In the

software development process In software engineering, a software development process is a process of dividing software development work into smaller, parallel, or sequential steps or sub-processes to improve design, product management. It is also known as a software deve ...

, a reference implementation (or, less frequently, sample implementation or model implementation) is a program that implements all requirements from a corresponding specification. The reference implementation often accompanies a

technical standard A technical standard is an established norm or requirement for a repeatable technical task which is applied to a common and repeated use of rules, conditions, guidelines or characteristics for products or related processes and production methods, ...

, and demonstrates what should be considered the "correct" behavior of any other implementation of it.

Characteristics and examples

Reference implementations of algorithms, for instance cryptographic algorithms, are often the result or the input of

standardization Standardization or standardisation is the process of implementing and developing technical standards based on the consensus of different parties that include firms, users, interest groups, standards organizations and governments. Standardizatio ...

processes. In this function they are often dedicated to the

public domain The public domain (PD) consists of all the creative work to which no exclusive intellectual property rights apply. Those rights may have expired, been forfeited, expressly waived, or may be inapplicable. Because those rights have expired ...

with their

source code In computing, source code, or simply code, is any collection of code, with or without comments, written using a human-readable programming language, usually as plain text. The source code of a program is specially designed to facilitate the ...

public domain software Public-domain software is software that has been placed in the public domain, in other words, software for which there is absolutely no ownership such as copyright, trademark, or patent. Software in the public domain can be modified, distribute ...

. Examples are the first CERN's httpd,

Serpent Serpent or The Serpent may refer to: * Snake, a carnivorous reptile of the suborder Serpentes Mythology and religion * Sea serpent, a monstrous ocean creature * Serpent (symbolism), the snake in religious rites and mythological contexts * Serp ...

cipher, base64 variants, and

SHA-3 SHA-3 (Secure Hash Algorithm 3) is the latest member of the Secure Hash Algorithm family of standards, released by NIST on August 5, 2015. Although part of the same series of standards, SHA-3 is internally different from the MD5-like struc ...

. The Openwall Project maintains a list of several algorithms with their reference

in the public domain. A reference implementation may or may not be production quality. For example, the Fraunhofer reference implementation of the

MP3 MP3 (formally MPEG-1 Audio Layer III or MPEG-2 Audio Layer III) is a coding format for digital audio developed largely by the Fraunhofer Society in Germany, with support from other digital scientists in the United States and elsewhere. Origin ...

standard usually does not compare favorably to other common implementations, such as LAME, in listening tests that determine sound quality. In contrast, CPython, the reference implementation of the

Python programming language Python is a high-level, general-purpose programming language. Its design philosophy emphasizes code readability with the use of significant indentation. Python is dynamically-typed and garbage-collected. It supports multiple programming p ...

, is also the implementation most widely used in production.

Testing

Testing An examination (exam or evaluation) or test is an educational assessment intended to measure a test-taker's knowledge, skill, aptitude, physical fitness, or classification in many other topics (e.g., beliefs). A test may be administered verba ...

the implementation-vs-specification relationship further enhances the production's inter-process efficiencies:

References

{{Reflist Test items Software engineering terminology