QP/C++ real-time event framework (RTEF) is a lightweight implementation of the asynchronous, event-driven, and non-blocking Active Object (a.k.a. Actor) model of computation specifically designed for real-time embedded systems, such as microcontrollers (MCUs). QP/C++ is both a software infrastructure for building applications consisting of Active Objects (Actors) and a runtime environment for executing the Active Objects in a deterministic, real-time fashion. Additionally, QP/C++ Framework supports Hierarchical State Machines with which to specify the behavior of Active Objects [UML 2.5], [Sutter:10], [ROOM:94]. The QP/C++ Framework can be viewed as a modern, asynchronous, and truly event-driven real-time operating system.
The QP/C++ RTEF provides a reusable, event-driven software architecture, which combines the model of concurrency, known as Active Objects (Actors) with Hierarchical State Machines. This approach offers numerous advantages over the traditional "shared state concurrency" based on a conventional Real-Time Operating System (RTOS)↑:
All QP editions are a natural fit for safety-related applications because they implement several best practices highly recommended by the functional safety standards, such as strictly modular design (Active Objects) or hierarchical state machines (semi-formal methods). Indeed, for decades, the QP/C and QP/C++ Frameworks have been widely used in safety-related applications↑, such as medical, aerospace, and industrial.
In functional safety standards, such as IEC 61508, the designations HR (highly recommended) and NR (not recommended) have a specific technical meaning. For a given safety integrity level (SIL), techniques marked as HR are expected to be applied unless a documented and justified rationale demonstrates that they are unnecessary or that an alternative measure provides equivalent risk reduction. Conversely, techniques marked as NR are generally not suitable for use at that SIL; if they are applied, the development team must provide a documented justification demonstrating that their use does not compromise the required safety integrity.QP real-time event frameworks form a family consisting of the following QP editions:
| QP Edition | Programming Language | API Compatibility | Safety Functions | Certification Artifacts | Licensing |
|---|---|---|---|---|---|
| Standard QP editions | |||||
| QP/C | C (C11) | Same as SafeQP/C | Assertions | Requirements, Architecture & Design Specifications | Open-source & Commercial (dual licensing)↑ |
| QP/C++ | C++ (C++17) | Same as SafeQP/C++ | Assertions | Requirements, Architecture & Design Specifications | Open-source & Commercial (dual licensing)↑ |
| SafeQP editions engineered for functional safety | |||||
| SafeQP/C | C (C11) | Same as QP/C | All identified Safety Functions | Complete Certification Kit | Commercial only↑ |
| SafeQP/C++ | C++ (C++17) | Same as QP/C++ | All identified Safety Functions | Complete Certification Kit | Commercial only↑ |
The SafeQP/C and SafeQP/C++ frameworks were initially derived from QP/C and QP/C++, respectively, but were extensively reengineered for the safety market using compliant Software Safety Lifecycle (SSL). In this process, the QP framework functional model has been subjected to a full Hazard and Risk Assessment, which identified all areas of weakness within the functional model and API. These findings led to the creation of Safety Requirements Specification and risk mitigation by Safety Functions, which were subsequently implemented, verified, and validated in the SafeQP editions.
The SafeQP frameworks are accompanied by the SafeQP Certification Kits, which provide developers with ready-to-use artifacts, enabling them to save time, mitigate risk, and reduce costs during application certification for safety-critical devices in the industrial, medical, aerospace, and automotive industries.
QP/C++ is fundamentally an object-oriented framework, which means that the framework itself and your applications derived from the framework are composed of classes and only classes can have state machines associated with them.
The behavior of active objects is specified in QP/C++ by means of hierarchical state machines (UML statecharts)↑. The framework supports manual coding of UML state machines in C as well as fully automatic code generation using the free graphical QM model-based design (MBD) tool↑.
The QP/C++ framework can run on bare-metal single-chip microcontrollers, completely replacing a traditional RTOS. The framework contains a selection of built-in real-time kernels, such as the non-preemptive QV kernel, the preemptive non-blocking QK kernel, and the preemptive, dual-mode, blocking QXK kernel (available as one of the QP/C++ Extras). "Native QP/C++ ports" and ready-to-use examples are provided for prominent embedded CPU families, such as ARM Cortex-M, ARM Cortex-R, and MSP430.
QP/C++ can also work with many traditional Real-Time Operating Systems (RTOSes) and General-Purpose OSes (GPOSes) (such as Linux (POSIX) and Windows).
Even though QP/C++ offers a higher level of abstraction than a traditional RTOS, when combined with the native built-in kernels, it typically outperforms equivalent traditional RTOS applications both in RAM/ROM footprint and in CPU efficiency. The specific measurements and results are reported in the Application Note: "QP/C++ Performance Tests and Results"↑:
Software tracing is a method of capturing and recording information about the execution of a software program. Software tracing is particularly effective and powerful in combination with the event-driven Active Object model of computation due to its inherent inversion of control. A running application built of Active Objects is a highly structured affair where all meaningful system interactions funnel through the underlying event-driven framework. This arrangement offers a unique opportunity for applying Software Tracing in a framework like QP.
QP/C++ offers unprecedented, bidirectional traceability among all work artifacts, which gives teams complete visibility from requirements through architecture, design, source code, tests, and back again.
With 20 years of continuous development, over 400 commercial licensees↑, and many times more open source users worldwide, QP Frameworks are the most popular such offering on the market. They power countless electronic products across a wide variety of markets↑, such as medical, consumer, IoT, defense, robotics, industrial, communication, transportation, semiconductor IP, and many others.
The two editions of the book, Practical Statecharts in C/C++↑, provide a detailed design study of the QP/C and QP/C++ frameworks and explain the related concepts.
The QP/C and QP/C++ frameworks are licensed under the dual licensing model↑, in which both the open source software distribution mechanism and traditional closed source software distribution models are combined.
If you are developing and distributing open source applications, you are free to use the QP™ framework software under the GPL version 3↑, or (at your option) any later GPL version.
If you are developing and distributing closed source applications, you can purchase one of the Quantum Leaps commercial licenses↑, which are specifically designed for users interested in retaining the proprietary status of their code. All Quantum Leaps commercial licenses expressly supersede the GPL open source license. This means that when you license Quantum Leaps software under a commercial license, you specifically do not use the software under the open source license, and therefore, you are not subject to any of its terms.
Commercial licensees also gain access to the QP/C++ Extras, which include:
Please post any technical questions to the Free Support Forum↑ hosted on SourceForge.net. Posts to this forum benefit the whole community and are typically answered the same day.
Direct Commercial Support is available to the commercial licensees. Every commercial license includes one year of Technical Support for the licensed software. The support term can be extended annually.
Training and consulting services are also available from Quantum Leaps. Please refer to the Contact web-page↑ for more information.
e-mail: [email protected]↑
