Webservice

A web service is a software system designed to support interoperable machine-to-machine interaction over a network. It exposes a well-defined interface that clients can discover and invoke, and it exchanges data using standard web protocols and data formats such as XML or JSON. The goal is to enable automated, programmatic communication between heterogeneous systems.

Two dominant architectural styles are SOAP-based services and RESTful services. SOAP-based web services use the Simple Object Access Protocol and a formal contract described by WSDL (Web Services Description Language). Messages are sent as XML envelopes and may include headers for security, routing, or transaction control. RESTful web services use a resource-oriented approach over HTTP, leveraging standard methods such as GET, POST, PUT, and DELETE, and representations typically encoded as JSON or XML. Other approaches include XML-RPC and JSON-RPC, which invoke remote procedures, and gRPC, which uses HTTP/2 and Protocol Buffers for defining service interfaces.

Operation and security involve a client issuing a request to a service endpoint, with the service authenticating and processing the request and returning a response. Security considerations commonly include HTTPS for transport-level encryption and token-based or credentialed authentication, with additional standards such as WS-Security in SOAP-based systems.

Description and discovery mechanisms vary by style. SOAP services are often described by WSDL to enable client-side stub generation. REST APIs are increasingly described by OpenAPI (formerly Swagger) to support tooling and discovery. Registry systems like UDDI were used historically but are now uncommon.

Web services enable interoperable integration across platforms and languages, supporting enterprise, cloud, and microservices ecosystems, but can introduce complexity, latency, and design challenges.