Remote Procedure CallEdit

Remote Procedure Call

Remote Procedure Call (RPC) is a foundational concept in distributed computing that lets a program on one computer invoke a procedure on a remote system as if it were a local call. By hiding the network details, serialization, and error handling behind a familiar function-call interface, RPC enables modular architectures where components can reside in separate processes, machines, or even data centers. Over the decades, RPC has matured from vendor-specific systems to broad, interoperable frameworks that underlie many enterprise services, cloud platforms, and microservice deployments.

From the perspective of pragmatic software design, RPC emphasizes clear service contracts, language-agnostic interfaces, and fast, predictable communication patterns. Proponents argue that well-designed RPC systems reduce development friction, improve testability, and support scalable architectures by enabling independent evolution of services. Critics, however, warn about over-reliance on distributed calls, the risk of performance and reliability bottlenecks, and the temptation to let centralized platforms dictate how services are exposed and consumed. The debates often center on how to balance openness and interoperability with security, resilience, and vendor independence.

History

The concept of calling code across process or network boundaries has roots that long predate modern cloud computing. Early work in distributed systems produced protocol stacks and abstractions that treated remote invocations as first-class operations. In the 1980s and 1990s, several influential RPC systems emerged to standardize this idea and make it practical across heterogeneous hardware and software stacks.

The Open Network Computing Remote Procedure Call (ONC RPC) family popularized network-transparent calls on Unix-like systems and used portable encoding formats to enable cross-platform compatibility. ONC RPC
Microsoft introduced DCOM (Distributed Component Object Model), integrating RPC concepts with its component model and Windows runtime, which helped drive widespread adoption in enterprise environments. DCOM
The Common Object Request Broker Architecture (CORBA) offered a language- and platform-agnostic TRO (transfer, remoting, and calling) framework backed by the Object Request Broker, influencing many later service-oriented designs. CORBA
In the open-source and web-era, XML-RPC and later JSON-RPC provided lightweight, text-based encodings suitable for Internet-scale services, appealing to developers seeking simplicity and interoperability. XML-RPC JSON-RPC

In the 2010s, the rise of microservices and cloud-native architectures spurred new generations of RPC frameworks that emphasized performance, streaming capabilities, and strong contracts. Google’s gRPC, built on HTTP/2 and Protocol Buffers, became a prominent option for high-throughput, multi-language service-to-service communication. gRPC Contemporary discussions often position RPC alongside REST and messaging systems as different ways to model interoperability in distributed systems. REST

Architecture and Semantics

RPC aims to make remote calls appear as local procedures, but several practical dimensions distinguish successful implementations from fragile ones:

Semantics and idempotence: RPC calls can be configured to be idempotent, at-least-once, or exactly-once in the presence of retries and network failures. Designers must choose semantics that align with the business logic and failure modes of the system. idempotence
Interfaces and contracts: Service definitions typically rely on an Interface Definition Language (IDL) to specify available procedures, parameters, return types, and error conditions. This interface-driven approach enables code generation, language interoperability, and clear versioning strategies. IDL
Marshalling and encoding: Arguments and results must be serialized into a transport-friendly form. Encoding choices range from compact binary formats (e.g., Protocol Buffers) to text-based representations (e.g., XML, JSON). The encoding choice affects performance, readability, and schema evolution. Protocol Buffers XML JSON
Transport and framing: RPC can run over various transports, including HTTP/2, TCP, or customized channels. HTTP/2, for instance, enables multiplexing and reduced latency for streaming or multiplexed calls. HTTP/2
Security and trust: Authentication, authorization, and encryption are integral to RPC in production. Transport-layer security (TLS), mutual TLS (mTLS), and standard identity federations help protect service calls across untrusted networks. TLS OAuth mTLS PKI
Error handling and resilience: Timeouts, retries, circuit breakers, and backoff strategies are essential to keep systems robust under partial failures. Proper error signaling helps clients distinguish transient from permanent failures. Retry pattern Circuit breaker

Implementations and Protocols

RPC has evolved into a family of protocols and frameworks, each with its own strengths and trade-offs:

gRPC: A modern, high-performance RPC framework using HTTP/2 and Protocol Buffers, designed for low-latency and polyglot environments. It supports streaming, authentication, and pluggable load balancing. gRPC
XML-RPC: A simple, XML-based protocol that emphasizes interoperability and ease of parsing across languages. It remains a touchstone for discussions of RPC design. XML-RPC
JSON-RPC: A lightweight protocol using JSON for encoding, favored in web-focused stacks and environments where human readability matters. JSON-RPC
CORBA: A long-running influence in the RPC space, offering language-agnostic object request brokering and a mature, though complex, ecosystem. CORBA
DCOM: Microsoft’s implementation linking remote calls to a component object model, tightly integrated with Windows environments. DCOM
SOAP: A protocol family built on XML that supports rich contracts, security features, and extensibility, often paired with web services workflows. SOAP
ONC RPC: The original Unix-friendly RPC approach that underpinned many services in academic and enterprise settings. ONC RPC
IDL and its descendants: Interface Definition Languages enable precise, compiler-friendly service contracts across languages. IDL

In practice, many organizations blend RPC with other communication styles, choosing RESTful endpoints for external-facing APIs and RPC for internal, high-performance service-to-service calls. The choice often reflects concerns about performance, ease of integration, and risk management. REST

Security, Reliability, and Risk

RPC exposes surface areas that demand careful governance:

Authentication and authorization: Ensuring that only legitimate clients and servers participate in a call chain is essential, especially when services cross trust boundaries. Federated identity and role-based access control are typical approaches. OAuth RBAC
Encryption and integrity: Transport security (e.g., TLS) helps protect data in transit, while signing and auditing support accountability for remote actions. TLS PKI
Boundary management: Exposing internal services to other teams, cloud tenants, or the public Internet increases the need for network segmentation, policy enforcement, and anomaly detection. Service mesh Firewall
Observability: Distributed tracing, metrics, and structured logging are critical for diagnosing latency and reliability issues in RPC-heavy architectures. Observability

From a pragmatic governance standpoint, some observers emphasize minimizing cross-domain dependencies to reduce risk. They argue that lightweight, clearly defined interfaces and the ability to swap implementations without large-scale rewrites are important for long-term stability and competitive markets. This aligns with a preference for open standards and vendor-neutral solutions that encourage multiple providers to compete on performance and reliability rather than on proprietary lock-in. The push toward widely adopted, open RPC protocols is often framed as pro-consumer and pro-innovation, even as it requires disciplined architecture and security discipline. Critics of heavy-handed platform control argue that centralized or closed ecosystems can dampen innovation and raise switching costs, a concern that advocates of open RPC ecosystems routinely address through interoperability commitments and transparent specifications. Open Source Software Kubernetes

Contemporary Trends and Debates

RPC sits at the intersection of performance, security, and organizational design. Several current debates reflect practical concerns about how best to deploy distributed systems:

Open standards vs. vendor ecosystems: Advocates emphasize that open RPC protocols and IDLs reduce lock-in and lower the cost of migrating services across clouds and platforms. Opponents argue that some vendor-specific enhancements can deliver performance or security advantages, provided teams are willing to accept deeper coupling with a single ecosystem. The balance often comes down to governance, procurement, and risk tolerance. Open standards Cloud computing
RPC vs REST vs messaging: While RPC excels at high-performance, tightly coupled service-to-service calls, REST and event-driven messaging can offer looser coupling, better caching, and asynchronous resilience. Organizations frequently adopt a hybrid approach, using RPC for internal services that demand speed and REST or messaging for public APIs and integration layers. REST Message-oriented middleware
Service meshes and distributed systems: Modern deployments frequently rely on service meshes to handle cross-service communication concerns—security, observability, and reliability—without embedding those concerns into each service. This shifts some RPC responsibilities into infrastructure rather than code. service mesh Kubernetes
Security in multi-tenant environments: As services span multiple teams and tenants, the emphasis on robust authentication, authorization, and encryption grows. Delegated authorization and auditable contracts are increasingly important in enterprise settings. IAM mTLS

From a practical, market-oriented view, the core value of RPC remains clear: defined contracts between services, language-agnostic interfaces, and predictable performance. Proponents stress that when implemented with disciplined versioning, strong security, and clear ownership, RPC supports scalable, maintainable systems that empower businesses to innovate without being trapped in a single vendor’s stack. Critics argue that without careful governance, RPC can become a source of brittle dependencies and security gaps, especially as service graphs grow and cross-border calls proliferate.

Woke criticisms of the technology landscape often focus on how infrastructure choices influence workers, access, and innovation. In the RPC domain, such critiques tend to miss the core technical question: how to design interfaces and security controls that are robust, auditable, and portable across environments. Supporters contend that the best path forward is open, interoperable standards and transparent implementations that empower customers and vendors alike to compete on quality rather than on access to exclusive platforms. In this light, the ongoing evolution of RPC frameworks reflects a broader tension between centralized leverage and distributed autonomy, with the market generally rewarding those that deliver reliability, clear contracts, and practical security.