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Extract common logic in invokers into base class

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Dave Syer
2018-03-20 17:28:29 +00:00
parent 9012143093
commit 0bd71e61e0
5 changed files with 387 additions and 353 deletions
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docs/src/main/asciidoc/spring-cloud-function.adoc
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@@ -49,11 +49,13 @@ As the table above shows the behaviour of the endpoint depends on the method and
Functions and consumers that are declared with input and output in `Message<?>` will see the request headers on the input messages, and the output message headers will be converted to HTTP headers.
When POSTing text the response format might be different with Spring Boot 2.0 and older versions, depending on the content negotiation (provide content type and accpt headers for the best results).
== Standalone Streaming Applications
To send or receive messages from a broker (such as RabbitMQ or Kafka) you can use the `spring-cloud-function-stream` adapter. Add the adapter to your classpath along with the appropriate binder from Spring Cloud Stream. The adapter will bind to the message broker as a `Processor` (input and output streams) unless the user explicitly disables one or the other using `spring.cloud.function.stream.{source,sink}.enabled=false`.
An incoming message is routed to a function (or consumer). If there is only one, then the choice is obvious. If there are multiple functions that can accept an incoming message, the message is inspected to see if there is a `stream_routekey` header containing the name of a function. The header is also added to outgoing messages from a supplier. Messages with no route key can be routed exclusively to a function or consumer by specifying `spring.cloud.function.stream.{processor,sink}.name`. A single supplier can be chosen for output messages (if more than one is available) using the `spring.cloud.function.stream.supplier.name`. Routing headers or function names can be composed using a comma or pipe separated name.
An incoming message is routed to a function (or consumer). If there is only one, then the choice is obvious. If there are multiple functions that can accept an incoming message, the message is inspected to see if there is a `stream_routekey` header containing the name of a function. Routing headers or function names can be composed using a comma- or pipe-separated name. The header is also added to outgoing messages from a supplier. Messages with no route key can be routed exclusively to a function or consumer by specifying `spring.cloud.function.stream.{processor,sink}.name`. If a single function cannot be identified to process an incoming message there will be an error, unless you set `spring.cloud.function.stream.shared=true`, in which case such messages will be sent to all compatible functions. A single supplier can be chosen for output messages from a supplier (if more than one is available) using the `spring.cloud.function.stream.source.name`.
NOTE: some binders will fail on startup if the message broker is not available and the function catalog contains suppliers that immediately produce messages when accessed. You can switch off the automatic publishing from suppliers on startup using the `spring.cloud.function.strean.supplier.enabled=false` flag.