MicroEJ Glossary

This glossary defines the technical terms upon which the MICROEJ VEE (Virtual Execution Environment) is built.

Add-On Library
An Add-On Library is a pure managed code (Java) library. It runs over one or more Foundation Libraries.
Abstraction Layer
An Abstraction Layer is the C code that implements a Foundation Library’s low-level APIs over a board support package (BSP) or a C library.

An Application is a software program that runs on a Powered by MicroEJ device.

Standalone Application
A Standalone Application is an Application that is directly linked to the C code to produce a Mono-Sandbox Firmware.
Sandboxed Application
A Sandboxed Application is an Application that can run over a Multi-Sandbox Firmware. It can be linked either statically or dynamically.
System Application
A System Application (formerly called a Resident Application) is a Sandboxed Application that is statically linked to a Multi-Sandbox Firmware, as it is part of the initial image and cannot be removed.
Kernel Application
A Kernel Application is a Standalone Application that implements the ability to be extended to produce a Multi-Sandbox Firmware.
An Architecture is a software package that includes the Core Engine port to a target instruction set and a C compiler, core Foundation Libraries ([EDC], [BON], [SNI], [KF]) and the Simulator. Architectures are distributed either as evaluation or production version.
Core Engine, also named “MEJ32”
The Core Engine, also named MEJ32, is a scalable 32-bit core for resource-constrained embedded devices. It is delivered in various flavors, mostly as a binary software package. The Core Engine allows applications written in various languages to run in a safe container.

A Firmware is the result of the binary link of a Standalone Application with a Platform. It can be programmed into the flash memory of a device.

Mono-Sandbox Firmware
A Mono-Sandbox Firmware is a Firmware that implements an unmodifiable set of functions. (formerly called a Single-app Firmware)
Multi-Sandbox Firmware
A Multi-Sandbox Firmware is a Firmware that implements the ability to be extended, by exposing a set of APIs and a memory space to link Sandboxed Applications. (formerly called a Multi-app Firmware)
Foundation Library
A Foundation Library is a library that provides core or hardware-dependent functionalities. A Foundation Library combines managed code (Java) and low-level APIs (C) implemented by one or more Abstraction Layers through a native interface (SNI).
A Mock is a mockup of a Board Support Package capability that mimics an hardware functionality for the Simulator.
Module Manager
MicroEJ Module Manager (MMM) downloads, installs and controls the consistency of all the dependencies and versions required to build and publish a MicroEJ asset. It is based on Semantic Versioning specification.
A Platform integrates a MICROEJ VEE, an Architecture, one or more Foundation Libraries with their respective Abstraction Layers, and the board support package (BSP) for the target Device. It also includes associated Mocks for the Simulator.
MICROEJ SDK allows Firmware developers to build a Powered by MicroEJ device, by integrating an Architecture with both Java and C software on their device.
The Simulator allows running Applications on a target hardware simulator on the developer’s desktop computer. The Simulator runs one or more Mock that mimics the hardware functionality. It enables developers to develop their Applications without the need of hardware.
The Studio is the part of the SDK that can be rebranded by customers for their specific ecosystem. It allows application developers to write a Sandboxed Application, run it on a Virtual Device, deploy it on a Powered by MicroEJ device, and publish it to a MicroEJ Forge instance.
MICROEJ VEE is an applications container. VEE stands for Virtual Execution Environment, and refers to the first implementation that embeds a virtual 32-bit processor, hence the term “Virtual”. MICROEJ VEE runs on any OS/RTOS commonly used in embedded systems (FreeRTOS, QP/C, uc/OS, ThreadX, embOS, Mbed OS, Zephyr OS, VxWorks, PikeOS, Integrity, Linux, QNX, …) and can also run without RTOS (bare-metal) or proprietary RTOS. MICROEJ VEE includes the small MEJ32, along with a wide range of libraries (Add-On Libraries and Foundation Libraries).
Virtual Device
A Virtual Device is a software package that includes the simulation part of a Firmware: runtime, libraries and application(s). It can be run on any PC without the need of the SDK. In case of a Multi-Sandbox Firmware, it is also used for developing a Sandboxed Application in the SDK.