Event-Driven Programming 101 – Guide to Applications and Development

Modern agile, scalable applications are now being written with event-driven programming.

Under event-driven applications, the processes do the work and then move to trigger events. At the same time, the others listen for triggered events to begin their work – in the end, triggering more successive events. It is simply out of the question to send in a request and then wait for multiple sequential processes to complete – before finally receiving a response.

  • But how are event-driven applications built for the cloud?
  • How can a data warehouse on a cloud listen for the event by the premises IoT device?
  • How to bring together all events from an application that are scattered in the cloud?

First, we should know the following;

Event-driven Programming

It is a model where services, objects, and other entities communicate via messages to and fro through an intermediary. These messages are stored in a queue before being handled by consumers.

Dissimilar to direct call – event-driven programming separates the consumer from the producer, reaping many important benefits. For instance, more than one producer and consumer can work together to process incoming requests. Here retrying for the failed operations and maintaining event history is also simplified. Additionally, event-driven programming makes it even easier to scale up the massive systems, building capacity by simply adding in consumers.

Factors of Event-Based Systems

  1. Consumers
  2. ProducersEvents
  3. Events
  4. Message queues


These are pieces of data sent by producers and consumed by consumers. A mouse-down event has the following informational data:

  • Pointer coordinates
  • The pressed mouse buttons 

Most events are structured but can also be blobs of data like a chunk of JSON – which consumers still should know how to handle and parse.

Consumers and Producers

Producers are event-generating entities that also send events to the message queue. At the same time, the consumers are either subscribers for receiving new events or polls periodically from the message queue. The main point of the event-driven paradigm is that producers and consumers are unaware of each other and only interact via a message queue.

Message Queues

A message queue is the repository of events or messages.

Messages can be stored in memory or/and in durable storage. Message queues are portioned into topics. Consumers and producers receive and send messages for particular topics specifically. Instead of this, a message broker ensures that messages sent to the queue get delivered to all subscribers. Some of the most popular message brokers today include;

  • Memphis – a message broker that is 9 times faster than Apache Kafka
  • RabbitMQ
  • Redis
  • Apache Kafka

Consumers use push or pull mode for consuming messages. In the pull mode – the message queue keeps messages for every consumer. When every consumer receives a message, it can be removed from the queue; however, this depends on the retention configuration. A few message queues also let consumers pull historical messages.

While for push mode, a message queue pushes new messages to all current subscribers.

Applications of Event-Driven Programming

Event-driven programming is used in the following;

  1. While programming games, when a set of objects carry out control flow
  2. While building server applications, it is unwanted to spawn the service processes for one reason or another.
  3. While building user interfaces, also including the graphical UI.

Event-Driven Programming Languages

Many programming languages work with the event-driven paradigm to different degrees. Below-mentioned languages offer complete support:

  1. JavaScript
  2. Perl events
  3. DAEMON and PRIO
  4. Delphi
  5. Action Script 
  6. C #

Other languages are known to support the events for exception handling.

Why is the event-driven paradigm special?

Let’s explore why the event-driven paradigm is special and what makes it amazing, and what makes it tricky;

Event-Driven Programming – The Future

The modern future of the digital world and the digital business lies in an intelligent and expanding digital mesh that is made of event-driven applications, cloud computing, IoT, AI, in-memory data management, and blockchain. With our digital world expanding, it goes without saying that the importance of event-driven programming and computing will grow tenfold. This expansion will eventually let business events be analyzed and detected faster and in great detail.

For the latest event-driven programming research, information, and practical applications – stay tuned with Memphis.

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