and categories of devices and has the following structure.

Java Virtual Machine (JVM) runs on top of the device's operating system and is customized for a specific operating system. The size and complexity of JVM depends on the particular J2ME configuration it supports.

The configuration layer should be of interest to you if you are involved in developing J2ME profiles. This layer specifies the minimum set of features and Java class libraries that the JVM should support, thereby specifying the Java functionality available for a particular category of devices.

J2ME defines two configurations. Connected Limited Device Configuration (CLDC) is meant for devices with limited power, memory, and network connectivity capabilities. JVM corresponding to this configuration is the highly optimized K Virtual Machine. (KVM can run in around 130 KB of memory.) Connected Device Configuration (CDC) is for more advanced devices with 32-bit processors and with more than 2 MB of memory. The corresponding VM is the full-featured Java C Virtual Machine (CVM).

The profile layer may be the most relevant to application developers. It defines a set of APIs for a particular category of devices. An application written for a particular profile can run on any other device that supports that profile. Mobile Information Device Profile (MIDP) is relevant to mobile wireless devices like mobile phones and PDAs. It includes a set of APIs related to user interface, storage, and networking (HTTP) capabilities. Also of interest is the J2ME Bluetooth profile, which provides standardized APIs for including Bluetooth capability.

The alternative: BREW BREW is an application execution platform that runs at the firmware level (CDMA chipset) and specially targets wireless applications that can be downloaded and executed on mobile devices. BREW runtime environment is available free of cost to CDMA device manufacturers. This runtime environment is much like the VM in Java, except that BREW runtime environment is not designed to provide portability from one device to another. BREW is currently available only to CDMA-based wireless devices sporting Qualcomm processors. The platform boasts enhanced capabilities that include GPS, VOIP, Bluetooth 1.1, MP3, and MIDI. The fact that BREW runtime platform runs at chipset level enables it to leverage the communication and multimedia capabilities of mobile devices more than J2ME.

The BREW suite of services includes TCP/UDP socket communications, HTTP support, SMS messaging, advanced telephony services, and support for file system access. BREW provides C/C++ software development, and the BREW C/C++ SDK easily integrates with Microsoft's Visual C++ development environment. As part of the BREW application platform, Qualcomm offers a BREW porting kit, a BREW SDK that provides development tools, documentation, APIs, etc., and a BREW distribution system, which we'll look at next.

Go to section: