.NET Languages
It's possible to write your function in using different .NET languages (C#, Visual Basic, or F#). The core task is the same in all languages—you create a class implementing one of the Functions Framework interfaces:
-
IHttpFunction - The generic
ICloudEvent<T> - The non-generic
ICloudEvent
This document provides examples for F# and Visual Basic.
Templates
Note that to run the examples in this document, you will use the templates :
-
Install the .NET SDK .
-
Install the template package:
dotnet new install Google.Cloud.Functions.Templates
Templates are provided for the three kinds of functions in C# (the default), F#,
and Visual Basic. When creating a new project from a template, specify -lang f#
to create an F# project, or -lang vb
to create a Visual Basic
project. For example, to create a new untyped CloudEvent function for Visual
Basic, you would run:
dotnet
new
gcf
-
untyped
-
event
-
lang
vb
HTTP function examples
You use HTTP functions
when you want to invoke
your function via an HTTP(S) request. The following examples output the message "Hello World!"
F#
namespace HelloWorldFSharp open Google.Cloud.Functions.Framework open Microsoft.AspNetCore.Http type Function () = interface IHttpFunction with member this . HandleAsync context = async { do ! context . Response . WriteAsync "Hello World!" | > Async . AwaitTask } | > Async . StartAsTask : > _
Visual Basic
Imports Google.Cloud.Functions.Framework Imports Microsoft.AspNetCore.Http Public Class CloudFunction Implements IHttpFunction Public Async Function HandleAsync ( context As HttpContext ) As Task Implements IHttpFunction . HandleAsync Await context . Response . WriteAsync ( "Hello World!" ) End Function End Class
Project files for HTTP examples
Here are the project files for the above samples:
F#
< Project Sdk = "Microsoft.NET.Sdk" > < PropertyGroup > < OutputType>Exe < / OutputType > < TargetFramework>net6 . 0 < / TargetFramework > < / PropertyGroup > < ItemGroup > < Compile Include = "Function.fs" / > < / ItemGroup > < ItemGroup > < PackageReference Include = "Google.Cloud.Functions.Hosting" Version = "2.2.1" / > < / ItemGroup > < / Project >
Visual Basic
< Project Sdk = "Microsoft.NET.Sdk" > < PropertyGroup > < OutputType>Exe < / OutputType > < RootNamespace>HelloWorldVb < / RootNamespace > < TargetFramework>net6 . 0 < / TargetFramework > < / PropertyGroup > < ItemGroup > < PackageReference Include = "Google.Cloud.Functions.Hosting" Version = "2.2.1" / > < / ItemGroup > < / Project >
Deploying the HTTP functions
F#
gcloud
functions
deploy
fsharp
-
helloworld
--
no
-
gen2
--
entry
-
point
HelloWorldFSharp
.
Function
--
runtime
dotnet6
--
trigger
-
http
--
allow
-
unauthenticated
Visual Basic
gcloud functions deploy vb-helloworld --no-gen2 --entry-point HelloWorldVb.CloudFunction --runtime dotnet6 --trigger-http --allow-unauthenticated
CloudEvent examples
You use CloudEvent functions when you want to have your Cloud Run function invoked indirectly in response to an asynchronous event, such as a message on a Pub/Sub topic, a change in a Cloud Storage bucket, or a Firebase event.
F#
namespace HelloPubSubFSharp open Google.Cloud.Functions.Framework open Google.Events.Protobuf.Cloud.PubSub.V1 open Microsoft.Extensions.Logging open System open System.Threading.Tasks type Function ( logger : ILogger<Function> ) = interface ICloudEventFunction<MessagePublishedData> with member this . HandleAsync ( cloudEvent , data , cancellationToken ) = let nameFromMessage = data . Message . TextData let name = if String . IsNullOrEmpty ( nameFromMessage ) then "world" else nameFromMessage logger . LogInformation ( "Hello {name}" , name ) Task . CompletedTask
Visual Basic
Imports System.Threading Imports CloudNative.CloudEvents Imports Google.Cloud.Functions.Framework Imports Google.Events.Protobuf.Cloud.PubSub.V1 Imports Microsoft.Extensions.Logging Public Class CloudFunction Implements ICloudEventFunction ( Of MessagePublishedData ) Private _logger As ILogger Public Sub New ( ByVal logger As ILogger ( Of CloudFunction )) _logger = logger End Sub Public Function HandleAsync ( cloudEvent As CloudEvent , data As MessagePublishedData , cancellationToken As CancellationToken ) As Task _ Implements ICloudEventFunction ( Of MessagePublishedData ). HandleAsync Dim nameFromMessage = data . Message ? . TextData Dim name = If ( String . IsNullOrEmpty ( nameFromMessage ), "world" , nameFromMessage ) _logger . LogInformation ( "Hello {name}" , name ) Return Task . CompletedTask End Function End Class
Deploying the CloudEvent functions
F#
gcloud
functions
deploy
fsharp
-
hello
-
pubsub
--
no
-
gen2
--
entry
-
point
HelloPubSubFSharp
.
Function
--
runtime
dotnet6
--
trigger
-
topic
my
-
topic
--
allow
-
unauthenticated
Visual Basic
gcloud functions deploy vb-hello-pubsub --no-gen2 --entry-point HelloPubSubVb.CloudFunction --runtime dotnet6 --trigger-topic my-topic --allow-unauthenticated
Test the CloudEvent examples
You can test the CloudEvent examples as follows:
-
Publish a message to your Pub/Sub topic to trigger your function:
gcloud pubsub topics publish my-topic --message Flurry
-
Look at the logs:
gcloud functions logs read --limit 10
You should see something like this, with a message that includes the name you published to the Pub/Sub topic:
D my-function ... Function execution started
I my-function ... Hello Flurry!
D my-function ... Function execution took 39 ms, finished with status: 'ok'
