Topic: Java

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πŸ”— Jazelle DBX: Allow ARM processors to execute Java bytecode in hardware

πŸ”— Computing πŸ”— Computing/Computer hardware πŸ”— Computing/Software πŸ”— Java

Jazelle DBX (direct bytecode execution) is an extension that allows some ARM processors to execute Java bytecode in hardware as a third execution state alongside the existing ARM and Thumb modes. Jazelle functionality was specified in the ARMv5TEJ architecture and the first processor with Jazelle technology was the ARM926EJ-S. Jazelle is denoted by a "J" appended to the CPU name, except for post-v5 cores where it is required (albeit only in trivial form) for architecture conformance.

Jazelle RCT (Runtime Compilation Target) is a different technology based on ThumbEE mode; it supports ahead-of-time (AOT) and just-in-time (JIT) compilation with Java and other execution environments.

The most prominent use of Jazelle DBX is by manufacturers of mobile phones to increase the execution speed of Java ME games and applications. A Jazelle-aware Java virtual machine (JVM) will attempt to run Java bytecode in hardware, while returning to the software for more complicated, or lesser-used bytecode operations. ARM claims that approximately 95% of bytecode in typical program usage ends up being directly processed in the hardware.

The published specifications are very incomplete, being only sufficient for writing operating system code that can support a JVM that uses Jazelle. The declared intent is that only the JVM software needs to (or is allowed to) depend on the hardware interface details. This tight binding facilitates the hardware and JVM evolving together without affecting other software. In effect, this gives ARM Holdings considerable control over which JVMs are able to exploit Jazelle. It also prevents open source JVMs from using Jazelle. These issues do not apply to the ARMv7 ThumbEE environment, the nominal successor to Jazelle DBX.

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πŸ”— List of Java virtual machines

πŸ”— Computing πŸ”— Lists πŸ”— Java

This article provides non-exhaustive lists of Java SE Java virtual machines (JVMs). It does not include a large number of Java ME vendors. Note that Java EE runs on the standard Java SE JVM but that some vendors specialize in providing a modified JVM optimized for Java EE applications. A large amount of Java development work takes place on Windows, Solaris, Linux and FreeBSD, primarily with the Oracle JVMs. Note the further complication of different 32-bit/64-bit varieties.

The primary reference Java VM implementation is HotSpot, produced by Oracle Corporation.

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πŸ”— Java Card

πŸ”— Java

Java Card is a software technology that allows Java-based applications (applets) to be run securely on smart cards and more generally on similar secure small memory footprint deviceswhich are called β€œsecure elements” (SE). Today, a Secure Element is not limited to its smart cards and other removable cryptographic tokens form factors; embedded SEs soldered onto a device board and new security designs embedded into general purpose chips are also widely used. Java Card addresses this hardware fragmentation and specificities while retaining code portability brought forward by Java.

Java Card is the tiniest of Java platforms targeted for embedded devices. Java Card gives the user the ability to program the devices and make them application specific. It is widely used in different markets: wireless telecommunications within SIM cards and embedded SIM, payment within banking cards and NFC mobile payment and for identity cards, healthcare cards, and passports. Several IoT products like gateways are also using Java Card based products to secure communications with a cloud service for instance.

The first Java Card was introduced in 1996 by Schlumberger's card division which later merged with Gemplus to form Gemalto. Java Card products are based on the specifications by Sun Microsystems (later a subsidiary of Oracle Corporation). Many Java card products also rely on the GlobalPlatform specifications for the secure management of applications on the card (download, installation, personalization, deletion).

The main design goals of the Java Card technology are portability, security and backward compatibility.

πŸ”— Project Looking Glass

πŸ”— Computing πŸ”— Computing/Software πŸ”— Java

Project Looking Glass is a now inactive free software project under the GPL to create an innovative 3D desktop environment for Linux, Solaris, and Windows. It was sponsored by Sun Microsystems.

Looking Glass is programmed in the Java language using the Java 3D system to remain platform independent. Despite the use of graphics acceleration features, the desktop explores the use of 3D windowing capabilities for both existing application programs and ones specifically designed for Looking Glass.

There is a Live CD available from Project Looking Glass. The Looking Glass environment is also included on a Live DVD (FunWorks 2007 edition) from the Granular Linux project.