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Summary – Your application exchanges require performance, scalability, interoperability, security, maintainability, third-party integrations, standardization, flexibility, controlled latency and clear governance; Solution: map data flows, partners and requirements (performance, security) → choose the architecture (REST, gRPC, GraphQL or hybrid) based on latency, flexibility and governance → formalize contracts, semantic versioning and interactive documentation (OpenAPI, SDL) with developer portals
Web services are software components accessible via HTTP protocols, allowing heterogeneous applications to communicate in a standardized way, independent of language or platform. By facilitating the exchange of data and functionality, they support the modularity and scalability of IT architectures.
This article clarifies the concept of a web service, distinguishes it from an API, then illustrates its practical uses before exploring the major architectures (RPC/gRPC, REST, GraphQL) as well as documentation and standardization challenges. Finally, it highlights current trends—especially the rise of GraphQL—to guide your technical choices with pragmatism.
Understanding the role and nature of a web service
A web service is a software service exposed on the web via a standard protocol (often HTTP). It enables distinct applications to exchange structured messages, regardless of their underlying technology.
How a web service works
A web service relies on a communication contract, often formalized by a description format (WSDL for SOAP, or a REST API documented in OpenAPI). Clients issue requests according to this contract, sending encoded data (XML, JSON, protobuf) and then await responses formatted in the same way.
The server hosts the business logic and processes incoming messages. The architecture remains decoupled: the client only needs to know the public interface, not the internal implementation of the service. This ensures great flexibility to evolve both sides independently.
The HTTP protocol, commonly used, provides a universal channel that can traverse firewalls and proxies. Security layers can be added (TLS, OAuth, JWT tokens) to protect the exchange and guarantee the authenticity of calls.
Differences between web service and API
The term API (Application Programming Interface) refers to any software interface exposed by a component, whether local, embedded or remotely accessible. By contrast, a web service is a subset of APIs, specifically exposed via web protocols.
All web APIs are APIs, but not all APIs are web services. Some APIs operate through shared library calls (local) or via private message buses (MQTT, AMQP) without using HTTP.
In practice, the choice between a native API, SOAP web service, REST or GraphQL impacts flexibility, performance and adoption by third-party developers. It’s a key criterion for system adaptability and maintainability.
Concrete example of a web service: electronic invoicing in the Swiss industry
A Geneva-based SME implemented a SOAP web service for automatic Electronic Data Interchange (EDI) invoicing with its logistics partners. This service exposes standardized operations (document creation, delivery status retrieval) in XML format.
This implementation demonstrated that a single, standardized interface reduces client-specific developments and ensures a consistent information flow. Teams automated 95% of invoice processing, minimizing manual errors and speeding up payments.
This case illustrates how a web service can structure and secure a critical business process while maintaining technological independence between production, ERP and transportation systems.
Concrete use cases of web services
Web services are deployed across many business scenarios, from online payments to mapping and booking. They simplify third-party service integration without sacrificing process consistency.
Online payment: integrating an external payment service
A Basel-based e-commerce platform connected its product catalog to an online payment service via a secure REST web service. POST calls transmit transaction data (amount, currency, session ID) and return a payment token to complete the operation on the client side.
This integration showed that outsourcing transaction management to a specialized provider frees IT teams from PCI-DSS compliance constraints and regulatory changes. The third party handles fraud prevention, while the platform focuses on user experience.
Result: deployment in two weeks and a 30% reduction in payment maintenance time, while maintaining top-level security and scalability during peak loads.
Social login authentication: Facebook Login
Many mobile and web applications offer the “Log in with Facebook” option. Behind this button, an OAuth2 web service exposes authorization and token endpoints. The application sends a request to Facebook, the user consents, and then receives an access token to fetch their profile.
This mechanism avoids managing an internal directory and forcing users to create a separate account. UX is smoother, and the company benefits from social-network-verified data while complying with GDPR and nLPD requirements.
By decoupling identity management, security improves and onboarding accelerates. Developers consume a simple REST interface while the social provider ensures email verification and authentication robustness.
Travel booking: accessing Amadeus feeds
In the tourism sector, agencies integrate Amadeus web services to query flight, hotel and car rental inventories. These SOAP or REST services expose search, booking and ticketing operations.
Thanks to these web services, a Swiss booking platform aggregated multiple competing providers into a single interface, offering a real-time comparison tool. Requests are orchestrated from a central back office, and results are merged to present the best rates.
This setup demonstrated that abstracting via a web service allows changing or adding a provider without impacting the front end. Business agility becomes a real competitive advantage.
Edana: strategic digital partner in Switzerland
We support companies and organizations in their digital transformation
Technical architectures: RPC, REST and GraphQL
The choice of web service architecture determines performance, standardization and adaptability of exchanges. Each paradigm has its strengths and limits.
RPC and gRPC: synchronous remote communication
Remote Procedure Call (RPC) simulates a function call over the network. The modern version, gRPC, uses HTTP/2 for transport and protobuf for binary serialization. Interfaces are described in .proto files, generating client and server code.
A large Zurich-based logistics group deployed gRPC for its critical internal microservices, reducing call latency to under 5 ms. This case demonstrated the superiority of binary encoding over text when volume and speed are paramount.
On the downside, gRPC requires a heavier infrastructure layer and proprietary encoding. It’s best suited to controlled environments where client and server versions can be managed synchronously.
REST: standardization and simplicity
REST (Representational State Transfer) is based on web principles: resources identified by URLs, CRUD operations mapped to HTTP verbs (GET, POST, PUT, DELETE), representation formats (JSON, XML). It’s the most widespread style for exposing web APIs.
Its ease of use, alignment with HTTP caching and mature ecosystem (clients, OpenAPI documentation, API gateways) make it an almost universal standard. Developers appreciate its low learning curve and design flexibility.
However, REST can suffer from over- and under-fetching: endpoints often return more or less data than needed, forcing multiple requests or ignoring unused fields.
GraphQL: returning control to the client
GraphQL provides a single schema describing types and possible queries. Clients specify exactly what they need, avoiding over- and under-fetching. Server-side resolvers dynamically assemble data from multiple sources.
This approach is particularly well suited to mobile or UI-rich applications where controlling data volume is crucial. Strong typing and introspection facilitate tool generation and automated documentation.
On the other hand, GraphQL requires strict governance: protecting expensive queries with rate limiting, managing caching more finely and avoiding too-powerful mutations. Its growing adoption in complex environments makes it a strategic choice for hybrid architectures.
Standards, documentation and upcoming evolutions
Clear documentation and standardized specifications drive web service adoption and maintainability. Modern tools automate and unify this work.
Documentation and developer portals
Interfaces documented in OpenAPI (REST) or SDL (GraphQL) enable automatic generation of client code, mocks, tests and discovery portals. Third-party developers explore, test and integrate faster.
Lack of up-to-date documentation is one of the main barriers to API adoption. Interactive portals (Swagger UI, GraphiQL) offer an engaging environment to understand and experiment before coding.
Practices like semantic versioning, release notes and deprecation strategies prevent service disruptions. They ensure controlled evolution, essential when multiple applications consume the same endpoints.
Standardization and exchange performance
Adhering to HTTP conventions, handling status codes, optimizing caching and compressing payloads are best practices to ensure web service responsiveness and resilience.
REST APIs often rely on gateways to manage security, quotas, monitoring and message transformation. GraphQL advocates continuous schema introspection to detect changes in real time.
These standardized mechanisms build trust and reduce support costs. They provide a common framework, regardless of the chosen protocol, and simplify integration with monitoring and automated testing tools.
Emerging trends: federation and hybrid ecosystems
GraphQL federation allows composing multiple subgraphs into a unified schema, giving developers a consolidated view while keeping teams autonomous over their services.
Hybrid architectures combine REST, GraphQL and gRPC as needed: REST for external integrations, gRPC for backend synchronization, GraphQL for the user interface. This mosaic is maturing along with its tooling.
API management platforms now include transformation capabilities between these protocols, simplifying migration or coexistence. Anticipating these evolutions ensures the longevity of your application ecosystem.
Optimize your application exchanges with web services
Web services lie at the heart of digital transformation, offering a standardized way to connect disparate applications. We’ve seen how they differ from local APIs, come in RPC/gRPC, REST or GraphQL architectures—each suited to specific needs—and how documentation is key to adoption and maintainability.
IT Directors, CTOs, CIOs and IT project managers face challenges around performance, security, scalability and cost control. Well-designed and documented web services address these concerns. Our independent, modular open-source experts are ready to help you define the solution best suited to your context.
