Flux.from() is cheap and can be used to marshal the inputs everywhere
internally. With this change users ought to be able to register any
function of any Publisher type.
It tends to pop back into function apps where it is not needed
otherwise. Users that want to use the library need to import
the FunctionConfiguration directly using the
@EnableFunctionDeployer convenience annotation..
There is now a JsonMapper strategy with implementations and
autoconfiguration for Gson and Jackson. If Jackson is present
it is preferred (just like in Spring Boot).
Fixes gh-150
This results in a better experience for users because the consumer
that they write is only applied to a Flux that is subscribed to
by the framework once. It gives better control over the flow of
foos, e.g. if some component wants to subscribe on a thread.
User can switch off source or sink behaviour (the default is to bind
to input and output streams), and then configure the name of a
supplier (for a source) or consumer (for a sink).
A Spring Boot 2.0 app should behave the same as a Spering Boot 1.5
app with this change. The key thing was to change the return type
of the FunctionController and move the computation of single
valuedness for the output there (instead of trying to do it in the
return value handler, which isn't used in Spring 5).
Makes it possible to support other "function" types in the future.
The user is always taking a risk with the lookup that the object
returned has the generic type desired (but that hasn't changed
with this commit). FunctionCatalog is a lot simpler as a result
and also a lot more flexible.
The web module doesn't really need to depend on tomcat and all of
the Spring Boot web stack, but users need a way to grab that stuff
quickly if they want it (hence the new starter).
Also removed all spring-boot-starter dependencies from core and
context modules.
Functions with Flux and Message (as well as POJOs and Flux of POJO
which were already supported) should now work if they are created in
an isolated class loader. Preconditions:
* The class loaders must have the reactor-core (and reactive-streams)
shared between the app and the function. Practically speaking this means
there has to be a parent class loader with just reactive types, and
sibling children for the app and the function. This is not a new
requirement (it was needed for Flux of POJO anyway).
* Message types are handled reflectively, so they don't have to be in a
shared class loader. But they do have to be on the class path on
both sides (obviously).
Use of BeanProcessor to catch a bean before it is used is a bit
agricultural these days. SmartInitializingSingleton is better and
frees application logs from one more annoying INFO log on an
early instantiation
2018-01-04 14:17:05.930 INFO 23472 --- [ Thread-0] trationDelegate$BeanPostProcessorChecker :
Bean 'org.springframework.cloud.function.web.flux.ReactorAutoConfiguration' of type
[org.springframework.cloud.function.web.flux.ReactorAutoConfiguration$$EnhancerBySpringCGLIB$$8d4844e]
is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)
With this change there are now 2 choices for web endpoints. The
stream servlet binder is useful for multi-binder use cases
(e.g. HTTP -> message broker).
A registered singleton doesn't have a BeanDefinition, but it might have
a compiled type with enough generic information to pull out the
input and output types.
Spring Boot apps often run with --debug (no boolean value), so
we need to be defensive and not barf if it's empty (and therefore
not convertible to a boolean)
