RESTEasy Classic
This guide is about RESTEasy Classic, which used to be the default Jakarta REST (formerly known as JAX-RS) implementation until Quarkus 2.8. It is now recommended to use Quarkus REST (formerly RESTEasy Reactive), which supports both traditional blocking workloads and reactive workloads equally well. For more information about Quarkus REST, please see the introductory REST JSON guide or the Quarkus REST reference documentation. |
There is another guide if you need a REST client based on RESTEasy Classic (including support for JSON). |
Architecture
The application created in this guide is straightforward: users can add elements to a list through a form, and the list gets updated accordingly.
All the information between the browser and the server is formatted as JSON.
Creating the Maven project
First, we need a new project. Create a new project with the following command:
For Windows users:
-
If using cmd, (don’t use backward slash
\
and put everything on the same line) -
If using Powershell, wrap
-D
parameters in double quotes e.g."-DprojectArtifactId=rest-json-quickstart"
This command generates a new project importing the RESTEasy/Jakarta REST and Jackson extensions, and in particular, adds the following dependency:
<dependency>
<groupId>io.quarkus</groupId>
<artifactId>quarkus-resteasy-jackson</artifactId>
</dependency>
implementation("io.quarkus:quarkus-resteasy-jackson")
To improve user experience, Quarkus registers the three Jackson Java 8 modules, so you do not need to do it manually. |
Quarkus also supports JSON-B, so if you prefer JSON-B over Jackson, you can create a project relying on the RESTEasy JSON-B extension instead:
For Windows users:
-
If using cmd, (don’t use backward slash
\
and put everything on the same line) -
If using Powershell, wrap
-D
parameters in double quotes e.g."-DprojectArtifactId=rest-json-quickstart"
This command generates a new project importing the RESTEasy/Jakarta REST and JSON-B extensions, and in particular, adds the following dependency:
<dependency>
<groupId>io.quarkus</groupId>
<artifactId>quarkus-resteasy-jsonb</artifactId>
</dependency>
implementation("io.quarkus:quarkus-resteasy-jsonb")
Creating the first JSON REST service
In this example, we will create an application to manage a list of fruits.
First, let us create the Fruit
bean as follows:
package org.acme.rest.json;
public class Fruit {
public String name;
public String description;
public Fruit() {
}
public Fruit(String name, String description) {
this.name = name;
this.description = description;
}
}
Nothing fancy. One important thing to note is that having a default constructor is required by the JSON serialization layer.
Now, create the org.acme.rest.json.FruitResource
class as follows:
package org.acme.rest.json;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.Set;
import jakarta.ws.rs.DELETE;
import jakarta.ws.rs.GET;
import jakarta.ws.rs.POST;
import jakarta.ws.rs.Path;
@Path("/fruits")
public class FruitResource {
private Set<Fruit> fruits = Collections.newSetFromMap(Collections.synchronizedMap(new LinkedHashMap<>()));
public FruitResource() {
fruits.add(new Fruit("Apple", "Winter fruit"));
fruits.add(new Fruit("Pineapple", "Tropical fruit"));
}
@GET
public Set<Fruit> list() {
return fruits;
}
@POST
public Set<Fruit> add(Fruit fruit) {
fruits.add(fruit);
return fruits;
}
@DELETE
public Set<Fruit> delete(Fruit fruit) {
fruits.removeIf(existingFruit -> existingFruit.name.contentEquals(fruit.name));
return fruits;
}
}
The implementation is pretty straightforward, and you just need to define your endpoints using the Jakarta REST annotations.
The Fruit
objects will be automatically serialized/deserialized by JSON-B or Jackson,
depending on the extension you chose when initializing the project.
When a JSON extension like To disable the default JSON behavior, set If you don’t depend on the JSON default, it’s highly advisable to use |
Configuring JSON support
Jackson
In Quarkus, the default Jackson ObjectMapper
obtained via CDI (utilized by Quarkus extensions) is set to ignore unknown properties (by disabling DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES
).
To revert to Jackson’s default behavior, set quarkus.jackson.fail-on-unknown-properties=true
in your application.properties
, or set it on a per-class basis with @JsonIgnoreProperties(ignoreUnknown = false)
.
Additionally, the ObjectMapper
formats dates and times in ISO-8601 (by disabling SerializationFeature.WRITE_DATES_AS_TIMESTAMPS
).
To restore Jackson’s default behavior, use quarkus.jackson.write-dates-as-timestamps=true
in your application.properties
.
For custom date format on a single field, use the @JsonFormat
annotation.
Quarkus simplifies Jackson configuration via CDI beans. Create a CDI bean of type io.quarkus.jackson.ObjectMapperCustomizer
to apply various Jackson settings. Here’s an example for registering a custom module:
@ApplicationScoped
public class MyObjectMapperCustomizer implements ObjectMapperCustomizer {
@Override
public void customize(ObjectMapper objectMapper) {
// Add custom Jackson configuration here
}
}
This approach is recommended for configuring Jackson settings.
import com.fasterxml.jackson.databind.ObjectMapper;
import io.quarkus.jackson.ObjectMapperCustomizer;
import jakarta.inject.Singleton;
@Singleton
public class RegisterCustomModuleCustomizer implements ObjectMapperCustomizer {
public void customize(ObjectMapper mapper) {
mapper.registerModule(new CustomModule());
}
}
Users can even provide their own ObjectMapper
bean if they so choose.
If this is done, it is very important to manually inject and apply all io.quarkus.jackson.ObjectMapperCustomizer
beans in the CDI producer that produces ObjectMapper
.
Failure to do so will prevent Jackson-specific customizations provided by various extensions from being applied.
import com.fasterxml.jackson.databind.ObjectMapper;
import io.quarkus.arc.All;
import io.quarkus.jackson.ObjectMapperCustomizer;
import java.util.List;
import jakarta.inject.Singleton;
public class CustomObjectMapper {
// Replaces the CDI producer for ObjectMapper built into Quarkus
@Singleton
ObjectMapper objectMapper(@All List<ObjectMapperCustomizer> customizers) {
ObjectMapper mapper = myObjectMapper(); // Custom `ObjectMapper`
// Apply all ObjectMapperCustomizer beans (incl. Quarkus)
for (ObjectMapperCustomizer customizer : customizers) {
customizer.customize(mapper);
}
return mapper;
}
}
JSON-B
As stated above, Quarkus provides the option of using JSON-B instead of Jackson via the use of the quarkus-resteasy-jsonb
extension.
Following the same approach described in the previous section, JSON-B can be configured using an io.quarkus.jsonb.JsonbConfigCustomizer
bean.
If, for example, a custom serializer named FooSerializer
for type com.example.Foo
needs to be registered with JSON-B, the addition of a bean like the following would suffice:
import io.quarkus.jsonb.JsonbConfigCustomizer;
import jakarta.inject.Singleton;
import jakarta.json.bind.JsonbConfig;
import jakarta.json.bind.serializer.JsonbSerializer;
@Singleton
public class FooSerializerRegistrationCustomizer implements JsonbConfigCustomizer {
public void customize(JsonbConfig config) {
config.withSerializers(new FooSerializer());
}
}
A more advanced option would be to directly provide a bean of jakarta.json.bind.JsonbConfig
(with a Dependent
scope) or, in the extreme case, to provide a bean of type jakarta.json.bind.Jsonb
(with a Singleton
scope).
If the latter approach is leveraged it is very important to manually inject and apply all io.quarkus.jsonb.JsonbConfigCustomizer
beans in the CDI producer that produces jakarta.json.bind.Jsonb
.
Failure to do so will prevent JSON-B specific customizations provided by various extensions from being applied.
import io.quarkus.jsonb.JsonbConfigCustomizer;
import jakarta.enterprise.context.Dependent;
import jakarta.enterprise.inject.Instance;
import jakarta.json.bind.JsonbConfig;
public class CustomJsonbConfig {
// Replaces the CDI producer for JsonbConfig built into Quarkus
@Dependent
JsonbConfig jsonConfig(Instance<JsonbConfigCustomizer> customizers) {
JsonbConfig config = myJsonbConfig(); // Custom `JsonbConfig`
// Apply all JsonbConfigCustomizer beans (incl. Quarkus)
for (JsonbConfigCustomizer customizer : customizers) {
customizer.customize(config);
}
return config;
}
}
JSON Hypertext Application Language (HAL) support
The HAL standard is a simple format to represent web links.
To enable the HAL support, add the quarkus-hal
extension to your project. Also, as HAL needs JSON support, you need to add either the quarkus-resteasy-jsonb
or the quarkus-resteasy-jackson
extension.
GAV | Usage |
---|---|
|
After adding the extensions, we can now annotate the REST resources to produce the media type application/hal+json
(or use RestMediaType.APPLICATION_HAL_JSON). For example:
@Path("/records")
public class RecordsResource {
@GET
@Produces({ MediaType.APPLICATION_JSON, "application/hal+json" })
@LinkResource(entityClassName = "org.acme.Record", rel = "list")
public List<TestRecord> getAll() {
// ...
}
@GET
@Path("/first")
@Produces({ MediaType.APPLICATION_JSON, "application/hal+json" })
@LinkResource(rel = "first")
public TestRecord getFirst() {
// ...
}
}
Now, the endpoints /records
and /records/first
will accept the media type, both json
and hal+json
, to print the records in Hal format.
For example, if we invoke the /records
endpoint using curl to return a list of records, the HAL format will look like as follows:
& curl -H "Accept:application/hal+json" -i localhost:8080/records
{
"_embedded": {
"items": [
{
"id": 1,
"slug": "first",
"value": "First value",
"_links": {
"list": {
"href": "http://localhost:8081/records"
},
"first": {
"href": "http://localhost:8081/records/first"
}
}
},
{
"id": 2,
"slug": "second",
"value": "Second value",
"_links": {
"list": {
"href": "http://localhost:8081/records"
},
"first": {
"href": "http://localhost:8081/records/first"
}
}
}
]
},
"_links": {
"list": {
"href": "http://localhost:8081/records"
}
}
}
When we call a resource /records/first
that returns only one instance, then the output is:
& curl -H "Accept:application/hal+json" -i localhost:8080/records/first
{
"id": 1,
"slug": "first",
"value": "First value",
"_links": {
"list": {
"href": "http://localhost:8081/records"
},
"first": {
"href": "http://localhost:8081/records/first"
}
}
}
Creating a frontend
Now let us add a simple web page to interact with our FruitResource
.
Quarkus automatically serves static resources located under the META-INF/resources
directory.
In the src/main/resources/META-INF/resources
directory, add a fruits.html
file with the content from this fruits.html file in it.
You can now interact with your REST service:
-
start Quarkus with:
CLIquarkus dev
Maven./mvnw quarkus:dev
Gradle./gradlew --console=plain quarkusDev
-
open a browser to
http://localhost:8080/fruits.html
-
add new fruits to the list via the form
Building a native executable
You can build a native executable with the usual command:
quarkus build --native
./mvnw install -Dnative
./gradlew build -Dquarkus.native.enabled=true
Running it is as simple as executing ./target/rest-json-quickstart-1.0.0-SNAPSHOT-runner
.
You can then point your browser to http://localhost:8080/fruits.html
and use your application.
About serialization
JSON serialization libraries use Java reflection to get the properties of an object and serialize them.
When using native executables with GraalVM, all classes that will be used with reflection need to be registered.
The good news is that Quarkus does that work for you most of the time.
So far, we have not registered any class, not even Fruit
, for reflection usage, and everything is working fine.
Quarkus performs some magic when it is capable of inferring the serialized types from the REST methods.
When you have the following REST method, Quarkus determines that Fruit
will be serialized:
@GET
public List<Fruit> list() {
// ...
}
Quarkus does that for you automatically by analyzing the REST methods at build time, and that is why we did not need any reflection registration in the first part of this guide.
Another common pattern in the Jakarta REST world is to use the Response
object.
Response
comes with some nice perks:
-
You can return different entity types depending on what happens in your method (a
Legume
or anError
for instance). -
You can set the attributes of the
Response
(the status comes to mind in the case of an error).
Your REST method then looks like this:
@GET
public Response list() {
// ...
}
Quarkus cannot determine at build time the type included in the Response
as the information is not available.
In this case, Quarkus won’t be able to register for reflection in the required classes automatically.
This leads us to our next section.
Using response
Let us create the Legume
class, which will be serialized as JSON, following the same model as for our Fruit
class:
package org.acme.rest.json;
public class Legume {
public String name;
public String description;
public Legume() {
}
public Legume(String name, String description) {
this.name = name;
this.description = description;
}
}
Now let’s create a LegumeResource
REST service with only one method that returns the list of legumes.
This method returns a Response
and not a list of Legume
.
package org.acme.rest.json;
import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.Set;
import jakarta.ws.rs.Consumes;
import jakarta.ws.rs.GET;
import jakarta.ws.rs.Path;
import jakarta.ws.rs.Produces;
import jakarta.ws.rs.core.MediaType;
import jakarta.ws.rs.core.Response;
@Path("/legumes")
@Produces(MediaType.APPLICATION_JSON)
@Consumes(MediaType.APPLICATION_JSON)
public class LegumeResource {
private Set<Legume> legumes = Collections.synchronizedSet(new LinkedHashSet<>());
public LegumeResource() {
legumes.add(new Legume("Carrot", "Root vegetable, usually orange"));
legumes.add(new Legume("Zucchini", "Summer squash"));
}
@GET
public Response list() {
return Response.ok(legumes).build();
}
}
Now, let us add a simple web page to display our list of legumes.
In the src/main/resources/META-INF/resources
directory, add a legumes.html
file with the content from this
legumes.html file in it.
Open a browser to http://localhost:8080/legumes.html, and you will see our list of legumes.
The interesting part starts when running the application as a native executable:
-
create the native executable with:
CLIquarkus build --native
Maven./mvnw install -Dnative
Gradle./gradlew build -Dquarkus.native.enabled=true
-
execute it with
./target/rest-json-quickstart-1.0.0-SNAPSHOT-runner
-
open a browser and go to http://localhost:8080/legumes.html
There are no legumes there.
As mentioned above, the issue is that Quarkus could not determine the Legume
class, which will require some reflection by analyzing the REST endpoints.
The JSON serialization library tries to get the list of fields of Legume
and gets an empty list, so it does not serialize the fields' data.
At the moment, when JSON-B or Jackson tries to get the list of fields of a class, if the class is not registered for reflection, no exception will be thrown. GraalVM will return an empty list of fields. Hopefully, this will change in the future and make the error more obvious. |
We can register Legume
for reflection manually by adding the @RegisterForReflection
annotation on our Legume
class:
import io.quarkus.runtime.annotations.RegisterForReflection;
@RegisterForReflection
public class Legume {
// ...
}
The @RegisterForReflection annotation instructs Quarkus to keep the class and its members during the native compilation.
More details about the @RegisterForReflection annotation can be found on the native application tips page.
|
Let us do that and follow the same steps as before:
-
hit
Ctrl+C
to stop the application -
create the native executable with:
CLIquarkus build --native
Maven./mvnw install -Dnative
Gradle./gradlew build -Dquarkus.native.enabled=true
-
execute it with
./target/rest-json-quickstart-1.0.0-SNAPSHOT-runner
-
open a browser and go to http://localhost:8080/legumes.html
This time, you can see our list of legumes.
Being reactive
For reactive workloads, please always use Quarkus REST. |
You can return reactive types to handle asynchronous processing. Quarkus recommends the usage of Mutiny to write reactive and asynchronous code.
To integrate Mutiny and RESTEasy, you need to add the quarkus-resteasy-mutiny
dependency to your project:
<dependency>
<groupId>io.quarkus</groupId>
<artifactId>quarkus-resteasy-mutiny</artifactId>
</dependency>
implementation("io.quarkus:quarkus-resteasy-mutiny")
Then, your endpoint can return Uni
or Multi
instances:
@GET
@Path("/{name}")
public Uni<Fruit> getOne(@PathParam String name) {
return findByName(name);
}
@GET
public Multi<Fruit> getAll() {
return findAll();
}
Use Uni
when you have a single result.
Use Multi
when you have multiple items that may be emitted asynchronously.
You can use Uni
and Response
to return asynchronous HTTP responses: Uni<Response>
.
More details about Mutiny can be found in Mutiny - an intuitive reactive programming library.
HTTP filters and interceptors
Both HTTP request and response can be intercepted by providing ContainerRequestFilter
or ContainerResponseFilter
implementations respectively.
These filters are suitable for processing the metadata associated with a message: HTTP headers, query parameters, media type, and other metadata.
They also can abort the request processing, for instance, when the user does not have permission to access the endpoint.
Let’s use ContainerRequestFilter
to add logging capability to our service. We can do that by implementing ContainerRequestFilter
and annotating it with the @Provider
annotation:
package org.acme.rest.json;
import io.vertx.core.http.HttpServerRequest;
import org.jboss.logging.Logger;
import jakarta.ws.rs.container.ContainerRequestContext;
import jakarta.ws.rs.container.ContainerRequestFilter;
import jakarta.ws.rs.core.Context;
import jakarta.ws.rs.core.UriInfo;
import jakarta.ws.rs.ext.Provider;
@Provider
public class LoggingFilter implements ContainerRequestFilter {
private static final Logger LOG = Logger.getLogger(LoggingFilter.class);
@Context
UriInfo info;
@Context
HttpServerRequest request;
@Override
public void filter(ContainerRequestContext context) {
final String method = context.getMethod();
final String path = info.getPath();
final String address = request.remoteAddress().toString();
LOG.infof("Request %s %s from IP %s", method, path, address);
}
}
Now, whenever a REST method is invoked, the request will be logged into the console:
2019-06-05 12:44:26,526 INFO [org.acm.res.jso.LoggingFilter] (executor-thread-1) Request GET /legumes from IP 127.0.0.1
2019-06-05 12:49:19,623 INFO [org.acm.res.jso.LoggingFilter] (executor-thread-1) Request GET /fruits from IP 0:0:0:0:0:0:0:1
2019-06-05 12:50:44,019 INFO [org.acm.res.jso.LoggingFilter] (executor-thread-1) Request POST /fruits from IP 0:0:0:0:0:0:0:1
2019-06-05 12:51:04,485 INFO [org.acm.res.jso.LoggingFilter] (executor-thread-1) Request GET /fruits from IP 127.0.0.1
CORS filter
Cross-origin resource sharing (CORS) is a mechanism that allows restricted resources on a web page to be requested from another domain outside the domain from which the first resource was served.
Quarkus includes a CORS filter at the HTTP layer level. For more information about the CORS filters and their usage, see the CORS filter section of the Quarkus "Cross-origin resource sharing" guide.
GZip Support
Quarkus comes with GZip support (even though it is not enabled by default). The following configuration knobs allow to configure GZip support.
quarkus.resteasy.gzip.enabled=true (1)
quarkus.resteasy.gzip.max-input=10M (2)
1 | Enable Gzip support. |
2 | Configure the upper limit on the deflated request body.
This is useful to mitigate potential attacks by limiting their reach. The default value is 10M .
This configuration option would recognize strings in this format (shown as a regular expression): [0-9]+[KkMmGgTtPpEeZzYy]? .
If no suffix is given, assume bytes. |
Once GZip support has been enabled, you can use it on an endpoint by adding the @org.jboss.resteasy.annotations.GZIP
annotation to your endpoint method.
There is also the quarkus.http.enable-compression configuration property, which enables HTTP response compression globally.
If enabled, a response body is compressed if the Content-Type HTTP header is set and the value is a compressed media type configured via the quarkus.http.compress-media-types configuration property.
|
Multipart Support
RESTEasy supports multipart via the RESTEasy Multipart Provider.
Quarkus provides an extension called quarkus-resteasy-multipart
to make things easier for you.
This extension slightly differs from the RESTEasy default behavior as the default charset (if none is specified in your request) is UTF-8 rather than US-ASCII.
You can configure this behavior with the following configuration properties:
Configuration property fixed at build time - All other configuration properties are overridable at runtime
Configuration property |
Type |
Default |
---|---|---|
Default charset. Note that the default value is UTF-8 which is different from RESTEasy’s default value US-ASCII. Environment variable: Show more |
|
|
The default content-type. Environment variable: Show more |
string |
|
Servlet compatibility
In Quarkus, RESTEasy can either run directly on top of the Vert.x HTTP server, or on top of Undertow if you have any servlet dependency.
As a result, certain classes, such as HttpServletRequest
are not always available for injection.
Most use cases for this particular class are covered by Jakarta REST equivalents, except for getting the remote client’s IP.
RESTEasy comes with a replacement API that you can inject:
HttpRequest
, which has the methods
getRemoteAddress()
and getRemoteHost()
to solve this problem.
RESTEasy and REST Client interactions
In Quarkus, the RESTEasy extension and the REST Client extension share the same infrastructure. One important consequence of this consideration is that they share the same list of providers (in the Jakarta REST meaning of the word).
For instance, if you declare a WriterInterceptor
, it will, by default, intercept both the servers calls and the client calls,
which might not be the desired behavior.
However, you can change this default behavior and constrain a provider to:
-
only consider server calls by adding the
@ConstrainedTo(RuntimeType.SERVER)
annotation to your provider; -
only consider client calls by adding the
@ConstrainedTo(RuntimeType.CLIENT)
annotation to your provider.
What’s Different from Jakarta EE Development
No Need for Application
Class
Configuration via an application-supplied subclass of Application
is supported but not required.
Only a single Jakarta REST application
In contrast to Jakarta REST (and RESTeasy) running in a standard servlet container, Quarkus only supports the deployment of a single Jakarta REST application.
If multiple Jakarta REST Application
classes are defined, the build will fail with the message Multiple classes have been annotated with @ApplicationPath which is currently not supported
.
If multiple Jakarta REST applications are defined, the property quarkus.resteasy.ignore-application-classes=true
can be used to ignore all explicit Application
classes.
This makes all resource-classes available via the application-path as defined by quarkus.resteasy.path
(default: /
).
Support limitations of Jakarta REST application
The RESTEasy extension doesn’t support the method getProperties()
of the class jakarta.ws.rs.core.Application
.
Moreover, it only relies on the methods getClasses()
and getSingletons()
to filter out the annotated resource, provider, and feature classes.
It does not filter out the built-in resource, provider, and feature classes and also the resource, provider, and feature classes registered by the other extensions.
Finally, the objects returned by the method getSingletons()
are ignored, only the classes are taken into account to filter out the resource, provider and feature classes, in other words the method getSingletons()
is managed the same way as getClasses()
.
Lifecycle of Resources
In Quarkus, all Jakarta REST resources are treated as CDI beans.
It’s possible to inject other beans via @Inject
, bind interceptors using bindings such as @Transactional
, define @PostConstruct
callbacks, etc.
If no scope annotation is declared on the resource class, then the scope is defaulted.
The quarkus.resteasy.singleton-resources
property can control the default scope.
If set to true
(default), then a single instance of a resource class is created to service all requests (as defined by @jakarta.inject.Singleton
).
If set to false
, then a new instance of the resource class is created per each request.
An explicit CDI scope annotation (@RequestScoped
, @ApplicationScoped
, etc.) always overrides the default behavior and specifies the lifecycle of resource instances.
Include/Exclude Jakarta REST classes with build time conditions
Quarkus enables the inclusion or exclusion of Jakarta REST Resources, Providers and Features directly thanks to build time conditions in the same that it does for CDI beans.
Thus, the various Jakarta REST classes can be annotated with profile conditions (@io.quarkus.arc.profile.IfBuildProfile
or @io.quarkus.arc.profile.UnlessBuildProfile
) and/or with property conditions (io.quarkus.arc.properties.IfBuildProperty
or io.quarkus.arc.properties.UnlessBuildProperty
) to indicate to Quarkus at build time under which conditions these Jakarta REST classes should be included.
In the following example, Quarkus includes the endpoint sayHello
if and only if the build profile app1
has been enabled.
@IfBuildProfile("app1")
public class ResourceForApp1Only {
@GET
@Path("sayHello")
public String sayHello() {
return "hello";
}
}
Please note that if a Jakarta REST Application has been detected and the method getClasses()
and/or getSingletons()
has/have been overridden, Quarkus will ignore the build time conditions and consider only what has been defined in the Jakarta REST Application.
Conclusion
Creating JSON REST services with Quarkus is easy as it relies on proven and well-known technologies.
As usual, Quarkus further simplifies things under the hood when running your application as a native executable.
There is only one thing to remember: if you use Response
and Quarkus cannot determine the beans that are serialized, you need to annotate them with @RegisterForReflection
.