What Is Remote Procedure Call (RPC)?

A remote procedure call (RPC) is a communication method that allows a program to execute functions or procedures on a different computer or server as if they were running locally.

What Is Remote Procedure Call?

Remote procedure Call is a protocol and programming concept that enables a computer program to execute a procedure on another machine across a network while appearing to the programmer as a local function call. It provides a mechanism for inter-process communication in distributed systems, hiding the complexity of the underlying network protocols and data transmission.

When RPC is used, the client process sends a request to the server process, which executes the specified procedure and returns the result. The entire exchange is handled through stubs and middleware that perform tasks such as marshalling arguments, handling network transport, and managing responses, so that developers can work with simple procedure calls instead of manually coding socket-level communication.

By creating this abstraction, RPC facilitates the design of client-server architectures, distributed applications, and services that run on different machines, operating systems, or environments while maintaining seamless interaction between components.

Types of Remote Procedure Calls

RPCs can be implemented in different ways depending on how they handle communication, data transfer, and execution flow. These variations affect performance, transparency, and reliability in distributed systems. Below are the main types of RPCs and their explanations:

• Synchronous RPC. In synchronous RPC, the client sends a request to the server and waits until the server finishes processing and returns a response. This approach is straightforward but can lead to delays if the server takes a long time to respond, as the client remains blocked until the operation completes.
• Asynchronous RPC. With asynchronous RPC, the client sends a request to the server and continues execution without waiting for the response. The server processes the request independently, and the client later retrieves the result through a callback, polling, or notification mechanism. This improves responsiveness but requires more complex programming to manage results.
• One-way RPC. One-way RPC allows the client to send a request to the server without expecting any return value or acknowledgment. It is typically used for operations like logging or notifications where confirmation is unnecessary. Since there is no waiting involved, one-way RPCs are efficient but provide no guarantee of delivery or success.
• Batch RPC. Batch RPC lets the client group multiple requests and send them to the server in a single call. The server executes each request and returns the results in one response. This reduces the overhead of multiple network calls and improves performance in scenarios with frequent or repetitive requests.
• Secure RPC. Secure RPC adds encryption, authentication, and integrity checks to the RPC mechanism. It ensures that communication between client and server is protected from unauthorized access, data tampering, or impersonation. This type of RPC is critical in environments where sensitive data is exchanged across networks.

Remote Procedure Call Example

An example of RPC can be seen in a client-server application where a client retrieves user information from a remote database service.

Suppose a developer wants to call a function getUserDetails(userID) in their local program. Instead of the function executing on the client machine, the call is sent across the network to a server hosting the user database.

The RPC system generates client stubs and server stubs. The client stub takes the function call, marshals the argument (the userID), and sends it as a request to the server over the network. The server stub receives the request, unmarshals the data, and invokes the actual function getUserDetails(userID) on the server. Once the server retrieves the user information (such as name, email, and account status), it sends the result back to the client stub, which unmarshals the data and returns it as if the function had executed locally.

From the client’s perspective, calling getUserDetails(42) looks identical to invoking a local function, but in reality, the computation and data access happened remotely on the server.

Remote Procedure Call Key Features

Remote Procedure Call introduces a set of features that make it easier for developers to build distributed applications by hiding the complexity of network communication. These features define how RPC works and why it is widely used in client-server and service-oriented architectures:

• Transparency. RPC makes remote function calls appear identical to local ones. Developers can call a remote procedure without worrying about the underlying network operations, data serialization, or communication details.
• Client-server model. RPC naturally supports a client-server structure, where the client requests services and the server provides them. This separation of roles simplifies distributed system design.
• Stubs and proxy mechanism. RPC uses stubs (on the client side) and skeletons or proxies (on the server side) to handle the packing (marshalling) and unpacking (unmarshalling) of parameters and results. This allows smooth communication without requiring manual handling of network protocols.
• Marshalling and unmarshalling. Arguments and return values are serialized (marshalled) into a format suitable for transmission over the network and then deserialized (unmarshalled) back into usable data structures. This ensures compatibility across heterogeneous systems.
• Communication abstraction. The RPC layer hides transport-level details, such as sockets, message formatting, and error handling. This abstraction allows developers to focus on application logic rather than networking code.
• Synchronous and asynchronous support. RPC can operate in synchronous mode, where the client waits for the server’s response, or asynchronous mode, where the client continues execution and processes the result later. This flexibility supports different application needs.
• Error handling. Since network failures or server issues can occur, RPC frameworks include mechanisms for exception handling, retries, or timeout detection to improve reliability.
• Language and platform independence. Many RPC implementations are designed to work across different operating systems, architectures, and programming languages. Protocols like gRPC or XML-RPC enable interoperability in heterogeneous environments.

RPC Architecture

The architecture of a remote procedure call is built around the client-server model, where the client requests a service and the server provides the execution of that service.

At the client side, the application invokes a remote function, which is intercepted by a client stub. The stub is responsible for marshalling the parameters, converting them into a standardized format suitable for network transmission. This data is then passed through the operating system’s communication subsystem and sent across the network to the server. From the client’s perspective, it appears as though the function was executed locally, even though the request traveled over a network.

On the server side, the request is received by a server stub (sometimes called a skeleton), which unmarshals the data back into its original format and passes it to the actual procedure implementation. After the server executes the requested function, the result is marshalled again and sent back across the network, following the reverse path through the server stub, network layer, client stub, and finally back to the client application.

This layered interaction (application, stubs, and communication system) forms the foundation of RPC architecture, enabling seamless communication between distributed components while abstracting away the details of network protocols, data representation, and error handling.

Remote Procedure Call Uses

RPCs are widely used in distributed systems and networked applications because it simplifies communication between processes running on different machines. Below are the main areas where RPC is commonly applied:

• Client-server applications. RPC is the foundation of many client-server systems, where clients request services like authentication, file access, or database queries, and servers provide the processing. It allows seamless interaction without requiring the client to manage network details.
• Distributed systems. In distributed environments, different components may run on multiple nodes. RPC enables these components to interact as if they were on the same machine, supporting tasks like distributed file systems, replicated databases, and load-balanced services.
• Microservices communication. Modern microservices often rely on RPC frameworks such as gRPC to communicate efficiently. These frameworks provide high-performance, language-agnostic communication that supports streaming, authentication, and scalability.
• Remote configuration and management. RPC is often used in network and system administration for remote configuration, monitoring, and management tasks. For example, sysadmins can call procedures on remote machines to update settings, check health status, or restart services.
• Cloud and web services. RPC underpins many cloud APIs and web services, where client applications interact with remote services over protocols like JSON-RPC or XML-RPC. This allows developers to integrate third-party functionality (e.g., payment gateways, messaging systems) into their applications.
• Parallel and distributed computing. In high-performance computing, RPC enables tasks to be distributed across multiple processors or machines. Each node can perform computations and return results, allowing large-scale problems to be solved more efficiently.

RPC Implementation

Implementing a remote procedure call involves setting up the practical workflow that enables a client to invoke functions on a remote server. The process covers everything from defining the procedures and generating supporting code to transmitting requests, executing them on the server, and returning results to the client. Each stage ensures that communication between client and server is transparent and reliable.

1. Define the interface. The procedures that can be invoked remotely are specified using an Interface Definition Language (IDL) or equivalent notation.
2. Generate stubs. From the interface definition, tools produce a client stub and a server stub (skeleton) that handle communication tasks.
3. Prepare the request. The client stub marshals the procedure name and arguments into a request message.
4. Transmit the request. The client’s communication module sends the request over a transport protocol such as TCP or UDP.
5. Receive the request. The server’s communication module captures the message and forwards it to the server stub.
6. Unmarshal the data. The server stub reconstructs the arguments into a usable format for the server application.
7. Execute the procedure. The server application runs the requested procedure using the unmarshalled arguments.
8. Return the results. The server stub marshals the return values and sends them back through the communication system.
9. Deliver the response. The client stub unmarshals the results and hands them to the client application.
10. Manage runtime details. The RPC runtime handles error detection, retries, timeouts, and any necessary data conversions between different architectures.

The Advantages and the Disadvantages of RCPs

RPC offers a convenient way to build distributed systems by hiding the complexity of network communication and making remote interactions feel like local function calls. While it provides clear benefits in terms of simplicity, scalability, and interoperability, it also comes with limitations such as latency, fault tolerance challenges, and implementation overhead.

RCP Advantages

PRC provides several benefits that make it a popular choice for building distributed systems. The protocol’s main strength lies in simplifying how applications interact across networks by abstracting the complexity of communication. Below are the key advantages:

• Transparency. RPC makes remote calls look and behave like local function calls. Developers do not need to deal with socket programming or low-level network protocols, which simplifies coding and improves productivity.
• Modularity and reusability. By separating client and server logic, RPC promotes modular application design. Server-side procedures can be reused across different client applications without rewriting code.
• Interoperability. Many RPC frameworks, such as gRPC, XML-RPC, or JSON-RPC, support cross-platform communication. This allows systems built in different programming languages or running on different operating systems to interact seamlessly.
• Scalability. RPC supports distributed architectures, enabling applications to scale by spreading workloads across multiple servers. This is especially useful for high-demand services and cloud-based systems.
• Ease of development. Developers can focus on application logic rather than network communication details. Stubs and middleware handle marshalling, unmarshalling, and transport, reducing complexity in implementation.

RCP Disadvantages

While RPC simplifies distributed computing, it also introduces several challenges that must be considered before implementation. These drawbacks often stem from the reliance on networks and the hidden complexity behind the abstraction:

• Network dependency. Unlike local function calls, RPC depends on network availability and stability. Network delays, packet loss, or outages can cause calls to fail or significantly slow down execution.
• Latency and performance overhead. Each RPC involves marshalling, transmission over the network, and unmarshalling, which adds overhead compared to local calls. High latency can affect system responsiveness, especially in synchronous RPCs.
• Complex error handling. Failures in RPC can arise from various sources, such as network issues, server crashes, or mismatched data formats. Handling these errors is more complex than in local procedure calls and requires careful design.
• Security risks. RPC exposes communication between clients and servers to potential threats such as interception, impersonation, or tampering. Without proper encryption and authentication, sensitive data can be compromised.
• Tight coupling. In many RPC systems, the client and server must agree on exact procedure definitions and data formats. This can make upgrades or changes difficult, as modifying one side often requires changes on the other.
• Implementation overhead. While RPC hides complexity for developers, setting up the infrastructure, such as generating stubs, defining interfaces, and configuring middleware, requires additional tools and effort.

RPC FAQ

Here are the answers to the most commonly asked questions about RPC.

Is It Safe to Disable Remote Procedure Call?

No. RPC is a core part of most operating systems, including Windows, Linux/UNIX, and macOS. Disabling it can break critical functions like authentication, file sharing, and system management. If you don’t need certain RPC-based services (e.g., NFS on Linux), disable those individually or restrict access with firewalls instead of turning off RPC entirely.

What Is the Difference Between API and RPC?

The main difference between an API (application programming interface) and RPC (remote procedure call) lies in their scope and the way they facilitate communication between software components.

An API is a broad concept that defines a set of rules, endpoints, or interfaces through which one piece of software interacts with another. APIs can be local or remote, and they come in many styles such as REST, SOAP, GraphQL, and RPC. Essentially, an API describes what operations are available and how to access them, providing a standardized contract for integration.

RPC, on the other hand, is a specific communication mechanism often used to implement APIs. It allows a program to execute a function or procedure on a remote system as if it were local, hiding the complexity of network communication.

While an API could be designed around RESTful principles (resource-oriented) or GraphQL (query-based), an RPC-style API is action-oriented, it models operations as procedure calls like getUserDetails() or updateRecord().

RCP vs. REST

Here’s a structured comparison of RPC vs. REST: