(Tcl) REST Download Binary to Memory (CkByteData) (Amazon S3)

Demonstrates how to make a REST call that returns a binary response body. This example is valid for reasonably small files that fit in memory. The example shows how to download a small JPG from the Amazon S3 service. For larger files, Chilkat provides streaming functionality to stream directly to a file, or to make an asynchronous call where the foreground thread can read the response body stream.

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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
set success [CkRest_Connect $rest "s3.amazonaws.com" $port $bTls $bAutoReconnect]

# ----------------------------------------------------------------------------
# Important: For buckets created in regions outside us-east-1,
# there are three important changes that need to be made.
# See Working with S3 Buckets in Non-us-east-1 Regions for the details.
# ----------------------------------------------------------------------------

# 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"
set success [CkRest_SetAuthAws $rest $authAws]

# Set the bucket name via the HOST header.
# In this case, the bucket name is "chilkat100".
CkRest_put_Host $rest "chilkat100.s3.amazonaws.com"

# 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 jpgData [new_CkByteData]

    set success [CkRest_ReadRespBodyBinary $rest $jpgData]
    if {[CkRest_get_LastMethodSuccess $rest] != 1} then {
        puts [CkRest_lastErrorText $rest]
    }     else {
        puts "Successfully received the JPG bytes.."
        # See the CkByteData online reference documentation for 
        # information about accessing and manipulating the byte data.
    }

} 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_CkByteData $jpgData