[Programming Model] Function Format

[asavaritayal]

Summary

TBD (general information about the function format)

Binding to arguments

Input bindings

1. Trigger input
   TBD

2. Additional input
   TBD

Output bindings

1. $return type
   TBD

2. Generic type
   TBD

3. Multiple output values for a single binding
   TBD

Referencing external modules

TBD

Logging

TBD

Async

TBD

[asavaritayal]

Noticed the label. Is there a question here? :)

[TylerLeonhardt]

I saw it more of like... this is your question that you're asking. :) I kinda wish we filled this out but I think we have an answer for most if not all of it.

Here's what I have:

Summary

In general, we embrace PowerShell concepts. We use a param block for inputs and the ability to return things as outputs. For multi-output functions, we use a cmdlet called Push-OutputBinding.

Binding to arguments

Input bindings

1. Trigger input

param($res)

or

param($res, $TriggerMetadata)

The user has access to the binding data via the param block of their function.

All trigger metadata will come in as $TriggerMetadata if they specify $TriggerMetadata in the param block. If they don't, then they won't have access to Trigger metadata.

2. Additional input

Additional binding data will come in the param block:

param($res1, $res2)

Output bindings

1. $return type
   The user is able to use the return powershell keyword or write directly to the pipeline. The last item in the pipeline will become the value that is stored in $return output binding.

2. Generic type
   TBD

3. Multiple output values for a single binding
   TBD

Referencing external modules

TBD

Logging

The user should be able to use the same Write-* cmdlets that they would do in a normal PowerShell script and those will get routed accordingly by log level.

Async

See #4

[TylerLeonhardt]

@asavaritayal can you dig into what these are:

Generic type
TBD

Multiple output values for a single binding
TBD

[asavaritayal]

Ah, got it!

By generic type, I meant a standard output type. You already answered that question.

For multiple output values for a single binding, I mean the scenario where we need to write multiple values to the same output binding. For e.g. if our function were to write 10 messages to the same queue, we shouldn't need to declare it 10 times in the function.json file. In C# we use a collector object for the same purpose and for python, we end up returning a tuple instead of a single value.

[TylerLeonhardt]

we end up returning a tuple instead of a single value

So this is a bit confusing to me because tuples or arrays aren't valid grpc types (AFAIK). So does the worker look for this tuple and iterates over it and sends messages for each item with the valid grpc types (int, string, bytes, json, etc)?

[asavaritayal]

I'm not certain about the implementation. @elprans can you please help out our PowerShell friends?