//tag::ref-doc[] = Http Request Processor A processor app that makes requests to an HTTP resource and emits the response body as a message payload. == Input === Headers Any Required HTTP headers must be explicitly set via the `headers` or `headers-expression` property. See examples below. Header values may also be used to construct: * the request body when referenced in the `body-expression` property. * the HTTP method when referenced in the `http-method-expression` property. * the URL when referenced in the `url-expression` property. === Payload The payload is used as the request body for a POST request by default, and can be any Java type. It should be an empty String for a GET request. The payload may also be used to construct: * the request body when referenced in the `body-expression` property. * the HTTP method when referenced in the `http-method-expression` property. * the URL when referenced in the `url-expression` property. The underlying https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/reactive/function/client/WebClient.html[WebClient] supports Jackson JSON serialization to support any request and response types if necessary. The `expected-response-type` property, `String.class` by default, may be set to any class in your application class path. Note that user defined payload types will require adding required dependencies to your pom file. == Output === Headers No HTTP message headers are mapped to the outbound Message. === Payload The raw output object is https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/http/ResponseEntity.html[ResponseEntity<?>] any of its fields (e.g., `body`, `headers`) or accessor methods (`statusCode`) may be referenced as part of the `reply-expression`. By default the outbound Message payload is the response body. Note that ResponseEntity (referenced by the expression `#root`) cannot be deserialized by Jackson by default, but may be rendered as a `HashMap`. == Options The **$$http-request$$** $$processor$$ has the following options: //tag::configuration-properties[link-to-catalog=true] https://github.com/spring-cloud/spring-functions-catalog/tree/main/function/spring-http-request-function#configuration-options[See Spring Functions Catalog for configuration options]. //end::configuration-properties[] //end::ref-doc[]