What are Real-Time Systems?
Computer systems that respond to events or inputs as they happen are called real-time systems. These systems process and deliver data almost instantly, sometimes within nanoseconds or milliseconds. There is a growing need for such real-time systems since certain events or input-based responses cannot be performed manually. Or for that matter, executed in an efficient, accurate or consistent manner. In such instances, automating such complex tasks is the only way to meet the stringent needs of such critical applications.
Benefits, Types & Requirements
Real-time systems come with solid benefits: since tasks are performed within a specific deadline, timeliness is guaranteed, For the very same reason, the execution of workloads is also guaranteed, offering reliability. Finally, some real-time systems can prioritize execution, given that some tasks might need to be completed within a timeframe to avoid system failure while others do not.
Now, depending on the maximum allowable response time, a variety of applications can be custom-built for specific use cases. Which is why real-time systems are further classified as hard, soft or firm systems. So, while it is imperative for hard real-time systems to meet its set time constraints, this is not a must with soft real-time systems. This is because each instance of tardiness can result in total system failure for hard real-time systems but result only in a drop in quality of service for those classified as soft real-time systems.
Generally, there are two requirements that such systems must meet. They have to respond within the said deadline but also sync with other system clocks to complete shared tasks. So, a real-time system is said to be predictable if it meets both these requirements effectively. Speaking of which, system predictability is determined by two factors namely system latency and compute jitter, where the former is the time between two events while the latter measures the latency variation between two responses.
Characteristics, Programming Languages & Use Cases
Now, apart from being timely and correct, there are certain characteristics that these critical systems must embody: being safe, stable, deterministic, fault tolerant, scalable and secure while functioning with a variety of devices and managing its resources effectively. Another important aspect to consider is that real-time systems should concurrently process non-real time tasks alongside its usual deadline-based responses.
That said, synchronous programming languages such as C, C++ and Rust are popular choices when it comes to building real-time systems. This is because of benefits such as direct memory management and safety, code flexibility, high performance and a lack of runtime overhead. Prominent examples of such systems include the air traffic controller, patient monitoring devices as well as auction and financial trading platforms.
