RPC vs REST: Similarities and Differences

Remote Procedure Call (RPC) and Representational State Transfer (REST) are two different communication mechanisms used for remote communication and service invocation in distributed systems. This article gives explanations of definitions, similarities, and differences between RPC and REST.

What Is Remote Procedure Call (RPC)?

Remote Procedure Call (RPC) is a software communication protocol utilized by one program to request a service from another program situated on a separate computer and network, all without necessitating an in-depth understanding of the underlying network intricacies. Essentially, RPC enables a program to invoke processes on remote systems as if they were local. This synchronous operation follows a client-server model, where the requesting program acts as the client and the service-providing program as the server. Leveraging lightweight processes or threads that share a common address space allows for concurrent execution of multiple RPCs. Interface Definition Language (IDL) plays a crucial role in RPC software, serving as the specification language that defines a software component's Application Programming Interface (API). By acting as a bridge between machines running different operating systems and programming languages, IDL facilitates the interoperability of RPC across platforms like Windows, Unix, and macOS. RPC serves as a fundamental tool for constructing and interacting with distributed systems, enabling seamless invocation of subroutines on remote computers without the caller's awareness of the remote nature of the procedure.

Application cases:

• Distributed Systems: RPC is widely used in building distributed systems, such as service invocations in microservices architecture and communication between nodes in clusters.

• Data Center Communication: In large data centers, RPC can be used for communication and collaboration between different services, such as calling storage services, computing services, and more.

• Cross-Language Communication: RPC can facilitate communication between different programming languages, allowing applications with different technology stacks to interact.

• Web Services: In web development, RPC can be used for communication between clients and servers, such as invoking remote APIs. RPC is commonly utilized in various network devices and systems to enable remote communication and control between devices. For instance, the FS S5800-48T4S switch supports RPC-API, providing a way to remotely call and interact through API interfaces. This advanced interface design can bring better control and usability, making remote management and configuration more flexible and efficient.

What Is Representational State Transfer (REST)?

Representational State Transfer (REST) is an architectural style for developing web services and systems that facilitates seamless communication between computer systems on the internet. REST does not constitute a protocol or standard but rather an approach that emphasizes simplicity and builds upon existing features of the HTTP protocol. In REST, systems interact by performing operations on resources, with resources encompassing all data and functionality. These resources are accessed via Uniform Resource Identifiers (URIs) and manipulated through basic operations.

RESTful systems, which adhere to the REST architectural style, are characterized by their statelessness and the clear separation of concerns between client and server components. The separation allows for independent development of client and server implementations without either side needing intricate knowledge of the other's internal workings. Changes to the client or server can be made without affecting the overall operation, promoting modularity and flexibility in system design. By hitting the same REST endpoints and receiving standardized responses, different clients can interact with the system consistently.

The statelessness constraint in REST means that servers do not retain information about the client's state, and vice versa. This design choice simplifies communication, as each message can be understood in isolation without requiring prior context. REST's reliance on resources, rather than custom commands, contributes to its reliability, performance, and scalability. By interacting through standard resource operations, RESTful applications can be managed, updated, and reused efficiently without disrupting the system's overall functionality.

Application cases:

• Web Services: REST is widely used in building web services, including APIs based on the HTTP protocol. Many internet applications and services utilize RESTful APIs for communication between clients and servers.

• Mobile Applications: Many mobile applications communicate with server-side RESTful services to fetch data and perform operations. REST's statelessness and resource-based design make it an ideal communication mechanism between mobile applications and servers.

• Cloud Services: RESTful architecture is commonly used in building cloud services, enabling communication and integration between various cloud services through a simple and flexible HTTP protocol.

• Internet of Things (IoT): In the Internet of Things, devices can communicate with the cloud using RESTful services, facilitating functions like data transfer, control, and monitoring.

• Microservices Architecture: In microservices architecture, REST is widely used for communication between services, with each microservice exposing its functionality through RESTful APIs.

• Social Media Platforms: Many social media platform APIs are designed based on REST, allowing developers to access platform data and functionalities.

• E-commerce Platforms: E-commerce websites and applications typically use RESTful APIs to implement features such as product catalogs, shopping carts, payments, and order management.

Similarities Between RPC and REST

• Purpose: Both RPC and REST are used to facilitate remote communication and service invocation in distributed systems.

• Network Communication: Both RPC and REST allow client applications to invoke services or access resources on remote servers over a network.

• Cross-Language: Both RPC and REST can facilitate communication across different programming languages and platforms.

Differences Between RPC and REST

• Architectural Style: RPC is a communication model designed to make remote calls look like local calls, emphasizing calling methods or functions of a service. REST is an architectural style that focuses on resource-oriented design, utilizing HTTP methods to interact with resources.

• Stateful vs Stateless: RPC is typically stateful, requiring the maintenance of certain state information during remote calls. REST is stateless, with each request containing all the necessary information for the server to fulfill it without saving client state.

• Interface Design: RPC interfaces are usually based on method calls to services, where clients directly invoke methods provided by the service. REST interfaces are designed around resources, allowing clients to interact with resources using HTTP methods.

• Self-Descriptiveness: RESTful systems convey state information through representations of resources, enabling clients to understand how to interact with resources. RPC often requires additional interface description languages (e.g., IDL) to define service interfaces and data structures.

• Flexibility and Scalability: REST's design is more flexible and scalable, utilizing standard HTTP methods and status codes, supporting hypermedia links to make systems more flexible. RPC tends to be more tightly coupled, requiring predefined interfaces and data structures.

Conclusion

In conclusion, RPC is suitable for service-oriented method calls, emphasizing state and interface definition, while REST is suitable for resource-oriented design, emphasizing statelessness and flexibility. The choice between RPC and REST depends on the specific requirements and design goals of the application.

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