Questions and Answers

A) Yes. eXtremeDB/rt provides full ACID transactions. Atomicity ensures that a transaction is completed in its entirety or not at all; consistency preserves database integrity; isolation prevents concurrent transactions from interfering with each other; and durability ensures that committed data in a persistent database survives a restart or failure. eXtremeDB/rt adds time constraints to these conventional transaction properties. Transactions can have deadlines, and the database uses real-time transaction scheduling and concurrency control to meet them. The application can also select a real-time policy that determines how eXtremeDB/rt handles transactions when their timing requirements cannot be met. ACID properties are preserved regardless of the real-time policy used.

A) No. eXtremeDB/rt is also designed for resource-constrained, deeply embedded systems. Its small code and RAM footprint, low stack requirements and extensive configurability allow the database to be tailored to the resources available on the target. It can run with an RTOS or on bare metal, making it well suited for applications such as sensor fusion, data acquisition, monitoring and control, where the database can be part of the application’s control path rather than used only to store logs, traces, configuration and diagnostic data.

eXtremeDB/rt also provides tightly integrated low-level storage. xFlash™ provides direct transactional access to raw NAND flash, eliminating the need for a separate FTL and file system. xFile™ provides a transactional storage layer over managed flash devices such as SD, eMMC, SSD and NVMe, where the FTL is implemented by the device controller. xFile can access these devices directly without a file system. This reduces the storage software stack, footprint and I/O overhead, and can improve performance.

A) eXtremeDB/rt requires a minimum of approximately 45 KB of RAM when execute-in-place (XIP) is available. In real applications, the memory footprint is normally larger and depends on the database layout, the features used and the application’s data and runtime requirements. That said, eXtremeDB/rt is highly configurable. Functionality that is not required by the application can be left out of the database kernel, allowing the code, RAM and stack requirements to be matched to the resources available on the target.

A) eXtremeDB/rt supports both transient and persistent databases. Transient databases typically reside in RAM. Persistent databases can use a variety of non-volatile storage media, with flash being the most common in embedded systems. For persistent hard real-time databases, eXtremeDB/rt uses xFlash™ to access raw NAND flash directly. Raw NAND operations have bounded execution times specified by the device manufacturer, allowing storage I/O to be included in transaction timing guarantees. For other persistent storage, xFile™ provides access to block devices and file-based storage. This includes managed flash devices such as SD, eMMC, SSD and NVMe, where flash management is performed by the device’s internal controller. Other non-volatile media can also be used through the appropriate storage interface.

A) eXtremeDB/rt is designed for deeply embedded systems with limited CPU and memory resources, particularly stand-alone systems that operate autonomously with little or no external control. These systems commonly use flash memory for local storage and need a small, self-contained database that can operate close to the hardware.

Robotics and IoT edge devices are contemporary examples of this architecture, while industrial and process control, automotive, transportation and avionics are more traditional applications. Sensor fusion, data acquisition, monitoring and instrumentation are other common use cases. Some require hard real-time database transactions; others benefit primarily from the small resource requirements, direct access to storage and small software stack of eXtremeDB/rt.

A) For database systems, “real-time” is often used simply to mean fast. Hard real-time is fundamentally different.

In a hard real-time system there is a line in the sand: a deadline. Completing an operation after that deadline is a failure, even if the system is extremely fast on average. Meeting the deadline every time requires predictable latency throughout the execution of an operation, latency that is bounded and known in advance. eXtremeDB/rt applies this principle to database transactions, scheduling and controlling their execution so they meet their hard deadlines. Its small execution path and very tight integration with the underlying RTOS and hardware also provide very low latency. The defining difference, however, is not simply speed, but predictable execution that allows transactions to meet their hard deadlines.

A) eXtremeDB/rt is available for a range of real-time and general-purpose operating systems, as well as bare-metal environments.

Real-time operating systems

Non-real-time operating systems

A) Yes. eXtremeDB/rt is available for selected safety- and security-certified RTOS environments, including DEOS, LynxOS-178, VxWorks 653 and INTEGRITY-178B. Certification applies to the underlying RTOS; eXtremeDB/rt is provided for use in these environments.

A) Yes. eXtremeDB/rt can run directly on bare-metal systems. If the platform provides access to a system timer, eXtremeDB/rt can provide its hard real-time transaction functionality without an RTOS.

This also applies to persistent hard real-time databases. With xFlash™, eXtremeDB/rt accesses raw NAND flash directly, giving the database direct control over the storage I/O path without requiring an operating system or file system.

A) An eXtremeDB/rt evaluation normally has two parts: developing the database and its access logic, and integrating the database kernel with the target platform. These two parts can be done in parallel. The database design and application logic can be developed and tested on a host machine, simplifying development of the database access logic. We also provide AI skills to help developers get started with the eXtremeDB/rt APIs and database development. The target hardware, operating system and toolchain can be selected and evaluated separately. For target integration, we provide source code and preconfigured source configurations for supported operating systems, hardware platforms and development toolchains. If your particular configuration is not already available, we create it for you. The evaluation package includes the documentation and integration guidelines needed to build the database kernel and add it to your application, and examples covering the major eXtremeDB/rt features. The flash simulator lets you develop and test persistent raw flash database configurations without the actual flash hardware. xPanel™ and the lightweight web server can be used to inspect a running database.

We know from experience that integrating third-party software with an embedded platform can take time and often involves board, RTOS, toolchain, storage and driver issues. It is in everyone’s interest to get through this part of the evaluation quickly, so our engineers work directly with your developers when needed. We help with integration problems, put together small PoCs and provide missing platform-specific pieces, such as low-level flash memory drivers, when necessary.

A) The RTOS and desktop distributions include the same database libraries, complete API documentation, RTOS integration guides, and a large collection of sample applications. The samples cover common database operations, persistent storage, and RTOS integration, allowing you to develop and test your application on a desktop system before moving to the target platform.

For applications that use persistent storage, the distributions also include a flash simulator. It lets you develop and test applications that use flash storage without requiring the target hardware. When you move to the target platform, replace the simulator with the appropriate storage driver.

A) eXtremeDB/rt is commercially licensed. Licensing depends on the target platform, application requirements, development team size and expected deployment volume. Contact McObject to discuss the appropriate license for your project.