src-openfeign

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Author	SHA1	Message	Date
Adrian Cole	24885fe962	Adds Feign.Builder.decode404() to reduce boilerplate for empty semantics This adds the `Feign.Builder.decode404()` flag which indicates decoders should process responses with 404 status. It also changes all first-party decoders (like gson) to return well-known empty values by default. Further customization is possible by wrapping or creating a custom decoder. Prior to this change, we used custom invocation handlers as the way to add fallback values based on exception or return status. `feign-hystrix` uses this to return `HystrixCommand<X>`, but the general pattern applies to anything that has a type representing both success and failure, such as `Try<X>` or `Observable<X>`. As we define it here, 404 status is not a retry or fallback policy, it is just empty semantics. By limiting Feign's special processing to 404, we gain a lot with very little supporting code. If instead we opened all codes, Feign could easily turn bad request, redirect, or server errors silently to null. This sort of configuration issue is hard to troubleshoot. 404 -> empty is a very safe policy vs all codes. Moreover, we don't create a cliff, where folks seeking fallback policy eventually realize they can't if only given a response code. Fallback systems like Hystrix address exceptions that occur before or in lieu of a response. By special-casing 404, we avoid a slippery slope of half- implementing Hystrix. Finally, 404 handling has been commonly requested: it has a clear use- case, and through that value. This design supports that without breaking compatibility, or impacting existing integrations such as Hystrix or Ribbon. See #238 #287	9 years ago
David Cobo	6b90c7c872	Adds jackson-jaxb codec	10 years ago

Author

SHA1

Message

Date

Adrian Cole

24885fe962

Adds Feign.Builder.decode404() to reduce boilerplate for empty semantics

This adds the `Feign.Builder.decode404()` flag which indicates decoders
should process responses with 404 status. It also changes all
first-party decoders (like gson) to return well-known empty values by
default. Further customization is possible by wrapping or creating a
custom decoder.

Prior to this change, we used custom invocation handlers as the way to
add fallback values based on exception or return status. `feign-hystrix`
uses this to return `HystrixCommand<X>`, but the general pattern applies
to anything that has a type representing both success and failure, such
as `Try<X>` or `Observable<X>`.

As we define it here, 404 status is not a retry or fallback policy, it
is just empty semantics. By limiting Feign's special processing to 404,
we gain a lot with very little supporting code.

If instead we opened all codes, Feign could easily turn bad request,
redirect, or server errors silently to null. This sort of configuration
issue is hard to troubleshoot. 404 -> empty is a very safe policy vs
all codes.

Moreover, we don't create a cliff, where folks seeking fallback policy
eventually realize they can't if only given a response code. Fallback
systems like Hystrix address exceptions that occur before or in lieu of
a response. By special-casing 404, we avoid a slippery slope of half-
implementing Hystrix.

Finally, 404 handling has been commonly requested: it has a clear use-
case, and through that value. This design supports that without breaking
compatibility, or impacting existing integrations such as Hystrix or
Ribbon.

See #238 #287

9 years ago

David Cobo

6b90c7c872

Adds jackson-jaxb codec

10 years ago

2 Commits (715e72b026eb0345b18dd2e41db41652c640d348)