Devoxx : being productive with JHipster

Being productive with
JHipster
Julien Dubois & Deepu K Sasidharan
1

Who we are
● Julien Dubois
○ JHipster creator & lead developer
○ Chief Innovation Officer at Ippon Technologies
● Deepu K Sasidharan
○ JHipster co-lead
○ Product developer at XebiaLabs
2

React to the talk!
● Mention @java_hipster
● We’ll do our best to answer you during the talk!
3J

Introduction to JHipster
● Spring Boot + AngularJS application generator
● Fully Open Source
● +250 contributors
● +5300 Github stars
● +320,000 installations
● +100 companies officially using it
4D

Section I Installation & Application
Generation
7

Installation
● Installation with NPM
● Alternative installations: Docker, JHipster Devbox
> npm install -g generator-jhipster@3.9.1
8D

oh-my-zsh
● oh-my-zsh is a framework for managing your ZSH configuration
○ http://ohmyz.sh/
● Specific JHipster plugin
○ Also recommended: git, docker and docker-compose plugins
> jh
9J

Creating an application
● Questions & answers to generate an application tailored to your needs
● Questions depend on the previous answers
● Validation & help to avoid mistakes
> mkdir myapp && cd myapp
> yo jhipster
10D

IDE configuration
● Intellij IDEA, Eclipse, Netbeans
○ Specific “IDE” profile for MapStruct
● Visual Studio Code
○ Usage with Maven/Gradle or JHipster App
> idea .
11J

What has been generated?
● Spring Boot application
● AngularJS application
● Liquibase changelog files
● Configuration files
12D

The generated screens: security
● Several generated screens
○ Login, logout, forgot password…
○ Account management
○ User management
● Useful for most applications
○ Pages must be tuned depending on business needs
○ User roles will be added/extended
● Provide also good examples of working screens
○ Forms, directives, validation...
13J

The generated screens: administration
● Administration screens
○ Monitoring
○ Health
○ Spring Boot configuration
○ Spring Security audits
○ Log management
● Very useful in production
● Will probably be a separate module in JHipster 4
14D

Maven / Gradle usage
● Maven/Gradle wrappers
● Available goals: clean, compile, run, test...
● Specific profiles: “dev” and “prod”
> ./mvnw clean test
15J

Docker and Docker Compose
● JHipster generates full Docker & Docker Compose configuration
○ Build an image for the current application
○ Launch services: MySQL, Elasticsearch, Kafka...
○ Sonar
● Very useful in development, and for microservices
> docker-compose -f src/main/docker/mysql.yml up -d
16D

SQL Database support
● Can use different development & production databases
● H2 disk-based and in-memory
● Supported databases: MySQL, MariaDB, PostgreSQL, Oracle
● Spring Data JPA
● HikariCP
17J

Liquibase
● Liquibase manages database updates
○ Using changelogs
● Great for working in team
○ After a “git pull”, your database is always up-to-date!
● Tables, relationships, data are all created by JHipster at generation time,
and applied when the application starts
18D

Hibernate 2nd level cache
● 3 options
○ No cache
○ Ehcache
■ Default for monoliths
■ Upgrade soon to Ehcache 3
○ Hazelcast
■ Default for microservices, with a specific configuration for clustering
● Automatically monitored
○ Production defaults are low, should be tuned depending on your business/hardware
19D

MongoDB
● Alternative to SQL databases
● Faster startup, works great for cloud applications
● Spring Data MongoDB
● Changelogs are managed by Mongobee
20J

Cassandra
● Another alternative to SQL databases
● Custom implementation using the DataStax Java Driver
● Custom changelog implementation
● Spring Boot Cassandra support comes from JHipster!
21J

Elasticsearch
● Optional add-on to the other options
○ Very popular
● Use Spring Data Elasticsearch
● Add server-side and client-side code for searching entities
● Uses by default an embedded server in development, we recommend the
Docker image for faster turnaround
22D

Kafka
● Optional add-on
○ For handling very large amount of events
○ Some people use it to handle load and failover with microservices
● Use Spring Cloud Stream
● Simple integration for the moment
23J

Security
● Session-based authentication
○ Stateful
○ Classical “form-based” authentication with Spring Security
○ Improved remember-me over the standard Spring Security implementation
● OAuth2
○ Stateless
○ Needs a specific back-end, only works with SQL and MongoDB
● JWT
○ Stateless
○ Very good for microservices
24D

Internationalization
● i18n is managed by Angular Translate on the client-side
● “normal” Java i18n is used on the server-side
● 26 langages out-of-the-box, easy to extend
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Swagger
● Automatic documentation for all REST APIs
● Executable and easy-to-use
● Great for AngularJS developers (no need to read the Spring MVC REST
code!)
26D

WebSockets
● Optional add-on
● Uses Spring WebSockets
○ Easy to integrate
○ Hard to scale on several nodes
● Sample generated screen to track users live
○ Tracks who is logged in, their current screen, all in real time
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Creating an entity
● The entity sub-generator is our more complete and more popular
sub-generator
● Creates an entity, with full CRUD support
○ Liquibase changelog
○ Spring Data JPA repository
○ Spring MVC REST endpoint
○ AngularJS router/controller/service/view
○ i18n
○ Tests
● Tip: use Git to save your work before/after running a sub-generator!
28D

Creating fields
● Fields are created one after the other
● Lots of types are available
○ Types depend on the underlying database (SQL/MongoDB/Cassandra)
● Validation is available
○ AngularJS validation on the client side
○ Bean validation used by Spring MVC REST and Hibernate
○ Database constraints
29J

Managing relationships
● Relationships only work for SQL databases
● All JPA relationship types are supported
○ one-to-one, many-to-one, one-to-many, many-to-many
● Unidirectional and bidirectional relationships
● Multiple relationships on the same 2 entities
30D

The “User” entity
● Specific entity, generated with the core application
○ Used by Spring Security
○ Can be extended
● Supports many-to-one, many-to-many (non owner side) and one-to-one
(non owner side) relationships
● Tip: some people do a one-to-one relationship to a specific “CustomUser”
entity, which they modify/extend (modifying the User entity can cause
issues when upgrading the application)
31J

Using DTOs
● DTOs = Data Transfer Objects
● Very useful in business applications, where basic CRUD entities are not
enough
○ Add business logic
○ Separate the view layer from the persistence layer
○ Helps with lazy-loading
● Uses MapStruct to generate the mapping
○ Java annotation processor
32D

Using a service layer
● Very useful in business applications, where basic CRUD entities are not
enough
○ Like DTOs
○ Usually both options are selected at the same time, but it depends on what you want to do
● Service beans are Spring beans: security, transactions, monitoring are
available
● Option to use just an implementation, or an interface + an implementation
33J

Pagination options
● 3 pagination options are available:
○ Simple pager
○ Pagination links
○ Infinite scroll
● Depends on your business needs and database capabilities (Cassandra
can’t do pagination links)
● Very useful if you have data (all situations except reference tables)
○ Common pitfall is to do Gatling tests on non-paginated entities
34D

Re-generating an entity
● The entity sub-generator can re-generate an existing entity
○ Just call it again with the entity name
○ Fields and relationships can be removed/added
● Tip: advanced users modify directly the .jhipster/*.json files
○ Internal JHipster configuration files
○ In fact just the answers serialized in JSON - easy to understand and modify if needed
35J

Upgrading an application
● Upgrades can be done automatically with the Upgrade sub-generator
● Use Git branches to generate the application with a different version
● Automatic merge if there is no problem
● Conflicts must be resolved manually
> npm install -g generator-jhipster@3.10.0
> yo jhipster:upgrade
36D

Section II Working with the Generated
Application
37

Setting up a good development environment
● “Developer Experience” is very important for JHipster
○ Lots of effort to make your development environment great
● Hot reload should work everywhere
● IDEs should work automatically
● Docker Compose for all 3rd-party tools, so they are easy to manage
38J

Spring Boot devtools
● Automatically reloads the application when a compilation occurs
○ The application classloader gets refreshed
○ The JVM and third-party libraries are not refreshed
● Hot reload is very quick: 2 to 4 seconds depending on your setup
● Liquibase being managed by JHipster, the database schema is also
automatically updated
● Tip: configure your IDE to do automatic compilation, and everything is
updated automatically!
39D

Spring Data JPA
● Easily generate SQL requests from Java method names
○ List<Product> findByOrderByName()
○ List<Item> findByUser(User user)
○ List<Customer> findByLastName(String lastName)
● Tip: type the method name in the REST controller that uses it, and then use
your IDE to automatically generate the method
40J

Fluent methods in JPA entities
● JPA entities generated by JHipster have fluent methods
● Allows to chain method calls on entities
Post post = new Post()
.title("Fluent methods are cool!")
.createdOn(LocalDate.now())
.addPostComment(postComment);
41J

Liquibase
● Changelogs are generated by JHipster, and can also be hand-coded
● Another solution is to use the Maven “liquibase:diff” goal
○ Modify the JPA code
○ Compile the application
○ Run “./mvnw liquibase:diff”
○ This will generate a changelog to update your database schema
○ Add the resulting changelog to the master changelog
● Changelogs are applied at application start-up (also works with Spring
Boot hot reload)
42D

Gulp & BrowserSync
● Gulp allows to run many JavaScript tasks: minification, injection, tests…
● One of its main usage with JHipster is to run BrowserSync
● BrowserSync has 2 great features
○ Synchronizes clicks, scrolls and inputs on different browsers: great for testing with several
screen resolutions!
○ Reloads the browser(s) when a file changes: great for doing web application development!
● Tip: combined with Spring Boot devtools and Liquibase, a correct JHipster
development environment should have everything hot reloaded
automatically!
43J

Bower
● Installation and update of JavaScript/CSS libraries for the client-side
application
● If BrowserSync runs in the background, libraries are automatically injected
in the index.html page (otherwise, do a “gulp inject” to force the injection)
● Tip: in JHipster 4.0, Bower should disappear, and will be totally replaced by
NPM
> bower install bootstrap-material-design#0.3.0 --save
44D

Profiles
● JHipster manages profiles both at runtime (Spring profiles) and at build
time (Maven/Gradle profiles)
● 2 main profiles
○ “dev” for development: focuses on great Developer Experience
○ “prod” for production: focuses on the best performance for production
● Other profiles are for specific situations
○ “swagger” Spring profile to enable/disable Swagger
○ “no-liquibase” Spring profile to disable liquibase
○ “ide” Maven profile to help configuring the IDE (for MapStruct usage)
45J

Working with AngularJS
● JHipster follows the John Papa style guide
○ Official guide, endorsed by the AngularJS team
○ Lots of rules and best practices, clearly explained
○ Gives a migration path to AngularJS 2
● JHipster uses a few third-party libraries
○ UI Router for routing
○ Twitter Bootstrap
○ Datepicker, infinite scrolling
● All other libraries are supposed to be installed easily through Bower
46D

A word on Angular 2
● Angular 2 support is coming soon in JHipster!
○ Work is 90% ready on the main generator
○ The entity sub-generator is not migrated yet
○ We will have a new option to generate either an AngularJS 1 or an Angular 2 project
○ Both options will live next to each other
○ Focus will shift to Angular 2 as more projects adopt it, and as it becomes more stable
● This will be the main focus of JHipster 4.0
47D

Customizing Bootstrap
● JHipster uses the “standard” Twitter Bootstrap classes
● They can be overridden as usual
○ Update the main.css file if using CSS
○ Update the main.scss if using Sass
● It’s also easy to install a specific theme (often automatic just using Bower)
● Bootstrap 4 support is coming in JHipster 4.0
48J

Section III Testing the Generated Application
49

Spring integration tests
● JHipster provides JUnit and Spring integration test support
○ Integration tests are fast as the Spring context and the database are re-used over each
test
○ Mockito is used to mock dependencies
○ @WithMockUser from Spring Security is great
○ Yes, using field injection with Spring is annoying for tests!
● The entity sub-generator generates specific tests for each CRUD operation
50J

Karma.js
● Unit tests are generated for the main application and for the entities
○ Uses mock to simulate the back-end
51D

Gatling
● Available as an option
● Generate load testing simulations for CRUD entities
○ Uses the 4 CRUD methods
○ Must be tuned depending on your real business needs
○ Generates a great dashboard
○ Don’t forget to use pagination!
● Gatling tests can be run directly from Maven
● Simulations are developed with a Scala DSL
○ Not very complex to use
○ Scala compilation is slow at startup!
52J

Cucumber
● Available as an option
● Behavior-driven tests becoming more and more popular
● Simple integration at the moment
○ Might not evolve as we can’t generate business code
53D

Protractor
● Great way to do integration testing with AngularJS
○ End-to-end test of the application
○ Needs a fully working back-end server
○ Uses by default a Firefox browser, which often leads to issues
54J

Code quality with Sonar
● Sonar gives a complete quality report of the application
○ Java and Spring code
○ JavaScript code
● JHipster provides a Docker Compose configuration with a fully working
Sonar server
> docker-compose -f src/main/docker/sonar.yml up -d
> ./mvnw clean test sonar:sonar
55J

Continuous integration
● Travis configuration is generated
○ Full test of both the back-end and the front-end
○ Similar to what the JHipster team uses to test the generator itself!
● Jenkins 2 configuration is generated
○ With complete documentation on the JHipster website for Jenkins 1 and 2
56D

Section IV Going to Production
57

JHipster production build
● Generates an executable WAR file with production options
○ Minified front-end
○ GZip filter
○ HTTP cache headers
> ./mvnw clean package -Pprod
> docker-compose -f src/main/docker/mysql.yml up -d
> cd target
> ./myapplication-0.0.1-SNAPSHOT.war
58J

Monitoring JHipster
● Standard Spring Boot Actuator endpoints are available
○ With a UI!
● Dropwizard Metrics is configured
○ JVM & HTTP request metrics
○ Spring Beans metrics
○ Ehcache metrics
● Logs can be sent to an ELK server
○ More about the JHipster Console in the “microservices” section
59D

Building a Docker image
● Full Docker configuration has been generated in the src/main/docker
folder
○ A Dockerfile
○ A Docker Compose configuration with the application and its dependencies
● The Docker daemon must be running when the Docker image is built
> ./mvnw package -Pprod docker:build
> docker-compose -f src/main/docker/app.yml up
60J

The Docker Compose sub-generator
● Works for both monoliths and microservices
● Allows for more complex setups than the default Docker Compose file
○ Adding monitoring with the JHipster Console
○ Mostly useful for microservices
61J

Docker Compose & Docker Swarm
● Docker Compose applications can be deployed to Docker Swarm cluster
○ Having a production-grade Docker Swarm cluster is very hard
○ Deploying to a cluster is similar as deploying locally
● Applications launched in a cluster can be scaled
○ Works out-of-the-box for microservices
○ A gateway/load balancer is necessary to handle port conflicts
○ Hibernate 2nd level cache must be disabled, or distributed
> docker-compose -f src/main/docker/app.yml scale myapplication-app=3
62D

Deploying on Kubernetes
● Kubernetes sub-generator is in BETA
○ Developed by Ray Tsang (@saturnism) from Google
○ Similar to the Docker Swarm sub-generator
> yo jhipster:kubernetes
63J

Deploying to Cloud Foundry
● Specific sub-generator to deploy to Cloud Foundry
● Uses the “cf” command-line to deploy the application, bind a database
service, etc.
○ Can only support services available on your Cloud Foundry marketplace
> yo jhipster:cloudfoundry
64D

Deploying to Heroku
● Specific sub-generator to deploy to Heroku
○ Developed by Joe Kutner from Heroku
● Uses the “heroku” command-line to deploy the application, bind a database
service, etc.
> yo jhipster:heroku
65J

Other deployment platforms
● AWS
● BoxFuse
● Application servers
● Executable WAR
66D

Section V Tooling & sub-projects
67

JDL
● JHipster Domain Language
● Makes generating complex entity models easily
● Supports all entity sub-generator features
○ Field types
○ Validation
○ Relationships
○ DTOs
○ Service
○ Enumerations
○ ...
68J

JDL Studio
● Open Source Web application
○ Available at http://jhipster.github.io/jdl-studio/
● Auto-completion and validation
● Sublime Text keymap
● Graphical view
● Share as URL
● Import/export models
69D

JHipster IDE
● IDE support for JDL
○ Eclipse, IDEA, Visual Studio Code
○ Still in Beta
70J

Modules
● JHipster modules gives all the power of JHipster sub-generator to
everyone
○ Modules are independent from JHipster
○ Modules are Yeoman generators, using the JHipster public API
○ Release when you want, use the license you want…
● If you want your module to be public, you can publish it on the JHipster
marketplace
○ Available at https://jhipster.github.io/modules/marketplace/
○ 24 modules available today
○ Free for everyone, as always with JHipster!
71D

Microservices architecture
● JHipster provides a full microservice architecture
● Gateway(s) to give access to the microservice architecture
○ Based on Netflix Zuul
● Registry to find services
○ JHipster Registry (based on Netflix Eureka) or Hashicorp Consul
● Microservices
● Security
● Monitoring
● Scaling
73J

Microservices architecture
74J

Gateway(s)
● Gateways are normal JHipster applications
○ Full JHipster capabilities
● Provide access to the microservices
○ Using Netflix Zuul for routing, load balancing, failover
○ Provide security using JWT or OAuth2
○ Provide quality of service using a custom Zuul filter + Cassandra
○ Provide full Swagger documentation for both the gateway and the microservices
● Tip: you can have several gateways, specialized on your business needs
75D

Microservices
● Microservices are normal JHipster applications, without the AngularJS
front-end
● All database combinations, Elasticsearch and other options are available
● The JDL Studio can also be used to generate the CRUD entities
● Main limit is that Websockets are not available
○ Will change with Zuul 2
76J

JHipster Registry
● JHipster Registry is an Open Source application developed specifically for
the JHipster microservices architecture
○ Uses Netflix Eureka for service registration/discovery
○ Uses Spring Cloud Config to push Spring Boot configuration to microservices
■ Very useful for pushing secrets (like database passwords)
■ Can re-configure microservices
■ Configurations can be stored in Git, allowing to version/tag them easily
○ Has an easy-to-use Web interface (built with JHipster!)
○ Is available pre-built as a Docker image on the Docker Hub
77D

HashiCorp Consul
● Alternative to the JHipster Registry
○ Focus on consistency (while Eureka focuses on availability)
● More efficient than Eureka on many points
○ Faster service registration/un-registration
○ Smaller footprint
○ DNS server included
○ UI included
● But the JHipster Registry is more stable, is easier to extend (it’s a JHipster
application) and has better Spring Cloud Config support
78J

JHipster Console
● Monitoring application built with ELK (Elasticsearch Logstash Kibana)
● Optimized for JHipster
○ Receives directly events from JHipster over a socket, with the correct format
○ Has pre-configured dashboards for JHipster
● Can be automatically set up with the Docker Compose sub-generator
● Available pre-built as a Docker image on the Docker Hub
79D

Customizing Netflix Zuul
● Gateways use Netflix Zuul to provide routing, load balancing and failover
● Netflix Zuul can be customized using filters
○ JHipster provides pre-built filters, for example for quality of service
● New filters can be added depending on your business needs
80J

Generating entities with microservices
● Entities can be generated for microservices, like any JHipster application
○ Only the back-end code is generated (no AngularJS client code is generated)
○ All usual options are available
○ The JDL Studio can be used as usual
● For Gateway(s), entities can also be generated from microservices
○ The front-end is generated on the gateway, and connect through Netflix Zuul to the
microservice back-end
○ Front-end applications can gather entities from several microservices, as well as from
entities from the gateway itself
81D

Hazelcast distributed cache for
microservices
● Hazelcast is the default Hibernate 2nd level cache for entities generated
on microservices
● JHipster generates specific configuration, using the JHipster Registry, so
that different instances of the same microservice join each other in the
same distributed cache
● Distributed cache with Hazelcast will work automatically with Docker
Swarm, when a microservice is scaled
> docker-compose scale mymicroservice-app=3
82J

Security for microservices
● Default security is JWT
○ The JWT token is generated by the gateway
○ All microservices accept the token, as they share a secret key with the gateway
○ This secret key is sent to all gateway(s) and microservices by the JHipster Registry, using
Spring Cloud Config
● Beta option to support OAuth2
○ Using the JHipster UAA server
83D

Deploying and scaling on Docker Swarm
● Same as deploying on a local Docker, but on a full cluster!
● Main difference is that we can scale microservices
○ This is why distributed cache and JWT are important
> docker-compose up -d
> docker-compose scale mymicroservice-app=3
84J

Deploying and scaling on Kubernetes
● Basically the same as Docker Swarm, but on Kubernetes
○ Works on Google Cloud Platform
○ Still in Beta
> kubectl apply -f myapplication
> kubectl scale --replicas=3 jhipster/myapplication
85D

Community help
● #1 rule: everything is public
● Questions are on StackOverflow with the “jhipster” tag
● Bugs & feature requests are on our GitHub issue tracker
● Please follow our contributing guidelines if you want help!
87J

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