PowerBuilder

AWS S3 File Streaming Upload

See more Amazon S3 (new) Examples

Demonstrates how to do a streaming upload from a file to the AWS S3 storage service. The AWS authorization presents some difficulties when the REST request body is to be streamed from a file (or from some other source). The issue is that the SHA-256 hash of the file data must be calculated. There are only two possible ways to do this: (1) stream the file into memory in its entirety and calculate the SHA-256 hash prior to uploading, or (2) pre-calculate the SHA-256 in a streaming fashion, and then provide it to the AWS authentication object.

If the application does NOT pre-compute the SHA-256, then Chilkat (internally) is forced to stream into memory, calculate the SHA-256, and then upload from the in-memory copy of the file.

PowerBuilder

integer li_rc
integer li_Success
oleobject loo_Crypt
string ls_FileToUploadPath
string ls_HashStr
oleobject loo_Rest
integer li_BTls
integer li_Port
integer li_BAutoReconnect
oleobject loo_AuthAws
oleobject loo_FileStream
string ls_ResponseStr

li_Success = 0

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

// This first part is optional.  AWS authentication requires
// the SHA-256 hash of the request body (i.e. the contents of the file
// to be uploaded).  We can choose to pre-calculate the SHA-256 in a streaming fashion
// and then provide it to the authenticator object.  This way, if the file is
// extremely large, it never needs to completely reside in memory.
loo_Crypt = create oleobject
li_rc = loo_Crypt.ConnectToNewObject("Chilkat.Crypt2")
if li_rc < 0 then
    destroy loo_Crypt
    MessageBox("Error","Connecting to COM object failed")
    return
end if
loo_Crypt.EncodingMode = "hex"
loo_Crypt.HashAlgorithm = "sha-256"
ls_FileToUploadPath = "qa_data/xml/hamlet.xml"
ls_HashStr = loo_Crypt.HashFileENC(ls_FileToUploadPath)

loo_Rest = create oleobject
li_rc = loo_Rest.ConnectToNewObject("Chilkat.Rest")

// Connect to the Amazon AWS REST server.
li_BTls = 1
li_Port = 443
li_BAutoReconnect = 1
li_Success = loo_Rest.Connect("s3.amazonaws.com",li_Port,li_BTls,li_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.
loo_AuthAws = create oleobject
li_rc = loo_AuthAws.ConnectToNewObject("Chilkat.AuthAws")

loo_AuthAws.AccessKey = "AWS_ACCESS_KEY"
loo_AuthAws.SecretKey = "AWS_SECRET_KEY"
loo_AuthAws.ServiceName = "s3"
// Provide the pre-computed SHA-256 here:
loo_AuthAws.PrecomputedSha256 = ls_HashStr

li_Success = loo_Rest.SetAuthAws(loo_AuthAws)

// Set the bucket name via the HOST header.
// In this case, the bucket name is "chilkat100".
loo_Rest.Host = "chilkat100.s3.amazonaws.com"

loo_FileStream = create oleobject
li_rc = loo_FileStream.ConnectToNewObject("Chilkat.Stream")

loo_FileStream.SourceFile = ls_FileToUploadPath

// Upload to the S3 Storage service.
// If the application provided the SHA-256 hash of the file contents (as shown above)
// then file is streamed and never has to completely reside in memory.
// If the application did NOT provide the SHA-256, then Chilkat will (internally) 
// load the entire file into memory, calculate the SHA-256, and then upload.
ls_ResponseStr = loo_Rest.FullRequestStream("PUT","/hamlet.xml",loo_FileStream)
if loo_Rest.LastMethodSuccess <> 1 then
    Write-Debug loo_Rest.LastErrorText
    destroy loo_Crypt
    destroy loo_Rest
    destroy loo_AuthAws
    destroy loo_FileStream
    return
end if

// When successful, the S3 Storage service will respond with a 200 response code,
// with an XML body.  
if loo_Rest.ResponseStatusCode = 200 then
    Write-Debug ls_ResponseStr
    Write-Debug "File uploaded."
else
    // Examine the request/response to see what happened.
    Write-Debug "response status code = " + string(loo_Rest.ResponseStatusCode)
    Write-Debug "response status text = " + loo_Rest.ResponseStatusText
    Write-Debug "response header: " + loo_Rest.ResponseHeader
    Write-Debug "response body: " + ls_ResponseStr
    Write-Debug "---"
    Write-Debug "LastRequestStartLine: " + loo_Rest.LastRequestStartLine
    Write-Debug "LastRequestHeader: " + loo_Rest.LastRequestHeader
end if



destroy loo_Crypt
destroy loo_Rest
destroy loo_AuthAws
destroy loo_FileStream