http-binding.puml

@startuml HTTP Binding

box Function Process in Local Environment or Container
control ENTRYPOINT
participant Main
participant Server
participant Express [
  Web Server
  ----
  ""Express""
]
participant Interceptor
participant "User Function" as UserFunction
participant DaprClient
end box

entity "Dapr Sidecar " as DaprSidecar

== OpenFunction Serving ==

ENTRYPOINT -> Main ** : execute
note over ENTRYPOINT, Main: Pass through __CLI arguments__ and \ncontainer __environment variables__

Main -> Main : load user function file
note left: ""function (req, res) {}"" 

Main -> Server ** : create
note over Main, Server: Hand over __user function__, __function type__ \nand __context__ parsed from env variables 

Server -> Express ** : new

Server -> Express : use init middleware
note over Server, Express: Store context in ""res.locals.context""

Server -> Interceptor ** : new
Server -> Express : use interceptor
|||
Server -> Express : use others middlewares
|||
Server -> UserFunction ** : wrap user function
note over Server, UserFunction: Use Node.js ""Domain"" to run function and catch exceptions  
Server -> Express : bind wrapper to "/*" route

...

== OpenFunction Invocation ==

[-> Express ++ : HTTP request to "/"

Express -> UserFunction ++ : execute user function
UserFunction --> Express -- : return execution result "data"

alt ""runtime"" = ""knative"" and ""outputs"" is not empty
  Express -> Interceptor ++ : invoke interceptor

  Interceptor -> Interceptor : load context
  Interceptor -> DaprClient ** : new

  loop each OpenFunction Output 
    Interceptor -> DaprClient ++ : send "data"

    DaprClient -> DaprSidecar ++ : invoke binding or publication with "data"
    DaprSidecar --> DaprClient -- : return result 

    DaprClient --> Interceptor -- : forward result
  end

  Interceptor -> DaprClient !!
  Interceptor --> Express -- : return "data" as response
end

[<- Express -- : send response

...

@enduml