Question

I currently use the following code to retrieve and decompress string data from Amazon C#:

GetObjectRequest getObjectRequest = new GetObjectRequest().WithBucketName(bucketName).WithKey(key);

using (S3Response getObjectResponse = client.GetObject(getObjectRequest))
{    
    using (Stream s = getObjectResponse.ResponseStream)
    {
        using (GZipStream gzipStream = new GZipStream(s, CompressionMode.Decompress))
        {
            StreamReader Reader = new StreamReader(gzipStream, Encoding.Default);    
            string Html = Reader.ReadToEnd();
            parseFile(Html);
        }    
    }
}

I want to reverse this code so that I can compress and upload string data to S3 without being written to disk. I tried the following, but I am getting an Exception:

using (AmazonS3 client = Amazon.AWSClientFactory.CreateAmazonS3Client(AWSAccessKeyID, AWSSecretAccessKeyID))
{
    string awsPath = AWSS3PrefixPath + "/" + keyName+ ".htm.gz";

    byte[] buffer = Encoding.UTF8.GetBytes(content);
    using (MemoryStream ms = new MemoryStream())
    {
        using (GZipStream zip = new GZipStream(ms, CompressionMode.Compress))
        {
            zip.Write(buffer, 0, buffer.Length);

            PutObjectRequest request = new PutObjectRequest();
            request.InputStream = ms;
            request.Key = awsPath;
            request.BucketName = AWSS3BuckenName;

            using (S3Response putResponse = client.PutObject(request))
            {
                //process response
            }
        }
    }
}

The exception I am getting is:

Cannot access a closed Stream.

What am I doing wrong?

EDIT:

The exception is occuring on the closing bracket of using (GZipStream zip

Stack trace:

at
System.IO.MemoryStream.Write(Byte[]
buffer, Int32 offset, Int32 count)
at
System.IO.Compression.DeflateStream.Dispose(Boolean
disposing) at
System.IO.Stream.Close() at
System.IO.Compression.GZipStream.Dispose(Boolean
disposing) at
System.IO.Stream.Close()

Answer 1

You need to flush and close the GZipStream and reset the Position of the MemoryStream to 0 before using it as input to the request:

MemoryStream ms = new MemoryStream();

using (GZipStream zip = new GZipStream(ms, CompressionMode.Compress, true))
{
    byte[] buffer = Encoding.UTF8.GetBytes(content);
    zip.Write(buffer, 0, buffer.Length);
    zip.Flush();
}

ms.Position = 0;

PutObjectRequest request = new PutObjectRequest();
request.InputStream = ms;
request.Key = AWSS3PrefixPath + "/" + keyName+ ".htm.gz";
request.BucketName = AWSS3BuckenName;

using (AmazonS3 client = Amazon.AWSClientFactory.CreateAmazonS3Client(
                             AWSAccessKeyID, AWSSecretAccessKeyID))
using (S3Response putResponse = client.PutObject(request))
{
    //process response
}

It might also be possible to use the GZipStream as input if you first fill the MemoryStream with the data, but I’ve never tried this yet.