ExampleApps.md

What Examples do we have?

• For the below examples we have branches with 'Java EE' and 'Quarkus', so we can tell the differences required to migrate from Java EE to Quarkus
• We have a script at data/fetch.sh which will fetch the sample apps we know about

From JBoss EAP QuickStarts

KitchenSink

• https://github.com/tqvarnst/jboss-eap-quickstarts/tree/quarkus-3.2/kitchensink

HelloWorld MDB

• This example started from JBoss EAP Quickstarts: https://github.com/jboss-developer/jboss-eap-quickstarts/tree/7.4.x/helloworld-mdb/src/main/java/org/jboss/as/quickstarts/mdb
• Our team then ported 'HelloWorld MDB' to Quarkus:https://github.com/savitharaghunathan/helloworld-mdb/tree/quarkus
  • Note these blog posts from prior work of modernizing this same HelloWorld app, the difference with our latest work and the below is the change our team did to also address JMS to Reactive changes:
    • https://developers.redhat.com/blog/2019/11/07/quarkus-modernize-helloworld-jboss-eap-quickstart-part-1#let_s_modernize_helloworld
    • https://developers.redhat.com/blog/2019/11/08/quarkus-modernize-helloworld-jboss-eap-quickstart-part-2
  • We also created some new rules for JMS to Reactive here:
    • windup/windup-rulesets#1043
  • https://github.com/jmle/rulesets/blob/jms-rule/default/generated/quarkus/05-jms-to-reactive-quarkus.windup.yaml

CoolStuff Store

• https://github.com/mathianasj/eap-coolstore-monolith.git

TicketMonster

• https://github.com/jmle/monolith.git

General

EJBs -> CDI

A general pattern with moving away from an EJB and embracing CDI is to:

1. Replace @Stateless and @Remote with @ApplicationScoped from CDI.
2. Add @Transactional to manage transactions declaratively from JTA (if needed).
3. Remove the remote interface, as CDI doesn't require separate interfaces for bean implementation.

Background reading

• https://quarkus.io/guides/cdi

Servlets

• Quarkus has a compatibility module quarkus-undertow which allows using Servlets and JSPs

CoolStuff Store

What was changed from EAP to Quarkus?

• javax -> jakarata
• java.util.logging.Logger -> org.jboss.logging.Logger
• rest
  • CartEndpoint.java
    • SessionScoped -> RequestScoped
    • JMSDestinationDefinitions removed
  • User.java was introduced (didn't exist on EAP side)
• service
  • CatalogService
    • Stateless -> ApplicationScoped
  • InventoryNotificationMDB
    • Looks like several JMS related changes
    • Removed implements MessageListener
  • OrderService
    • Stateless -> ApplicationScoped
  • OrderServiceMDB
    • Perhaps similar pattern to InventoryNotificationMDB
  • ProductService
    • Stateless -> ApplicationScoped
  • PromoService
    • javax -> jakarata
  • ShippingService
    • Stateless -> RequestScoped
      • NEED to identify difference of when to go to ApplicationScoped vs RequestScoped
  • ShoppingCarOrderProcessor
    • java.util.logging.Logger -> org.jboss.logging.Logger
    • JMS to Reactive messaging (org.eclipse.microprofile.reactive.messaging)
    • Stateless -> RequestScoped
  • ShoppingCartService
    • javax -> jakarata
    • Stateful -> SessionScoped
    • java.util.logging.Logger -> org.jboss.logging.Logger
• utils
  • Transformers
    • javax -> jakarata
  • (Deleted) - Don't know why these were deleted going to Quarkus
    • DataBaseMigrationStartup
    • Producers
    • StartupListeners
• resources
  • META-INF
    • DELETED: persistence.xml
• webapp
  • DELETED: keycloak.json
• pom.xml
  • Removed: war
  • Various updates to move to Quarkus and remove Java EE specifics

Helloworld-mdb App

source code: https://github.com/savitharaghunathan/helloworld-mdb/compare/main...quarkus

What was changed from EAP to Quarkus?

• javax -> jakarata

• java.util.logging.Logger -> org.jboss.logging.Logger

• mdb

  • HelloWorldQueueMDB.java
    • javax -> jakarta
    • java logging -> jboss logging
    • javax jms changes -> eclipse microprofile smallrye changes
    • removed mdb config
    • Added @ApplicationScoped annotation
  • HelloWorldTopicMDB.java
    • same as above

• servlet

  • HelloWorldMDBServletClient.java
    • javax -> jakarta import changes
    • webservlet annotation -> path
    • removed jms destination config
    • replaced @Resource(lookup = "java:/queue/HELLOWORLDMDBQueue") -> Incoming and Channel annotation with the queue name
    • refactored doGet function
      • logic change for obtaining the url paramater
      • rewrote templating using string builder
      • Added a function that generates messages, prints them on console, sends them to the queue/topic
    • removed doPost func (I wasnt sure if it did anything and removing it, did not alter the application behavior)

• Moved index.html to /src/main/resources/META-INF

• application.properties

  • Added config for AMQP

• pom.xml

  • Removed war
  • JMS dependency changes
  • java ee -> quarkus lib changes