Write once, run anywhere (WORA), or sometimes Write once, run everywhere (WORE), was a 1995 slogan created by

Sun Microsystems Sun Microsystems, Inc. (Sun for short) was an American technology company that sold computers, computer components, software, and information technology services and created the Java programming language, the Solaris operating system, ZFS, t ...

to illustrate the

cross-platform In computing, cross-platform software (also called multi-platform software, platform-agnostic software, or platform-independent software) is computer software that is designed to work in several computing platforms. Some cross-platform software ...

benefits of the

Java language Java is a high-level, class-based, object-oriented programming language that is designed to have as few implementation dependencies as possible. It is a general-purpose programming language intended to let programmers ''write once, run anywh ...

. Ideally, this meant that a Java program could be developed on any device, compiled into standard

bytecode Bytecode (also called portable code or p-code) is a form of instruction set designed for efficient execution by a software interpreter. Unlike human-readable source code, bytecodes are compact numeric codes, constants, and references (norma ...

, and be expected to run on any device equipped with a

Java virtual machine A Java virtual machine (JVM) is a virtual machine that enables a computer to run Java programs as well as programs written in other languages that are also compiled to Java bytecode. The JVM is detailed by a specification that formally describe ...

(JVM). The installation of a JVM or Java interpreter on chips, devices, or software packages became an industry standard practice. A programmer could develop code on a PC and expect it to run on Java-enabled

mobile phone A mobile phone, cellular phone, cell phone, cellphone, handphone, hand phone or pocket phone, sometimes shortened to simply mobile, cell, or just phone, is a portable telephone that can make and receive calls over a radio frequency link whi ...

s, as well as on routers and mainframes equipped with Java, without any adjustments. This was intended to save software developers the effort of writing a different version of their software for each

platform Platform may refer to: Technology * Computing platform, a framework on which applications may be run * Platform game, a genre of video games * Car platform, a set of components shared by several vehicle models * Weapons platform, a system or ...

operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may also i ...

they intend to deploy on. This idea originated no later than the 1960s, with the

IBM M44/44X The IBM M44/44X was an experimental computer system from the mid-1960s, designed and operated at IBM's Thomas J. Watson Research Center at Yorktown Heights, New York. It was based on an IBM 7044 (the 'M44'), and simulated multiple 7044 virtual mach ...

, and in the late 1970s the

UCSD Pascal UCSD Pascal is a Pascal programming language system that runs on the UCSD p-System, a portable, highly machine-independent operating system. UCSD Pascal was first released in 1977. It was developed at the University of California, San Diego (U ...

system was developed to produce and interpret

p-code Bytecode (also called portable code or p-code) is a form of instruction set designed for efficient execution by a software Interpreter (computing), interpreter. Unlike Human-readable code, human-readable source code, bytecodes are compact nume ...

. UCSD Pascal (along with the Smalltalk virtual machine) was a key influence on the design of the JVM, as is cited by

James Gosling James Gosling (born May 19, 1955) is a Canadian computer scientist, best known as the founder and lead designer behind the Java programming language. Gosling was elected a member of the National Academy of Engineering in 2004 for the conception ...

. The catch is that since there are multiple JVM implementations, on top of a wide variety of different operating systems, there could be subtle differences in how a program executes on each JVM/OS combination, possibly requiring an application to be tested on each target platform. This gave rise to a joke among Java developers: Write Once, Debug Everywhere. In comparison, the

Squeak Squeak is an object-oriented, class-based, and reflective programming language. It was derived from Smalltalk-80 by a group that included some of Smalltalk-80's original developers, initially at Apple Computer, then at Walt Disney Imagineering, ...

Smalltalk programming language and environment boasts of being truly write once run anywhere, because it runs bit-identical images across its wide portability base. Like Squeak, MicroEJ provides a virtual execution environment that guarantees one unique Java thread policy across all implementations, ensuring a true WORA semantic across millions of devices.

References

{{DEFAULTSORT:Write Once, Run Anywhere Software engineering folklore American advertising slogans Sun Microsystems Computer programming folklore Computing acronyms 1995 neologisms Interoperability

See also

References