SQL Server

S3 Streaming Upload with Expect: 100-continue

See more Amazon S3 (new) Examples

Demonstrates how to do an S3 streaming upload that includes an "Expect: 100-continue" request header. The purpose of sending an "Expect: 100-continue" header is to cleanly handle the case when the request fails, for whatever reason. (Failure reasons can be anything, such as a permissions problem, invalid authentication, etc.)

If no "Expect: 100-continue" header is included, and the AWS server rejects the request immediately after receiving the header, then this is what happens: The server closes the connection immediately after processing the request header. This results in a half-closed connection. Meanwhile, the client continues with sending the file data in the body of the HTTP request. Eventually, because nothing is consuming the data on the server-side, the outgoing socket buffer on the client (i.e. local machine) fills up, and an error such as "WSAECONNABORTED An established connection was aborted by the software in your host machine." is returned.

When the "Expect: 100-continue" is inclued, the server sends a response immediately after receiving the request header. A 100 response status code indicates that all is OK and the client should continue with sending the request body (i.e. file data), after which the server will respond with a final response.

SQL Server

-- Important: See this note about string length limitations for strings returned by sp_OAMethod calls.
--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @iTmp0 int
    -- Important: Do not use nvarchar(max).  See the warning about using nvarchar(max).
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @success int
    SELECT @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.
    DECLARE @crypt int
    EXEC @hr = sp_OACreate 'Chilkat.Crypt2', @crypt OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    EXEC sp_OASetProperty @crypt, 'EncodingMode', 'hex'
    EXEC sp_OASetProperty @crypt, 'HashAlgorithm', 'sha-256'
    DECLARE @fileToUploadPath nvarchar(4000)
    SELECT @fileToUploadPath = 'qa_data/xml/hamlet.xml'
    DECLARE @hashStr nvarchar(4000)
    EXEC sp_OAMethod @crypt, 'HashFileENC', @hashStr OUT, @fileToUploadPath

    DECLARE @rest int
    EXEC @hr = sp_OACreate 'Chilkat.Rest', @rest OUT

    -- Connect to the Amazon AWS REST server.
    DECLARE @bTls int
    SELECT @bTls = 1
    DECLARE @port int
    SELECT @port = 443
    DECLARE @bAutoReconnect int
    SELECT @bAutoReconnect = 1
    EXEC sp_OAMethod @rest, 'Connect', @success OUT, '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.
    DECLARE @authAws int
    EXEC @hr = sp_OACreate 'Chilkat.AuthAws', @authAws OUT

    EXEC sp_OASetProperty @authAws, 'AccessKey', 'AWS_ACCESS_KEY'
    EXEC sp_OASetProperty @authAws, 'SecretKey', 'AWS_SECRET_KEY'
    EXEC sp_OASetProperty @authAws, 'ServiceName', 's3'
    -- Provide the pre-computed SHA-256 here:
    EXEC sp_OASetProperty @authAws, 'PrecomputedSha256', @hashStr

    EXEC sp_OAMethod @rest, 'SetAuthAws', @success OUT, @authAws

    -- Add an Expect: 100-continue request header
    EXEC sp_OAMethod @rest, 'AddHeader', @success OUT, 'Expect', '100-continue'

    -- Set the bucket name via the HOST header.
    -- In this case, the bucket name is "chilkat100".
    EXEC sp_OASetProperty @rest, 'Host', 'chilkat100.s3.amazonaws.com'

    DECLARE @fileStream int
    EXEC @hr = sp_OACreate 'Chilkat.Stream', @fileStream OUT

    EXEC sp_OASetProperty @fileStream, 'SourceFile', @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.
    DECLARE @responseStr nvarchar(4000)
    EXEC sp_OAMethod @rest, 'FullRequestStream', @responseStr OUT, 'PUT', '/hamlet.xml', @fileStream
    EXEC sp_OAGetProperty @rest, 'LastMethodSuccess', @iTmp0 OUT
    IF @iTmp0 <> 1
      BEGIN
        EXEC sp_OAGetProperty @rest, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @crypt
        EXEC @hr = sp_OADestroy @rest
        EXEC @hr = sp_OADestroy @authAws
        EXEC @hr = sp_OADestroy @fileStream
        RETURN
      END

    -- When successful, the S3 Storage service will respond with a 200 response code,
    -- with an XML body.  
    EXEC sp_OAGetProperty @rest, 'ResponseStatusCode', @iTmp0 OUT
    IF @iTmp0 = 200
      BEGIN

        PRINT @responseStr

        PRINT 'File uploaded.'
      END
    ELSE
      BEGIN
        -- Examine the request/response to see what happened.

        EXEC sp_OAGetProperty @rest, 'ResponseStatusCode', @iTmp0 OUT
        PRINT 'response status code = ' + @iTmp0

        EXEC sp_OAGetProperty @rest, 'ResponseStatusText', @sTmp0 OUT
        PRINT 'response status text = ' + @sTmp0

        EXEC sp_OAGetProperty @rest, 'ResponseHeader', @sTmp0 OUT
        PRINT 'response header: ' + @sTmp0

        PRINT 'response body: ' + @responseStr

        PRINT '---'

        EXEC sp_OAGetProperty @rest, 'LastRequestStartLine', @sTmp0 OUT
        PRINT 'LastRequestStartLine: ' + @sTmp0

        EXEC sp_OAGetProperty @rest, 'LastRequestHeader', @sTmp0 OUT
        PRINT 'LastRequestHeader: ' + @sTmp0
      END

    EXEC @hr = sp_OADestroy @crypt
    EXEC @hr = sp_OADestroy @rest
    EXEC @hr = sp_OADestroy @authAws
    EXEC @hr = sp_OADestroy @fileStream


END
GO