crnk example application
This is a Spring-based showcasing the use of Crnk. Further smaller example applications integrating into various frameworks can be found at crnk-integration-examples.
WARNING: this example project is still in development and subject to various improvements, see roadmap
Requirements
Crnk requires Java 8 or later.
Licensing
Crnk is licensed under the Apache License, Version 2.0. You can grab a copy of the license at http://www.apache.org/licenses/LICENSE-2.0.
Building from Source
Crnk make use of Gradle for its build. To build the project run
gradlew build
Running the application
In order to run this example do:
gradlew run
or
docker run --name=crnk -p 8080:8080 crnk/example
The JSON API endpoint will be available at:
http://localhost:8080/api/
Some further URLs to play around that show the power of Crnk:
http://127.0.0.1:8080/api/movie
http://127.0.0.1:8080/api/movie/44cda6d4-1118-3600-9cab-da760bfd678c
http://127.0.0.1:8080/api/movie/44cda6d4-1118-3600-9cab-da760bfd678c
http://127.0.0.1:8080/api/movie/44cda6d4-1118-3600-9cab-da760bfd678c/project
http://127.0.0.1:8080/api/movie/44cda6d4-1118-3600-9cab-da760bfd678c/relationships/project
http://127.0.0.1:8080/api/movie?sort=-name
http://127.0.0.1:8080/api/movie?sort=-id,name
http://127.0.0.1:8080/api/movie?sort=id&page[offset]=0&page[limit]=2
http://127.0.0.1:8080/api/movie?filter[name]=Iron Man
http://127.0.0.1:8080/api/movie?filter[name][EQ]=Iron Man
http://127.0.0.1:8080/api/movie?filter[name][LIKE]=Iron
http://127.0.0.1:8080/api/schedule
http://127.0.0.1:8080/api/meta/resource
http://127.0.0.1:8080/api/vote?fields=name // demos fields set & performance issues
http://127.0.0.1:8080/api/secrets // demos error
http://127.0.0.1:8080/api/facet?filter[resourceType]=movie // get movie facets
IDE
Make sure to enable annotation processing support when using IntelliJ IDEA. Otherwise it will not be able to find the generated sources from the Crnk annotation processor (type-safe Query objects).
Build Setup
The project makes use of https://github.com/rmee/gradle-plugins/ for the build setup.
- if no JAVA_HOME is configured (recommended), a suitable JDK will be downloaded automatically
by the
jdk-bootstrapplugin. src/main/helmholds a Helm chart to deploy to Kubernetes.- Deployment to Kubernetes is triggered by the
deploytask. All the deployment is confined to Docker images and a project-specific home directory located inbuild/home. No installation of any tooling necessary thanks to the plugins in use. Further wrapper scripts like./kubectlallow to use this deployment setup from a shell (GitBash, Linux, etc.). For deploymentCRNK_GCLOUD_REGION,CRNK_GCLOUD_PROJECT,CRNK_GCLOUD_CLUSTERenvironment variables must be set and credentials be available incrnk-example-service/secrets/gcloud.key.
Pointers
The crnk-example-service project showcases:
- Use of Lombok to avoid getter/setter boiler-plate.
- Integration of Crnk into Spring Boot
io.crnk:crnk-format-plain-jsonhas been applied for slightly simplified version of JSON:API withoutattributes,relationships,includessection.- A simple in-memory repository with
ScreeningRepositorythat keeps all resources in a map. - Exposing entities with crnk-jpa using
MovieRepository,PersonRepository, etc. extendingJpaEntityRepositoryBase. Behind the scenes theQuerySpecis translated to an efficient JPA Criteria query. - A manually written repository with
VoteRepository. It makes use of Thread.sleep to simulate heavy work. - A custom exception is introduced with
CustomExceptionMapperthat is mapped to a JSON API error and HTTP status code. - using
@JsonApiRelationIdwithScreeningRepositoryto handle use cases where the related ID is easy to get, which in turn allows to omit having to implement relationship repositories. - implementing a relationship repository with
AttributeChangeRelationshipRepository. - implementing a multi-valued nested resource with
Secretand its identifierSecretId. - implementing a single-valued nested resource with
SecreeningStatus. Shared the same ID as the screening itself and make use ofSerializeType.EAGERto directly be shown with the screening (see http://127.0.0.1:8080/api/screening) - introducing new relationships to existing resources
without touching those resources with
AttributeChangeFieldProvider. PersonEntityas dynamic resource by annotating aMap-based field with@JsonAnyGetterand@JsonAnySetterSecurityConfigurationperforms a OAuth setup with GitHub as provider.LoginRepositorygives access to information about the logged-in user through http://localhost:8080/api/user. Enable spring security in theapplication.yamlto make use of the security features. Security is disabled by default to facilitate playing with the example app. The security setup is still work in progress.CSRF(resp.XSRFin Angular terminology) protection throughSpringSecurityConfiguration.ExampleSecurityConfigurerto setup role-based access control.ScheduleDecoratorFactoryto intercept and modify requests to repositories.- The documentation gets generated to
build/asciidocupon executinggradlew build. Have a look at thebuild.gradlefile and the capturing based onAsciidocCaptureModulewithin the test cases. - Support for facetted search by applying
crnk-data-facets.MovieEntity.yearas been marked as being facetted with@Facet. Seehttp://127.0.0.1:8080/api/facet?filter[resourceType]=movie. MovieRepositoryprovides an interface for theMovieRepositoryImplwhich allows type-safe access to movie result lists inCrnkClient.MovieRepositorymakes use ofHasMoreResourcesMetaInformationthrough a customMovieListtype. This triggers the use of a previous/next paging strategy, rather than always computing the total count in a second, potentially expensive query.
The TestDataLoader will automatically setup some test data upon start.
The project itself makes use of an number of third-party plugins to bootstrap a JDK, build Helm packages and allow a Kubernetes installation to Google Cloud. For more information see https://github.com/rmee/gradle-plugins/.
Feedback and PRs very welcomed!