* If there is only one function, use it unconditionally
* If no functions match, ensure that null is not the selector
* If a conversion succeeds, check the type of the result
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)
The io.spring sample referred to in the openwhisk README isn't
in this repo, so users generally don't have it installed locally.
This change makes it more obvious that you have to create your
own.
Also fixes the `wsk ...` command lines (the order of arguments
was wrong - maybe the CLI changed?).
If the output is a Message we grab the headers from the first one
and send those as response headers.
A function can add headers to messages. The HTTP response will
contain only headers that are in x-* _or_ were added to the message
by user (i.e. they weren't in the request).
We certainly do not want to pass through all HTTP headers (request
headers can conflict with or invalidate response headers).
The FunctionInspector needs to be able to distinguish between a
function of Flux<Foo> and a function of Flux<Message<Foo>>. Then
it can do the conversion a level below.
Only supports Message->Message or POJO->POJO (no mixtures), so there
is only one new method in FunctionInspector.
No support in the web endpoints yet. But it's probably not so hard
to add.
If there is only one function you shouldn't have to set any configuration
to get a stream app to run. This also implementation supports multiple
functions, trying to guess which one to use based on the type of
the incoming message payload. In principle that could be strategized
as a simple router function (e.g. to look for a header with a function
name).
If there are functions and consumers in the same app, they will
subscribe to the same input channel (and hence by default Spring
Integration will load balance between them). This could also probably
use some more features, to specify the desired behaviour.
If user *does* supply spring.cloud.function.stream.endpoint then it
is used and overrides all other possible routes.
The compiled functions implement that interface which means you can inspect
the signature of the method that created them and discover its
generic types.
Compiled functions always show up with no metadata, and you can only
guess what the types are from the bean definition. Probably we should
add more information to the bean definition if we have it when we
compile the function.
There is still a problem if user defines functions that are not of
Flux<String> (but that has always been the case).
Lambdas generally only deal with single values anyway, but for
consistency we should return similar results from a Lambda handler
as from an MVC handler in s-c-f-web.
If the request is a single value, we already know, so if we also
know that the function returned a single-valued type, then we can
render the single value, instead of an array with a single item.
See gh-36
These can be used to more reliably discover whether the user
has declared a function with flux types or "bare" POJOs. They
then pave the way to supporting single valued types in a special
way.
Also consolidate and simplify the logic in FunctionInspector
So that single Strings can be POSTed without JSON conversion.
There's still some work to do to support single POJOs in JSON, and
to reach parity with the WebFlux reactive type handlers, but it's
now closer to what we had before we moved the String conversion
out of the function layer.
There is one behaviour change (you have to POST an array to a function
endpoint if you are sending a body), and also a message converter that
needed to be removed so that arrays are not toStringed in the response
body.
