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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
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You can use the following options in OpenApiFeature.

Expand
Table 54.1. OpenApiFeature operations
NameDescriptionDefault

basePath

The context root path+ (see also the usePathBasedConfig option)

null

contact

Your contact information+

"users@cxf.apache.org"

description

A description+

"The Application"

filterClass

A security filter+

null

host

The host and port information+

null

ignoreRoutes

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

null

license

The license+

"Apache 2.0 License"

licenceUrl

The license URL+

http://www.apache.org/licenses/LICENSE-2.0.html

prettyPrint

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

false

resourcePackage

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

A list of service classes configured at the endpoint

runAsFilter

Runs the feature as a filter

false

scan

Generates the OpenAPI documentation+

true

scanAllResources

Scans all resources including non-annotated JAX-RS resources (see also the ignoreRoutes option)++

false

schemes

The protocol schemes+

null

openapiUiConfig

OpenAPI UI configuration

null

termsOfServiceUrl

The terms of service URL+

null

title

The title+

"Sample REST Application"

usePathBasedConfig

Prevents OpenAPI from caching the value of the basePath option.

false

version

The version+

"1.0.0"

+ The option is defined in OpenAPIs’s BeanConfig

++ The option is defined in OpenAPI’s ReaderConfig

54.2. Karaf Implementations
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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
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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
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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:

    • Importing the OpenAPI annotations for each annotation required by the service: 

      import io.openapi.annotations.*
      Copy to Clipboard Toggle word wrap

      where * = Api, ApiOperation, ApiParam, ApiResponse, ApiResponses, and so on.

      For details, go to https://github.com/openapi-api/openapi-core/wiki/Annotations.

      For an example, see Example 55.5 Example Resource class.

    • Adding OpenAPI annotations to the JAX-RS annotated endpoints (@PATH, @PUT, @POST, @GET, @Produces, @Consumes, @DELETE, @PathParam, and so on).

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>
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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.openapi.annotations.Api;
import io.openapi.annotations.ApiOperation;
import io.openapi.annotations.ApiParam;
import io.openapi.annotations.ApiResponse;
import io.openapi.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;
    }

.
.
.

}
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54.3. Spring Boot Implementations
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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
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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
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Enabling Swagger involves:

  • In the REST application:

    • Importing Swagger2Feature: 

      import org.apache.cxf.jaxrs.swagger.Swagger2Feature;
      Copy to Clipboard Toggle word wrap

    • Adding Swagger2Feature to a CXF endpoint: 

      endpoint.setFeatures(Arrays.asList(new Swagger2Feature()));
      Copy to Clipboard Toggle word wrap

      For an example, see Example 55.1 Example REST application.

  • In the Java implementation file, importing the Swagger API annotations for each annotation required by the service: 

    import io.swagger.annotations.*
    Copy to Clipboard Toggle word wrap

    where * = Api, ApiOperation, ApiParam, ApiResponse, ApiResponses, and so on.

    For details, see https://github.com/swagger-api/swagger-core/wiki/Annotations.

    For an example, see Example 55.2 Example Java implementation file.

  • In the Java file, adding Swagger annotations to the JAX-RS annotated endpoints (@PATH, @PUT, @POST, @GET, @Produces, @Consumes, @DELETE, @PathParam, and so on).

    For an example, see Example 55.3 Example Java file.

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();
    }
}
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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!!!";
    }

}
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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);

}
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54.4. Accessing OpenAPI Documents
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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
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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
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    • 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
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      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>
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