(DataFlex) REST Receive Response in Chunks

See more REST Examples

Demonstrates how to receive a REST HTTP response in chunks.

Note: This example requires Chilkat 10.1.0 or greater.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

Use ChilkatAx-win32.pkg

Procedure Test
    Handle hoRest
    Boolean iBTls
    Integer iPort
    Boolean iBAutoReconnect
    Boolean iSuccess
    Integer iStatusCode
    String sOutputFile
    Handle hoFac
    Variant vBd
    Handle hoBd
    Integer iStatus
    String sTemp1
    Integer iTemp1

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    Get Create (RefClass(cComChilkatRest)) To hoRest
    If (Not(IsComObjectCreated(hoRest))) Begin
        Send CreateComObject of hoRest
    End

    // Connect to the web server
    Move True To iBTls
    Move 443 To iPort
    Move True To iBAutoReconnect
    Get ComConnect Of hoRest "chilkatsoft.com" iPort iBTls iBAutoReconnect To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoRest To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Send the request.
    // This can be *any* kind of request: POST, GET, PUT, etc. using *any* of the Chilkat REST methods that send requests.
    // For this example, we'll just GET a simple XML document that is about 274K in size.

    Get ComSendReqNoBody Of hoRest "GET" "/hamlet.xml" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoRest To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Get the response header.
    Get ComReadResponseHeader Of hoRest To iStatusCode
    If (iStatusCode < 0) Begin
        Get ComLastErrorText Of hoRest To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln "response status code = " iStatusCode

    Move "c:/temp/qa_output/hamlet.xml" To sOutputFile

    Get Create (RefClass(cComCkFileAccess)) To hoFac
    If (Not(IsComObjectCreated(hoFac))) Begin
        Send CreateComObject of hoFac
    End
    Get ComOpenForWrite Of hoFac sOutputFile To iSuccess
    If (iStatusCode < 0) Begin
        Get ComLastErrorText Of hoFac To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Get the response in chunks.
    // (Note: There are more efficient ways to simply download a file from a web server, such as by calling Chilkat's Http.Download method.
    // The purpose of this method is to show how to receive a response chunk-by-chunk.)
    Get Create (RefClass(cComChilkatBinData)) To hoBd
    If (Not(IsComObjectCreated(hoBd))) Begin
        Send CreateComObject of hoBd
    End
    Move 1 To iStatus
    While (iStatus = 1)
        // Read a minimum of 16000 bytes.
        // Note: Because of TLS message lengths, or the possibility of the response being either compressed (gzip/deflate) or in the HTTP chunked encoding,
        // the amount of data received in each call can be greater than the specified min size.
        // Chilkat will return from the call as soon as it has received an amount equal to or more than the specified size,
        // except for the very last chunk, which can be less that the min size or even 0 bytes.

        // The status will be one of three values:
        // -1 = error
        // 0 = received the last chunk of the response.
        // 1 = received a chunk, and more chunks are coming..

        // The received data is *appended* to the contents of the BinData object.
        Get pvComObject of hoBd to vBd
        Get ComReadRespChunkBd Of hoRest 16000 vBd To iStatus
        If (iStatus >= 0) Begin
            Get ComNumBytes Of hoBd To iTemp1
            Showln "Received chunk: " iTemp1 " bytes"
            Get pvComObject of hoBd to vBd
            Get ComFileWriteBd Of hoFac vBd 0 0 To iSuccess
            Get ComClear Of hoBd To iSuccess
        End

    Loop

    Send ComFileClose To hoFac

    Showln "Success."


End_Procedure