(Tcl) (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 Tcl Extension Downloads Chilkat Tcl Extension Downloads

load ./chilkat.dll

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

set rest [new_CkRest]

# Connect to the Amazon AWS REST server.
set bTls 1
set port 443
set bAutoReconnect 1
# The file is located in the bucket named "chilkat100", which becomes part of the domain:
set success [CkRest_Connect $rest "chilkat100.s3.amazonaws.com" $port $bTls $bAutoReconnect]

# Provide AWS credentials for the REST call.
set authAws [new_CkAuthAws]

CkAuthAws_put_AccessKey $authAws "AWS_ACCESS_KEY"
CkAuthAws_put_SecretKey $authAws "AWS_SECRET_KEY"
CkAuthAws_put_ServiceName $authAws "s3"

# For AWS Signature Version 2, the following two properties need to be set:
CkAuthAws_put_SignatureVersion $authAws 2
# See http://docs.aws.amazon.com/AmazonS3/latest/dev/RESTAuthentication.html#ConstructingTheCanonicalizedResourceElement
CkAuthAws_put_CanonicalizedResourceV2 $authAws "/chilkat100/starfish.jpg"

set success [CkRest_SetAuthAws $rest $authAws]

# Send the request to download the JPG.
set success [CkRest_SendReqNoBody $rest "GET" "/starfish.jpg"]
if {$success != 1} then {
    puts [CkRest_lastErrorText $rest]
    delete_CkRest $rest
    delete_CkAuthAws $authAws
    exit
}

# Read the response header.
set responseStatusCode [CkRest_ReadResponseHeader $rest]
if {$responseStatusCode < 0} then {
    puts [CkRest_lastErrorText $rest]
    delete_CkRest $rest
    delete_CkAuthAws $authAws
    exit
}

puts "Response status code = $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} then {

    set bodyStream [new_CkStream]

    # The stream's sink will be a file.
    CkStream_put_SinkFile $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.
    set success [CkRest_ReadRespBodyStream $rest $bodyStream 1]
    if {$success != 1} then {
        puts [CkRest_lastErrorText $rest]
        delete_CkRest $rest
        delete_CkAuthAws $authAws
        delete_CkStream $bodyStream
        exit
    }

    puts "Successfully received the JPG file."

} else {
    set errResponse [CkRest_readRespBodyString $rest]
    if {[CkRest_get_LastMethodSuccess $rest] != 1} then {
        puts [CkRest_lastErrorText $rest]
    }     else {
        puts "$errResponse"
    }

}


delete_CkRest $rest
delete_CkAuthAws $authAws
delete_CkStream $bodyStream