(PureBasic) (using AWS Signature Version 2) Streaming Download to File

The main purpose of this example is to demonstrate how to use the older Signature Version 2 authentication w/ S3. It uses V2 authentication to download a file.

Chilkat PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkStream.pb"
IncludeFile "CkAuthAws.pb"
IncludeFile "CkRest.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 Amazon AWS REST server.
    bTls.i = 1
    port.i = 443
    bAutoReconnect.i = 1
    ; The file is located in the bucket named "chilkat100", which becomes part of the domain:
    success.i = CkRest::ckConnect(rest,"chilkat100.s3.amazonaws.com",port,bTls,bAutoReconnect)

    ; Provide AWS credentials for the REST call.
    authAws.i = CkAuthAws::ckCreate()
    If authAws.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkAuthAws::setCkAccessKey(authAws, "AWS_ACCESS_KEY")
    CkAuthAws::setCkSecretKey(authAws, "AWS_SECRET_KEY")
    CkAuthAws::setCkServiceName(authAws, "s3")

    ; For AWS Signature Version 2, the following two properties need to be set:
    CkAuthAws::setCkSignatureVersion(authAws, 2)
    ; See http://docs.aws.amazon.com/AmazonS3/latest/dev/RESTAuthentication.html#ConstructingTheCanonicalizedResourceElement
    CkAuthAws::setCkCanonicalizedResourceV2(authAws, "/chilkat100/starfish.jpg")

    success = CkRest::ckSetAuthAws(rest,authAws)

    ; Send the request to download the JPG.
    success = CkRest::ckSendReqNoBody(rest,"GET","/starfish.jpg")
    If success <> 1
        Debug CkRest::ckLastErrorText(rest)
        CkRest::ckDispose(rest)
        CkAuthAws::ckDispose(authAws)
        ProcedureReturn
    EndIf

    ; Read the response header.
    responseStatusCode.i = CkRest::ckReadResponseHeader(rest)
    If responseStatusCode < 0
        Debug CkRest::ckLastErrorText(rest)
        CkRest::ckDispose(rest)
        CkAuthAws::ckDispose(authAws)
        ProcedureReturn
    EndIf

    Debug "Response status code = " + Str(responseStatusCode)

    ; We expect a 200 response status if the JPG data is coming.
    ; Otherwise, we'll get a string response body with an error message(or no response body).
    If responseStatusCode = 200

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

        ; The stream's sink will be a file.
        CkStream::setCkSinkFile(bodyStream, "qa_output/starfish.jpg")

        ; Read the response body to the stream.  Given that we've
        ; set the stream's sink to a file, it will stream directly
        ; to the file.
        success = CkRest::ckReadRespBodyStream(rest,bodyStream,1)
        If success <> 1
            Debug CkRest::ckLastErrorText(rest)
            CkRest::ckDispose(rest)
            CkAuthAws::ckDispose(authAws)
            CkStream::ckDispose(bodyStream)
            ProcedureReturn
        EndIf

        Debug "Successfully received the JPG file."

    Else
        errResponse.s = CkRest::ckReadRespBodyString(rest)
        If CkRest::ckLastMethodSuccess(rest) <> 1
            Debug CkRest::ckLastErrorText(rest)
        Else
            Debug errResponse
        EndIf

    EndIf



    CkRest::ckDispose(rest)
    CkAuthAws::ckDispose(authAws)
    CkStream::ckDispose(bodyStream)


    ProcedureReturn
EndProcedure