Migration Spring PetClinic to Quarkus

Agenda
1. who am i
2. what can you expect
3. what is quarkus
4. why migrate
5. migration
a. application description
b. steps
6. performance comparative
7. summary
8. references

$ whoami
JUG leader in the BarcelonaJUG
Organiser at JBCNConf ( Barcelona )
Software Engineer at Red Hat
App. Modernisation and Migration
team
Learning to play guitar
Learning Frozen songs to sing with my
daughter.
@vilojona
jvilalop@redhat.com
aytartana.wordpress.com
github.com/jonathanvila

What can you expect ?
My experience
v 2.1.5
v 1.1.1
opinionated option
magistral lecture
something that works
THE way

what is quarkus
A Kubernetes Native, Java, Scala, Kotlin stack
tailored for GraalVM and OpenJDK HotSpot
crafted from the best of breed Java libraries and standards.

10x faster 100x smaller focused on easy to code
opensource fast paced releases tons of extensions
Quarkus key facts

Quarkus extensions ( > 90 )
Kafka
Camel
Keycloak
Spring
Vert.x
RestEasy
….
Microprofile
Openshift
Jaegger
Flyway
Hibernate
Infinispan
...

Quarkus evolution
2018-12 v 0.0.1
2019-06 v 0.15.0
2019-11 v 1.0.0 Release
2020-01 v 1.2.0
1 minor version every 2 weeks !!! (+/-)

Migration of
Spring PetClinic REST

Why to migrate
My experience
with an easy CDI, REST, …
long startup times, eternal tests,
applications super big,
easy to develope applications
feeling of “lots of things happen under the
hood”
easy to develop applications,
fast
lightweight
not everything ready

Application migrated
Spring Data ( repositories, jdbc , ... )
Spring Web ( REST )
Spring Security
Spring documentation ( Swagger )
Spring actuators
Spring micrometer
Spring CDI
Hibernate Panache
JaxRS
Quarkus Security
OpenAPI
SmallRye Health
Microprofile Metrics
CDI

Elements not migrated
Spring JDBC querying
* no helper methods to work with Inserts, Updates….
* no equivalent to org.springframework.jdbc.core classes
* we need to reimplement everything using AGROAL
Beans activated by Profile
* no annotation built in
* feasible with methods by hand
JMX
* not supported by GraalVM definition
Method Caching
* could use Infinispan but waiting for the local cache method

CDI
● Replace Autowired by Inject
● Beans declaration using @ApplicationScope
● Auto injection on Constructors
● Lazy by default

CDI
PROs
● straight forward migration for Beans
● no feature missing
CONs
● no annotation built-in beans injection depending on Profile
● no private members on injection

JPA Repositories
● Repository classes to implement PanacheRepository<T>
Quarkus will generate the implementation of the usual methods :
list , find, persist, delete

JPA Repositories
PROs
● straightforward migration
CONs
● no Query DSL methods

Application
● Removed SpringApplication class
Quarkus doesn’t need a main entry application class
( needed to configure OpenApi )

Spring REST to JAX-RS
● Move from Spring REST to the standard JAX-RS
@RestController
@RequestMapping, @GetMapping,
@PostMapping, @PutMapping,
@DeleteMapping
@PathVariable
@Path
@GET,
@POST, @PUT
@DELETE
@PathParam

Spring REST to JAX-RS
PROs
INFO
● Spring also supports JAX-RS as 3rd party lib

Spring REST Security to Quarkus Security
● replaced Spring REST Security

Spring REST JDBC Security to Elytron JDBC realm
Add extension dependency : elytron-security-jdbc
Configure on properties file and remove configureGlobal method

Spring REST Security to Quarkus security
PROs
● Almost the same result
● By configuration rather than code
CONs
● Quarkus doesn’t have an expression language

CORS
● configured CORS in the application.properties file

CORS
PROs
● easy to enable , no code involved
CONs
● at global level, not per Controller

Metrics
● Add smallRye metrics extension
● Annotate each method ( for custom metrics )

Metrics
PROs
● OpenMetrics standard naming
CONs
● different naming than micrometer
( compatibility toggle being developed )
● not the same metrics
● no AOP so you need to annotate every
method
● hard to do metrics on super classes

Validation
● Spring Validation to Hibernate Validator
● Move from @ControllerAdvice to JAX-RS ExceptionMapper

Validation
PROs
● standard
● easy
CONs
● Spring has more MVC features

Swagger ( OpenAPI v 3.0 )
● Add extension “openapi”
● Add RestApplication

Swagger ( OpenAPI v 3.0 )
PROs
● standard and easy way to configure
● Swagger-UI OOTB
CONs
● not REST paths scan configuration

AOP for metrics on Repositories
● use of CDI interceptors

AOP for metrics on Repositories
PROs
● standard
● easy to create interceptors
CONs
● need to annotate ALL methods one by one
● no expression language to define methods affected

Test : REST
MockMVC -> RestAssured

Test REST
PROs
● RESTassured is easy to handle and looks very intuitive
CONs
● No way to simulate Roles without creating an user for each role to test
INFO
● Changed JSonPath to GPath

Test : Mocking
Create a Java class extending your real class and put it in Test folder
Tbh, I haven’t done it… I prefer to use Mockito

Test - resources
● Annotate test suites with @QuarkusTest to boot the app
● Annotate test suites with @QuarkusTestResource to load an embedded
resource

BUT……
Spring API compatible with Quarkus

Spring WEB ( REST) : spring-web extension
Using same Spring API for REST Supported Annotations
@RestController
@RequestMapping
@GetMapping
@PostMapping
@PutMapping
@DeleteMapping
@PatchMapping
@RequestParam
@RequestHeader
@MatrixVariable
@PathVariable
@CookieValue
@RequestBody
@ResponseStatus
@ExceptionHandler

Spring DI : spring-di extension
Using same API as Spring DI
Annotations Supported
@Autowired @Repository
@Qualifier @Scope
@Value @Component
* doesn’t support an expression language
@Configuration @Service
@Bean

Spring Data : spring-data-jpa
Using same API for Spring Data Supported
Any interface of : Repository,
CrudRepository, PagingAndSortingRepository,
JpaRepository
Derived Query Methods
User defined Queries
Not Supported
Invocations to any method of
QueryByExampleExecutor
QueryDSL

Spring Security: spring-security extension
Using same API as Spring Security
Annotations Supported
@Secured
@Preauthorized
Expressions allowed
hasAnyRole
permitAll
denyAll
isAnonymous
isAuthenticated
#paramName ==

Performance comparative ( not exhaustive )
SPRING QUARKUS
JVM
QUARKUS
GraalVM
build
( uber-jar )
4 s
43 Mb
13 s
43 Mb
133 s
85 Mb
boot 7.985 s
634.2 Mb
0.901 s
287.3 Mb
0.431 s
15.9 Mb

Summary
● Using specialised standard and open libraries
● Easy to code
● Full of documentation and examples
● Quarkus team/community is awesome
● Fast release cadence
● Few bugs on extensions ( but they fix them like Speedy Gonsales )
● No-reflection goal can have some limitations ( JMX, AOP … )
● Not everything has a 1:1 migration ( Query DSL Methods , … )

References
Repositories
● Spring REST PetClinic
https://github.com/spring-petclinic/spring-petclinic-
rest
● Quarkus REST PetClinic
https://github.com/jonathanvila/spring-petclinic-
rest/tree/quarkus
Documentation/News/Help
● https://quarkus.io
● @QuarkusIO
● https://developers.redhat.com/search/?t=quarkus
● quarkus-dev@googlegroups.com

Interactive Tutorials ( Katacoda )
● https://developers.redhat.com/courses/quarkus/
List of Tutorials
● Getting Started
● For Spring Devs
● Streaming with
Kafka
● Hibernate and
Panache
● Prometeus &
Grafana

Cheat Sheet
● https://lordofthejars.github.io/quarkus-cheat-sheet/
by Alex Soto

Do you want to start coding with Quarkus ?
https://code.quarkus.io/

Windup
● Opensource tool to help on applications migrations
○ https://github.com/windup
○ to cloud readyness
○ to EAP...
○ soon to Quarkus

Thank you for having the patience to attend
and also to all who have
directly or indirectly helped me on this talk.
Special thanks to :
David Gómez, Alejandro Martinez, Abel Salgado
Alex Soto, Georgios Andrianakis
and the rest of Red Hat Quarkus team

Migration Spring PetClinic to Quarkus

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