Function Signatures

Comparison of different function signatures

There’re three function signatures in OpenFunction: HTTP, CloudEvent, and OpenFunction. Let’s explain this in more detail using Go function as an example.

HTTP and CloudEvent signatures can be used to create sync functions while OpenFunction signature can be used to create both sync and async functions.

Further more OpenFunction signature can utilize various Dapr building blocks including Bindings, Pub/sub etc to access various BaaS services that helps to create more powerful functions. (Dapr State management, Configuration will be supported soon)

	HTTP	CloudEvent	OpenFunction
Signature	`func(http.ResponseWriter, *http.Request) error`	`func(context.Context, cloudevents.Event) error`	`func(ofctx.Context, []byte) (ofctx.Out, error)`
Sync Functions	Supported	Supported	Supported
Async Functions	Not supported	Not supported	Supported
Dapr Binding	Not supported	Not supported	Supported
Dapr Pub/sub	Not supported	Not supported	Supported

Samples

As you can see, OpenFunction signature is the recommended function signature, and we’re working on supporting this function signature in more language runtimes.

	HTTP	OpenFunction
Go	Hello World, log processing	Sync function with output binding, Kafka input & HTTP output binding, Cron input & Kafka output binding, Cron input binding, Kafka input binding, Kafka pubsub
Nodejs	Hello World
Python	Hello World
Java	Hello World
DotNet	Hello World

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