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Thread: timer / doevents / inet problem

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    timer / doevents / inet problem

    In my script I have actived a Timer with DIALOG SET TIMER. The interval value is 250.
    When the timer is fired it runs the DOEVENTS ON command.
    CASE %WM_TIMER
    DOEVENTS ON

    Also I use some INET_URLdownload commands. But I noticed that when INET_URLdownload is running the timer is not active anymore. But when I put also "DOEVENTS ON" after INET_URLdownload the timer will be hit again. I don't understand how this exactly works and how i can improve my code.

    I hope my problem is clear, otherwise I will show some code.

    thanks in advance for any help

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    thinBasic author ErosOlmi's Avatar
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    Re: timer / doevents / inet problem

    Martin,

    first never call a DOEVENTS inside a timer because it will create unpredictable results. Timer events are already releasing cpu to other process.

    The problem is INET_URLdownload: it is a synchronous function, it means it will not return until it has finished to download the file. So if you call that function inside a timer event again you will get unpredictable results again.

    What you need is an asynchronous function, that is a function you fire and than you can check its going on till finished.
    In this case you could fire the function when needed and than install a timer to check download status.

    Problem is that I need to create such a function.
    Something like \SampleScripts\TcpUdp\DownloadPage.tBasic

    I will see what I can do.
    Eros
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    thinBasic author ErosOlmi's Avatar
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    Re: timer / doevents / inet problem

    Martin,

    I think I've already developed something interesting.
    Be patient for 1 or 2 days and I will release something to test.

    Eros
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    Re: timer / doevents / inet problem

    Wonderful!!

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    thinBasic author ErosOlmi's Avatar
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    Re: timer / doevents / inet problem

    Ok,

    I've already developed something but I'm not 100% satisfied.
    Application is working fine, you have full control of what to download and control of download stepping but I would like to have more: download callback in order to be able for thinBasic INet module to automatically call a script function indicated by the programmer as soon as there is an event in download stepping.

    Anyhow, for the moment is not bad. Below an example of the code and a bundled exe you can check. I think when I will release you will be able to use also in a timer callback: you will need to add some checking in the timer in order to see if current data chunk has already been downloaded or you have to wait till next timer event.

    New features will be present in next release (out very soon).
    I'm not sure if I will be able to already include a callback version.

    Ciao
    Eros

    [code=thinbasic]
    '---Declare need modules
    uses "console"
    uses "INET"
    uses "file"

    '---Some needed variables
    LOCAL bResult AS LONG
    LOCAL hSession AS DWORD
    LOCAL hInternet AS DWORD

    LOCAL sUrl AS string

    LOCAL strBuffer AS STRING
    LOCAL pstrBuffer AS long
    LOCAL strBufferLen AS long
    LOCAL strData AS STRING

    LOCAL cbBytesRead AS DWORD
    local TotalBytesRead as dword
    local FileSize as dword

    local nSecs as long
    local T0, T1 as double

    local lBufferLen as long = 1024

    '---Initializes an application's use of the WinINet Internet functions.
    hSession = INET_Internet_Open("Test download from thinBasic script", %INTERNET_OPEN_TYPE_DIRECT, "", "", 0)
    IF hSession = %NULL THEN
    printl "INET_Internet_Open error"
    stop
    END IF

    '---Opens a resource specified by a complete HTTP URL.
    '---More or less like a standard local OPEN file operation
    sUrl = "http://www.thinbasic.biz/projects/th...c_1.7.8.0.zip"
    printl "Downloading " & sUrl
    hInternet = INET_Internet_OpenUrl(hSession, sUrl, "", 0, %INTERNET_FLAG_NO_CACHE_WRITE, 0)
    IF hInternet = %NULL THEN
    printl "INET_Internet_OpenUrl error"
    INET_Internet_CloseHandle hSession
    stop
    END IF

    '---Setup a %BufferLen bytes buffer
    strBuffer = STRING$(lBufferLen, $SPC)
    pstrBuffer = STRPTR(strBuffer)

    '---Query remote server about the size of the file we are going to download
    INET_Http_QueryInfo(hInternet, %HTTP_QUERY_CONTENT_LENGTH, pstrBuffer, lBufferLen)
    FileSize = val(left$(strBuffer, lBufferLen))
    printl "Real file size in bytes: " & FileSize

    '---Ok we can start a loop for file download. This can be automated in a loop or in a timer function
    '---Reads the data in %BufferLen bytes chunks
    T0 = timer
    DO
    bResult = INET_Internet_ReadFile(hInternet, pstrBuffer, len(strBuffer), cbBytesRead)
    IF bResult = 0 OR cbBytesRead = 0 THEN EXIT DO
    IF cbBytesRead = LEN(strBuffer) THEN
    strData &= strBuffer
    ELSE
    strData &= LEFT$(strBuffer, cbBytesRead)
    END IF
    TotalBytesRead += cbBytesRead
    T1 = timer
    printat "Elapsed seconds : " & format$(T1-T0, "#0") , 40, 3
    printat "Bytes read so far : " & TotalBytesRead , 40, 4
    printat "KBytes per second : " & format$((TotalBytesRead / max(T1-T0, 1))/1024, "#0.00"), 40, 5
    printat "Estimated seconds : " & format$((FileSize * (T1-T0))/TotalBytesRead, "#0") , 40, 6
    LOOP

    '---Closes all used handles
    INET_Internet_CloseHandle hInternet
    INET_Internet_CloseHandle hSession

    '---Output buffer to a file
    printl
    printl
    printl
    printl
    printl
    printl "---Saving file: " & app_sourcepath & "thinBasic_1.7.8.0.zip"
    file_save(app_sourcepath & "thinBasic_1.7.8.0.zip", strData)
    printl
    printl "---All done! Press any key to finish---"
    WAITKEY

    [/code]
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    Re: timer / doevents / inet problem

    Hello Eros, thanks for your explanation. I didn't realize that a DoEvent inside a timerfunction is unwise. The example and code looks very promising and I am looking forward (i think we all do) to the new official release. I want to thank you for always answering my/our questions and for your hard work to realize our wishes and requests. It's unbelievable what you're doing for us and sometimes I wonder if you have time to sleep.

    Martin

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    thinBasic author ErosOlmi's Avatar
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    Re: timer / doevents / inet problem

    Quote Originally Posted by martin
    It's unbelievable what you're doing for us and sometimes I wonder if you have time to sleep.
    Yes, be sure I have time to sleep, work in real job, family and even other (little) things.

    One of the big advantage of thinBasic (those developing thinBasic modules know what I mean) is its internal structure. Adding new keywords is very straightforward.
    The most difficult part is to understand what is the right direction for solving a problem but when you have got it, adding in thinBasic is easy.

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  8. #8
    thinBasic author ErosOlmi's Avatar
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    Re: timer / doevents / inet problem

    I think I have my first callback monitored Internet download version done.
    I'm still discovering this functionality by myself because I didn't find much help on the web apart people having problems with it

    API function I'm using is InternetSetStatusCallback and the relative CallBack template function

    Hope to succeed and have something to release very soon.

    Eros
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    Re: timer / doevents / inet problem

    That's really great news Eros. I'm looking forward to try this new function

  10. #10
    thinBasic author ErosOlmi's Avatar
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    Re: timer / doevents / inet problem

    Attached a preview on how it will look like. I'm working on adding more internal error checking and help material.

    Mainly after having opened connection with
    [code=thinbasic]INET_Internet_OpenUrl[/code]

    and you have a valid Internet handle, you setup a callback for the that handle using
    [code=thinbasic]INET_Internet_SetStatusCallBack[/code]

    From that moment at every status change, INet will automatically call your designated callback.

    Considering you are developing a User Interface application I suppose you will work in a way like the following:
    • setup some data to be able to control your download (a UDT is perfect)
    • setup a callback function (maybe common to all downloads)
    • somewhere, open your url and get its Internet handle
    • setup a timer (maybe common to all active downloads) active only if you have one or more downloads active
    • in you timer event use INET_Internet_ReadFile to get data from active connections and this will automatically call your designated callback. In there your will monitor your download status


    Ciao
    Eros
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