Essay by Maria Tsvetkova(maantsvetkova@edu.hse.ru)
In a microservice architecture, the key role is played by the organization of interactions between services, ensuring scalability and fault tolerance. The choice of technologies for these communications depends on architectural features, application complexity, performance requirements, and specific scenarios. It is necessary to take into account the frequency of service interactions and the expected load volumes. Particular attention should be paid to streaming data transfer. Streaming data transfer is a data transfer method in which data is transferred in a continuous stream, rather than in portions or packets [1]. The choice of a specific implementation of such data transfer requires an analysis of the type and volume of data, latency requirements, and message delivery guarantees. To determine in which cases a WebSockets is better suited, in which cases it is good to use gRPC and in which MQ, you need to consider their features.
WebSockets provide a full-duplex communication channel over a single, long-running HTTP connection, allowing real-time, two-way communication between client and server [2-4]. This is especially useful for applications that require instant data exchange, such as chat applications or live notifications.
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gRPC (Google Remote Procedure Call) is a modern, high-performance framework for building distributed applications [5-7]. While gRPC's traditional unary RPCs are great for single request-response interactions, its streaming capabilities provide a powerful way to handle scenarios involving continuous or large amounts of data. gRPC's streaming APIs allow you to send a sequence of messages over a single connection, offering significant efficiency improvements for a variety of use cases.
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Message Queues (MQs) are a fundamental building block in distributed systems, enabling asynchronous communication between different components or services [8]. Instead of direct, synchronous interactions, MQs act as intermediaries, storing messages temporarily until the recipient is ready to process them. This decoupling of components offers significant advantages in terms of scalability, reliability, and flexibility. Two popular message broker implementations:
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Thus, while WebSockets, gRPC, and message queues are often considered when choosing streaming APIs in a microservice architecture, implementing them successfully requires a detailed understanding of the application needs, existing infrastructure, and operational challenges. Each technology has its own strengths and weaknesses, and combining them wisely will create a robust architecture that leverages the best qualities of each. WebSockets are best suited when your primary need is real-time, bidirectional communication in a web browser. gRPC is great when you need high-performance, strongly typed communication between backend services, especially if streaming data is involved. Message queues are ideal when you need asynchronous communication, decoupled components, and reliable message delivery, as is often the case with task and event-driven systems. A combination of these technologies is often the most effective approach, such as using WebSockets for dynamic UI updates, gRPC for communication between microservices, and message queues for background job processing.