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Chapter 54. Extending JAX-RS Endpoints with OpenAPI Support

Abstract

The CXF OpenApiFeature (org.apache.cxf.jaxrs.openapi.OpenApiFeature) allows you to generate OpenAPI documents by extending published JAX-RS service endpoints with a simple configuration.

The OpenApiFeature is supported in both Spring Boot and Karaf implementations.

54.1. OpenApiFeature options

You can use the following options in OpenApiFeature.

Table 54.1. OpenApiFeature operations

NameDescriptionDefault

configLocation

The OpenAPI configuration location

null

contactEmail

The contact email+

null

contactName

The contact name+

null

contactUrl

The contact link+

null

customizer

The customizer class instance

null

description

The description+

null

filterClass

A security filter++

null

ignoredRoutes

Excludes specific paths when scanning all resources (see scanAllResources)++

null

license

The license+

null

licenseUrl

The license URL+

null

prettyPrint

When generating openapi.json, pretty-print the JSON document++

true

propertiesLocation

The properties file location

/swagger.properties

readAllResources

Read all operations also with no @Operation++

true

resourceClasses

A list of resource classes which must be scanned++

null

resourcePackages

A list of package names where resources must be scanned++

null

runAsFilter

Runs the feature as a filter

false

scan

Scan all JAX-RS resources automatically

true

scanKnownConfigLocations

Scan known OpenAPI configuration location (classpath or filesystem), which are:

openapi-configuration.yaml
openapi-configuration.json
openapi.yaml
openapi.json

true

scannerClass

The name of the JAX-RS API scanner class, used to scope the application, resource packages, resource classes and classpath scanning, please refer to Resource Scanning section

null

securityDefinitions

A list of security definitions+

null

supportSwaggerUi

Turns on/off SwaggerUI support

null (== true)

swaggerUiConfig

Swagger UI configuration

null

swaggerUiMavenGroupAndArtifact

The Maven artifacts to pinpoint SwaggerUI

null

swaggerUiVersion

The version of SwaggerUI

null

termsOfServiceUrl

The terms of service URL+

null

title

The title+

null

useContextBasedConfig

If set, the unique Context Id is going to be generated for each OpenApiContext instance (please see Using Multiple Server Endpoints). Also, you may want to set scan property to false.

false

version

The version+

null

+ The option is defined in the OpenAPI class

++ The option is defined in the SwaggerConfiguration class

54.2. Karaf Implementations

This section describes how to use the OpenApiFeature in which REST services are defined inside JAR files and deployed to a Fuse on Karaf container.

54.2.1. Quickstart example

You can download Red Hat Fuse quickstarts from the Fuse Software Downloads page.

The Quickstart zip file contains a /cxf/rest/ directory for a quickstart that demonstrates how to create a RESTful (JAX-RS) web service using CXF and how to enable OpenAPI and annotate the JAX-RS endpoints.

54.2.2. Enabling OpenAPI

Enabling OpenAPI involves:

  • Modifying the XML file that defines the CXF service by adding the CXF class (org.apache.cxf.jaxrs.openapi.OpenApiFeature) to the <jaxrs:server> definition.

    For an example, see Example 55.4 Example XML file.

  • In the REST resource class:

For an example, see Example 55.5 Example Resource class.

Example 55.4 Example XML file

<blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:jaxrs="http://cxf.apache.org/blueprint/jaxrs"
    xmlns:cxf="http://cxf.apache.org/blueprint/core"
    xsi:schemaLocation="
      http://www.osgi.org/xmlns/blueprint/v1.0.0
https://www.osgi.org/xmlns/blueprint/v1.0.0/blueprint.xsd
      http://cxf.apache.org/blueprint/jaxrs
http://cxf.apache.org/schemas/blueprint/jaxrs.xsd
      http://cxf.apache.org/blueprint/core
http://cxf.apache.org/schemas/blueprint/core.xsd">

    <jaxrs:server id="customerService" address="/crm">
        <jaxrs:serviceBeans>
            <ref component-id="customerSvc"/>
        </jaxrs:serviceBeans>
        <jaxrs:providers>
           <bean class="com.fasterxml.jackson.jaxrs.json.JacksonJsonProvider"/>
        </jaxrs:providers>
        <jaxrs:features>
        <bean class="org.apache.cxf.jaxrs.openapi.OpenApiFeature">
          <property name="title" value="Fuse:CXF:Quickstarts - Customer Service" />
          <property name="description" value="Sample REST-based Customer Service" />
          <property name="version" value="${project.version}" />
        </bean>
        </jaxrs:features>
    </jaxrs:server>

    <cxf:bus>
        <cxf:features>
          <cxf:logging />
        </cxf:features>
        <cxf:properties>
            <entry key="skip.default.json.provider.registration" value="true" />
        </cxf:properties>
    </cxf:bus>

    <bean id="customerSvc" class="org.jboss.fuse.quickstarts.cxf.rest.CustomerService"/>

</blueprint>

Example 55.5 Example Resource class

.
.
.

import javax.ws.rs.Consumes;
import javax.ws.rs.DELETE;
import javax.ws.rs.GET;
import javax.ws.rs.POST;
import javax.ws.rs.PUT;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.Response;

import io.swagger.annotations.Api;
import io.swagger.annotations.ApiOperation;
import io.swagger.annotations.ApiParam;
import io.swagger.annotations.ApiResponse;
import io.swagger.annotations.ApiResponses;

.
.
.

@Path("/customerservice/")
@Api(value = "/customerservice", description = "Operations about customerservice")
public class CustomerService {

    private static final Logger LOG =
          LoggerFactory.getLogger(CustomerService.class);

    private MessageContext jaxrsContext;
    private long currentId                = 123;
    private Map<Long, Customer> customers = new HashMap<>();
    private Map<Long, Order> orders       = new HashMap<>();

    public CustomerService() {
        init();
    }


    @GET
    @Path("/customers/{id}/")
    @Produces("application/xml")
    @ApiOperation(value = "Find Customer by ID", notes = "More notes about this
        method", response = Customer.class)
    @ApiResponses(value = {
            @ApiResponse(code = 500, message = "Invalid ID supplied"),
            @ApiResponse(code = 204, message = "Customer not found")
            })
    public Customer getCustomer(@ApiParam(value = "ID of Customer to fetch",
        required = true) @PathParam("id") String id) {
        LOG.info("Invoking getCustomer, Customer id is: {}", id);
        long idNumber = Long.parseLong(id);
        return customers.get(idNumber);
    }


    @PUT
    @Path("/customers/")
    @Consumes({ "application/xml", "application/json" })
    @ApiOperation(value = "Update an existing Customer")
    @ApiResponses(value = {
            @ApiResponse(code = 500, message = "Invalid ID supplied"),
            @ApiResponse(code = 204, message = "Customer not found")
            })
    public Response updateCustomer(@ApiParam(value = "Customer object that needs
        to be updated", required = true) Customer customer) {
        LOG.info("Invoking updateCustomer, Customer name is: {}", customer.getName());
        Customer c = customers.get(customer.getId());
        Response r;
        if (c != null) {
            customers.put(customer.getId(), customer);
            r = Response.ok().build();
        } else {
            r = Response.notModified().build();
        }

        return r;
    }

    @POST
    @Path("/customers/")
    @Consumes({ "application/xml", "application/json" })
    @ApiOperation(value = "Add a new Customer")
    @ApiResponses(value = { @ApiResponse(code = 500, message = "Invalid ID
        supplied"), })
    public Response addCustomer(@ApiParam(value = "Customer object that needs to
        be updated", required = true) Customer customer) {
        LOG.info("Invoking addCustomer, Customer name is: {}", customer.getName());
        customer.setId(++currentId);

        customers.put(customer.getId(), customer);
        if (jaxrsContext.getHttpHeaders().getMediaType().getSubtype().equals("json"))
    {
            return Response.ok().type("application/json").entity(customer).build();
        } else {
            return Response.ok().type("application/xml").entity(customer).build();
        }
    }

    @DELETE
    @Path("/customers/{id}/")
    @ApiOperation(value = "Delete Customer")
    @ApiResponses(value = {
            @ApiResponse(code = 500, message = "Invalid ID supplied"),
            @ApiResponse(code = 204, message = "Customer not found")
            })
    public Response deleteCustomer(@ApiParam(value = "ID of Customer to delete",
        required = true) @PathParam("id") String id) {
        LOG.info("Invoking deleteCustomer, Customer id is: {}", id);
        long idNumber = Long.parseLong(id);
        Customer c = customers.get(idNumber);

        Response r;
        if (c != null) {
            r = Response.ok().build();
            customers.remove(idNumber);
        } else {
            r = Response.notModified().build();
        }

        return r;
    }

.
.
.

}

54.3. Spring Boot Implementations

This section describes how to use the Swagger2Feature in Spring Boot.

Note that for OpenAPI 3 implementations, use the OpenApiFeature(org.apache.cxf.jaxrs.openapi.OpenApiFeature).

54.3.1. Quickstart example

The Quickstart example (https://github.com/fabric8-quickstarts/spring-boot-cxf-jaxrs) demonstrates how you can use Apache CXF with Spring Boot. The Quickstart uses Spring Boot to configure an application that includes a CXF JAX-RS endpoint with Swagger enabled.

54.3.2. Enabling Swagger

Enabling Swagger involves:

Example 55.1 Example REST application

package io.fabric8.quickstarts.cxf.jaxrs;

import java.util.Arrays;

import org.apache.cxf.Bus;
import org.apache.cxf.endpoint.Server;
import org.apache.cxf.jaxrs.JAXRSServerFactoryBean;
import org.apache.cxf.jaxrs.swagger.Swagger2Feature;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;

@SpringBootApplication
public class SampleRestApplication {

    @Autowired
    private Bus bus;

    public static void main(String[] args) {
        SpringApplication.run(SampleRestApplication.class, args);
    }

    @Bean
    public Server rsServer() {
        // setup CXF-RS
        JAXRSServerFactoryBean endpoint = new JAXRSServerFactoryBean();
        endpoint.setBus(bus);
        endpoint.setServiceBeans(Arrays.<Object>asList(new HelloServiceImpl()));
        endpoint.setAddress("/");
        endpoint.setFeatures(Arrays.asList(new Swagger2Feature()));
        return endpoint.create();
    }
}

Example 55.2 Example Java implementation file

import io.swagger.annotations.Api;

@Api("/sayHello")
public class HelloServiceImpl implements HelloService {

    public String welcome() {
        return "Welcome to the CXF RS Spring Boot application, append /{name} to call the hello service";
    }

    public String sayHello(String a) {
        return "Hello " + a + ", Welcome to CXF RS Spring Boot World!!!";
    }

}

Example 55.3 Example Java file

package io.fabric8.quickstarts.cxf.jaxrs;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;

import org.springframework.stereotype.Service;

@Path("/sayHello")
@Service
public interface HelloService {

    @GET
    @Path("")
    @Produces(MediaType.TEXT_PLAIN)
    String welcome();

    @GET
    @Path("/{a}")
    @Produces(MediaType.TEXT_PLAIN)
    String sayHello(@PathParam("a") String a);

}

54.4. Accessing OpenAPI Documents

When OpenAPI is enabled by OpenApiFeature, the OpenAPI documents are available at the location URL constructed of the service endpoint location followed by /openapi.json or /openapi.yaml.

For example, for a JAX-RS endpoint that is published at http://host:port/context/services/ where context is a web application context and /services is a servlet URL, its OpenAPI documents are available at http://host:port/context/services/openapi.json and http://host:port/context/services/openapi.yaml.

If OpenApiFeature is active, the CXF Services page links to OpenAPI documents.

In the above example, you would go to http://host:port/context/services/services and then follow a link which returns an OpenAPI JSON document.

If CORS support is needed to access the definition from an OpenAPI UI on another host, you can add the CrossOriginResourceSharingFilter from cxf-rt-rs-security-cors.

54.5. Accessing OpenAPI through a reverse proxy

If you want to access an OpenAPI JSON document or an OpenAPI UI through a reverse proxy, set the following options:

  • Set the CXFServlet use-x-forwarded-headers init parameter to true.

    • In Spring Boot, prefix the parameter name with cxf.servlet.init:

      cxf.servlet.init.use-x-forwarded-headers=true
    • In Karaf, add the following line to the installDir/etc/org.apache.cxf.osgi.cfg configuration file:

      cxf.servlet.init.use-x-forwarded-headers=true

      Note: If you do not already have an org.apache.cxf.osgi.cfg file in your etc directory, you can create one.

  • If you specify a value for the OpenApiFeature basePath option and you want to prevent OpenAPI from caching the basePath value, set the OpenApiFeature usePathBasedConfig option to TRUE:

    <bean class="org.apache.cxf.jaxrs.openapi.OpenApiFeature">
        <property name="usePathBasedConfig" value="TRUE" />
    </bean>