PureBasic

(using AWS Signature Version 2) Streaming Download to File

See more Amazon S3 (new) Examples

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. PureBasic

IncludeFile "CkStream.pb"
IncludeFile "CkAuthAws.pb"
IncludeFile "CkRest.pb"

Procedure ChilkatExample()

    success.i = 0

    ; 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 = 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