====== When, why and how to develop async applications? ======


====== Introduction ======

In today's world, in which development does not stand still, asynchronous applications are becoming an important part of the information society. This approach provides convenient and effective solutions for data processing and parallel execution of multiple operations. The need for asynchronous applications is increasing every day in the context of dynamic development in the modern world, because many modern systems require instant access to data and processing large amounts of information in a short period of time. Asynchronous applications have an important distinguishing feature, unlike synchronous ones, if synchronous applications perform operations sequentially, which increases the execution time of operations, asynchronous ones allow efficient use of system resources, which minimizes the waiting time for the operation. Asynchronous applications are also being developed in order to increase productivity in the context of distribution systems. This is especially true in areas where response and data processing speeds are critical, such as financial services, online shopping and social platforms. It should be noted that asynchronous applications have advantages in the field of energy efficiency, because they allow systems to distribute the load more efficiently and switch to standby mode when inactive. The key technologies supporting asynchronous programming are asynchronous APIs, frameworks, and libraries that provide convenient tools for creating effective applications. [1]

In this essay, we will consider when, why and how to develop asynchronous applications, identifying their advantages and contribution to modern information technology.

====== Asynchronous programming, what is it? ======

Asynchronous programming is a software development methodology, the main feature of which is operations that are performed independently of each other and do not block the application execution process. Unlike the synchronous method, where operations are performed sequentially, asynchronous applications allow you to perform several tasks in parallel, independently of each other. This approach in the development of software products significantly improves the responsiveness and productivity of the system as a whole.[2]

The main feature of the asynchronous programming approach is asynchronous operations that are performed independently of the main program flow. This is usually achieved using mechanisms such as callbacks, promises, or asynchronous functions (async/await), which allow the program to continue performing other tasks while waiting for a certain operation to complete.

An example of asynchronous programming is input/output (I/O) processing, database queries, asynchronous network operations, and other tasks where execution time may vary and blocking the main execution flow would lead to inefficiency.

====== When? ======

The development of asynchronous applications may be necessary in cases where efficient information processing, reduced response time, and system responsiveness are required. 
In which cases is it necessary to use the asynchronous programming approach:

1. The use of asynchronous applications is preferable in areas where a large amount of real-time data is being processed. Examples can be financial systems where transactions require an instant response.

2. Web development. Working with databases, processing server requests and web sockets are among the most important elements for ensuring the dynamism of web applications. Asynchronous approaches allow you to process multiple simultaneous requests, maintaining high performance and ensuring smooth operation of web services.

3. Development of microservice architectures. In a distributed system environment where each service performs its own tasks, asynchronous methods can improve the responsiveness of the system as a whole. The event-oriented architecture and the use of message queues make it possible for microservices to interact effectively.

4. Mobile devices, IoT sensors (Internet of Things) and other energy-efficient platforms benefit from the use of asynchronous methods, since they allow switching to standby mode in cases when there is no active operation.

Asynchronous applications are needed when responsiveness, efficient data processing and high performance are important for the system.[3]

====== Why? ======

The work of synchronous applications has proven itself quite well in systems where basically all functions and operations are sequential and do not require work in multiple threads. Why is there a need to develop asynchronous applications?
There are several factors:

**Ensuring responsiveness:** Responsive interfaces and systems can be created using an asynchronous programming approach. In synchronous applications, there may also be long operations that block the main flow of program execution, which is why the user just has to wait. This degrades the user experience. In asynchronous systems, these operations are performed in the background, which allows the user to continue interacting with the application even while performing heavy tasks.

**Efficient data processing:** In the context of modern data volumes, asynchronous programming is becoming necessary for efficient and fast information processing. Operations such as database access, network queries, and big data analysis can be optimized using asynchronous methods, which improves performance and reduces the waiting time for results.

**Parallel execution of tasks:** System resources are spent more efficiently when the system allows you to perform multiple tasks in parallel. This behavior is only possible in asynchronous applications. This is very convenient when the system has a large number of elements that work independently of each other. Parallel execution of tasks contributes to more efficient use of computing power and speeds up the overall execution time of the application.

**Energy efficiency:** Asynchronous applications are often used in the development of applications for mobile devices and other energy-dependent platforms where efficient use of energy is critically important. Asynchronous applications allow the system to go into standby mode when inactive, which helps to reduce power consumption and increase the battery life of devices.

**Modern web technologies:** In web development, especially with the development of asynchronous web technologies such as AJAX and WebSocket, asynchronous programming is becoming an integral component of creating dynamic and interactive web applications. Asynchronous requests to the server allow you to update the page content without completely reloading it, which significantly improves the user experience.

**Development of technologies and standards:** With the development of programming languages and the advent of asynchronous frameworks such as Node.js, asynchronous application development is becoming more accessible and efficient. Standards such as Promises and async/await make asynchronous programming easier by making it more understandable and supported.[4]

====== How? ======

The development of asynchronous applications requires good knowledge in programming, understanding of processes, understanding the nature of asynchrony in order to control fully asynchronous threads, correctly handle errors that occur in them, properly use resources, avoid memory leaks and deadlocks.

To create an asynchronous application, some factors should be considered:


**Programming language and framework:** It is necessary to choose a language that supports operations in multiple threads. Some languages such as Python and JavaScript, as well as frameworks such as Node.js and asyncio allow you to use asynchronous approaches conveniently.[5]

**Using asynchronous data structures:** When working with big data, it is necessary to use asynchronous data structures such as queues, dictionaries, and publishers. They will help you manage your data effectively and prevent deadlocks.

**Error and Exception management:** Exceptions can occur in both synchronous and asynchronous operations. It is necessary to explore the possibilities and means of error handling in asynchronous operations provided by the programming language. These mechanisms will help to avoid loss of control over the application. 

**Asynchronous test development:** Asynchronous test development will make sure that the application is working correctly at any time.

**Monitoring and debugging:** A mechanism such as logging is usually used as monitoring, which can show the state of an asynchronous operation.

====== Conclusion ======

In conclusion, the creation of asynchronous applications is becoming a necessity in today's high-tech world. Responsiveness, efficient data processing, scalability and energy efficiency are the main advantages of asynchronous programming for developers. Choosing the right languages, frameworks, and tools, effective asynchronous processing management, and attention to optimization are key factors in the successful implementation of asynchronous applications.

====== References ======

1. Habr. Asynchrony in programming. [[https://habr.com/ru/companies/jugru/articles/446562/]]

2. Itanddigital. Synchronous and asynchronous programming: what is the difference?. [[https://itanddigital.ru/synchrondev#:~:text=Что%20такое%20асинхронное%20программирование%3F,в%20иерархическом%20или%20последовательном%20порядке.]]   

3. Skillfactory. When asynchrony is applied. [[https://blog.skillfactory.ru/glossary/asinhronnoe-programmirovanie/]]   

4. Rust-lang. What is asynchrony for?. [[https://doc.rust-lang.ru/async-book/01_getting_started/02_why_async.html]]   
 
5. Wikipedia. Asynchronous programming. [[https://ru.wikipedia.org/wiki/Асинхронное_программирование#:~:text=Модели%20асинхронного%20программирования%20существуют%20во,.NET%2C%20Python%20и%20других.]]