CODEWITHSUNDEEP
c#asp.net-coreazure-blob-storage
oli
oli

Reputation: 136

How to efficiently send files from Azure Blob Storage to client?

I'm storing large media files in Azure Blob Storage (audio, images, videos) that need to be previewed on my web client application.

Currently the client requests a media file and my server downloads the entire blob to memory, then returns the file to the client.

Controller Action

[HttpGet("[action]/{blobName}")]
public async Task<IActionResult> Audio(string blobName)
{
    byte[] byteArray = await _blobService.GetAudioAsync(blobName);
    return File(byteArray, AVHelper.GetContentType(blobName));
}

Download Service Method

private async Task<byte[]> GetAudioAsync(CloudBlobContainer container, string blobName)
{
    using (MemoryStream stream = new MemoryStream())
    {
        CloudBlockBlob blob = container.GetBlockBlobReference(blobName);
        await blob.DownloadToStreamAsync(stream);
        return stream.ToArray();
    }
}

I'm concerned that this is not good design as the file is being downloaded twice in serial which would cause slower downloads and heightened server memory usage. File sizes can be several hundred MB.

Is there some recommended method for doing this? Maybe something where the server is downloading from blob storage and streaming the file to the client pseudo simultaneously? So the client doesn't have to wait for the server to completely download the file to start its download, and the server can remove already transmitted file contents from memory.

Upvotes: 3

Views: 1391

Answers (1)

Tom Luo
Tom Luo

Reputation: 612

To make the answer visible to others, I'm summarizing the answer shared in comment:

The suggestion is to redirect to the Blob Url directly so that the file download can start to client machine directly and the web application don't need to download it to stream or file on the server. Steps:

1.When client clicks on Download, an AJAX request comes to the server.

2.the server code performs necessary verification and returns the file URL of Azure Storage.

3.The AJAX code get the URL returned from the server and opens up a new browser window and redirects it to the URL.

Upvotes: 2

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