Code uses WebClient but blocks

[marschall]

The code uses the reactive WebClient but ends up calling #block() which, as the name suggests, blocks and therefore defeats the whole purpose of using WebClient in the first place. Examples:

• CovidCertificate-Api-Gateway-Service/src/main/java/ch/admin/bag/covidcertificate/gateway/service/ValueSetsService.java

  Line 51 in 4633b18

  .block();

• CovidCertificate-Api-Gateway-Service/src/main/java/ch/admin/bag/covidcertificate/gateway/service/CovidCertificateRevocationService.java

  Line 39 in 4633b18

  .block();

• CovidCertificate-Api-Gateway-Service/src/main/java/ch/admin/bag/covidcertificate/gateway/service/CovidCertificateGenerationService.java

  Line 52 in 4633b18

  .block();

The code should instead do one of the following:

• Avoid calling #block() and instead call #subscribe()
• Switch from the reactive WebClient to the blocking RestTemplate

Considering all the rest of the code is blocking (WebServiceTemplate, JpaRepository, …) WebClient seems like the better match.

[delixfe]

@marschall Thanks for your feedback.

According to https://stackoverflow.com/questions/58513071/spring-mvc-to-spring-webflux-migration-block-vs-subscribe, using block seems to be the best way in our situation.

[marschall]

The thread is explicit that going Mono / Flux and #subscribe is the way to go if you want to be reactive. #block is a good choice for cases when you want to migrate an existing servlet based application to reactive in a step by step fashion. If you decide to go down that route you still needs solutions for JPA and SOAP which to my knowledge have no reactive options.