(PureBasic) 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 PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkBinData.pb"
IncludeFile "CkRest.pb"
IncludeFile "CkFileAccess.pb"

Procedure ChilkatExample()

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

    rest.i = CkRest::ckCreate()
    If rest.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Connect to the web server
    bTls.i = 1
    port.i = 443
    bAutoReconnect.i = 1
    success.i = CkRest::ckConnect(rest,"chilkatsoft.com",port,bTls,bAutoReconnect)
    If success = 0
        Debug CkRest::ckLastErrorText(rest)
        CkRest::ckDispose(rest)
        ProcedureReturn
    EndIf

    ; 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.

    success = CkRest::ckSendReqNoBody(rest,"GET","/hamlet.xml")
    If success = 0
        Debug CkRest::ckLastErrorText(rest)
        CkRest::ckDispose(rest)
        ProcedureReturn
    EndIf

    ; Get the response header.
    statusCode.i = CkRest::ckReadResponseHeader(rest)
    If statusCode < 0
        Debug CkRest::ckLastErrorText(rest)
        CkRest::ckDispose(rest)
        ProcedureReturn
    EndIf

    Debug "response status code = " + Str(statusCode)

    outputFile.s = "c:/temp/qa_output/hamlet.xml"

    fac.i = CkFileAccess::ckCreate()
    If fac.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkFileAccess::ckOpenForWrite(fac,outputFile)
    If statusCode < 0
        Debug CkFileAccess::ckLastErrorText(fac)
        CkRest::ckDispose(rest)
        CkFileAccess::ckDispose(fac)
        ProcedureReturn
    EndIf

    ; 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.)
    bd.i = CkBinData::ckCreate()
    If bd.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    status.i = 1
    While status = 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.
        status = CkRest::ckReadRespChunkBd(rest,16000,bd)
        If status >= 0
            Debug "Received chunk: " + Str(CkBinData::ckNumBytes(bd)) + " bytes"
            CkFileAccess::ckFileWriteBd(fac,bd,0,0)
            CkBinData::ckClear(bd)
        EndIf

    Wend

    CkFileAccess::ckFileClose(fac)

    Debug "Success."


    CkRest::ckDispose(rest)
    CkFileAccess::ckDispose(fac)
    CkBinData::ckDispose(bd)


    ProcedureReturn
EndProcedure