Reactive What Is

Reactive is a term that is often used in the context of computer programming and software development. It describes a system or component that responds to events or changes in its environment by reacting to them in some way. In other words, a reactive system is one that is triggered to take action based on certain conditions or stimuli, rather than being proactive and driving its own behavior independently.

Here are some key characteristics of reactive systems:

1. Event-Driven: Reactive systems are typically event-driven, meaning they respond to events that occur in the system or its external environment. These events could include user inputs, changes in data, or external signals.

2. Asynchronous Processing: In a reactive system, tasks are often executed asynchronously. This means that when an event occurs, the system may initiate a task to handle the event without blocking other operations from continuing. This allows for greater responsiveness and concurrency.

3. Message-Oriented Communication: Reactive systems often use message-based communication to pass data and information between different components. This type of communication is well-suited for event-driven architectures and allows for loose coupling between components.

4. Non-Blocking I/O: Reactive systems often employ non-blocking I/O operations to avoid blocking the main execution thread. Non-blocking I/O allows the system to continue processing other tasks while waiting for I/O operations to complete.

5. Scalability: Reactive systems are often designed to be scalable, allowing them to handle increasing loads or demands without significant performance degradation. This scalability can be achieved through various techniques such as horizontal scaling (adding more resources) or load balancing.

Some common examples of reactive systems include:

- Web servers that respond to HTTP requests and generate dynamic responses.

- Event-driven applications such as chat clients, messaging apps, and games that react to user inputs and real-time events.

- IoT (Internet of Things) systems that monitor and respond to changes in sensor data or device states.

- Data processing applications that react to new data arrivals and trigger appropriate actions or transformations.

Reactive systems are often built using reactive programming paradigms and frameworks, such as reactive streams, RxJS, and Reactor. These frameworks provide abstractions and tools to help developers create event-driven, non-blocking, and scalable applications.