Software engine

A software engine refers to a central part of a computer program. The concept has however taken on slightly different meanings depending on context.

The term Engine when used to describe a piece of software is frequently used by developers when speaking to a wider, layman audience, to describe what they would otherwise refer to as a library, SDK or object, to denote an encapsulated block of functionality.

The term often appears in marketing material that need to describe software internals, as well as in product names.

This way of using the term is metaphorical, and marketing oriented.

The field of computer science uses the term Engine to provide a mental model of software components an order of magnitude more complex than ordinary modules of software (such as the libraries, SDKs or objects mentioned above). Software modules remain static until called upon by another module. In response to the call, the instruction pointer of the computer begins tracing its way through the code in the called upon module. A software module is a Turing machine, which changes its state based on the algorithms that it contains.

In contrast, the mental model a software engine is a mechanical engine, which one can start and stop, and which may run idle for periods of time. Examples of software engines include relational database engines, workflow engines, inference engines and search engines. A common characteristic of software engines is metadata that provides models of the real data that the engine processes. Software modules pass data to the engine, and the engine uses its metadata models to transform the data into a different state.

Another characteristic of software engines consistent with their mental model is the ability to tune software engines for optimal performance. In contrast, software modules can be "tuned" only by rewriting them.

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Wikipedia