(SQL Server) Fetch S3 Object Metadata

Demonstrates how to get the metadata for an S3 object using the REST API.

The HEAD operation retrieves metadata from an object without returning the object itself. This operation is useful if you are interested only in an object's metadata. To use HEAD, you must have READ access to the object.

A HEAD request has the same options as a GET operation on an object. The response is identical to the GET response except that there is no response body.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

-- 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 @sTmp1 nvarchar(4000)
    -- This example requires the Chilkat API to have been previously unlocked.
    -- See Global Unlock Sample for sample code.

    DECLARE @rest int
    -- Use "Chilkat_9_5_0.Rest" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.Rest', @rest OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    -- Connect to the Amazon AWS REST server using the correct region (in this example, "us-west-2")
    DECLARE @bTls int
    SELECT @bTls = 1
    DECLARE @port int
    SELECT @port = 443
    DECLARE @bAutoReconnect int
    SELECT @bAutoReconnect = 1
    DECLARE @success int
    EXEC sp_OAMethod @rest, 'Connect', @success OUT, 's3-us-west-2.amazonaws.com', @port, @bTls, @bAutoReconnect

    -- Provide AWS credentials for the REST call.
    DECLARE @authAws int
    -- Use "Chilkat_9_5_0.AuthAws" for versions of Chilkat < 10.0.0
    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'
    -- Make sure the Region agrees with the region in the Connect.
    EXEC sp_OASetProperty @authAws, 'Region', 'us-west-2'
    EXEC sp_OAMethod @rest, 'SetAuthAws', @success OUT, @authAws

    -- User-defined metadata are name/value pairs, and are returned in the HTTP response header.
    -- Metadata header names begin with "x-amz-meta-" to distinguish them from other HTTP headers.
    -- Note that Amazon S3 stores user-defined metadata keys in lowercase.

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

    -- Send the HEAD request.
    EXEC sp_OAMethod @rest, 'SendReqNoBody', @success OUT, 'HEAD', '/seahorse.jpg'
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @rest, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @rest
        EXEC @hr = sp_OADestroy @authAws
        RETURN
      END

    -- Read the response header.
    DECLARE @responseStatusCode int
    EXEC sp_OAMethod @rest, 'ReadResponseHeader', @responseStatusCode OUT
    IF @responseStatusCode < 0
      BEGIN
        EXEC sp_OAGetProperty @rest, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @rest
        EXEC @hr = sp_OADestroy @authAws
        RETURN
      END


    PRINT 'Response status code = ' + @responseStatusCode
    IF @responseStatusCode <> 200
      BEGIN
        EXEC sp_OAGetProperty @rest, 'ResponseHeader', @sTmp0 OUT
        PRINT @sTmp0

        PRINT 'Object does not exist.'
        EXEC @hr = sp_OADestroy @rest
        EXEC @hr = sp_OADestroy @authAws
        RETURN
      END

    -- Show the full response header that was received:

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

    PRINT '--'

    -- Here is an example response header:

    -- 	x-amz-id-2: uS4Flff04M8x5YWajU231TP0ClBL19mMhuyfU5ZVQd6NsUHXVhHK+H3b0sjxY98Fujet1ejhyzk=
    -- 	x-amz-request-id: 27950009AA8E68AA
    -- 	Date: Mon, 23 Jan 2017 20:12:58 GMT
    -- 	Last-Modified: Fri, 20 Jan 2017 00:22:57 GMT
    -- 	ETag: "a8551f0a5437f43a796fca7623ee9232"
    -- 	x-amz-meta-species: big-belly seahorse
    -- 	x-amz-meta-genus: Hippocampus
    -- 	x-amz-meta-habitat: shallow tropical and temperate waters
    -- 	Accept-Ranges: bytes
    -- 	Content-Type: image/jpg
    -- 	Content-Length: 24388
    -- 	Server: AmazonS3

    -- Examine particular response headers (the object metadata headers..)

    EXEC sp_OAMethod @rest, 'ResponseHdrByName', @sTmp0 OUT, 'x-amz-meta-species'
    PRINT 'x-amz-meta-species: ' + @sTmp0

    EXEC sp_OAMethod @rest, 'ResponseHdrByName', @sTmp0 OUT, 'x-amz-meta-genus'
    PRINT 'x-amz-meta-genus: ' + @sTmp0

    EXEC sp_OAMethod @rest, 'ResponseHdrByName', @sTmp0 OUT, 'x-amz-meta-habitat'
    PRINT 'x-amz-meta-habitat: ' + @sTmp0

    PRINT '--'

    -- It is possible to iterate over the header fields to find all x-amz-meta* headers
    DECLARE @i int
    SELECT @i = 0
    DECLARE @numHeaders int
    EXEC sp_OAGetProperty @rest, 'NumResponseHeaders', @numHeaders OUT
    DECLARE @sbName int
    -- Use "Chilkat_9_5_0.StringBuilder" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.StringBuilder', @sbName OUT

    WHILE @i < @numHeaders
      BEGIN
        EXEC sp_OAMethod @rest, 'ResponseHdrName', @sTmp0 OUT, @i
        EXEC sp_OAMethod @sbName, 'SetString', @success OUT, @sTmp0
        EXEC sp_OAMethod @sbName, 'StartsWith', @iTmp0 OUT, 'x-amz-meta', 0
        IF @iTmp0 = 1
          BEGIN
            EXEC sp_OAMethod @sbName, 'GetAsString', @sTmp0 OUT

            EXEC sp_OAMethod @rest, 'ResponseHdrValue', @sTmp1 OUT, @i
            PRINT @sTmp0 + ': ' + @sTmp1
          END
        SELECT @i = @i + 1
      END

    -- The output:

    -- 	x-amz-meta-species: big-belly seahorse
    -- 	x-amz-meta-genus: Hippocampus
    -- 	x-amz-meta-habitat: shallow tropical and temperate waters

    EXEC @hr = sp_OADestroy @rest
    EXEC @hr = sp_OADestroy @authAws
    EXEC @hr = sp_OADestroy @sbName


END
GO