OpenApiFeature

Introduction

The CXF OpenApiFeature allows you to generate OpenAPI v3.0 documents from JAX-RS service endpoints with a simple configuration. This feature can be configured programmatically in Java or using Spring or Blueprint beans.

Setup

<dependency>
    <groupId>org.apache.cxf</groupId>
    <artifactId>cxf-rt-rs-service-description-openapi-v3</artifactId>
    <version>3.2.4</version>
</dependency>

The cxf-rt-rs-service-description-openapi-v3 is only available in 3.2.x and above due to Java 8 baseline. For older releases, as well as for the users of older Swagger specifications 1.x/2.x, there is a dedicated converter provided: org.apache.cxf.jaxrs.swagger.openapi.SwaggerToOpenApiConversionFilter.

Properties

The following optional parameters can be configured in OpenApiFeature. Note that although there are some similarities with Swagger specifications 1.x/2.x, OpenAPI v3.0 is a significant revamp of the specification (in a good sense of it).

Name	Description	Default value (if applicable)	Sample value (if applicable)
configLocation	the OpenAPI configuration location	null	/config/openapi-configuration.yml
scanKnownConfigLocations	scan known OpenAPI configuration location (classpath or filesystem), which are: openapi-configuration.yaml openapi-configuration.json openapi.yaml openapi.json	true	true
propertiesLocation	the properties file location	/swagger.properties	/swagger.properties
securityDefinitions	a list of security definitions*	null	["basicAuth" -> new SecurityScheme().type(Type.HTTP))]
customizer	the customizer class instance	null	new OpenApiCustomizer()
swaggerUiMavenGroupAndArtifact	the Maven artifacts to pinpoint SwaggerUI	null	"org.webjars.swagger-ui'
swaggerUiVersion	the version of SwaggerUI	null	"3.13.0"
supportSwaggerUi	turns on/off SwaggerUI support	null (== true)	true
filterClass	a security filter**	null	"com.example.filter.SampleFilter"
resourceClasses	a list of resource classes which must be scanned**	null	["com.example.rest.SampleResource"]
resourcePackages	a list of package names where resources must be scanned**	null	["com.example.rest"]
ignoredRoutes	excludes specific paths when scanning all resources (see scanAllResources)**	null	["/api/test"]
prettyPrint	when generating openapi.json, pretty-print the JSON document**	true	true
runAsFilter	runs the feature as a filter	false	false
scan	Scan all JAX-RS resources automatically	true	true
readAllResources	Read all operations also with no @Operation**	true	true
termsOfServiceUrl	the terms of service URL*	null	null
licenseUrl	the license URL*	null	"http://www.apache.org/licenses/LICENSE-2.0.html"
license	the license*	null	"Apache 2.0 License"
contactUrl	the contact link*	null	null
contactEmail	the contact email*	null	"users@cxf.apache.org"
contactName	the contact name*	null	null
description	the description*	null	"The Sample REST Application with OpenAPI integration"
title	the title*	null	"Sample REST Application"
version	the version*	null	"1.0.0"

* - the properties are defined in the OpenAPI class

** - the properties are defined in the SwaggerConfiguration class

Configuring from Code

import org.apache.cxf.jaxrs.openapi.OpenApiFeature;
import io.swagger.v3.oas.models.security.SecurityScheme;
import io.swagger.v3.oas.models.security.SecurityScheme.Type;

...

final OpenApiFeature feature = new OpenApiFeature();
feature.setContactEmail("cxf@apache.org");
feature.setLicense("Apache 2.0 License");
feature.setLicenseUrl("http://www.apache.org/licenses/LICENSE-2.0.html");           
feature.setSecurityDefinitions(Collections.singletonMap("basicAuth",new SecurityScheme().type(Type.HTTP)));

Configuring from Spring

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:cxf="http://cxf.apache.org/core"
       xmlns:jaxrs="http://cxf.apache.org/jaxrs"
       xsi:schemaLocation="http://cxf.apache.org/core http://cxf.apache.org/schemas/core.xsd
                           http://cxf.apache.org/jaxrs http://cxf.apache.org/schemas/jaxrs.xsd
                           http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
    ... 
    <!-- JAXRS providers -->
    <bean id="jsonProvider" class="com.fasterxml.jackson.jaxrs.json.JacksonJsonProvider" />
 
    <!-- Application resources -->
    <bean id="sampleResource" class="demo.jaxrs.openapi.server.Sample" />
 
    <!-- CXF OpenApiFeature -->  
    <bean id="openApiFeature" class="org.apache.cxf.jaxrs.openapi.OpenApiFeature">
        <!-- customize some of the properties -->
    </bean>
 
    ...

    <jaxrs:server id="sampleServer" address="/swaggerSample">
        <jaxrs:serviceBeans>
            <ref bean="sampleResource" />
        </jaxrs:serviceBeans>
        <jaxrs:providers>
            <ref bean="jsonProvider" />
        </jaxrs:providers>
        <jaxrs:features>
            <ref bean="openApiFeature" />
        </jaxrs:features>
    </jaxrs:server>
</beans>

Configuring in Blueprint

In case of Apache Karaf, the OpenAPI v3.0 integration is available as cxf-rs-description-openapi-v3 feature.

feature:install cxf-rs-description-openapi-v3

<blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:cxf="http://cxf.apache.org/blueprint/core"
       xmlns:jaxrs="http://cxf.apache.org/blueprint/jaxrs"
       xsi:schemaLocation="http://www.osgi.org/xmlns/blueprint/v1.0.0 http://www.osgi.org/xmlns/blueprint/v1.0.0/blueprint.xsd
                           http://cxf.apache.org/blueprint/core http://cxf.apache.org/schemas/blueprint/core.xsd
                           http://cxf.apache.org/jaxrs http://cxf.apache.org/schemas/blueprint/jaxrs.xsd"> 
    ...
    <!-- JAXRS providers -->
    <bean id="jsonProvider" class="com.fasterxml.jackson.jaxrs.json.JacksonJsonProvider" />
 
    <!-- Application resources -->
    <bean id="sampleResource" class="demo.jaxrs.openapi.server.Sample" />
 
 
    <!-- CXF OpenApiFeature -->  
    <bean id="openApiFeature" class="org.apache.cxf.jaxrs.openapi.OpenApiFeature">
        <!-- customize some of the properties -->
    </bean>
 
    ...

    <jaxrs:server id="sampleServer" address="/swaggerSample">
        <jaxrs:serviceBeans>
            <ref component-id="sampleResource" />
        </jaxrs:serviceBeans>
        <jaxrs:providers>
            <ref component-id="jsonProvider" />
        </jaxrs:providers>
        <jaxrs:features>
            <ref component-id="openApiFeature" />
        </jaxrs:features>
    </jaxrs:server>
</blueprint>

Configuring in CXFNonSpringJaxrsServlet

<web-app>
    <context-param>
        <param-name>contextParam</param-name>
        <param-value>contextParamValue</param-value>
    </context-param>

    <servlet>
        <servlet-name>CXFServlet</servlet-name>
        <display-name>CXF Servlet</display-name>
        <servlet-class>org.apache.cxf.jaxrs.servlet.CXFNonSpringJaxrsServlet</servlet-class>
        <init-param>
            <param-name>jaxrs.serviceClasses</param-name>
            <param-value>org.apache.cxf.systest.jaxrs.BookStore</param-value>
        </init-param>
        <init-param>
            <param-name>jaxrs.features</param-name>
            <param-value>org.apache.cxf.jaxrs.openapi.OpenApiFeature</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
     
    <servlet-mapping>
        <servlet-name>CXFServlet</servlet-name>
        <url-pattern>/*</url-pattern>
    </servlet-mapping>
     
</web-app>

Configuring from Property files

It is possible to supply the configuration from the property files. The default location for a properties file is "/swagger.properties". OpenApiFeature will pick it up if it is available, and the location can be overridden with a 'propertiesLocation' property. Additionally, the complete OpenAPI configuration could be supplied from the property file (usually openapi-configuration.json or openapi-configuration.yml), controlled by 'configLocation' property. By default, OpenApiFeature scans for known OpenAPI configuration locations and loads them if available (the behavior could be switched off by setting scanKnownConfigLocations to false). Please take into account that there is a certain level of the overlap between both.

Note that the properties, if available, do not override the properties which may have been set as suggested above from the code or Spring/Blueprint contexts or web.xml. Instead they complement and serve as the default configuration properties: for example, if some properties have been set from the code then the values for the same properties found in the properties file will not be used.

Spring Boot Auto Configuration

Please consult samples/jax_rs/spring_boot and on how to create OpenApiFeature as a @Bean or/and samples/jax_rs/spring_boot_scan on how to auto-enable it.

Enabling Swagger UI

Adding a Swagger UI Maven dependency is all what is needed to start accessing Swagger documents with the help of Swagger UI.

<dependency>
    <groupId>org.webjars</groupId>
    <artifactId>swagger-ui</artifactId>
    <version>3.13.0</version>
</dependency>

For example, let's assume a JAX-RS endpoint is published at 'http://host:port/context/services/'.

Open the browser and go to 'http://host:port/context/services/api-docs/?url=/openapi.json' which will return a Swagger UI page.

CXF Services page will also link to Swagger UI. Go to 'http://host:port/context/services/' and follow a Swagger link which will return a Swagger UI page.

See samples/jax_rs/description_openapi_v3 as an example.

To deactivate automatic Swagger UI integration please set 'supportSwaggerUi' property to "false".

Samples

CXF's distribution contains the following samples.

samples/jax_rs/description_openapi_v3: the OpenAPI v3.0 standalone sample using OpenApiFeature programmatically
samples/jax_rs/description_openapi_v3_osgi: the OpenAPI v3.0 OSGi application sample using OpenApiFeature using Blueprint
samples/jax_rs/description_openapi_v3_web: the OpenAPI v3.0 sample using OpenApiFeature inside WAR-based deployment

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