Improve developer experience with Spring Interface Clients Spring I/O 2024

Spring now allows you to easily create elegant, highly readable, interface-based HTTP and RSocket clients. In this session we will discuss how developers can best use the clients in their applications to make HTTP and RSocket communication seamless.

During the presentation, we will go over various popular use-cases, but we will also discuss more complex scenarios, including how to best handle errors, override preset elements in individual requests, work with URIs, or pass attributes to underlying filter functions. We will show how to set up Spring Interface Clients with different underlying HTTP clients and how to easily integrate them with Spring Cloud LoadBalancer. Last but not least, we will take a peek into auto-configurations for Interface Clients.

Transcript

1. Olga Maciaszek-Sharma Improve developer experience with Spring Interface Clients Copyright © 2022 VMware, Inc. or its affiliates.
2. About Olga Staff Software Engineer in Spring Cloud team Spring Cloud LoadBalancer, Spring Cloud OpenFeign, Spring Cloud Netflix, AOT and native image support in Spring Cloud projects, Spring Interface Clients
3. What is a declarative client?
4. Sample applications Customer Service Verification Service HTTP POST /verify Customer Verification Result
5. Direct use of HTTP client
6. Client interface
7. Implementation
8. Implementation with helper methods
9. Client interface usage
10. Annotated interface ⭆ HTTP calls Libraries/ frameworks already do it for us!
11. Declarative/ interface client Client interface method calls HTTP calls Proxy
12. Other implementations and support in Spring
13. Feign & Spring Cloud OpenFeign https://github.com/OpenFeign/feign https://github.com/spring-cloud/spring-cloud-openfeign
14. OpenFeign/Feign
15. A declarative/ interface client
16. Retrofit & Spring Cloud Square https://github.com/spring-projects-experimental/spring-cloud-square
17. Retrosocket https://github.com/spring-projects-experimental/spring-retrosocket
18. Spring Interface Clients HTTP
20. @HttpExchange
26. @HttpExchange attributes url method contentType accept
28. @HttpExchange @GetExchange @PostExchange @PatchExchange @PutExchange @DeleteExchange
29. Parameters
32. Overriding URI
33. “/”
35. Overriding base URL
39. Object Map/ MultiValueMap Collection
41. Object Map/ MultiValueMap Collection
42. Object Map/ MultiValueMap Collection
43. WebClient - working with request attributes
47. Return values
48. Blocking
49. Reactive
50. Status, headers, body
51. Headers
52. Execute only
53. Instantiating HTTP clients • Create HttpServiceProxyFactory bean • Create service instance bean
58. Error handling
62. Load-balancing Use instrumented WebClient/ RestClient/ RestTemplate
63. DiscoveryClient Eureka Consul Zookeeper Kubernetes SimpleDiscoveryClient
65. Load-balanced client builder bean You can use @LoadBalanced as qualifier serviceId in place of host:port
66. Load-balanced client builder bean You can use @LoadBalanced as qualifier serviceId in place of host:port
67. Load-balanced client bean You can use @LoadBalanced as qualifier serviceId in place of host:port
68. Tracing Provided by instrumented WebClient/ RestClient/ RestTemplate
69. @HtttpExchange on server side
71. Spring Interface Clients RSocket
72. RSocket Reactive Streams semantics on protocol level • Message-driven, asynchronous • No client/ server distinction once connection is made • 4 modes ◦ Fire and Forget ◦ Request/ Response ◦ Request/ Stream ◦ Channel
73. RSocket Reactive Streams semantics on protocol level • Binary • Flow control ◦ Backpressure ◦ Leasing • Protocol support: ◦ TCP ◦ WebSockets ◦ Aeron ◦ QUIC?
75. @RSocketExchange
77. Destination
78. Parameters
82. Handle added metadata in responder
83. Return values
86. Instantiating RSocket clients • Create RSocketServiceProxyFactory bean • Create service instance bean
87. Set up RSocket strategies, including encoders and decoders
89. @RSocketExchange annotated responders
91. AutoConfigurations
92. Enable AutoConfiguration A separate switch annotation/ a property/ looking for per-client annotation
93. Find annotated interfaces Any interface with @...Exchange/ Dedicated annotation per client
94. Match HTTP clients with infrastructure • Find/ create WebClient/ RestClient/ RestTemplate/ RSocketRequester • Find/ create HTTP/ RSocket ServiceProxyFactory • Qualifier/ dedicated annotation/ naming convention • Default and per client implementations
95. Registering bean definitions ImportBeanDefinitionRegistrar/ BeanDefinitionRegistryPostProcessor/ FactoryBean
96. Existing implementations https://github.com/joshlong/declarative-client-registration https://github.com/maciejwalkowiak/spring-boot-http-clients
97. GitHub issue https://github.com/spring-projects/spring-boot/issues/31337
98. SAMPLE
99. https://github.com/OlgaMaciaszek/interface- clients-spring-io-2024-demo
100. 100 Broadcom Proprietary and Confidential. Copyright © 2024 Broadcom. All Rights Reserved. The term “Broadcom” refers to Broadcom Inc. and/or its subsidiaries. Check out what’s happening at the VMware Tanzu Booth! And beyond Meet & Greet Josh Long | May 30 16:00-16:30 Customer appreciation party | May 30 21:00- 23:00 | Camping Mar Spring Office Hours Live with DaShaun Carter and Dan Vega | May 31 11:00 - 12:30 Grand Raffle | May 31 16:30
101. Thank you olga.maciaszek-sharma@broadcom.com @olga_maciaszek © 2020 Spring. A VMware-backed project.