B4J Question StartMessageLoop was not called

[mbenam]

Hi,

trying to learn "wait for" in a non ui app. I get the error "Program terminated (StartMessageLoop was not called)." Here is my code.

Sub Process_Globals

End Sub

Sub AppStart (Args() As String)
    
    Wait For (getUrl) Complete (Result As Boolean)
    Log("Hello world!!!")
    StartMessageLoop
End Sub

Sub getUrl() As ResumableSub
    Dim client As HttpJob
    
    client.Initialize("",Me)
    client.Download("https://www.google.com")
    
    Wait For (client) JobDone (res As HttpJob)
    If res.Success=False Then
        Log("error")
        Return False
    End If
    Dim CookieContainer As String = res.Response.GetHeaders.Get("set-cookie")
    Log(CookieContainer)
    Return True
End Sub

 

[EnriqueGonzalez]

Scratch the wait for line.
Change it to just geturl

You are not using the url result, so then you don't have to return a value. Instead of returning just call stopmessageloop

 

[Erel]

Remember the number #1 rule of resumable subs: a call to Wait For or Sleep is equivalent to a call to Return, from the calling sub perspective.
This means that the code flow will return at line 7 and the program will end, as there is no message loop.

This will work as you expect:

Sub AppStart (Args() As String)
    MyStart
    StartMessageLoop
End Sub

Sub MyStart
   Wait For (getUrl) Complete (Result As Boolean)
     Log("Hello world!!!")
End Sub

 

[mbenam]

Erel,

I have been doing what you suggested in your code. But doing that it seems like I need to pile up all the code that I want to execute right after the httpjob within the MyStart sub. I wanted to avoid that and make codes modular. I know that I can call various subs within myStart. But if I have to do another httpjob later in the code, then I start the rabbit hole again. Not sure if I am making myself clear. I watched your video on resumable subs and thought the code I posted might work.

Thanks.

 

[mbenam]

Mod,

please delete my previous message. Upon further testing everything is working the way I intended. Thanks Erel.