After more than a year of using JHipster for real on several applications, I share the different technics we used to upgrade generated code

1. https://jhipster.tech @java_hipster
Custom and
Generated Code Side
by Side
@agoncal

2. https://jhipster.tech @java_hipster

3. https://jhipster.tech @java_hipster
Website
Call for
Paper
Scheduling Mobile App
Ticketing
Scanning
Digital
Signage
Tweet wallAccounting
Sponsor
Venue
3rd party

4. https://jhipster.tech @java_hipster

5. https://jhipster.tech @java_hipster
Website
Call for
Paper
Scheduling Mobile App
Ticketing
Scanning
Digital
Signage
Tweet wallAccounting
Sponsor
Venue
3rd party
Grew up organically
No communication
No SSO
No multitenancy
No container
Fed up of polyglot

6. https://jhipster.tech @java_hipster

7. https://jhipster.tech @java_hipster
Website
Call for
Paper
Scheduling Mobile App
Ticketing
Scanning
Digital
Signage
Tweet wallAccounting
Sponsor
Venue
3rd party
Deployer

8. https://jhipster.tech @java_hipster
Patterns We Used
Prototype Bootstrap Side by side
Quickly test
Throw away

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Prototype

10. https://jhipster.tech @java_hipster
Prototype
JDL

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Patterns We Used
Prototype Bootstrap Side by side
Quickly test
Throw away
Bootstrap code
Bootstrap model
Change the
generated code

12. https://jhipster.tech @java_hipster
Bootstrap
JDL

13. https://jhipster.tech @java_hipster
Patterns We Used
Prototype Bootstrap Side by side
Quickly test
Throw away
Bootstrap code
Bootstrap model
Change the
generated code
JDL centric
Regenerate code
frequently
Don’t change
generated code
Develop our own
code

14. https://jhipster.tech @java_hipster
Side by Side
JDL

15. https://jhipster.tech @java_hipster
Contact/Organisation JDL
entity Organisation (spn_organisation) {
name String required maxlength(NAME_MAX_LENGTH),
description String maxlength(DESCRIPTION_MAX_LENGTH),
businessIdentification String,
corporateName String,
}
entity Contact (spn_contact) {
firstName String required maxlength(NAME_MAX_LENGTH),
lastName String required maxlength(NAME_MAX_LENGTH),
email String required minlength(EMAIL_MIN_LENGTH) maxlength(EMAIL_MAX_LENGTH),
}
relationship OneToMany {
Organisation{contacts(lastName)} to Contact{organisation(name) required}
}

16. https://jhipster.tech @java_hipster
Contact/Organisation Code
organisation
.json
Domain
Contact
Organisation
1..*
Organisation
Repository
RepositoryService
Organisation
Service
REST
Organisation
Resource
Angular
Organisation
Service
Organisation
/api
Organisation
Component
Organisation
Repository
Extended
Organisation
Service
Extended
Organisation
Resource
Extended
Organisation
Service
Extended
/api/ext
Organisation
Component
Extended
organisation-
extended.json

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Repository
@Repository
public interface OrganisationRepository extends JpaRepository<Organisation, Long>,
JpaSpecificationExecutor<Organisation> {
}
@Repository
public interface OrganisationRepositoryExtended extends OrganisationRepository {
@Query("select spn_organisation from Organisation spn_organisation left join fetch
spn_organisation.contacts where spn_organisation.id =:id")
Optional<Organisation> findOneWithEagerRelationships(@Param("id") Long id);
}

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Service
@Service @Transactional
public class OrganisationService {
private final OrganisationRepository organisationRepository;
public OrganisationService(OrganisationRepository organisationRepository) {
this.organisationRepository = organisationRepository;
}
@Service @Transactional
public class OrganisationServiceExtended extends OrganisationService {
private final OrganisationRepositoryExtended organisationRepository;
public OrganisationServiceExtended(OrganisationRepositoryExtended organisationRepository) {
super(organisationRepository);
this.organisationRepository = organisationRepository;
}

19. https://jhipster.tech @java_hipster
Resource
@RestController
@RequestMapping("/api")
public class OrganisationResource {
private final OrganisationService organisationService;
@RestController
@RequestMapping("/api/extended")
public class OrganisationResourceExtended {
private final OrganisationServiceExtended organisationService;

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Angular Service
@Injectable({ providedIn: 'root' })
export class OrganisationService {
private resourceUrl = SERVER_API_URL + 'api/organisations';
constructor(private http: HttpClient) {}
create(organisation: IOrganisation): Observable<EntityResponseType> { }
@Injectable({ providedIn: 'root' })
export class OrganisationExtendedService extends OrganisationService {
private resourceUrlExtended = SERVER_API_URL + 'api/extended/organisations';
constructor(private httpExt: HttpClient) {
super(httpExt);
}

21. https://jhipster.tech @java_hipster
Contact/Organisation Code
organisation
.json
Domain
Contact
Organisation
1..*
Organisation
Repository
RepositoryService
Organisation
Service
REST
Organisation
Resource
Angular
Organisation
Service
Organisation
/api
Organisation
Component
Organisation
Repository
Extended
Organisation
Service
Extended
Organisation
Resource
Extended
Organisation
Service
Extended
/api/ext
Organisation
Component
Extended
organisation-
extended.json
DTO
Mapper
Exception

22. https://jhipster.tech @java_hipster
First Sprints (development)
● Start with a monolith
● JWT
● Avoid liquibase changeset
● Liquibase context for dev data
● Use Query filters
● Our side-by-side code
○ Components
○ Repositories
○ Services
○ Endpoint

23. https://jhipster.tech @java_hipster
Later Sprints (production)
● Moved to microservices
● Keycloak
● Use liquibase changeset
● Add Gatling / Protractor
● Production in the cloud

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Lessons Learnt
● Start will less tech/features, add them later
● Keep JDL up to date
● Never touch generated code
● Keep up with JHipster version
● Use DTO
● Use Query filters
● Run -Pprod builds from start
● Introduce new i18n when needed
● Use PrimeNG components

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Lessons Learnt
● PostgreSQL is a fantastic DB (JSon, full text)
● Same DB in dev and prod
● Stick to JHipster
● Docker is good for dev (we don’t use it in prod)
● Reduce the number of technologies
○ Microservices are difficult enough
○ Each new service has a cost in the Cloud

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What’s Missing?
● Better directory structure / naming convention
○ Using angularSuffix for now
● Richer model
○ One-to-many unidirectional, Embeddable, List<datatypes>
● More best practices
○ Exception handling in services, Async calls
● Flexible endpoints
○ /api, /internal, /public
● More PostgreSQL support
○ Full text search, JSON

27. https://jhipster.tech @java_hipster
What’s Missing?
● Generate more code with a richer JDL
○ Constants (ending up in Constants.java)
○ Enums (with no entity), helper classes...
○ Repository
○ Service
○ Endpoint
○ Angular services

28. https://jhipster.tech @java_hipster
Contributing back
● Full-text search with PostgreSQL
● Reference data
○ Country (iso2, iso3, name, dial, continent, flag, latitude, longitude, zoom)
○ Language (alpha3b, alpha2, name, flag32)
○ Currency (alphabeticCode, name, numericCode, minorUnit, symbol)

29. https://jhipster.tech @java_hipster
Website
Call for
Paper
Scheduling Mobile App
Ticketing
Scanning
Digital
Signage
Tweet wallAccounting
Sponsor
Venue
3rd party
Deployer
Road Map

30. https://jhipster.tech @java_hipster
Thanks
https://github.com/agoncal/agoncal-talks/tree/master/2018-06-JHipsterConf
@agoncal