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JHipster Conf 2018 : Connect your JHipster apps to the world of APIs with OpenAPI and gRPC

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Connect your JHipster apps to the world of APIs with OpenAPI and gRPC

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JHipster Conf 2018 : Connect your JHipster apps to the world of APIs with OpenAPI and gRPC

  1. 1. https://jhipster.tech @java_hipster Connect your JHipster apps to the world of APIs with OpenAPI and gRPC + +
  2. 2. https://jhipster.tech @java_hipster Le me ● Working at Engie (but soon CDiscount) ● JHipster core team member ● Swagger-codegen former core team member ● OpenAPI-generator core team member @cbornet_
  3. 3. https://jhipster.tech @java_hipster Evolution of SOA protocols RMI CORBA DCOM SOAP REST gRPC ? AVRO THRIFT XML-RPC GraphQL ?
  4. 4. https://jhipster.tech @java_hipster Today, everybody does REST...
  5. 5. https://jhipster.tech @java_hipster Today, everybody does REST… Richardson maturity model
  6. 6. https://jhipster.tech @java_hipster Today, everybody does REST… Roy Fielding : HATEOAS* is a pre-condition to REST *HATEOAS: Hypermedia As The Engine Of Application State
  7. 7. https://jhipster.tech @java_hipster Today, everybody does REST… or not In practice, this is the state of the art, including JHipster “I am getting frustrated by the number of people calling any HTTP-based interface a REST API.” - Roy Fielding
  8. 8. https://jhipster.tech @java_hipster Why Swagger/OpenAPI ?
  9. 9. https://jhipster.tech @java_hipster Why Swagger/OpenAPI ? CORBA-IDL module BankDemo { typedef float CashAmount; typedef string AccountId; interface Account { readonly attribute AccountId account_id; readonly attribute CashAmount balance; void withdraw(in CashAmount amount) raises (InsufficientFunds); void deposit(in CashAmount amount); } }
  10. 10. https://jhipster.tech @java_hipster Why Swagger/OpenAPI ? SOAP’s WSDL <definitions name = "HelloService" targetNamespace = "http://www.examples.com/wsdl/HelloService.wsdl" xmlns = "http://schemas.xmlsoap.org/wsdl/" xmlns:soap = "http://schemas.xmlsoap.org/wsdl/soap/" xmlns:tns = "http://www.examples.com/wsdl/HelloService.wsdl" xmlns:xsd = "http://www.w3.org/2001/XMLSchema" > <message name = "SayHelloRequest" > <part name = "firstName" type = "xsd:string" /> </message> <message name = "SayHelloResponse" > <part name = "greeting" type = "xsd:string" /> </message> <portType name = "Hello_PortType" > <operation name = "sayHello" > <input message = "tns:SayHelloRequest" /> <output message = "tns:SayHelloResponse" /> </operation> </portType> <binding name = "Hello_Binding" type = "tns:Hello_PortType" > <soap:binding style = "rpc" transport = "http://schemas.xmlsoap.org/soap/http" /> <operation name = "sayHello" > <soap:operation soapAction = "sayHello" /> <input> <soap:body encodingStyle = "http://schemas.xmlsoap.org/soap/encoding/" namespace = "urn:examples:helloservice" use = "encoded" /> </input> <output> <soap:body encodingStyle = "http://schemas.xmlsoap.org/soap/encoding/" namespace = "urn:examples:helloservice" use = "encoded" /> </output> </operation> </binding> <service name = "Hello_Service" > <documentation> WSDL File for HelloService </documentation> <port binding = "tns:Hello_Binding" name = "Hello_Port" > <soap:address location = "http://www.examples.com/SayHello/" /> </port> </service> </definitions>
  11. 11. https://jhipster.tech @java_hipster Why Swagger/OpenAPI ? REST No need for an IDL, with REST my API is dynamic and self-describing...
  12. 12. https://jhipster.tech @java_hipster Why Swagger/OpenAPI ? REST But you’re not doing HATEOAS ! ...
  13. 13. https://jhipster.tech @java_hipster Why Swagger/OpenAPI ? So let’s document our API with word/pdf/asciidoc/...
  14. 14. https://jhipster.tech @java_hipster Why Swagger/OpenAPI ? So let’s document our API with excel/pdf/asciidoc/... - Tedious to write - Hard to find - Inaccurate, errors, not up-to-date - Lots of boilerplate code to write by hand from reading the doc
  15. 15. https://jhipster.tech @java_hipster From code to doc : springfox + swagger-ui - No additional work - Doc in sync with the code - No errors (except in case of Springfox bug) - Easy to find
  16. 16. https://jhipster.tech @java_hipster From doc to client SDK ● OpenAPI-generator (previously swagger-codegen) ○ generate client SDK in 50+ languages/libraries ○ supports Swagger v2.0 and OpenAPI v3.0 ○ SDK for Spring-Cloud FeignClient ● Module generator-jhipster-swagger-cli ○ Module that wraps Openapi-generator to generate back-end clients in JHipster ○ Next step : support React and AngularX front-end client
  17. 17. https://jhipster.tech @java_hipster API-first development ● Write the OpenAPI spec first then generate server stub code from it ○ early review feedback from peers and client developers (with PRs) ○ clear separation of WHAT vs. HOW ○ single source of truth ○ infrastructure tooling ● JHipster’s “API-First” option ○ configures the openapi-generator-maven-plugin to generate interfaces at compile time from the OAI spec ○ supports OAI spec v3.0
  18. 18. https://jhipster.tech @java_hipster gRPC “gRPC is a modern open source high performance RPC framework that can run in any environment. It can efficiently connect services in and across data centers with pluggable support for load balancing, tracing, health checking and authentication.”
  19. 19. https://jhipster.tech @java_hipster gRPC vs HTTP-JSON ● API centered ● Built for performance ● Protobuf ○ binary format ○ strongly typed ● IDL built-in ● Strongly typed ● HTTP/2 by default ● 10+ languages ● Service discovery, load balancing, fault tolerance, monitoring, tracing integrated ● Resource centered ● Built for simplicity ● JSON ○ text format ○ weakly typed ● IDL optional (OpenAPI) ● Weakly typed ● HTTP/2 optional ● All languages ● Service discovery, load balancing, fault tolerance, monitoring, tracing with the good framework (Netflix/Spring Cloud)
  20. 20. https://jhipster.tech @java_hipster gRPC other nice features ● Bidirectional streaming ● Deadline propagation ● Cancellation propagation ● Async non-blocking / reactive JAVA implementation ● Flow Control (pull type with back-pressure) at the wire level (beware of OOME !!) ● Reactive-gRPC extension ○ https://github.com/salesforce/reactive-grpc by Salesforce ○ Wraps gRPC’s reactive type into Reactor’s Mono/Flux types ○ Passes the Reactive-Streams TCK
  21. 21. https://jhipster.tech @java_hipster gRPC in JHipster ● generator-jhipster-grpc module ○ actuator endpoints ○ entities ○ your own grpc services ○ uses reactive-grpc lib ● Next steps ○ integrate with the future JH “reactive” option for end-to-end reactive services from gRPC client to DB. ○ finish security config ○ production features (service discovery, LB, tracing, …) ○ integration of gRPC-web ?
  22. 22. https://jhipster.tech @java_hipster Questions ? https://github.com/cbornet/generator-jhipster-swagger-cli https://github.com/cbornet/generator-jhipster-grpc https://github.com/OpenAPITools/openapi-generator https://github.com/salesforce/reactive-grpc
  23. 23. https://jhipster.tech @java_hipster More information on JHipster Main website https://jhipster.tech GitHub https://github.com/jhipster/generator-jhipster Twitter https://twitter.com/java_hipster Stack Overflow https://stackoverflow.com/questions/tagged/jhipster?sort=newest

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